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 Introduction
 If we can't define it or measure...
 Results
 Conclusions
 Figures
 Reference






Title: Agricultural sustainability as an operational criterion
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Table of Contents
    Introduction
        Page 1
    If we can't define it or measure it, let's program it
        Page 2
        Page 3
    Results
        Page 4
    Conclusions
        Page 4
    Figures
        Page 5
        Page 6
    Reference
        Page 7
Full Text









AGRICULTURAL SUSTAINABILITY
AS AN OPERATIONAL CRITERION1

Peter E. Hildebrand
and
Malik Ashraf2



It has been surprisingly difficult to find careful definitions of the term
sustainability. This is at least in part because "sustainability", if it is to provide a
useful rhetoric for reform, must be able to accommodate the several traditions that
must march under its banner. (Ruttan, 1988, p. 129).


Sustainability, a widely used term, is easily understood -- in casual conversation. Not so
when attempting to introduce the term into a more rigorous framework. In a casual context,
sustainable agricultural production (or productivity) carries the connotation of production (or
productivity) that at least does not decline. But Ruttan, among others, argues that "A meaningful
definition of sustainability must include the enhancement of agricultural productivity" (Ruttan,
1988, p.128). As world population and incomes increase, it is argued, agricultural productivity
must also increase to keep pace. In this context, there is an overlap of the concept of agricultural
sustainability with that of sustainability of human life in its present or an improved state. The
implications of the sustainability of agricultural systems, and of human systems, are very
different when the term sustainable is operationalized. Altieri and Anderson (1986) argue that
productivity in agricultural systems cannot be increased indefinitely. "A ceiling is placed on
potential productivity by the physiological limits of crops, the 'carrying capacity' of the habitat,
and the external costs incurred during efforts to increase production" (p.32). Implied by the
concept of habitat carrying capacity is concern for environmental survival. Hence, perpetual
sustainability of agricultural systems (ignoring increases in human population and income) can be
conceived. The same is not possible of human systems (even ignoring detrimental effects on
environment).

Beyond these problems of conceptualization, we also have problems with measuring or
quantifying sustainability. First, it may well be difficult to get agreement on what are
appropriate evaluation criteria, which will be location- and perspective-specific. Second, even if
we agree, for example, that increasing product per unit of chemical used is "more sustainable" we
still are not able to determine "how much more sustainable" it is. Given these problems, an
attempt is made here to develop a means to evaluate the implications of imposing sustainability
constraints on an existing farming system.





Presented at the ninth annual International Farming Systems Symposium,
University of Arkansas, Fayetteville, October 8 11, 1989.

Professor and Visiting Professor, respectively, Food and Resource
Economics Department, University of Florida, Gainesville, FL 32611.

A special acknowledgement is made to B. T. Kang, IITA, Ibadan, Nigeria,
for his useful estimates on fallow and fertilizer requirements and
on productivity of the various systems.









2

If We Can't Define It or Measure It. Let's Program It

In this paper, we present an approach to evaluating the implications associated with
attempts to influence 'sustainability' in such a way that 1) agricultural productivity (the
agricultural system), 2) environmental survivability (the ecological system) and 3) human
population and income changes (the human system) are all involved.

The procedure used to operationalize the concept of sustainability is by means of linear
programming. The farming system used as an example is representative of the area near Ijaye in
southern Nigeria.

Iiave Area

The Ijaye area, consisting of a main village and 5 surrounding hamlets, lies in the derived
Guinea savanna of southwestern Nigeria at a latitude of 7* North. It is located in the transitional
zone between the humid and sub-humid high rainfall ecologies of West Africa. The population is
Yoruba, one of the three largest tribes in Nigeria. The natural vegetation is a forest savanna
mosaic with a rolling topography and small V-shaped valleys.

The bi-modal rainfall ranges between 1200 and 1500 mm and is spread from April to
October. Soils are well drained, coarsely textured, and low in organic matter and cation exchange
capacity. Nutrient and water-holding capacity of soils is extremely poor. Soils are moderately
acidic with pH generally less than 6.0. The annual temperature ranges between 21.3. and 31.2. C.
Mean monthly relative humidity reaches a minimum in February and maximum in August.
Potential evapotranspiration peaks in March and falls to its lowest level in August.

A bush-fallow or slash-and-burn system of cultivation is practiced. After 1 to 3 years of
cropping, fields are left fallow for 3 to 5 years. During the short fallow, natural grasses and
woody shrubs restore soil chemical and physical properties. However the wide spread infestation
by imperata has created limits on the soil's ability to regenerate during the short fallow.

Traditionally, land is held communally and the cultivation rights are distributed by the
village chief. However, with the increase in rural population, most families maintain inherited
possession rights of land and within the joint family the family head allocates land among its
members. Outside the inherited land farmers still seek temporary use rights through the village
chief. Land closer to the village is more intensively cultivated and cash renting of this land has
also emerged. Most farmers cultivate 3 to 5 plots of varying size and irregular shape. The
amount of arable land depends on family labor or the family's ability to hire labor especially for
land clearing. Average amount of arable land for a household is 2 to 3 hectares with another 5 to
8 hectares in fallow.

The farming system in the Ijaye area consists of tree crops including oil palm, cacao and
plantain and arable crops including cassava, yams, maize, and leafy vegetables. Mixed cropping
is commonly practiced. Some poultry and small ruminants are kept. Women play active roles in
farming including processing, storage, and marketing of farm produce. In addition to cultivating
their individual plots, women help raise and handle crops on men's plots. Average family size is
6 to 10 and more than 70% of the members are young children. Most farmers are old. The
grown male children often leave the villages in search of non-farming jobs. Farming is done
manually with the help of small hand tools. Use of chemical fertilizers, although low, has
increased steadily over the past 5 to 8 years. Insecticides are used only for cacao and cowpea,
and at present, herbicides are not used. Due to the high risk of crop failure caused by irregular
and uncertain rains, especially during the second rainy season, farmers are food security
conscious and they invest a considerable amount of their resources in drought tolerant food crops
like cassava and in mixed cropping systems.









3

In the Ijaye area there is a market every five days throughout the year. Wives of most
farmers are also market traders and they are responsible for selling their crops locally or in
nearby town markets.

Conceptualizing sustainability

The linear program format used is a standard profit maximization tableau subject to
minimum land and food subsistence constraints (to incorporate the human element) and two
equations to incorporate agricultural and ecological sustainability concerns. One 'sustainability'
equation accounts for the proportion of a farm that remains in bush fallow. The other accounts
for the use of external chemical inputs (in this case, only fertilizer).

Agricultural activities were constructed with a minimum fallow requirement to maintain
constant agricultural productivity over several cycles. Within limits, chemical fertilizer and alley
cropping can substitute for fallow and natural fertility maintenance, and this effect was
incorporated in developing the individual activities. There are four basic alternatives considered.
The traditional production system without fertilizer but with an appropriate amount of land in
fallow. A second alternative in which fertilizer substitutes for part of the fallow. A third
alternative, alley cropping without fertilizer, also substitutes for some fallow, as does the fourth
alternative, alley cropping with fertilizer, Table 1. Productivity coefficients for these activities
were estimated from experimental data, survey and expert opinion.

The first series of solutions was not limited by amount of fertilizer which could be
applied, although modest rates were utilized. Population pressure was reflected by decreasing
farm size. Because of the requirement to maintain family subsistence levels, the solution became
infeasible as different constraints were introduced.

A second series was run with 1) chemical fertilizer restricted to half that applied under
the unrestricted model and 2) no fertilizer allowed. The purpose was to analyze the effect of
reducing dependence of the system on chemical inputs.

A third series of solutions was run after doubling the fallow requirement. The purpose
was to analyze the effect of requiring the maintenance of minimum levels of fallow for ecological
reasons beyond the amount required for maintenance of agricultural productivity.


Table 1. Minimum fallow requirements for selected crop production to maintain
productivity in different systems. Ijaye, Nigeria.



No fertilizer With fertilizer No fertilizer With fertilizer
No alley crop No alley crop with alley with alley


ha fallow/ha crop

Maize/cassava 4.00 0.67 2.00 0.50
Cassava 2.00 0.67 1.33 0.50

Source: B. T. Kang, Soil Scientist, IITA, personal communication. 1989.









4

Results

All feasible solutions had .15 ha of compound crops to provide necessary vegetables and
relishes. With 10 ha available per farm and with the minimum fallow requirement, the solutions
approximated present conditions in Ijaye. This included about 1.7 ha (17%) in unfertilized crops,
7% in tree crops and the remainder (about 75%) in bush fallow. If no fertilizer was allowed, and as
farm size was reduced, unfertilized alley cropping appeared, utilizing 33% of the land in a 4 ha
farm where it completely replaced unfertilized cropping without alleys, Figure 1. In this case
fallow occupied 50% of the farm. With no fertilizer available, 4 ha was the minimum farm size for
which family subsistence requirements could be met. As more fertilizer is allowed into the system,
fertilized crops and fertilized alley cropping replace the unfertilized crops and alley. Neither
unfertilized alleys nor unfertilized crops appear when full fertilizer is allowed, Figure 2. It is
important to note that permitting fertilizer into the systems allows farm size to decrease more than
would otherwise be possible (farm size decreases to 3 ha with intermediate fertilizer and to 2.25 ha
with full fertilizer).

If the most restrictive sustainability constraints are placed on the system, double fallow and
no fertilizer, farm size is infeasible below 5.5 ha. At this size, the farm consists exclusively of
fallow, tree crops, alley cropping and the compound crops, Figure 3.

The use of fertilizer helps maintain farm income and food production (family sustainability)
as population pressure increases and farm size diminishes, Figure 4. However, farm size can be cut
to half (5 ha) with little income effect, even without the use of fertilizer. This is not true,
however, if the fallow requirement is doubled, Figure 5.

Conclusions

Although the concept of sustainability is widely used and its meaning intuitively evident, it
is not easy to use in rigorous analysis. In this paper, we attempted to formulate a means of utilizing
it as an operational criterion. We mostly failed! We anticipated being able to create a means of
measuring the "longevity" of each alternate system or solution. That is, how long each would
maintain a specified level of productivity. We were far short of the necessary data and would
anticipate that it will be difficult to obtain with reasonable costs and time. We were not able,
either, to devise a means of judging how much more sustainable one system is over another.

However, the use of a linear program does provide a means of conceptualizing the impact of
imposing sustainability constraints on a system. Depending on the quality of the coefficients, it is
possible to estimate the effects of growing population pressure and the concomitant reduction in
farm size. It is also possible to estimate the effects of controlling the use of chemicals, or the effects
of insisting on the maintenance of a specified amount of bush or forest fallow. For example, the
effects of a tradeoff between chemical use and bush or forest fallow can be seen. As a matter of
fact, IITA is cognizant that such a tradeoff will be necessary in the future (Stifel, 1989).

The quality of our data could, and should, be improved. This same need will challenge all
who work in agricultural and agroforestry research. In the case of Ijaye, with increasing population
pressure and decreasing farm size, it would appear that farm incomes can be maintained, up to a
point, but this will require the use of chemical fertilizers. It would also appear that alley cropping
is more feasible if fertilized rather than unfertilized. If society becomes concerned with the
disappearance of bush and forest, and manages to limit the amount that can be cleared for
cropping, requirements for chemicals will be even greater. This is not particularly a concern in
much of Africa today, but it may become so in the future.

One final conclusion of this analysis is that sustainable agriculture, facing an ever increasing
human population, will not be an agriculture free of chemical use, at least with the kinds of
technology we know today. Without finding a way to control population, the term 'sustainable
agriculture' will not be sustainable for very long!









4

Results

All feasible solutions had .15 ha of compound crops to provide necessary vegetables and
relishes. With 10 ha available per farm and with the minimum fallow requirement, the solutions
approximated present conditions in Ijaye. This included about 1.7 ha (17%) in unfertilized crops,
7% in tree crops and the remainder (about 75%) in bush fallow. If no fertilizer was allowed, and as
farm size was reduced, unfertilized alley cropping appeared, utilizing 33% of the land in a 4 ha
farm where it completely replaced unfertilized cropping without alleys, Figure 1. In this case
fallow occupied 50% of the farm. With no fertilizer available, 4 ha was the minimum farm size for
which family subsistence requirements could be met. As more fertilizer is allowed into the system,
fertilized crops and fertilized alley cropping replace the unfertilized crops and alley. Neither
unfertilized alleys nor unfertilized crops appear when full fertilizer is allowed, Figure 2. It is
important to note that permitting fertilizer into the systems allows farm size to decrease more than
would otherwise be possible (farm size decreases to 3 ha with intermediate fertilizer and to 2.25 ha
with full fertilizer).

If the most restrictive sustainability constraints are placed on the system, double fallow and
no fertilizer, farm size is infeasible below 5.5 ha. At this size, the farm consists exclusively of
fallow, tree crops, alley cropping and the compound crops, Figure 3.

The use of fertilizer helps maintain farm income and food production (family sustainability)
as population pressure increases and farm size diminishes, Figure 4. However, farm size can be cut
to half (5 ha) with little income effect, even without the use of fertilizer. This is not true,
however, if the fallow requirement is doubled, Figure 5.

Conclusions

Although the concept of sustainability is widely used and its meaning intuitively evident, it
is not easy to use in rigorous analysis. In this paper, we attempted to formulate a means of utilizing
it as an operational criterion. We mostly failed! We anticipated being able to create a means of
measuring the "longevity" of each alternate system or solution. That is, how long each would
maintain a specified level of productivity. We were far short of the necessary data and would
anticipate that it will be difficult to obtain with reasonable costs and time. We were not able,
either, to devise a means of judging how much more sustainable one system is over another.

However, the use of a linear program does provide a means of conceptualizing the impact of
imposing sustainability constraints on a system. Depending on the quality of the coefficients, it is
possible to estimate the effects of growing population pressure and the concomitant reduction in
farm size. It is also possible to estimate the effects of controlling the use of chemicals, or the effects
of insisting on the maintenance of a specified amount of bush or forest fallow. For example, the
effects of a tradeoff between chemical use and bush or forest fallow can be seen. As a matter of
fact, IITA is cognizant that such a tradeoff will be necessary in the future (Stifel, 1989).

The quality of our data could, and should, be improved. This same need will challenge all
who work in agricultural and agroforestry research. In the case of Ijaye, with increasing population
pressure and decreasing farm size, it would appear that farm incomes can be maintained, up to a
point, but this will require the use of chemical fertilizers. It would also appear that alley cropping
is more feasible if fertilized rather than unfertilized. If society becomes concerned with the
disappearance of bush and forest, and manages to limit the amount that can be cleared for
cropping, requirements for chemicals will be even greater. This is not particularly a concern in
much of Africa today, but it may become so in the future.

One final conclusion of this analysis is that sustainable agriculture, facing an ever increasing
human population, will not be an agriculture free of chemical use, at least with the kinds of
technology we know today. Without finding a way to control population, the term 'sustainable
agriculture' will not be sustainable for very long!










Figure 1.
CROPPING PLAN
Minimum Fallow, Unfertilized
Ijaye, Nigeria

COMPOUND CROPS 5 UNFERTIUZED CROPS U UNFERTIUZED ALLEY
O TREE CROPS FALLOW
100


0
U-
z 60
L INFEASIBLE
0
Ul 40


20

0 -
10 7.5 6.5 5.5 5 4 3 2.5 2.25
FARM SIZE, HECTARES


Figure 2.
CROPPING PLAN
Minimum Fallow, Fertilized
Ijaye, Nigeria

I COMPOUND CROPS UNFERTIUZED CROPS [ FERTIUZED CROPS
O FERTIUZED ALLEY O TREE CROPS 5 FALLOW
100









20


10 7.5 6.5 5.5 5 4 3 2.5 2.25
FARM SIZE, HECTARES









Figure 3. 6
CROPPING PLAN
Double Fallow, Unfertilized
Ijaye, Nigeria

COMPOUND CROPS 3 UNFERTILZED CROPS U UNFERTILIZED ALLEY
O TREE CROPS 3 FALLOW
100
1 0 0 .... .... ............................

80.........................


z 60
"' ::::W : ::::-:":":":":":":':"::" IN FEASIBLE
L 40
a-

20


10 7.5 6.5 5.5 5 4 3 2.5 2.25
FARM SIZE, HECTARES



Figure 4.
NET FARM INCOME AND FERTILIZER USE
MINIMUM FALLOW
IJAYE, NIGERIA
NFl, FERTILIZED .. NF, INT. FERTILIZER NF, NO FERTIZER
--- KG/HA FERTIUZED KG/HA INT. FERTILIZER

4,000 100

60


S2,000
40 0
1,000 -
...--- ,--' .\- 420 I

0 -- -r-.""'-'' "T "" "-I -- I --I---- l I-- I-- 0
10 7.5 6.5 5.5 5 4 3 2.5 2.25
FARM SIZE, HECTARES









Figure 5.
NET FARM INCOME AND FERTILIZER USE
DOUBLE FALLOW
IJAYE, NIGERIA
R FERnZED ........ N NT. FEURZE ---- NR, NO FER
------ AFERnlZED -- K-A NT. FERTILZER

4,000 100


80
3,000 -... ........ -....... .............. tz

\ 60
| 2,000
z I-
40 0

1,000 ----
^ -t-\ 20 s


0 I I II I I 0
10 7.5 6.5 5.5 5 4 3 2.5 2.25
FARM SIZE, HECTARES





REFERENCES
Altieri, M. A. and M. K. Anderson. 1986. An ecological basis for the development of alternative
agricultural systems for small farmers in the third world. Amer. J. Alternative Agric. 1:30-38.

Ruttan, V. W. 1988. Sustainability is not enough. Amer. J. Alternative Agric. 3:128-130.

Stifel, L. D. 1989. Transforming Nigerian agriculture: The role of research. A lecture given at
the Nigerian Institute of International Affairs, Lagos. IITA, Ibadan.

221p.sust




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