Front Cover
 Title Page
 Table of Contents
 Part 1 : Program Rationale
 Part 1 : Program History
 Part 3 : Program Accomplishmen...
 Part 4 : Groundwork for the...

Group Title: Looking to the earth : a foundation for global development : TropSoils, 1981-1993
Title: Looking to the earth
Full Citation
Permanent Link: http://ufdc.ufl.edu/UF00072496/00001
 Material Information
Title: Looking to the earth a foundation for global development : TropSoils, 1981-1993
Alternate Title: Foundation for global development
TropSoils, 1981-1993
Physical Description: 46 p. : ill. (some col.), maps (some col.) ; 28 cm.
Language: English
Creator: Soil Management Collaborative Research Support Program
Publisher: Soil Management CRSP
Place of Publication: Raleigh NC
Publication Date: 1994
Subject: Soil management -- Tropics   ( lcsh )
Genre: government publication (state, provincial, terriorial, dependent)   ( marcgt )
non-fiction   ( marcgt )
Statement of Responsibility: prepared by the Management Entity Office, Soil Management CRSP, North Carolina State University.
General Note: "April 1994."
 Record Information
Bibliographic ID: UF00072496
Volume ID: VID00001
Source Institution: University of Florida
Rights Management: All rights reserved by the source institution and holding location.
Resource Identifier: oclc - 32529412

Table of Contents
    Front Cover
        Front Cover
    Title Page
        Page 1
        Page 2
    Table of Contents
        Page 3
    Part 1 : Program Rationale
        Page 4
        Page 5
        Page 6
    Part 1 : Program History
        Page 7
        Page 7
        Page 8
        Page 9
        Page 10
    Part 3 : Program Accomplishments
        Page 11
        Page 11
        Page 12
        Page 13
        Page 14
        Page 15
        Page 16
        Page 17
        Page 18
        Page 19
        Page 20
        Page 21
        Page 22
        Page 23
        Page 24
        Page 25
        Page 26
        Page 27
        Page 28
        Page 29
        Page 30
        Page 31
        Page 32
        Page 33
        Page 34
        Page 35
        Page 36
        Page 37
        Page 38
        Page 39
        Page 40
        Page 41
        Page 42
        Page 43
        Page 44
    Part 4 : Groundwork for the Future
        Page 45
        Page 45
        Page 46
Full Text

oil Management CRSP
ollaborative Research Support Program

TropSoils, 1981-1993

A Foundation for
Global Development

fSoil Management CRSP
SCollaborative Research Support Program

Prepared by
The Management Entity Office
Roger G. Hanson, Director
The Soil Management CRSP
North Carolina State University
Raleigh, NC 27695-7113

Charles B. McCants, Technical Consultant
Timothy P. McBride, Writer
Karl E. Larson, Graphic Designer

April 1994

The Soil Management Collaborative
Research Support Program (TropSoils)
is funded in part by the U.S. Agency for
International Development.

A Foundation for

Global Development

TropSoils, 1981-1993


Soil Management CRSP
R Collaborative Research Support Program


Founded in 1981 under Title XII of the
United States Foreign Assistance Act,
the Soil Management CRSP (referred
to as TropSoils), was a collaborative
endeavor among four land-grant
universities, developing countries in
the tropics, and USAID. The U.S.
institutions were Cornell University,
the University of Hawaii, North
Carolina State University, and Texas
A&M University. The primary host-
country participants represented three
major agroecological zones: the humid
tropics (Peru and Indonesia), the
semiarid tropics (Niger and Mali), and
the acid savannas (Brazil).
During the 12 years covered
in this report, TropSoils has expanded
the soils knowledge base and reshaped
our understanding of basic soil-
management principles. We have
helped collaborators improve their soil
inventories and their overall under-
standing of the land resource base. We
have learned to manage soil nutrients
so that continuous cropping can
replace slash-and-burn systems, thus
reducing the need to clear more land.
We have demonstrated that degraded
lands can be restored to economic and
environmental productivity. We have
shown that biological nitrogen inputs
can increase food production and
reduce the need for expensive nitro-
gen fertilizers. We have developed
technologies to improve the efficiency
of water use in both arid and humid
Our most important technical
accomplishment, however, has been

recognizing that the fundamental
principles governing soil systems do
not change with geographic bound-
aries. This means that what we learn in
any one region is applicable around the
world. Rather than managing tropical
soils, we can now work to manage soils
in the tropics. That small shift in syntax
has profound implications for develop-
ing countries, for it indicates that a
vast knowledge base can be employed
to serve their needs.
Human resource development
complements TropSoils' technical
achievements. More than I 15 persons,
most from developing countries, have
earned advanced degrees while
studying at one of our four universi-
ties. Most of these graduates have now
assumed leadership positions that will
enable them to shape farm practices
and agricultural policies for years to
Our understanding of soil and
water systems has improved dramati-
cally over the last 12 years. The
principal challenge has now become
applying what we know to location-
specific problems. TropSoils' technical
and human-resource accomplishments
provide the foundation for a science-
based program to develop and pro-
mote tools capable of responding to
this challenge. How effectively we
translate what we know into what we do
will go a long way toward shaping the
outcome of the world's most pressing
environmental, economic, and agricul-
tural problems.

p r o j e c t

a Soil Management CRSP
o Collaborative Research Support Program

c o n t e n t s

PART I. FO REG RO UN D ................................................. .......................................... 5

PART 2. PRO G RAM HISTO RY ........................................................................................ 7

PART 3. PROGRAM ACCOMPLISHMENTS............................. ....................... .... I

Increasing Agricultural Production ................................................... I

M managing the Environm ent ........................................ ............. .............................. 2 1

Using What We Know: Decision Support Systems .............................................. 3

Building Hum an Resources .............................................. ........................................ 37

PART 4. GROUNDWORK FOR THE FUTURE ............................................... ............. .. 45

d e d i c a t i o n

Dr. John L. Malcolm served as USAID's Project Manager for
TropSoils from the program's conception through the end of 1992.
He has been a consistent and enthusiastic supporter, a bulwark
against bureaucratic impediments, and a balm for bruised academic
egos. His unflinching confidence in the program and its personnel
has been a source of strength and motivation. His contributions to
TropSoils' successes are gratefully acknowledged.



tal-the very stuff of life. A source of
food, fuel, and fiber, it was also
described-from Africa to Asia to the
Americas-as the raw material from
which mankind was created. In the
Mideast, this bond was embedded in
the language: adam (both "Adam" and
"humanity") derives from adama
("cultivated earth").
A profound insight unites these
details. At its core is an enduring truth,
a recognition that transcends dogma.
We are linked to the soil, our ances-
tors perceived. We depend on it for
survival. We cannot degrade it without
in some sense degrading ourselves.
History suggests that civilizations
disregard this insight at their peril. It
demonstrates that soils are, quite
literally, fundamental: they are the
fundament, the essence, the crux.
Indeed, whether the topic is crops or
livestock, family nutrition or economic
vigor, genetic diversity or global
warming, the underlying issue is the
same: how are we using the land?
TropSoils begins here. We know
that sustained agricultural productivity,
rural economic development, and long-
term environmental security depend
on the responsible use of our finite soil
resources. We know, too, that when
nations degrade those resources,
catastrophe results-crops fail, econ-
omies founder, malnutrition increases,
and the quality of life declines.

For more than 12 years, TropSoils
has worked with developing countries
and U.S. government agencies to avoid
these kinds of problems. At research
sites representative of broad
agroecological zones, we have shown
that tropical soils respond to directed
management, and we have helped to
clarify the specific practices best suited
to particular sites. Equally important,
we have learned that many farm
principles applicable to temperate soils
also apply in the tropics. Thus, a
wealth of new information is available
to increase food production and
improve tropical resource manage-

Experience has con-
firmed the vision of

those who established

the program: To
address problems of

hunger, poverty, and

the environment, we

must start at the

foundation. We must

look to the earth.

Although local conditions in places like the Philip-
pines (above) or the Sahel (right) may present special
challenges, the fundamentals of soil science apply
wherever one goes.

This report summarizes our
contributions to that effort. After
outlining the program's history, we will
describe selected research and devel-
opment projects, giving particular
emphasis to the impact of scientific
findings on real-world problems. We
will also cast an eye to the future, for
as this document nears completion, a
newly expanded and refocussed
TropSoils is preparing to build on the
accomplishments of the first 12 years.

Much has changed since we began.
Much remains to be done. Population
increases and dwindling reserves of
arable land have sharpened the
challenge that lies ahead. But experi-
ence has confirmed the vision of those
who established the program: to
address problems of hunger, poverty,
and the environment, we must start at
the foundation. We must look to the

6 LOOKING TO THE EARTH: A Foundation for Global Development

44 ;rM


The Formative Period

four decades ago. Shortly after World
War II, philanthropic organizations and
many national governments sought to
help developing countries increase
food production. Aware that large-
scale food shortages were not merely
a Malthusian potential but an impend-
ing reality, planners focused particular
attention on those nations with rapidly
increasing populations and weak to
nonexistent agricultural research and
education programs.
Having proven themselves at home,
U.S. land-grant universities were asked
to play a key role in this effort. Among
those called upon were the four
schools who would eventually become
TropSoils: Cornell University, the
University of Hawaii, North Carolina
State University (NCSU), and Texas
A&M University. Each had broad
expertise in agronomy and soil sci-
ence-both at the basic and applied
levels. In addition, all four had on-site
experience in developing countries and
an institutional commitment to
promote their advancement.
At first, each university formed its
own partnerships with the host
country and the funding agency--
primarily international offices within
the U.S. government. But experience
soon revealed that complex produc-
tion problems called for a more
integrated approach, one that drew on

the respective specialties of each
The relationship between Cornell
and NCSU in the Brazilian Cerrado
typifies this kind of integration.
Although each school had a separate
contract with the predecessor to the
U.S. Agency for International Develop-
ment, details of the overall research
program were jointly developed under
a single administrative arrangement.
Backed by the combined expertise of
the two schools, scientists at Brazil's
national research center were able to
develop a more comprehensive soil-
management program than had
previously been possible.
As the potential contributions of
land-grant universities became appar-
ent, men and women of vision within
the funding agencies recognized that
U.S. researchers needed to enhance
their field-level expertise and to

The seeds of the CRSPs
were sown when U.S.
land-grant universities
began to help develop-
ing countries increase
food production.

strengthen their collaborative linkages.
Section 211 d of the Foreign Assistance
Act provided grants to achieve these
ends. Among the projects it funded
was the Consortium on Tropical Soils,
made up of Cornell University, the
University of Hawaii, North Carolina
State University, the University of
Puerto Rico, and Prairie View Univer-

sity. The schools worked under a five-
year grant that provided significant
funds and-equally important-
afforded considerable flexibility in the
use of those funds.
The Consortium set three priori-
ties: scientists would travel to develop-
ing countries, establish research
contacts, and conduct on-site experi-
ments designed to clarify the basic
properties of tropical soils. That plan
soon proved effective. As the knowl-
edge base expanded, university faculty

developed new courses, and students
from around the world began to
confront the challenges of tropical soil
management. The achievements that
followed led many to recognize that
land-grant universities could play an
even greater role in international

The Emergence
of TropSoils

Until the mid-1970s, land-grant
universities participated in interna-
tional development primarily through
contracts with USAID (or its prede-
cessors). Under this arrangement, the
Agency was responsible for most of
the planning: they identified problems,
established priorities, developed
general approaches, and invited
performance bids.
As universities gained experience,
however, they pressed for a greater
role in the planning process. After all,
researchers argued, who was in a
better position to understand the
technical obstacles to agricultural
development? Congress was convinced
that this expertise should be more
fully engaged, and in 1975, it passed
Title XII to the Foreign Assistance
Act-an amendment which increased
the land-grant universities' involve-
ment in planning and implementing
development programs. The change
was now official: universities were no
longer simply contractors; they were
now partners with USAID in a pro-
gram of mutual interest.
Title Xll's broad objective is "to
prevent famine and establish freedom
from hunger." It created the Board for

8 LOOKING TO THE EARTH: A Foundation for Global Development


"Th Cngrssdecars hat i orerto reen

famin and stabish feedomfromhunge, th

United States should strengthen the capacitiesrll

International Food and Agricultural
Development (BIFAD), which, in turn,
created the Collaborative Research
Support Programs as a means of
fulfilling its legislative mandate.
The CRSPs were to operate as
follows: Universities would plan
programs responsive to USAID's goals
and host-countries' needs. Costs were
to be shared by the three partners-
USAID providing up-front funds, the
universities and host countries provid-
ing in-kind support. Management
would be the responsibility of an entity
separate from the ones involved in
BIFAD took the lead in establishing
the topical subjects for the CRSPs. Soil
management was the fourth subject
selected, following small ruminants
(1978), sorghum/millet (1979), and
bean/cowpea (1980). Preparations
began in 1979, with the selection of
North Carolina State University as the
Planning Entity.
Led by a panel of international
experts, the Planning Entity reviewed
the current state of soils information
and systematically detailed deficiencies
in the knowledge base. They also
developed a program goal: TropSoils
would foster the development and
adoption of soil-management tech-
nologies that were agronomically,
economically, and environmentally
Because these objectives could not
be achieved simultaneously in every
tropical nation, the planners recom-
mended that research projects be
developed so that results would be
applicable over broad areas with

similar soils and environments. These
areas-or agroecological zones-
became the focal points for the
program's research efforts.
Consortium members NCSU,
Cornell, and the University of Hawaii
were joined by Texas A&M University
to form the core organization. When
TropSoils' initial proposal was ap-
proved in September of 1981, each
university assumed a lead role in one
of the agroecological zones.
Based on its accomplishments in
Brazil's Cerrado, Cornell University
took charge on the acid savannas,
establishing a research site near
Brasilia. The wealth of dryland experi-
ence at Texas A&M University made it
the logical choice to lead the semi-arid
research, at sites in Niger and Mali. In
the humid tropics, both NCSU and the
University of Hawaii took lead roles.
Building on two decades of experience
in South America, NCSU established
research sites at Yurimaguas, Peru, and
Manaus, Brazil. Hawaii, because of its
long experience in Asia, assumed the
lead in a new program based in the
transmigration settlements of West
Sumatra, Indonesia.


So that research results
would be applicable over
broad areas with similar
soils and environments,
TropSoils organized its
projects according to
agroecological zones.

Sem-Aid roic


As researchers moved on-site, they
began the slow process of building and
equipping teams, bridging cultures,
breaking new ground. Though they
confronted the inevitable start-up
problems that plague any new venture,
particularly those in remote regions,
basic information about soil types,
fertilizer responses, and water require-
ments soon began to accumulate.
Before long, farmers and scientists in
each agroecological zone were using
this information to improve soil
fertility and boost production levels.
This kind of rapid response would
not have been possible but for the
support of USAID field missions. Their
long-term on-site presence helped
researchers identify local needs and
establish collaborative links with a
variety of regional and national organi-
zations. In addition, the missions
provided valuable grassroots informa-
tion about local traditions, values, and
Host-country administrators and
scientists also enhanced TropSoils'
responsiveness. Their guidance and
cooperation, their willingness to work

The Work Begins

10 LOOKING TO THE EARTH: A Foundation for Global Development

as partners, helped establish a dynamic
program that could be modified in the
face of new contingencies. Equally
important was the role played by
foreign and domestic graduate stu-
dents, who conducted on-site research
in the face of difficulties seldom
described in a textbook.
In the U.S., university administra-
tors provided valuable support, both
by their enthusiastic endorsement of
the CRSP concept and by encouraging
and supporting faculty participation in
the program. Administrators were also
crucial in helping influential support
groups perceive the relationship
between the goals of the CRSP and the
goals of the universities.
This alliance of talent and support
has served TropSoils for the past 12
years. It has been the foundation for
the broad range of program accom-
plishments to which we will now turn
our attention.

"The objective of this

CRSP is to develop and

adapt improved soil-

management technolo-

gies which are agro-

nomically, ecologically,

and economically sound

for developing coun-

tries of the tropics."

Planning Entity

PA T 3 P O R M


Over the past 20 years, world population has
increased from 3.8 to 5.4 billion. By the year
2000, that figure is expected to reach 6.25 billion.
Most of this growth will occur in developing coun-
tries. Indeed, over the next 20 years, only 50 of
every 10,000 births will occur in nations currently
classified as developed.
More people. Fixed land supplies. The problem
is starkly framed: at current production levels, .5
hectares of land is required to meet the basic
human needs of each person on the planet; even
if we exploit the small remaining reserves of arable land, only 15 hectares per
person is expected to be available by the year 2050.
Simple arithmetic makes clear that unless we increase productivity, the con-
sequences will be catastrophic. Developing countries are particularly at risk.
Although they currently account for 77% of the world's population, they earn only
15% of the total global income. And the bulk of this income is derived from land
that exhibits one or more severe constraints to sustainability.
TropSoils has responded to this challenge by designing technologies that improve
land-use efficiency. From innovative pasture systems, to slash-and-burn alternatives,
to improved nutrient- and water-management technologies, our goal has been to
increase the production of food, fuel, fiber, and shelter materials without degrading
the resource base upon which future development will depend.

I. Slash-and-Burn
Gives Ground to Fixed

Given abundant land and limited
populations, slash-and-burn agriculture
is marginally sustainable: farmers grow
crops in the forest ash until nutrients
become limiting, weeds uncontrollable,

To meet the needs of
growing populations, we
must generate sustained
increases in the produc-
tivity of our soil and
water resources.

and diseases unmanageable; the land is
then returned to fallow, a new site is
cleared, and the cycle begins again.
Once population grows abundant
and land becomes limited, however,
the system collapses. Across much of
the tropics, clear fault lines foretell just
this kind of collapse: fallow periods

have shortened, productive lands have
been degraded, and farmers have been
forced to cultivate fragile, less produc-
tive soils. Unless we find ways to alter
this progression, the human and
environmental consequences will
prove severe.
Researchers have long recognized
the solution: slash-and-burn agriculture
must give ground to permanent
systems. By increasing production and
reducing the need to abandon the best
lands, such systems would reduce the
strain on marginal, easily degraded
soils. The question, of course, has
been this: "Are permanent systems
possible on inherently infertile tropical
Long-term research suggests the
answer is an emphatic "Yes." Studies
on representative low-fertility soils
show that, with appropriate inputs, 37
consecutive crops (to date) can be
grown without yield reductions.
Spanning more than 17 years, these
experiments show that tropical
farmers-and the environment which
supports them-need not permanently
suffer the pernicious consequences of
slash-and-burn production.

Researchers found that although
soil acidity and nutrient deficiencies
often constrain yields, both problems
can be managed through well-estab-
lished liming and fertilizer practices.
The same holds true for controlling
weeds and diseases. Moreover, the
fear that continuous cropping would
harden the soil or otherwise impair its
physical structure has proven un-
founded: after 17 years, overall
physical properties remain stable, and
subsoil properties have improved.
Both scientific evidence and field
experience demonstrate that continu-
ous cropping can replace slash-and-
burn practices and eliminate the need
to abandon cleared land, thereby
reducing deforestation. Economic
policies that enable more farmers to
adopt such technologies would thus
yield important human and environ-
mental benefits.

2. Out of the Loop:A Role
for Low-input Farming

Slash-and-burn farmers draw on two
resources: their own labor and the
rain forest. Neither is being used to

12 LOOKING TO THE EARTH: A Foundation for Global Development

3 ~ hin ii

S- I,:PBs~ls

Are permanent
systems possible on
infertile tropical soils?
Grain yields for 37
consecutive crops on
soils with appropriate
inputs indicate that
they are. Results were
obtained over a 17-
year period at
Yurimaguas, Peru.

advantage. Year after year, new-cut
jungle yields one or two crops; then
weeds proliferate, fertility drops, and
the pattern starts anew.
In such a system, human effort
generates few long-term rewards. The
ladder of progressive accomplishment
familiar to the stationary farmer is
replaced by a loop of perpetual
poverty. As overcrowding shortens
fallows and reduces soil fertility, the
loop begins a downward spiral.
How do we break this pattern?
How can shifting cultivators move
toward permanent systems when
policy and penury often conspire
against such a change?
TropSoils' research suggests that
low-input technologies may provide an
answer. Without requiring the capital
or infrastructure necessary for con-
tinuous fertilizer-based systems, low-
input agriculture produces ample food,
reduces the need to clear new land,
and forms the foundation upon which
permanent systems can be built.
A low-input system developed in
Yurimaguas, Peru, demonstrates how
this transition can work. After slashing
and burning the forest fallow, farmers
replace their traditional crop varieties
with a rotation of acid-tolerant rice
and cowpea cultivars. To maximize
nutrient recycling, only the grain is
removed at harvest. More than 50% of
the nitrogen and magnesium, about
90% of the potassium and calcium, and
about 37% of the phosphorous
biomass are returned to the soil in this
These changes enable farmers to
grow seven stable crops where
previously they could grow only one

TropSoils' technologies provide alternatives to slash-and-

burn systems. Studies at Yurimaguas, Peru, show that

each hectare under continuous-cropping, low-input

agriculture, or legume-based pastures saves, respectively,

8.8, 4.6, and 10.5 hectares per year from deforestation.

or two. And the improvement occurs
without fertilizers, lime, off-farm
organic inputs, or other amendments,
except locally available herbicides and
insecticides-which account for only
8% of total production costs. More-
over, the improved system is highly
productive: over a three-year period,
seven continuous crops (five rice and
two cowpea) produced 13.8 tons of
grain per hectare; under traditional
methods, the system produced only
one rice crop of 1.7 tons per hectare,
after which the land was planted to
cassava and plantains and then aban-
doned for secondary forest regrowth.
As practical as it is, however, low-
input agriculture is not a sustainable
system: after the third year, weed
pressure destabilizes yields, and
farmers must modify their practices or
plant a legume fallow. Nonetheless,
low-input's economic and environmen-
tal benefits make it a useful bridge to


permanent agriculture. Not only does
it slow the rate of deforestation, but it
also helps to break the loop of poverty
that ensnares the shifting cultivator.
Instead of having to clear three plots in
three years, farmers can turn their
energies to increasing production on
fixed sites and to exploring permanent
agroforesty, pasture, and continuous-
cropping alternatives.

an te umd roic o Idoesa ho ta

3. Soil Management
Reduces Water Stress

Water stress frequently limits plant
growth. Such stress may be caused by
low water content in the soil, ineffi-
cient absorption by the plant, or
chemical constraints in the root zone.
Although generally recognized as a
problem in arid and semi-arid regions,
water stress also occurs in both humid
and sub-humid regions, often during
critical stages of plant growth. Con-

ventional wisdom typically recom-
mends supplemental irrigation-on the
assumption that available water is
limiting yield.
TropSoils' research has shown that
this assumption is often inaccurate. In
many cases, soil-management practices
such as fertilization, acidity correction,
and tillage can increase yields even
though available water remains
constant. This finding is particularly
important in areas where irrigation is
unavailable, impractical, or environ-
mentally destructive.
Efficient resource management for
Sahelian Africa has been the focus of
an ongoing collaboration between
TropSoils and Mali's Institute of Rural
Economy. Recognizing that appropriate
tillage practices and nutrient inputs are
crucial to the productive use of the
Sahel's limited water resources,
researchers compared seedbed
preparation techniques-with and
without fertilization-for their impact
on the growth, yield, and water-use
efficiency of grain sorghum and
The results are encouraging:
fertilization combined with various
ridged-tillage practices increased
sorghum and cowpea grain yields by
157% and 123%, respectively; cowpea
hay yield increased by 87%. Sorghum
stover yield increased by 13 1%, an
important gain given stover's dual use
as an animal feed and a ground cover.
Results also suggest that fertiliza-
tion and improved tillage practices
increase water- and nutrient-use
efficiency. Such efficiency is crucial if
production is to be sustained on the
17-million hectares of clay-loam soil

14 LOOKING TO THE EARTH: A Foundation for Global Development

Africans use to grow sorghum. Increas-
ing yields on those soils best suited to
the continuous cropping of sorghum
and cowpeas can reduce the need for
such cropping on the less productive
and easily degraded soils that dominate
the region.
Unlike semi-arid Mali, large parts of
humid Indonesia receive high rainfall
levels. Rain readily infiltrates the
region's sandy-textured soils, resulting
in substantial amounts of stored water.
Nevertheless, water stress occurs
during critical stages of maize growth.
The problem is caused by an acid
subsoil, which is common throughout
the humid tropics. Toxicity confines
roots to the surface soil and thus
prevents the absorption of water
stored at lower depths. Consequently,
these crops experience water stress
after as little as three rainless days.
Deep placement of lime often
solves this problem. By neutralizing
acidity, it improves root growth, thus
allowing plants to extract water from
greater depths and increasing yields by
as much as 357%.

4. Improved Pastures Boost
Profits, Conserve Land

Abandoned pastures cover 10 million
hectares of what was Amazonian rain
forest. The pattern of degradation has
become all too familiar: ill-adapted
grasses thrive briefly on acid and easily
degraded soils; then animal productiv-
ity declines, and producers must lower
their stocking rates or cut more
forest. Scarred by overgrazing, large
tracts of land soon support neither
crops nor livestock.

Deep placement of lime is the key to
optimizing benefits on acid soils.
Results above are averages over a
three-harvest period in Indonesia.

Through long-term adaptive
research, TropSoils has found ways to
improve soil fertility, reclaim degraded
pastures, and treble or quadruple beef
and milk production. The significance
of this work is readily apparent:
improved systems can help sustain
meat and milk production across the
large areas of the humid tropics
unsuitable for food crops.
Grass and legume forage varieties
developed by the International Center
for Tropical Agriculture (CIAT)
provide the raw material for these
systems. In the Amazon, for example, a
carefully selected mixture of acid-
tolerant grasses and legumes remains
stable and productive after 13 years of
grazing-with little added fertilizer.
More than 80% of the applied P, K, and
Ca is recycled to the soil, and the
legumes provide the grasses with the
equivalent of 150 kg/ha of urea nitro-
gen. With appropriate stocking rates
and rotational grazing practices, soil
physical properties remain good, and


TropSoils has

shown that nutrient

deficiencies and soil

acidity can reduce

water use efficiency.

Correcting these

problems signifi-

cantly improves

plant growth.


Native pasture estimate

0 100 200 300 400

500 600 700

kg/ha/yr (mean of eight years)



pastures protect

the soil, require

few cash inputs,

make productive

use of land unsuit-

able for food crops,

and produce meat

and milk from

animals that re-

cycle most of the

nutrients they


soil chemical properties have im-
In addition to designing sustainable
systems for newly cleared land,
TropSoils is also working to rejuvenate
abandoned pastures. Vulnerable
steepland systems, for example, have
been reclaimed using minimum tillage
and phosphate rock to establish
palatable grass and legume species.
Proper combinations of tillage and
herbicide have also been developed so
that improved species can replace
undesirable ones. Not only do these
practices stabilize sloping lands, but
they also enrich the grazing animals'
Such enrichment pays big dividends
in animal productivity: grazing trials on
pastures receiving low levels of ferti-
lizer have produced live weight gains
six to eight times higher than those on
native pastures. And even under heavy
grazing pressure, complete soil cover
eliminates the risk of erosion.
Too many hectares, too few
animals. For years that complaint has
summed up much that was wrong with
pasture systems in the humid tropics.
Although many questions remain, what
we now know suggests that the

B. decumbens D. ovalifoium

16 LOOK I N G TO THE EART H: A Foundation for Global Development

Improved pastures can produce
dramatic live weight gains for cattle.

economic and environmental liabilities
of the traditional system can be
overcome. With improved technolo-
gies and low-cost inputs, managed
pastures can be both profitable and
environmentally sound.

5. Agroforestry: Modern
Science, Ancient Art

Growing trees is, in one researcher's
words, "the natural occupation of the
land." So it's not surprising that
generations of farmers have integrated
plants and woody perennials as a
means of increasing and diversifying
production. Indeed, farmers have long
recognized that what we call
agroforestry is a key to efficient land
Modern science builds on this
ancient art. Evaluating a wide range of
genetic materials and cropping strate-
gies, researchers design management
systems compatible with local econo-
mies and environments. TropSoils'
agroforestry work has focused
primarily on the humid tropics, where
the need for productive and ecologi-
cally stable alternatives to slash-and-
burn agriculture has become an issue
of world-wide import.


In the humid tropics, a farmer tradi-
tionally cuts and burns a section of the
jungle, grows a crop or two, and
moves on to clear more land. When

I I r I


population pressure is low, 20 years
may pass before an abandoned field is
cleared again. During that period, the
natural forest fallow restores soil
fertility by mining nutrients deep in the
ground and recycling them to the soil
Enriched fallows improve the
efficiency of this process. The method
is simple and inexpensive: just before
harvest, farmers scatter the seeds of
perennials best equipped to rebuild the
soil. Because favored species get a
head start, the forest grows back in a
configuration designed to increase
subsequent yields. Moreover, by
allowing farmers to return to produc-
tive land in as little as four years, the
system reduces the need to clear
additional forest.
In correlating fallow species with
yield increases, TropSoils discovered
some surprises. Contrary to initial
expectations, for example, researchers
found that the fallow's nitrogen-fixing
ability is less important than its total
biomass in determining crop produc-
tion levels; indeed, results indicate that
crop production is directly propor-
tional to the biomass of the enriched
From a practical standpoint, this
means that a legume like kudzu-
prized by farmers because it is low-
growing, easy to cut, and capable of
fixing a lot of N-is inferior to a
number of nitrogen-fixing trees that
produce more biomass. Among these,
Inga edulis has been particularly
valuable. In Peru a 4.5-year enriched
fallow containing this species produced
crop yields 34% greater than the
natural-fallow treatment.

Alley-cropping systems can help stabilize sloping lands. Here Inga
edulis trees border a recently harvested rice crop.


At any one time, enriched fallows can
convert only 20% of the forest to food
production, a limitation with dire
consequences for growing populations.
Alley cropping has shown potential as
a more productive alternative, allowing
farmers to increase yields while
remaining situated in one place. It can
thus serve either as a permanent
practice or as a transitional technology
between shifting cultivation and high-
input continuous cropping.
The system works like this: farmers
grow crops between rows of woody
perennials, which are cut periodically
to provide mulch. The perennials
recycle nutrients, reduce soil tempera-
ture, retain soil moisture, control
weeds, and contribute organic matter.
In some sense, the alley walls simulate
a fallow, but with an important
distinction: because they don't remove
fields from production, they encourage
intensive management and ultimately
increase per-hectare food production.
Moreover, because new land need not


be cleared each year, labor can be
more evenly and efficiently distributed.
Although alley cropping has proven
successful on fertile soils, it has only
recently been tested on the acid,
infertile soils of the humid tropics.
While initial results have been encour-
aging, researchers are quick to point
out that the system is not a panacea,
explaining that nutrient levels are

sometimes so low as to preclude
significant recycling. To mitigate that
limitation, researchers work to
establish the tree/crop/fertilizer
combinations best suited to particular
environments, thereby maximizing the
efficiency of chemical inputs.
Research in Peru, for example, has
demonstrated that Cassia reticulata

prunings recycle as much P as is
extracted in the grain of harvested
crops. After 40 months of continuous
cropping with low amendment levels,
rice and cowpea yields have remained
stable, available P has increased, and
soil acidity has declined. Similarly,
experiments with Paraserianthes
falcataria hedges in Indonesia have
doubled rice yields and quadrupled
cowpea yields compared to control
plots; when low levels of lime were
applied, increases proved even greater.
And results at a number of sites have
shown that food production is highest
when chemical fertilizers are applied
directly to the crops. Initial speculation
suggested that these inputs should be
applied to the trees.
Researchers have also helped
determine the most productive
planting geometries. They have found,
for example, that yields near the edges
of a five-meter alley decreased over a
seven-crop cycle, while yields near the
center increased. Concluding that
competition between crops and trees
for light and nutrients had caused the
decline, researchers devised a system
with "more center and less edge" (i.e,
eight-meter alleys bordered by two
rows of trees), thus significantly
increasing food production.
Studies on the timing and method
of pruning are also producing useful
results. Prunings from various woody
perennials release N at widely different
rates, variations that seem to be
controlled by the polyphenolic concen-
trations in the mulch. This information
will be crucial to synchronizing nutri-
ent supply and crop demand. Crops
with high initial N demands, for

18 LOOKING TO THE EARTH: A Foundation for Global Development

develop economically viable alternative crops. Suc

alternativs are essntial if armers ar to compl

wit Boivi's ocaandCotroledSubtanes aw

whchsekstophseou oc podctonby198

example, will require mulches that
release nutrients rapidly, while many
fruit and commercial crops will benefit
from delayed N release. In either case,
producers must be careful to prune
the trees at various heights and cut
points, a minor adjustment with major
consequences: many perennials die for
lack of such variation.


Tree crops provide another transition
to continuous cultivation. Farmers
have expressed particular interest in
tree fruits and live fences, essential
components of permanent orchard and
pasture systems.
Peach-palm research has been most
encouraging. Grown on a small scale,
the trees provide a fruit high in
protein, vitamins, and oils. By planting
forages around the trees, producers
can readily establish permanent silvo-
pastural systems. And when canning
facilities are available, large scale
producers can grow heart-of-palm, a
valuable cash crop.
In addition to evaluating peach-
palm varieties and establishing fertilizer
requirements, researchers have also
identified tree species suitable for
living fences. Unlike cut posts, these
fences don't rot, and thus they provide
durable structures that are "horse
high, bull strong, and pig tight."
Large differences in growth rates
and productivity among various species
emphasize the importance of exploring
a wide range of genetic stock, espe-
cially when exotic or nonadapted
species are being tested. Recent
experiments with Gliricidia sepium, for

example, have identified a regional
variety that significantly outperforms
other varieties. These findings promise
to have a broad impact, since this
variety tolerates acid, infertile soils,
and the species is widely used for fuel
wood, fodder, live fences, and green

6. Challenges in Soil

Soil physical, chemical, and biological
properties often vary significantly-
even across areas as small as a few
meters. Such variation causes uneven
plant growth and compounds the
problem of selecting appropriate
management practices. By masking the
effect of fertilizers and other treat-
ments, variability can also confound
research trials, particularly on small
plots. Unless soil scientists develop
ways to overcome this problem,
developing-country farmers will
continue to forfeit a large percentage
of their cultivated land.
Until recently, researchers and
policy-makers were unable to specify
the loci and extent of the variability
problem. Color infrared videography
has reduced that difficulty. In western


Note the large
barren patches in
this uniformly
treated field. By
quantifying the
physical and
chemical makeup
of nonproductive
areas, researchers
can now identify
components of
the problem.

Niger, for example, we now know that
14% of the millet fields produced no
grain during a recent growing season-
even though rainfall levels were
Ground verification of video images
further allows researchers to quantify
the physical and chemical makeup of

the nonproductive areas. Thus, in
Niger, we can now identify manageable
components of the problem: thinner
surface soils, higher acidity levels,
lower relative field positions, and
inadequate levels of calcium, magne-
sium, and phosphorous.
Many of these difficulties can be
partially corrected by established
practices such as intercropping,
residue management, manuring,
fertilizing, and liming. Those practices
which trap nutrient-rich wind-borne
dust can also help rejuvenate degraded
Researchers have also determined
that, in some regions at least, nutrient
deficiencies are not the sole cause of
spatial variability. Biological constraints
also play a role, as do adverse soil
conditions such as crusting and sealing,
which limit infiltration and water
recharge, thereby increasing erosion
and the loss of valuable soil materials.



In the U.S., "coII~l~llecting dust" applies to the useless1

ings are theresult of UAID-supportd collabora

tions among Trop1oilsthe International Crop

ReeachIntiut fr h SmiArd roic,.h

International Fertilizer Development Center, andII~~1IL`II

Niger's Nationa~llllrllll nstitut for Agonomic esearch

Over a five-ear periodcollaboratos found tha

mulched soils showed a I 5-cm increase in surfaceI'r.I1II


Soil and water are the natural-resource founda-
tion, the long-term capital on which nations
build and grow. History reveals that when
societies degrade these resources, they foretell
their own collapse.
Recent assessments of global soil loss
provide alarming evidence that such problems
may be impending. According to the World
Resources Institute, more than one billion
hectares have been degraded over the last 45
years, an area roughly equal to India and China
combined. At present, about 17% of the earth's vegetative surface is so seriously
degraded that restoration has become costly or-in some cases-impossible.
The enormity of this degradation is difficult to comprehend. On a practical level,
it means that many lakes and rivers have been so contaminated from runoff that
they are now biologically dead. It means that untold species have been destroyed.
That the atmosphere is in danger. That future generations may inherit a planet
incapable of meeting their most basic needs.
TropSoils' research is helping to break this pattern. How? By designing strategies
to prevent and reverse land degradation. By identifying potential problems before
they reach a critical stage. By clarifying the way water, nutrients, and pollutants
move through the soil. And by developing systems that stabilize the land as they
provide nutrients to crops. In these and other instances, our energies are directed at
a common goal: the responsible management of our natural resources.

I.What Happens in
a Natural Forest?

This theme emerges again and again:
agricultural development must not
jeopardize the environment. In the
humid tropics, converting forests to

Soil erosion is the most
significant environmen-
tal problem in the
Philippines, where over
half the nation's 30-
million hectares exhibit
slopes of 18% or
greater. Collaborators
from TropSoils and
the International Rice
Research Institute are
designing systems that
reduce hillside erosion
and make upland
agriculture economi-
cally productive and
environmentally sound.

farmland excites special concern,
particularly on steep areas subject to
soil erosion.
Unfortunately, attempts to design
agricultural systems compatible with
these areas have been hampered by a



1988 YurimguasPeru)

*~~ ~ ~ S-

*~~O -f S S-

O d fe c s r

in unitre foes sysem. Alhog soi scietist
h e g l -g t t te p s t

place under these cond s d c e

m y rn f

ites at which OF occurred

large gap in our knowledge: we simply
don't know much about how the
natural systems behave. As a result,
assessments of man-induced modifica-
tions are often based on false assump-
To quantify the impact of various
farm practices, researchers need
benchmark data on hydrologic and
erosion processes in natural systems.
After all, we can't very well determine
how we've changed an environment
unless we know what the environment
was like to begin with.
"Without baseline information,"
says one researcher, "we're a bit like
the rooster who notices that when-
ever he crows the sun comes up.
Unless we have a way of isolating our
influence, we're apt to draw some
misguided conclusions. We need to be
able to distinguish natural effects from
development-generated effects."
One difficulty in filling this gap,
however, is that the constant presence
of researchers tends to change the
natural environment. TropSoils
scientists in Peru took considerable
pains to avoid these kinds of distor-
tions-even setting up an elaborate

H: A Foundation for Global Development

network of elevated walkways to keep
from altering patterns of rainfall and
water movement within a representa-
tive watershed.
The results were worth the effort.
Indeed, they have revised some
commonly held misconceptions about
rainfall intensity, water infiltration, and
surface runoff in undisturbed tropical
forests. Most important, perhaps, they
provide direct evidence to refute the
widely accepted notion that overland
flow has no significant impact in these
systems. TropSoils' findings indicate
that this kind of runoff is extremely
common and that it exerts a significant
influence on sediment and solute
transport-even before man disturbs
the system. Indeed, over a two-year
period, one out of three rainfall events
caused overland runoff at 50% or more
of the experimenters' 72 flow detec-
Besides demonstrating that over-
land flow occurs, researchers have also
clarified the mechanisms by which it
takes place. Particular attention has
been devoted to the impact of various
topographic and pedologic variables on
water movement. Such information
will help researchers base nutrient-
management strategies on a realistic
view of landscape processes and
constraints. It will also prove useful in
transferring findings to other water-

2. Retracing Bypass Flow

When water flows through the soil,
soluble plant nutrients are often
removed from the root zone. Such
movement can reduce plant growth

and increase groundwater pollution.
These problems are particularly acute
when water drains rapidly through
large soil pores. Drainage that avoids
the smaller pores-and hence the bulk
of the soil's reactive surface-is called
bypass flow.
The classical view maintains that
bypass flow does not occur unless all
pores close to the soil surface are
filled (or nearly filled) with water. For
the microaggregated soils common
throughout the tropics, this means
that bypass flow would not begin until
water had filled both the small pores
within the soil aggregates and the larger
pores between the aggregates. Because
this state is almost never achieved on
these soils, researchers have assumed
that bypass flow seldom takes place.
TropSoils' collaborative research
suggests that the classical view under-
estimates the prevalence-and hence
the perniciousness-of bypass flow.
Studies of microaggregated soils show


For researchers to
assess the environ-
mental impact of
technologies like this
hedgerow system,
they need baseline
information on how
the natural system

Schematic representation of pores found in (a) microaggregated
soils and (b) other soils. Although both soil types may contain
micropores and macropores, only microaggregated soils exhibit
large amounts of interpedal porosity. Drainage that avoids the
micropeds and moves rapidly through these interpedal pores is a
form of bypass flow that has been largely ignored.

that bypass flow will occur whenever
water application rates exceed the
infiltration capacity of the small intra-
aggregate pores. Since rainfall rates
typically exceed this capacity, research-
ers conclude that bypass flow may be
the rule rather than the exception on
many well-aggregated soils, particularly
volcanic and forest soils.


0.1 m


3, O.lm

24 LOOKING TO THE EARTH: A Foundation for Global Development

This change in paradigm has
profound implications for farmers,
researchers, and policy-makers. By
altering our view of the way water,
nutrients, and pollutants move though
microaggregated soils, these findings
call for a reevaluation of some basic
environmental and agricultural assump-
tions: At what rate are nutrients
entering and leaving the soil matrix?
How does leaching from the forest
floor affect root uptake? How can
fertilizer strategies be redesigned to
increase incorporation and minimize
leaching to the groundwater? Answer-
ing these questions is crucial to the
responsible management of our natural

3. Red Next to Yellow ...

Outdoorsmen have a rhyme that helps
them identify the markings on a coral
snake: Red next to yellow can kill a fellow.
On the high plateaus of the Brazilian
savannas (the Cerrado), the same
color pattern provides equally useful
information: it helps producers select
and manage agricultural land.
Cerrado plateaus consist primarily
of dark-red Oxisols bordered by red-
yellow Oxisols. In trying to account for
this pattern, researchers found
something unexpected. Although
yellow soils are located only 0 to 2%
downslope from the red soils, their
water tables are comparatively higher
throughout the year. This means that
the yellow soils are more moist-
although they contain none of the tell-
tale grayness usually associated with
poorly drained soils.

The difference in moisture affects
soil mineralogy in a way that runs
counter to farmers' intuitions. Produc-
ers knew, for example, that che color
difference between the two soils was
related to differences in iron mineral-
ogy. And because the yellow mineral,
geothite, fixes more phosphorus than
the red mineral, hematite, producers
tended to avoid the yellow soils in
favor of the red soils.
CRSP research has shown that this
decision was ill-advised. What farmers
didn't realize was that both soils
contain equal amounts of the yellow
mineral, whose presence is simply
disguised in the dark-red soil. Indeed,
yellow soils are what the red soils
become after the hematite is removed
from the upper portion of the profile,
primarily as a result of higher moisture
levels. Because both geothite and
hematite fix phosphorus (P), deficien-
cies will be more severe on dark-red
Researchers have also found that
the higher soil-moisture content of the
yellow soils does not hurt crop
production. On the contrary, the
higher water tables help to reduce the
risk of drought stress. This difference
can be particularly important during
the May to August dry season.
As one researcher points out, soil
color can help Cerrado farmers make
some very practical decisions: "If
people have a choice about what land
to cultivate, they should preferentially
select the yellow soil. And if they
intend to cultivate some of both, soil
color can help guide their water- and
P-management decisions."

4. Land Clearing and Bulldozed land in
Reclamation Indonesia became a
kind of "moonscape"
In the humid tropics, the question isn't where nothing would
"Are we going to clear more land?" grow. Lime andfertl-
Rather, policy-makers and producers lizer treatments have
ask, "How can we clear it in a way that since helped to rebuild
maximizes long-term productivity and the soil and sustain
minimizes environmental damage?" crop production.
The urgency of this request
underlines a significant problem: land-
clearing practices can be destructive-
removing topsoil, compacting subsoil,
and encouraging erosion. Because crop
yields rapidly decline under these
conditions, large tracts of newly
cleared land have had to be aban-
doned. TropSoils is helping to break
this pattern by identifying optimal land-
clearing methods and developing land-
reclamation strategies for those areas
where inappropriate methods have
degraded the soil.
The newly formed TropSoils began
evaluating land-clearing practices at
Yurimaguas, Peru. Over a two-year
period, researchers found that experi-
mental plots cleared with chain saws
and machetes generated yields 22%
higher than plots cleared with a
straight-blade bulldozer. Production on


Soil compaction can form an
impenetrable layer that
prevents roots from extracting
water and nutrients from the
subsoil (a). Breaking up the
compacted layer (b) enables
roots to extend into the
subsoil, thus increasing plant

the bulldozed plots declined steadily,
and they were eventually abandoned.
Six-years later, they were still barren
of secondary forest regrowth.
These plots became the site of
TropSoils' first land-reclamation
experiment. An analysis of soil physical
and chemical properties quickly
revealed the problem: in addition to
removing topsoil and organic matter,
the bulldozer had created a compacted
zone 15 to 45 cm below the surface.
Deep tillage practices such as chisel
plowing and subsoiling relieved the
compaction, thus increasing water
infiltration and root proliferation. As a
result, mean relative grain yields
increased from 57 to 89%, as com-
pared with a slash-and-burn mean of
100%. Thirteen years later, the
reclaimed land is still under continuous
crop production.
The success in reclaiming bulldozed
land led researchers to experiment
with various land-clearing, tillage, and
management combinations. Particularly
noteworthy was the replacement of
the bulldozer's straight blade with a
shear blade-so named because it

shears off vegetation while minimizing
disturbance to the soil. When re-
searchers used this blade in conjunc-
tion with burning and disking, mean
relative grain yields approached those
obtained for manual clearing.
In Indonesia, large-scale bulldozer
clearing produced a different set of
problems. Six years after a govern-
ment-sponsored project had cleared
the land, researchers arrived to find a
"moonscape" almost entirely devoid of
topsoil and vegetation. Despite
farmers' best efforts, almost nothing
would grow in their fields.
A battery of tests revealed that in
this case the culprit was not soil
physical properties, but soil fertility-
specifically, high soil acidity and low
soil P levels. Applying principles
derived in previous projects, research-
ers developed a series of liming and
fertilizing treatments designed to
rebuild the soil and sustain crop
Results clearly indicate that
catastrophic devastation of the sort
produced in Indonesia can be reversed
by the judicious application of chemical

26 LOOKING TO THE EARTH: A Foundation for Global Development

inputs. Indeed, with just modest
additions of lime and fertilizer, rice
grain yields were 15 times greater than
control-plot yields. Based on an
interpretation of critical soil-test levels
and yield responses, researchers can
now make lime and fertilizer recom-
mendations for the region's six main
food crops. Researchers have also
found that organic matter-particu-
larly crop residues and green manures
-can increase yields and decrease
purchased input requirements.

5. Second-Generation
Research: A Key to
Sustainable Savannas

Any list of soil science's greatest
achievements would have to include
this entry: the development of technolo-
gies to turn acid savannas into productive
farmland. Indeed, strategies for over-
coming acidity and phosphorus
problems have opened up an area
many see as comparable to the U.S.
corn belt-only larger.
Such comparisons are not far-
fetched. Huge stretches of South
American and African savannas exhibit
excellent physical conditions and a
topography that lends itself to large-
scale mechanized cultivation. Properly
managed, these regions could dramati-
cally increase world food production.
Consider Brazil: with less than 30% of
the suitable land cleared for agricul-
ture, the savannas already produce
40% of the nation's soybeans, 35% of
its coffee, and 42% of its cattle.
For such progress to be sustained,
the impact of modern farm practices
on long-term soil productivity must be


carefully monitored. Second-genera-
tion research by TropSoils and its
collaborators, for example, has
forewarned producers that continuous
tillage can degrade the physical struc-
ture of savanna soils, particularly those
with high clay contents. Comparisons
of cultivated and uncultivated fields
reveal that current tillage practices
create a compact layer in the subsoil, a
condition which restricts root growth
and thus limits water and nutrient
absorption. By reducing infiltration
rates, hardened subsoil pans also
increase the risk of moisture stress
during dry periods and soil erosion
during the brief but intense rainstorms
common to the area. Over time, such
problems will reduce crop yields.
Shallow rooting of the region's
predominant crop, soybean, has been
clearly linked to degraded soil struc-
ture. Indeed, increased penetration
resistance, reduced macroporosity,
and poor aeration-rather than
aluminum toxicity or low nutrient
status in the subsoil-seem to be the
chief impediments to root growth. A
study of a field cultivated for 17 years
showed that 52% of the soybean roots
were severely deformed by subsoil
pans, and many roots showed signs of



When Brazilian savannas
are cultivated for many
years, penetration
resistance can increase
dramatically unless
appropriate soil-manage-
ment techniques are
applied. Such resistance
severely inhibits root

4000 -------

3500 -

: 3000 Tephrosia candida

S2500 C. brasiliensis

S---- 2 Mucuna aterrinma
(3 1500
Q) r -M. cochichinensis
0 Canavalia ensiformis

0 1
0 50 100 150 200
kg N/ha as Urea

Yield response of maize to fertilizer N and comparative response
to various green-manure legumes (DM refers to dry matter).

strangulation, thinning, and fissuring.
Moreover, when roots are stunted in
this fashion, they typically remain
confined to the surface 10 to 15 cm
of the soil, thus reducing the efficiency
of lime and fertilizer investments.
Compacted layers occur for several
reasons. Normal farm traffic with
heavy tractors and harvesters contrib-
utes to wheel-track packing, while the
traditional practice of tilling with heavy
disk harrows almost certainly aggra-
vates structural problems. And once
compacted, these soils have no natural
correction mechanism since cycles of
shrink and swell or freeze and thaw do
not occur in the tropics.
By carefully monitoring mechanical
impedance, TropSoils has alerted
savanna farmers to a potential con-
straint before it reached a critical stage.
Second-generation research has made
clear that management practices to
avoid soil compaction must be an

integral part of any system for sus-
tained crop production and soil
productivity. Such practices are
currently being evaluated.

6. Selective Management:
Legumes and the Soil

Legume green manures can improve
soil productivity by fixing nitrogen (N),
adding organic matter, controlling
erosion, and suppressing pests. These
potential benefits have often created
the misleading impression that legumes
are an agricultural cure-all. A more
realistic view recognizes the contribu-
tions legumes offer without minimizing
the complications they present.
TropSoils has worked to clarify both
elements so that producers can make
reasoned choices about the when,
where, and how of legume management.


Legumes are most widely known for
supplying N, a particularly important
contribution in developing countries,
where chemical fertilizers are often
unavailable or unaffordable. Legumes
have the ability to take N from the
atmosphere and use it for their own
growth-something nonlegumes
cannot do. After legumes die, this
biomass N becomes available to other
Properly managed, legumes can
supply most or all of the N required by
succeeding nonlegume crops. Indeed,
TropSoils' research in Brazil shows
that legumes can supply sufficient N to
grow 6 to 8 t/ha of maize, thus
replacing 150 kg/ha of N fertilizer.

28 LOOKING TO THE EARTH: A Foundation for Global Development

Just as important-though less
well-publicized-is the role legumes
can play in improving soil physical
conditions and in controlling diseases.
In certain areas of Brazil, for example,
farmers grow mucuna legumes for no
other reason than to suppress cotton
and soybean nematodes. Deep-rooting
legumes are also being used to allevi-
ate compaction on intensively culti-
vated soils. In addition, legumes can
provide ground cover, reduce erosion,
control weeds, supply organic matter,
and promote the growth of mycorrhi-
zae that can help crops extract slightly
soluble nutrients.


But if legumes provide benefits unavail-
able from chemical fertilizers, they also
impose some costs. To grow legumes,
for example, farmers must often use
land normally devoted to food or cash
crops, a sacrifice that can be justified
only if subsequent returns are large
enough to compensate for the dis-
placed crop and the production cost of
the legume. Nonetheless, where
fertilizer N is scarce, total production
may increase when green manures are
included in cropping sequences.
Farmers must also realize that the
management requirements of green
manures are no less stringent than
those of subsequent crops. Legumes
often must be inoculated, for instance,
and the soil's physical and chemical
environment must not be limiting.
Once the legume is grown, effec-
tive management is also required to
take advantage of the available N.

Legumes like mucuna that survive the dry season and
grow rapidly at the onset of the rainy season can play an
important role in savanna cropping systems.

Unlike fertilizer N-applications of
which can be readily synchronized to
match plant uptake patterns-legumes
must generally be cut before the food
or cash crop is planted. Whether
incorporated into the soil or applied as
a mulch, cut legumes decompose
rapidly. TropSoils' research shows that
release mineralizationn) of organic N
begins almost immediately after the
legumes are applied, and after 50 to 60
days, most of the organic N has been
converted into available mineral N.
Thus, to receive maximum benefits,
nonlegume crops should be planted
within a few days after incorporating
the legume into the soil.



These complications suggest that while
legumes have much to offer, manage-
ment systems must be sensitive to
site-specific physical and economic
variables. On tropical savannas, for
example, farmers have confronted the
following dilemma: planted during the
wet season, legumes displace impor-
tant food or cash crops, an economic
liability few producers can afford;
planted during the dry season, the
legumes do not survive.
Although the first constraint is
unalterable, U.S. and Brazilian scien-
tists felt they could overcome the
second constraint by identifying
drought-resistant legumes. Research-
ers reasoned that if legumes planted at
the end of the wet season could
survive the dry season and grow
rapidly at the onset of the rainy
season, they might provide a viable-
and valuable-management system for
sustaining long-term crop production.
Experiments across a broad genetic
base have now identified a number of
legumes that can survive a severe dry
season and produce over 5000 kg/ha of
dry matter and over 100 kg/ha of N for
the following maize crop. These
results suggest that legumes can be
matched to a wide range of savanna
cropping systems. Canavalia brasiliensis
and Mucuna aterrima appear especially

Because legumes survive the dry
season by extending their roots deep
enough to extract subsoil water,
researchers reasoned that the plants
might also recycle N from depths
below the rooting zone of the wet-
season crop. Results have confirmed
this conjecture: fallow plots contained
more subsoil N than did plots planted
to legumes, an indication that N is
being recycled. Such recycling not only
benefits the subsequent crop, but it
also reduces the risk of groundwater
pollution. In a similar fashion, legumes
may also recycle nutrients such as
potassium, calcium, and magnesium.
In addition to these immediate
benefits, drought-resistant legumes
also help control erosion, crusting, and
other forms of degradation that occur
when neither crops nor legumes
stabilize the dry-season landscape.
Along with improved fertility, such
benefits suggest that legumes are a key
to the environmentally responsible
management of savanna soils.
Developing similar systems in other
parts of the world will require an
understanding of the following vari-
ables: the availability and cost of
fertilizer N, the suitability of particular
legumes to specific conditions, the
availability of seed, the farmers' ability
to incorporate residues into the soil,
the amount of water in the soil profile,
the chemical and physical conditions of
the soil, and the farmers' management

30 LOOKING TO THE EARTH: A Foundation for Global Development


legumes help

control erosion,

crusting, and

other forms of soil

degradation that

occur when neither

crops nor legumes

stabilize the dry-

season landscape.



We understand soil and water systems much better than we did 20 years ago.
Increasingly, the challenge has become applying our knowledge to solve specific
management and policy problems. How do we do that? How do we structure what
we know so that the growing body of research information can be used for practical
The answer will depend, in large part,
on the quality of our information and the
kind of problem we want to solve. Making
field-level decisions about soil acidity or soil
phosphorus calls for one kind of tool;
projecting regional fertilizer requirements
calls for another; simulating the effect of
mulching on a system's water budget calls
for yet another.
TropSoils has developed a variety of
decision-support tools to meet the needs of
technology-transfer personnel, policy-makers, and developing-country researchers.
From expert systems to simulation models to technical classification systems, these
tools provide a new and effective kind of developmental assistance. With the aid of
modern computer programs, they respond to increasingly complex problems with a
swiftness and efficiency undreamed of a generation ago.

I. ADSS: Expertise
.n a Disk information into formats useful to
on a Disk
policy-makers and activists working at
Soil-management information increases the production level: extension agents,
daily, but resource-poor producers representatives of private voluntary
often cannot avail themselves of it. To organizations, and producer associa-
overcome that problem, the National tions and cooperatives."
Research Council states that research The Soil Management CRSP's
organizations "should be encouraged Acidity Decision Support System
and funded to synthesize available (ADSS) performs just this kind of

In Indonesia and
elsewhere around the
world, the ADSS system
helps users increase
profits by evaluating
the impact of various
soil, crop, and manage-
ment options on costs
and returns.

* ,I; ".' ''*, (.i i,_ i,, l-l' l'i i{ k .'-llii:- ,l- ,iI *. ill- .. l.'.'/

r.' ii J i *:l .. n. 1 L a Ar 1 *i r W i
.l. -i k' L 0 i -li i, t' 1il .. 1 .. 1 ., .k". u|,, .. 71 1.

k! k.vj*- Me r:l '*k* -
_*H i.J. r-l,. '.. |t^.).J-l 7 i',1 ,.'ih .--ti' "l~t il |,i~ h .r II I I ; iii -. i 11 1i r, -.,

r. -lll '.-) -.li1,_tl? lt" l- -r L: l

e0 i tn. :4 !@ mi ra 1
I' lF ^@ 19 i ,ii. .i i, _. I-_,i ,-. 1 l ii' i. ii i-il i",

. l ','! i.j4 1_l "ii.tl.. ," I r;I- i t't._* i !- _(- *[-i. i *r ; .,-'l ".) i,'[ ni -, '.l- ",
-irftiL-iil'l_ ;iij"' ...r.\ -.' *.in *.r' iii-, i_. L- 1t.l "i'-; ,- r f ).^.tt i., il ,

]i!li, iil,.!,, ilf l'##+i-Iil *.;l['g-'>.',/; r c 4.c)-,gii. -.^ -"--J,,l'!

,_i'i'j n,-, -i fr-t?1,?! _/-. i, j[ iipj, .if. [{, i. -' .^ri. L r l -.:._. ni, lL-

Jl~li~t :it^.' i "i~ll **' .'_it-J *'i' r i u -'i -'jl*:^ ..ll*l^ ,j
-in tr t-i'l,- -@JJ_.lle .

"^i.l]- li,- Il'/ 1f'' i .ir) l;j .-t lf- -' "/ l,-l l..'rii. *|J r....i.- ; #tiiili
^"^By $l :'ll|ilii-l;' '- l-- -ji ^'.'<-i' 4.1.1* it.ii.t -'in -fut -' *(*J i

1*TJ! sk>- rii\; w{[" J-d lW-in?- '*'^lif e .- hie-il-> "II ,"LE
r .1

*-w w .- ..*.l--l wi| ."i .-lil .l ii ,lu ..-s.i^ .i 'a s l "'tl .>i -.- l' ;

i. .-i*,< a'z .- utl' l )l i,,l u.. ]t _'- 'i.* -* l.
.4 M 9Ii 1i!'. 1 ^i I ti!J L 4 If' .?' ''ii-' I. tj;" -''!i 490J7

synthesis: by allowing users to evaluate
a complex range of physical, chemical,
biological, and economic variables, it
turns raw information into useful
knowledge. In a quick, logical, and
inexpensive manner, expertise gained
through years of research and hands-
on experience can be available to help
local people manage their soils.
ADSS is a menu-driven computer
program that allows users to diagnose

and correct soil acidity problems. Like
the Phosphorus and Nitrogen Decision
Support Systems also being developed
by TropSoils, ADSS belongs to a new
generation of computer programs
called expert systems. Using symbolic
logic and heurisitics (rules of thumb),
these systems enable nonexperts to
solve problems that would normally
require a specialist.
ADSS asks users a series of ques-
tions about soil, crops, liming materi-
als, and input-output prices. The
program then evaluates this data and
recommends efficient soil-management
strategies. Instead of relying on
guesswork or trial and error, users can
make informed decisions based on the
same logic and problem-solving
methods an experienced soil or crop
scientist might use.
ADSS software permits users to
evaluate the impact of various soil,
crop, and management options on
costs and returns-options that are
too numerous or time-consuming for
even an expert to calculate. ADSS is
especially helpful where soil surveys
are complete and soil-testing informa-
tion is available. In such circumstances,
it allows users to make site-specific
adjustments. Copies of the system are
being provided upon request to
developing-country scientists, exten-
sion workers, and policy-makers.
Thanks to expert systems, valuable
information need no longer be con-
fined to a research site or circum-
scribed by the movement of a special-
ist. By allowing researchers to organize
what they know into a problem-solving
product, expert systems also expose
knowledge gaps and guide research

32 LOOKING TO THE EARTH: AFoundationfor Global Development

priorities in ways that encourage the
efficient use of limited funds. The
systems help researchers avoid doing
what has already been done and
rediscovering what is already known.

2. FCC Links Soil Classi-
fication and Agronomy

In the early 1970s, researchers were
frustrated: too often, developing-
country agronomists and extension
agents made inappropriate fertility-
management recommendations-even
when their advice was based on soil
tests. Wouldn't farmers be better
served, researchers asked, if their
advisors could more clearly organize
and analyze the soil chemical and
physical properties most crucial to
plant growth?
With the help of farsighted donors
and insightful collaborators, planners
now have a tool that lets them do just
that-the Fertility Capability Classifi-
cation System (FCC). Its development
is an encouraging example of what can
be accomplished through the long-
term teamwork of land-grant universi-
ties, developing-country organizations,
and U.S. foreign-assistance agencies.
The FCC was designed to bridge
the gap between two subdisciplines:
soil classification and soil fertility. As
a technical classification system, the
FCC focuses on a specific use of the
information generated by natural
classification systems, such as soil
taxonomy or the legend of the FAO-
UNESCO Soil Maps of the World. The
natural classification systems are
essentially records of inherent soil
properties: they attempt to organize

all of the features that can be mea-
sured in a soil. As repositories of
knowledge, such systems are invalu-
able scientific tools and indispensable
references for evaluating diverse land
uses. But they were not intended to
serve as site-specific guides for agrono-
mists, many of whom have limited
taxonomic training.
The FCC was designed for pre-
cisely that purpose. It is a technical
classification system for grouping soils
according to the fertility-management
problems they present. Unlike natural
classification systems, the FCC targets
only those soil properties that directly
influence soil-management decisions
germane to crop production. These
tend to occur in the upper portion of
the soil profile where root activity is
greatest and management strategies
most influential. By limiting the
number of properties used to define a
given soil class, the FCC greatly
reduces the range of soil types an
agronomist must consider in order to
make an informed decision. From the
potentially overwhelming volume of
soil-characterization data, the system
helps users extract and organize
meaningful management information.
The development of a computer
program has made the FCC easy to
use and widely available. Anyone with
a basic understanding of soils can
classify a particular plot and review
corrective strategies simply by answer-
ing a few basic questions. And although
the system is most effective when used
with quantitative data, it has been
designed so that qualitative data can be
used as well. This flexibility is particu-
larly important in developing nations


Plant growth is

determined, in

large part, by a

soil's physical and

chemical proper-

ties. Agricultural

advisors have long

needed a practical

method for classify-

ing those proper-

ties in ways that

reveal the manage-

ment practices

best suited to

particular soils.

Across large parts

of the world, the

Fertility Capability


System is helping

to meet that need.

with limited laboratory resources. At
present, thirty-four countries and eight
international organizations use the
FCC as an aid to research and technol-
ogy transfer.
FCC developers are quick to point
out that no technical classification
system can replace basic soil tax-


inrae by 12 to $90. Fialy whe ferilze
e d fr FC ut an s-

sl te r s i b 2 t
Thee inins ndcae hewa i wic te CCan

soil teting ca compleent eac other

onomy, soil testing, and research. They
note that classification follows science,
adding that as our understanding of
natural systems changes, the way we
use those systems will change as well.
Thus, no matter how useful the FCC
system is, it will continue to need
updating and refinement.
To date, the system has produced a
number of important accomplish-
ments. By matching soil characteristics
to amendment strategies, for example,
the FCC improves fertilizer efficiency.
By integrating soil-fertility and soil-
survey information, the system also

increases returns on diagnostic
expenditures. And by promoting an
internationally acceptable classification
system that focuses on the needs of
extension workers, the FCC helps
transfer research information to the
farmers who need it.

3. Plugging GAPS:
A General Purpose
Simulation Model

Can we grow corn in this region or
will drought destroy our crops? What
if we increase soil fertility? Rooting
depth? Irrigation levels?
To evaluate these kinds of risks and
remedies, planners and researchers
must understand the way water moves
through the soil-plant-atmosphere
continuum (SPAC). Our insight into
this movement has been greatly
enhanced by the development of
dynamic simulation models that use
numerical techniques to solve equa-
tions based on a mechanistic view of
the components.
Unfortunately, most of these
models have been developed for a
single purpose, such as predicting
evapotranspiration for a given crop or
predicting leaching in a given system.
Coded for this task only, the tools are
seldom used by anyone but the
TropSoils researchers felt that a
more flexible model would be more
widely used, and, as a consequence,
would help close crucial knowledge
gaps in our understanding of the
system as a whole. To that end, they
designed a General-purpose Atmo-
sphere-plant-soil Simulator (GAPS).

34 LOOKING TO THE EARTH: A Foundation for Global Development

GAPS makes simulation modeling
more accessible to users and more
adaptable to various research objec-
tives. Where previous systems called
for a rigid set of input requirements,
GAPS offers more than one way to
simulate a particular process, the
choice being dependent on available
information, the desired level of
complexity, and the user's ultimate
aim. Someone without one type of
evapotranspiration data, for example,
is allowed to substitute other data
rather than being forced to abandon
the model.
While most SPAC models do not
let the user simulate specific parts of
the system (such as evapotranspiration
or water flow without evapotranspira-
tion), GAPS readily allows this kind of
customizing. In essence, GAPS enables
users to create their own simulation
models, tailored to their own needs
and interests. Users with some
computer programming experience
can also add components to the
system (e.g., root-growth models),
thus achieving an even wider range of
GAPS' developers are convinced
that if the system is to be employed
intelligently, users need a clear sense
of how the model simulates various
processes. Thus, the program is
carefully documented, allowing users
to make educated choices regarding
the selection of model components.
Developers also provide a number of
"user-friendly" features so that even
inexperienced modelers can move
rapidly from one part of the program
to another.


GAP ha seve imotn ro.e bot athmn

abod As par of. a* 5c prjc in Sotestsa
for example, it ha been usd to p t te wy t

GAP has als bee use as a teahin tol allwin
students to explor- e the syte -wd i
chne i aialssuha srae vpraino

water movement below the root zone.l~l

IV. Predicting Long-Term
N Requirements

Across the world, deficiencies in native
soil nitrogen (N) often limit crop
production. Tropical climates tend to
exacerbate this problem-either by
rapidly converting N into forms plants
cannot use or by leaching it from the
rooting zone.
To combat these deficiencies with
fertilizer N, producers must estimate
how much N the soil supplies on its
own. These estimates, in turn, require
an understanding of long-term changes
in soil N pools. By adapting a summary
model previously applied in temperate
climates, TropSoils has developed a
tool that enables users to make such
The model is relatively easy to use.
Initially, users need to specify two
details: how much N must the crop


/ Fert.
/ 'i -
Organic i /


.50 Organic N


.20 Rain &
Flood N

.50 Bio. N

SStable .5
Organic N

S N 1

On tropical soils, this
model helps predict long-
term fertilizer require-
ments by accounting for
nitrogen sources and
sinks. The transfer
coefficients on each line
indicate what fraction
of the nitrogen moves in
a given direction.
(Adapted from Wolf et al.,
1989, Modeling long-term
crop response to fertilizer
and soil nitrogen, Plant and
Soil, 120.)

take up in order to reach a target yield
(a figure determined from a response
curve to fertilizer N), and how much
N does the crop take up from the
unfertilized soil (a figure assumed to
remain fairly constant for a given soil
Once users establish the quantity
of N required to reach the target yield,
they account for the amount of N
supplied by the following sources:
rainfall, biological nitrogen fixation,
organic materials (e.g. plant residues,
manures), and potentially active soil
organic N (i.e., labile N-estimated
from the soil's organic N content). For
each of these sources, the model
either provides or calculates a transfer
coefficient, indicating the percentage of
the total that is partitioned to the
crop, lost from the system, or trans-
ferred to the active or inactive organic
N pools. By calculating the amount of
N transferred to the crop and sub-
tracting that figure from the target N

rate, planners can readily estimate the
amount of fertilizer N they need to
"The model employs a mass-
balance approach," says one re-
searcher. "There are only so many
places N can come from and so many
places it can go. We are simply trying
to keep track of the multiple sources
and sinks. Our assumptions about the
dynamics of the system are contained
in the transfer coefficients."
Those coefficients also allow users
to estimate the effects of prolonged
cropping on soil organic-matter pools.
Since a reduction in this pool increases
the amount of N that must be supplied
from external sources, this information
allows users to establish long-term
fertilizer N requirements. Short of
conducting prolonged fertilizer trials at
every site, this model gives planners
the best available estimate of long-
term N fertilizer needs.

36 LOOKING TO THE EARTH: A Foundation for Global Development

I I I '


Imagine a nation completely dependant on

foreign specialists and technologies. How likely is

it to solve problems peculiar to its own physical,

social, and economic conditions? How often will

the needs and wishes of its citizens be disre-

garded? What are its prospects for long-term


TropSoils recognizes that truly sustainable

soil-management systems are never developed

for host countries, but always with them or by

them. Two conditions must be met, however, before such development can occur.

First, a nation must possess a critical level of in-country expertise in soil science and

related disciplines. Second, those experts must be capable of working together,

across disciplines, to respond to the expressed needs of farmers.

Through training programs, research networks, and innovative field methodolo-

gies, TropSoils helps host countries meet both of these prerequisites. University

programs give students from around the world an opportunity to learn from-and

establish life-long contacts with-preeminent scientists. Research networks widen

the perimeter of TropSoils' impact, both by conveying information and identifying

research gaps. And innovative methodologies provide a framework for linking

scientific knowledge to the experiences, values, and insights of local people.

I.Training with a Twist:
Send the Students Home

Complex problems threaten our
future. The current generation of
scientists will not solve them. Indeed,
with each shift in technology and social
arrangement, unexpected challenges

TropSoils' social-
science research in
Bolivia has helped
clarify the most
common reasons
why farmers reject
or adopt cropping
alternatives to coca.
Findings indicate
that farmers are
willing to change if
their credit and
problems are

emerge, hydra-like, from the very
ground of our triumphs.
From its inception, TropSoils has
recognized that careful development of
human resources is the key to agricul-
tural and environmental security.
While much of our work is devoted to

Texas A&M graduate Mamadou Ouattara (right) is now the
Director General of the Institut National de Recherche
Agronomique du Niger. Here he discusses a CRSP watershed
project with a former professor.

finding immediate solutions to short-
term resource-management problems,
an equally significant effort has gone
into building the technical capabilities
and leadership qualities without which
long-term progress cannot be
A stark fact underscores the
importance of this kind of training: as
long as developing countries depend
on imported technologies, agricultural
and environmental productivity will
suffer. After all, farm systems are not
video recorders. Niger or Honduras or
the Philippines cannot simply plug in
products that work in other parts of
the world; they must design and adapt
systems suitable to their own physical
and social environments. To do that,
they need a critical mass of in-country
technical expertise. They need re-
searchers thoroughly schooled in soil-
science fundamentals and intimately
familiar with local conditions.
TropSoils cultivates both of these
qualities. On-campus classes and
seminars give students from around
the world a detailed understanding of

soil-management processes, as well as
a sense of how agronomic, economic,
and political variables relate to re-
search objectives. Equally important,
students are required to apply class-
room abstractions to real-world
particulars-usually by conducting field
research in a developing country.
Rather than becoming experts on
North Carolina or Texas soils, stu-
dents thus learn to solve problems
relevant to the well-being of their own
Give a man a fish and he eats for a
day; teach him to fish, and he eats for a
lifetime. The familiar adage might well
serve as a motto for TropSoils'
training program. To date, more than
I 15 students-most from developing
countries-have earned advanced
degrees while studying at one of our
four universities. The majority of these
students return home ready to assume
influential research and decision-
making roles. Having established
contacts with a world-wide network of
peers, graduates provide the founda-
tion upon which their countries are
building an essential body of soil-
management expertise. In a very real
sense, these students constitute
TropSoils' most enduring legacy, for in
the years to come, more and more of
them-and the people they affect-
will be shaping farm practices and
agricultural policies.

2. Research Networks
Broadcast Information

The jargon is symptomatic: outreach,
feedback, technology diffusion. They're
what research organizations tend to

38 LOOKING TO THE EARTH: A Foundation for Global Development

do worst. How do we change that
fact? How do we keep projects
responsive to the needs of farmers?
How do we make sure new technolo-
gies reach the people who need them?
TropSoils' RISTROP Network (Red
de Investigation de Suelos Tropicales)
suggests an answer: we develop more
efficient partnerships with national
institutions in developing countries. By
linking programs and personnel,
research networks accelerate the flow
of information from scientists to
farmers and, equally important, from
farmers to scientists. Networks thus
provide an efficient means of combat-
ting what the National Research
Council calls one of the most intrac-
table problems yet to be faced by the
development community: the lack of
two-way communication between the
farm and the experiment station.
Created in 1986 by participants at
a TropSoils training workshop at
Yurimaguas, Peru, RISTROP is now
promoting that kind of communication
in eight Latin American nations.
RISTROP broadens TropSoils' impact
by transferring management technolo-
gies to regions beyond the program's
primary research sites. Not only do
participants adapt and refine these
technologies to meet site-specific
needs, but their first-hand knowledge
of local problems helps scientists
redirect priorities to target the most
significant research gaps.
The inaugural planning workshop
proved crucial to RISTROP's success.
The 21-day event allowed researchers
to review soil-management theories
and to discuss current field and


Glance at a soil map and you can see that thell) T

humid andsubhumidregions f Africaand Sout

America have much in common. Trop~oils has

taken advntage of hese simiarities b fosterin

the direct exchnge of researchinformation be

Tropical Soils Management and Land Development%1l~~

Practices, held in Yurimaguas, Peru.C~IIII~ I11I(I

Patterned after the meting that launched th

RIS TROP Network, the Yurimaguas Workshop(~I 1`1

enabled scientists from 16 African countries tol I~,I

learn about new techniques for managing acid soils.lll ~ l

The progam consited of ecturesfield an Iabora

tory eercise, compter wok, andgroup iscus

sions. 111.11111

laboratory techniques. Topics ranged
from the planting stick to the latest
developments in computer software.
Equally important, participants clarified
the most pressing soil-management
problems in their particular regions.



Following the workshop, TropSoils'
network coordinator worked with
host-country coordinators and institu-
tions to refine experimental details and
obtain administrative support. Subse-
quent workshops, field trips, and
newsletters have encouraged commu-
nication among the collaborators, thus
building interest in the program and

I ~sl~:E~e ~ j4 '~j'A7.

I!X r ..

40 LOOKING TO THE EARTH: A Foundation for Global Development


further strengthening its effectiveness.
One of RISTROP's chief goals has
been to help collaborating countries
develop the expertise needed to solve
their own soil-management problems.
Already, that expertise is beginning to
emerge. Perhaps the clearest sign of
that change is in the attitude of the
collaborators themselves: when the
network began, many host-country
scientists looked to TropSoils for
preset research formulas; three years
later, however, collaborators were
vigorously shaping research priorities
and insisting that treatments be kept
flexible so that they could respond to
site-specific constraints.
"As scientists, we tend to seek a
quantitative index of our accomplish-
ments," says one TropSoils researcher.
"When we talk about networks like
RISTROP, however, some of the most
important results are qualitative. The
changing attitudes of host-country
researchers may not be something you
can plot on a graph, but long-term self-
sufficiency is impossible until these
kinds of changes occur."

3. Putting Farmers First

Too often, research and development
programs adopt an immunization
model: carefully packaged solutions are
administered to passive recipients in
the hope of producing uniformly
beneficial results. That method may
save patients from viruses. But natural-
resource systems are not viruses, and
farmers are not patients.
TropSoils recognizes that success-
ful soil-management technologies must
conform not just to environmental

contexts, but also to social ones. Just
as Niger soils are not Texas soils, so
Nigerians are not Texans: they have
different aspirations and taboos,
different social organizations and
economic opportunities, different
family structures and world views.
Although soil scientists have
developed sophisticated technologies
for assessing and remedying soil
constraints to plant growth, they often
lack similarly sophisticated tools for
assessing and responding to cultural
variation. Results from a three-year
TropSoils study in a transmigration
area of Indonesia have narrowed this
gap by designing and applying a holistic
approach to development research.
A significant component of that
approach requires scientists to learn
more of what local people know.
Through surveys, interviews, and time-
allocation studies, researchers not only
gain a sense of farmers' broad philo-
sophical views, but they also acquire a
wealth of practical information about
local conditions. Such indigenous
knowledge can direct-and sometimes
revolutionize-research approaches.
Without an understanding of
Indonesian social structures and work
patterns, for example, TropSoils
researchers would have focused
exclusively on upland rice fields, thus
overlooking the economically essential
home gardens managed by women.
Similarly, if researchers had ignored
indigenous knowledge, they would
have underestimated the potential
contributions of local species to
agroforestry systems.
Why is this kind of information
often neglected? The makeup of the

CRSP research in Indonesia has clarified the impor-
tance of involving women in agricultural planning

research team may be the key. Rather
than the traditional group of like-
minded specialists, TropSoils as-
sembled a diverse mixture of social
and natural scientists. Like comple-
mentary lenses in a telescope, these
groups worked together to provide a
more accurate view of farmers and
their problems than any one group
could have achieved on its own.
Researchers put aside myopic single-
issue concerns and focused instead on
the larger picture: developing sustain-
able agricultural systems that would
meet the human needs of the Indone-
Unlike the top-down approach
characteristic of most development
projects, TropSoils' methodology
makes the farmer a partner in every



Because the IMAW
project focused
on a representa-
tive watershed,
results can be used
to increase land
productivity across
large areas of the

phase of the effort. By integrating a
broad base of scientific knowledge
with an equally broad base of indig-
enous knowledge, researchers antici-
pated-and received-a powerful
synergism. That success clarifies the
importance of adopting new and
responsive research methods.
As one Indonesian team-member
has pointed out, "Sustainability will
only be a dream until the advances of
science are wed to the experiences,
values, and knowledge of local people."

4. A Watershed for
Farmers and Researchers

On the millet-producing watersheds
outside Niamey, Niger, legend main-
tains that the rainbow drinks the rain.
An arresting image, it underscores the
hard covenant of the Sahel, a region
where even the most luminous vista
inspires a watchful wariness.

"These red soils weren't part of
any green revolution," says one
researcher. "Drought and erosion can
be equally destructive here. It's a
complex and difficult environment."
Responding to a request from the
USAID mission in Niger, TropSoils has
designed ways to cope with that
complexity. The cornerstone of this
effort was a project on the Integrated
Management of Agricultural Water-
sheds (IMAW). Perhaps the project's
most important product is a method-
ology for using local knowledge,
customs, and preferences to develop
improved soil- and plant-management
In Phase I of the project, research-
ers characterized the watershed soils
and conducted four related social
surveys: village chiefs and elders were
interviewed to obtain historical and
demographic information; all farmers
within the watershed were identified;
the land history of cultivated and
fallow areas was documented; and
farmers were interviewed to clarify
land tenure, indigenous knowledge,
and local perceptions of problems and
solutions. These activities then helped
researchers identify distinct land-
management units.
Phase II of the project then began
to develop, test, and refine environ-
mentally sound land-management
systems suited to the land types and
farmer preferences identified in Phase
I. What made this process particularly
effective was the active participation of
"We wanted villagers to test soil-
and crop-management options in their
own fields, and we wanted to demon-

42 LOOKING TO THE EARTH: A Foundation for Global Development

~d~' -i~4I

-- ~
.h~rri: C;fl L~Y~AEI

state the need for community partici-
pation in the rejuvenation of degraded
common lands," says one researcher.
He adds that on-farm agronomic trials
often prove illuminating in ways that
traditional experiment-station work
does not: "For the first time in their
lives, some of these farmers have been
able to compare different treatments
side-by-side over the same growing
season. I'm encouraged that so many
villagers seemed eager to ask ques-
tions, exchange ideas, and compare
On-farm trials involving mulch,
fertilizer, manure, and intensive plant
spacing may have revealed a key to
sustaining production in the region.
Over the past decade, fallow periods
across the Sahel have been reduced,
and larger areas of marginal land have
come under cultivation. As a result,
the vegetative cover has been stripped
away and more land has been exposed
to erosion and other degrading forces.
Intensive methods suggest a way to
reverse that trend, increasing produc-
tion on small, intensively farmed plots
so that other parts of the land can be
allowed to regenerate.

The watershed project has also
clarified the interdependence of
various landscape components-
particularly the relationship between
the plateau surface and the adjoining
millet fields. "The plateau is common
land where farmers gather wood,
fodder, and food," says a TropSoils
hydrologist. "No one owns the land,
so no one is directly responsible for its
maintenance. As population pressures
have risen, the plateau has been
degraded, runoff and erosion have
increased, and millet crops far from
the plateau have been buried or
washed away."

INRAN's Mamadou
Gandah points out that
"trees are being
established on the
plateau in areas where,
previously, grosses
wouldn't grow." This
sequence of photo-
graphs illustrates that
rejuvenation over a
two-year period.


. ..

"Many INRAN scien-

tists were trained by

the Soil Management

CRSP. I'm pleased

with their progress

and excited about the

new dimension our

relationship is taking.

INRAN is assuming

the leadership, and

we are becoming the

partner. That's the

way it should be."

-TropSoils Professor

Mamadou Gandah, head of the
Ecological Research Department at the
Institute National de Recherche
Agronomique du Niger (INRAN), says
calling attention to that problem may
be the most important achievement of
the project. Crossing a plateau so
barren and hard-packed that truck
tires leave no impress, he points out
that "farmers tend to overlook the
relationship between what happens up
here and what happens in their fields.
We've opened a dialogue about that
connection. It's an important first step
toward stabilizing the landscape."
"Many farmers have been encour-
aged to see that trees are being
established on the plateau in areas
where, previously, grasses wouldn't
grow," Gandah adds. "And a number

of farmers have expressed an interest
in carrying on this work themselves."
Although Phase II of the project
ended in June of 1993, INRAN Direc-
tor General Mamadou Ouattara is
confident that "INRAN researchers
have been so thoroughly integrated
into the project that we can continue
the valuable work that has been
started." One of Ouattara's former
professors at Texas A&M is equally
hopeful: "Many INRAN scientists were
trained by the Soil Management CRSP.
I'm pleased with their progress and
excited about the new dimension our
relationship is taking. INRAN is
assuming the leadership, and we are
becoming the partner. That's the way
it should be."

44 LOOKING TO THE EARTH: A Foundation for Global Development



gram. Twelve years later, we're a
program that manages soils in the
tropics. That small shift in syntax
underscores one of our largest
accomplishments: as our knowledge of
soil systems has grown, we've come to
recognize that their governing prin-
ciples do not alter suddenly at the
borders of Capricorn and Cancer.
Local conditions may present special
challenges, climates may vary, but no
part of the globe is a world unto itself.
The fundamentals of soil science apply
wherever one goes.
The importance of this insight is
difficult to overstate. It means that
what we learn in one part of the world
can be modified and adapted to other
regions. It means that the dramatic
increases in soil-science understanding
that TropSoils has contributed to over
the last decade can have a world-wide
impact. It means what we know about
soil acidity, nutrient deficiencies, water
stress, land degradation, and other
problems can be used to develop
systems in which the word sustainable
is not just empty rhetoric.
In the developed world, informa-
tion is already being used in this
fashion. Extension systems adapt
research results to the needs of local
farmers. Refinements and modifica-
tions quickly follow. And farm effi-
ciency improves.
In the developing world, however,
tools and technologies to solve

Careful stewardship of our land
resources is a key to meeting the needs
of future generations.

location-specific problems are still
Herein lies the challenge for the
years ahead. Rather than working
primarily to expand the knowledge
base, programs like TropSoils must
now work more diligently to apply
what we have already learned. We
need to shift from component re-
search to a product-oriented systems
approach in which greater emphasis is
placed on information analysis, adapta-
tion, and transfer. Our aim should be
to identify the most important man-
agement problems and to develop
tools that nonexperts can use to solve
those problems on a location-specific
As a USAID official has recently
pointed out, it is no longer enough to
say that we know how to better


manage the world's soils if those soils
are not in fact being better managed.
After years of work by devoted
scientists, we now have enough
information to increase and sustain soil
productivity across large parts of the

globe. How effective we are in applying
this information will determine to a
large extent the fate of the world's
most pressing environmental, eco-
nomic, and agricultural problems.

Collaborators from 14 countries
attended the CRSP's Global
Planning Workshop in 1993.
Each year the CRSP responds
to information requests from
more than 75 countries around
the world.

46 LOOKING TO THE EARTH: A Foundation for Global Development

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