TEXAS A & M UNIVERSITY
DR ALBERT N
I ~ I
TABLE OF CONTENTS
INTRODUCTION OF NEW VARIETIES 5
ON-THE-FARM TESTS II
First Growing Season
Yield Components in the Corn Experiments 12
Standard Experimental Procedures 14
Corn Variety Tests 15
Nitrogen Rate and Time of Application Studies 24
Planting Rate Studies 37
Planting Method Studies 44
Planting Date Studies 48
Weed Control 52
Soil Insect Control 54
Recommended Production Practices for the Oriente 56
Standard Experimental Procedures 60
Variety Tests 62
Date of Seeding 67
Nitrogen Fertilization 71
Weed Control 75
Soil Insect Control 76
Suggested Production Practices 79
Decision Making Corn or Black Beans 81
Second Growing Season
Variety Tests 87
Nitrogen Fertilization 89
Phosphorus Fertilization 93
Planting Method 97
Variety Tests 100
Nitrogen Fertilization 103
Phosphorus Fertilization 105
ON-THE-FARM PROOFS 109
Corn Varieties 110
Bean Varieties (First growing season) III
Grain Sorghum Varieties 112
Nitrogen Fertilization of Grain Sorghum 112
Grain Sorghum Planting Method 116
Interviews with Farmers' Purchasin seed 116
Black Beans Varieties (Second growing season) 119
Nitrogen Fertilization of Black Beans 119
Cowpea-Soybean Observation Plots 119
FIELD DAYS 125
PROGRAM SUGGESTIONS 127
Corn-Grain Sorghum 128
Black Beans 131
Proof of Technology 141
This report to the General Director of ICTA and USAID Guatemala covers
services rendered under the agreement between the Instituto of Agricultural Science
and Technology and Texas A&M University for the services of Dr. Albert N Plant
through December 31, 1975.
Specific services requested under the agreement were:
I Design and carry out necessary research en varietal adaptability, yield poten-
tial, disease resistance, market acceptance, and the physical and cultural aspects
of the basic grain food crops production and also their potential for inclusion in
crop associations and multiple cropping systems.
2 Act as basic grains production team leader.
3 Asist ICTA to develop basic grains production programs provide professional gui-
dance, expeetise and training to counterpart technicians in planning and executing
production and research programs.
4 Provide on-the-job training seminars and lectures for Ministry of Agriculture
technicians charged with extension and credit supervision of basic grains production
5 On the basis of Guatemalan field experience, develop procedures for the pro-
motion of basic food grains production programs.
6 Asist ICTA to develop a system for the maintenance of sufficient seed stocks of
improved varieties of the basic food grains to assure the success of future rural
INTRODUCTION OF NEW VARIETIES
INTRODUCTION OF NEW VARIETIES
The seed introduction project was initiated for several reasons. First, to in-
troduce new varieties to the farmer as soon as they become available. Second, to
show the value of using good seed and third, to create a demand or desire for seed
sufficient to interest the private sector in seed production and distribution.
In the Oriente, rapid gains in production can be brought about rapidly just
by the use of better varieties, or better quality seed. The problem was "how to
bring about these changes?" No infrastructure for seed distribution existed in the
Oriente. The new varieties were not known by the farmers. Farm size indicated
that the target population would not go looking for these seed even if their existen-
ce were known because the smallest quantity of seed sold (50# bag) was often seve-
ral times the quantity of seed required.
Guatemala has very strict laws concerning the selling of products on con-
signment and from this there has developed an infrastructure for consignment selling,
in fact, much of the products in the village stores are consignment placed.
ICTA took advantage of the existing infrastructure by packaging units that
were of a size that any farmer could afford to try them and placing them on consign-
ment in the village stores where they would be readily available to the local farmers.
In addition these same seeds were made available to the farmers at the production
center, the local cooperative, and at other government agencies within the region.
The following numbers of introductions were made by this project.
Corn 2767 sacks
Beans 695 sacks
Grain Sorghum 924 sacks
Rice 144 sacks
TOTAL 4530 sacks
Distribution of varieties by size of sack is shown in Table 54.
NUMBER AND SIZE OF SACKS OF SEED SOLD IN
THE SEED INTRODUCTION PROJECT IN THE ORIENTED
** = 40#
SIZE OF SACK (Lbs.)
CROP VARIETY 2 5 10 25 qq.
Corn B-1 94 304 35.10
Corn Trop-102 302 1,400 603 64 152.34
Beans N. Jalpatagua 252 256 76.60
Beans Turrialba-1 30 113 28.75
Beans Cuilapa-72 50 82 33.00
Beans S.P. Pinula 3 .30
Sorghum Guatex Bl. 2 52 13.20
Sorghum Guatecau 574 285 63 72.95
Rice CICA-4 40** 49* 65 31.92
* = 7. 5#
It is certain that some farmers bought more than one sack; however, the vil-
lage stores report that only about two farmers per ten bought more than one sack.
Even if the efficiency is only fifty percent, it is an excellent method of introducing
the new varieties at a minimum cost.
Problems encountered, or resistance on the part of the farmer centered on
beans and rice. Price of the beans and their maturity dates limited distribution. Lack
of acceptance by the mills was listed as the primary reason for not buying the rice
variety CICA-4. Secondary reason pertained to its growth habit and the concimitant
problem in weed control.
In both corn and grain sorghum much more seed could have been sold has it
been available, especially sorghum.
The bags, with the exception of the 25-pound paper bags were made of
cloth by the program of Transference of Technology and printed by hand in two
colors using the silk screen process. These bags were also filled by hand in the
Cooperative "Cuna del Sol" and the Production Center in Jutiapa.
It is suggested that this project be continued, but that ICTA place all phases
except distribution under the Seed Production program and not with Transference of
Pricing policy should be reviewed. It is suggested that the year of introduc-
tion the price should be somewhat lower than in subsequent years, more or less a
special introductory offer for the farmer to make an on-the-farm test.
- II -
ON THE FARM TESTS
YIELD COMPONENTS IN THE CORN EXPERIMENTS
The yield of corn grain from any given field can be factored into four yield
components as follows:
Number of plants per hectare harvested X average number of ears per plant
X average number of grains per ear X average weight of each grain.
Since there are so many ways that a given yield can be obtained it is im-
possible to extrapolate corn yield data without a knowledge of the yield compo-
nents involved. The yield components are interrelated. Change one, and the other
three may change also. Thus, for ease in interpreting data it is desirable to state
the yield components relative to a set of standard values.
Standard values for the Oriente were selected based on investigation and ex-
perience in the temperate regions under climatic conditions which are similar to
those prevailing in Oriente. These are:
1) 40,000 plants per hectare harvested;
2) 0.95 ears per plant;
3) Ears weighing one-half pound with 80 percent grain;
4) 1,500 grains per pound of seed.
These standard values produce 38,000 ears per hectare each averaging 600
grains per ear that have a standard grain weight of 0.3 gram. The yield per
- 13 -
hectare produced under these conditions would be 6,840 kilograms per hectare
or 105.3 quintales per manzana.
The standard component values were fixed numerically as 1.000 and the
experimental values were calculated as decimal percent of the standard values.
Thus, a calculated yield component factor may be either more than, or less than
1.000. Multiplying the four standard yield compoment factors produces a relative
yield factor which when multiplied by 6,840 will produce the actual yield obtained
in the field.
The yield components are extremely valuable because they permit the resear-
cher to study the effect of changing one variable on the other three variables.
Often the yield components point out otherwise hidden problems and, if not, they
definitely delineate problem areas and help establish research priorities.
Yield component factors will be utilized throughout this report.
STANDARD EXPERIMENTAL PROCEDURES
To allow for comparisons between experiments within areas and within
experiments between areas, a standardized experimental design was employed.
All factors were held constant throughout the region with the exception of the
factor being studied. These were:
Rows per plot
Length of rows
Soil Insect Control
Foliar Insect Control
2 rows x 10 meters
2 plants per hill, 50 cm. apart
60 60* 0 Kg/Ha
* When soil analysis for "P" was less than 6 PPM, 60 kilograms per hectare
P205 from triple superphosphate were applied.
CORN VARIETY TESTS
Most of the corns planted in the Oriente are local varieties. They are
early dwarf types having eight to twelve rows of kernels and "finger-sized
The early dwarf types are the lowest yielding of all the major corn types
found in Guatemala. Their use seems to be based on their earliness and the
ability to produce some grains, even under very adverse conditions. Progressive
farmers plant either H-3 or H-5 hybrids which are imported from El Salvador. An
opinion held by most researchers is that corn varieties adapted to the Pacific
Coastal Plain are also adaptable to the Oriente. Several hybrids from the Pioneer
Seed Company and several varieties and one hybrid produced by ICTA were reported
to be giving excellent results in the Pacific Coastal Plain.
The objective of the twelve variety trials in the six areas of the pilot region
was to determine if the coastal hybrids offered an advantage of the hybrids presently
being utilized in the Oriente and if the open-polllinated variety ICTA B-1 should
be substituted for the local criolla varieties. The entries and some of their charac-
teristics are presented in Table I.
Table 2 presents the yield data for the seven entries as averages per municipio.
In each municipio sub-region there were two corn variety tests.
CORN ENTRIES IN THE PILOT REGION TESTS AND SOME OF THEIR
ENTRY SOURCE HYBRID OR SEED DAYS TO
VAR I ETY COLOR FLOWER
H-3 El Salvador Hybrid White 53 56
H-5 El Salvador Hybrid White 56 62
X 105-A Pioneer Seed Co. Hybrid White 55 58
X 304-A Pioneer Seed Co. Hybrid Yellow 55 58
Tropical 102 ICTA Hybrid White 55 60
B-1 ICTA Variety White 53 58
Criollas Farmer's Seed Varieties White 40 50
FOR THE SEVEN
YIELD OF CORN GRAIN (Kg/Ha AT 13% MOISTURE)
ENTRIES SEEDED IN THE VARIOUS MUNICIPIOS OF PILOT AREA
PIO Trop. PIO ICTA
H-5 X105-A H-3 102 X304-A B-1 CRIOLLA
Agua Blanca 4081 3526 3668 3613 3249 3650 2592
Asunci6n Mita 4470 3796 3616 3964 3631 3552 3037
Atescatempa 5332 4490 4980 4292 4217 4030 3928
El Progreso 3218 3127 2662 3216 3535 2934 1652
Sta. Catarina Mita 2922 2847 2199 2851 2408 2705 2194
Yupiltepeque Jerez 4522 4620 4837 3950 4362 3971 3606
AVERAGE 4091 3734 3660 3648 3575 3474 2835
Yield data averages showed that H-5 had a 357 Kg/Ha advantage over its
nearest competitor, that all of the hybrids produced more corn grain than the open
pollinated varieties tested, and that the improved variety ICTA B-1 has a greater
yield potential than the open pollinated criolla varieties presently being grown by
Adaptability of the entries to the various climatic and soil conditions also
indicated that H-5 performed better under widely varying conditions than any of
the other entries. H-5 was always one of the higher yielding entries in each of
the twelve test sites. Adaptability of the entries can be estimated from the data in
Table 3 which shows the percentage of total yield of each entry relative to all en-
tries under three different climatic conditions.
PERCENTAGE YIELD OF THE INDIVIDUAL ENTRIES RELATIVE TO
THE YIELD OF ALL ENTRIES UNDER THREE DIFFERENT
DRY HUMID WET
ENTRY CLIMATE CLIMATE CLIMATE
H-5 16.0 16.9% 16.1%
X 105-A 15.5 14.5 14.9
H-3 12.6 14.4 16.1
Tropical 102 15.8 15.0 13.5
X304-A 15.4 13.7 14.0
B-1 14.7 14.3 13.1
Criolla 10.0 11.2 12.3
Relatively, H-5 yielded well under all three conditions of climate. H-3 is
not drought resistant; however it performed equal to H-5 under wet conditions. On
the other hand, ICTA Tropical 102 and ICTA B-1 performed relatively better under
drier conditions. This is probably related to the poor shuck coverage of the ICTA
entries and thus increased head rotting in the field. It is also interesting to note
that the criollas varieties are not resistant to drought as believe by the local farmers.
Rather, they are early varieties that usually tend to escape the drought periods.
The percentages in Table 3 do not appear highly variables until one recalls
that absolute values are seven times the tabular values and that the absolute values
cannot be estimated across the different climatic conditions.
The effect of climate on yields was always positively associated with increased
rainfall. Some effects of climate on yields and increased value of production are
shown in Table 4.
EFFECT OF CLIMATE ON YIELDS OF CORN GRAIN OF
FIVE HYBRIDS AND ONE IMPROVED VARIETY UNDER THREE DIFFERENT
CLIMATES AND THE CONCOMITANT EFFECT ON VALUE OF PRODUCTION
DRY AVERAGE HUMID
CLIMATE CLIMATE CLIMATE
X Yield of Entries (Kg/Ha) 2885 3739 4467
% Increase 29.60% 54.84%
Value of Increase Q.131.52 Q243.63
Climate is probably the one factor most limiting production in the Oriente and
is evident in this series of variety tests. The local criolla varieties produced as much
corn grain under the humid climatic conditions as the hybrids did under the average
climatic conditions and considerably more than the hybrids under dry climatic con-
Since H-5 proved to be not only the highest yielding entry, but also the most
adaptable to the entire region, a partial economic analysis was performed to estimate
the value of use of this hybrid in relation to the other entries. This data is shown in
INCREASED VALUE OF PRODUCTION OBTAINED BY THE USE
OF THE HYBRID H-5 RELATIVE TO THE OTHER CORN ENTRIES
Entry Production Value of Cost of Comparable
Kg/Ha Production Seed/Ha Value Q/Ha
H-5 4091 630.01 14.30 615.71
X 105-A 3734 575.04 14.30 560.74 54.97
H-3 3660 563.64 14.30 549.34 66.37
Tropical 102 3648 561.79 8.04 553.75 61.69
X 304-A 3575 550.55 14.30 536.25 79.46
B-1 3474 535.00 6.08 528.92 86.79
Criolla 2835 436.59 2.50 431.09 84.62
Data from Table 5 shows that the hybrid H-5 produced corn having a value of
Q54.97 more per hectare than X 105-A,Q66.37 more than H-3, and Q184.62 more
than the criolla variety. All comparisons are shown in Table 6 and are expressed as
INCREASED VALUE OF PRODUCTION OF EACH ENTRY
RELATIVE TO THE OTHER ENTRIES IN THE TEST
B-1 22.7% 3-1
X 304-A 24.4% 1.4% X 304-A
H-3 27.4% 3.9% 2.4% H-3
Trop 102 28.4% 4.7% 3.3% 0.8% TROP-2
X 105-A 30.1% 6.0% 4.6% 2.1% 1.3% X 105-A
H-5 42.8% 16.4% 14.8% 12.1% 11.2% 9.8%
Since the target population is the medium and small sized farm unit, capital
is generally the factor most limiting; thus, the farmer should invest where he will
get the greatest return per unit invested. Table 7 shows the benefit cost ratios for
some of the various alternatives that the farmer might choose.
- 21 -
BENEFIT CDST RATIOS THAT CAN BE DERIVED FROM
ACCEPTION OF ALTERNATIVE CORN VARIETIES
Difference Difference in
in value of Seed B : C
ALTERNATIVE Production COST Ratio
H-5 vs Trop-102 61.96 6.26 9.90
H-5 vs B-1 86.79 8.22 10.56
Trop-102 vs B-1 24.83 1.96 12.67
H-5 vs Criolla 184.62 11.80 15.65
Trop-102 vs Criolla 122.66 5.54 22.14
B-1 vs Criolla 97.83 3.58 27.33
H-5 vs X 105-A 54.97 0
- 22 -
If capital is almost non-existent, then ICTA B-1 would be an alternative
choice over H-5, but it will cost the farmer 16.4% in profit relative to H-5 or
$86.79 per hectare.
1. H-5 is the highest yielding and the most adaptable of all of the entries tested
in these experiments. This increased yield can be attributed to lower plant
mortality and more grains per ear which maintain an average size.
2. Pioneer X 105-A was the second highest yielding entry. This hybrid showed
the tendency to produce more than one ear per stalk and an average number of
grains; however, the grain size was considerably smaller than the other entries.
3. H-3 was the most variable entry in the tests. This hybrid performed very well
under favorable climatic conditions, but shows little resistance to advserse
conditions. It is probably the best entry for planting with beans in the areas
of Atescatempa and Yupiltepeque Jerez during the first growing season.
4. ICTA Tropical 102 performed well under dry climatic conditions, but was not
well adapted to the wet areas. Poor shuck coverage permitted many ears to rot
before they were harvested. This hybrid should be recommended only for special
5. Pioneer X 304-A is a yellow seeded hybrid and shows no distinct yield advan-
tage. Under the conditions of these yield tests it produced very small ears and
will not be recommended for the pilot region.
6. ICTA B-1, the only open pollinated improved variety, yielded less than any of
the hybrids, but significantly better than the criolla varieties. Its greatest
drawback is the tendency to produce barren stalks. It will be recommended to
replace the criolla varieties for those farmers who do not wish to plant hybrids.
NITROGEN RATE AND TIME OF APPLICATION
STUDIES IN CORN
That corn needs nitrogen is probably the most proven fact in the field of Agronomy.
Yet, year after year studies continue on nitrogen fertilization of corn.
Not only does the response of corn to nitrogen applications vary with climate,
but also, to the levels of technology being applied. Thus, the introduction of a hybrid
with improved yield potential, or a more effective control of weeds and insects are re-
flected in responses to increased levels of nitrogen fertilization.
There is a paucity of data concerning nitrogen fertilization of corn in the Oriente.
The purpose of this study was to determine (1) the response of corn to nitrogen applicat-
ions under medium levels of management as are practical, or possible for the medium or
small farm unit in the Oriente; (2) the best method of applying this fertilizer; and (3)
how the fertilizer practices affect corn yields components.
All experimental plots were treated as given in the general plan with the ex-
ception of 15 nitrogen treatments which were applied as shown in Table 8.
KILOGRAM PER HECTARE OF NITROGEN APPLIED
TO CORN UNDER A REGIME OF FROM 1 TO 5
Overall NUMBER OF APPLICATIONS
Rate (Kg/Ha) 1 2 3 4 5
30 30 15 -
45 45 22.5 15 -
60 60 30 20 15
75 75 37.5 25 18.75 15
This regime allows for the study of 0,30,45,60 and 75 kilograms per hectare
of nitrogen in either one or two applications and 0,45,60, and 75 kilograms per hec-
tare of nitrogen in three applications. In addition, the effects of multiple applications
of lesser quantities within individual overall rates can be studied. Finally, it is pos-
sible to determine if applications can be substituted for nitrogen.
Table 9 shows the yield responses of corn grain corrected to 13% moisture for
the nitrogen tests in six municipios of Jutiapa. With the exception of Asunci6n Mita,
all of the experimental sites were highly responsive to nitrogen fertilization. Asun-
ci6n Mita was significant at the ten percent level by the F test.
CORN GRAIN YIELD (Kg/Ha) RESPONSES TO RATES
AND TIMES OF NITROGEN APPLICATIONS IN SIX MUNICIPIOS IN
JUTIAPA CORRECTED TO 13% MOISTURE
Overall Number of Agua Asunc. Atesca- El Yupil-
Rate Applic. Blanca Mita tempa Progreso Jerez tepeque Average
1) 0 0 2732 3036 1638 3316 2189 2577 2581
2) 30 1 4736 3294 3598 4529 4693 3838 4115
3) 30 2 3906 3080 3871 4407 4001 4223 3915
4) 45 1 4050 2876 4861 5590 4702 4742 4470
5) 45 2 4983 3566 3780 3842 4674 5140 4331
6) 45 3 4202 3064 4324 4760 4596 5058 4334
7) 60 1 4498 3833 4949 4988 4804 5313 4731
8) 60 2 4602 3711 4250 4640 4983 5281 4578
9) 60 3 4710 3632 5058 4861 5842 5662 4961
10) 60 4 5010 3174 5505 3338 5380 5338 4958
11) 75 1 4591 3970 5283 4764 5009 5516 4856
12) 75 2 4673 3656 5281 4958 5953 5512 5006
13) 75 3 4808 3492 5452 4820 5487 5393 4909
14) 75 4 4970 4046 5315 4805 5520 5752 5068
15) 75 5 4811 3666 5145 4987 6040 5738 5064
Table 10 presents the statistical values of the F test for the various sub-treat-
ments discussed in the paragraph above.
F VALUES FOR CORN GRAIN YIELD RESPONSE TO NITROGEN
RATES AND APPLICATIONS IN SIX EXPERIMENTAL SITES
Sub- Agua Asunci6n Atesca- El Yupilte-
Treatment Blanca Mita tempa Progreso Jerez peque
All rates in :
1 Application 9.16** 3.17 16.92** 9.30** 19.19** 30.60**
2 Applications 6.90** 1.21 17.30** 5.01* 29.6** 16.87**
3 Applications 25.17** 2.76 26.29** 3.44* 23.26** 3.80**
45 Kg rate 2.26 2.90 5.48* 7.73* .05 .82
60 Kg rate .54 1.43 4.50* .59 2.68 .69
75 Kg rate .54 1.89 .06 .06 4.11 .43
Average yield response data of corn to applications of nitrogen are presented in
figure 1. Of particular importance is the initial slope value. Application of 30 kilo-
grams per hectare of nitrogen increased the average corn grain yields 1434 kilograms
per hectare, or 47.8 kilograms of grain for each kilogram of nitrogen applied. Appli-
AVERAGE RESPONSE OF CORN TO NITROGEN APPLICATIONS
IN SIX MUNICIPIOS IN JUTIAPA, GUATEMALA
2.5 "ERTl COST
cation of a second 30 kilograms increased yields an additional 792 kilograms, or
26.4 kilograms of corn grain per kilogram of nitrogen applied. Thus, the first
increment of applied nitrogen is nearly twice as effective as the second increment
for the production of corn grain. From the point of view of total production within
region VI it would be advantageous to obtain as wide a distribution of nitrogen fer-
tilizer as is physically possible. Two quintales of nitrogen fertilizer distributed to
two different farmers will produce 28.84 percent more corn grain than when distri-
buted to only one farmer.
When capital is not limiting, the farmer can apply any of the higher rates
profitably. As can be seen in Table 11, increased profits per hectare from nitrogen
applications range from Q190.57 to Q301.99 and generated a labor income of
Q11.20 to Q18.07 per hectare. Benefit-cost ratios ranged from 4.47 to Q6.30
per quetzal invested when generated labor costs were included and from Q6.94 to
Q10. 86 per quetzal invested when the farmer does not have a direct outflow of cash
PRODUCTION, VALUE, COST OF PRODUCTION, PROFITS AND
BENEFIT-COST RATIOS PRODUCED BY NITROGEN APPLICATIONS TO
CORN IN SIX MUNICIPIOS IN JUTIAPA, GUATEMALA
Value of Cost of Benefit-
Application Production Increased Increased Cost
Rate Increase Production Production Profit Ratio
RETURN TO LABOR & CAPITAL
30 1434 220.84 18.62 202.22 10.86
45 1797 276.74 27.93 248.81 8.91
60 2226 342.80 37.24 305.56 8.20
75 2400 369.60 46.54 323.06 6.94
RETURN TO CAPITAL
30 1434 220.84 30.27 190.57 6.30
45 1797 276.74 43.78 232.96 5.32
60 2226 342.80 56.59 286.21 5.06
75 2400 369.60 67.61 301.99 4.47
Actual production costs for the increased corn grain varied from Q.0130 to
Q.0194 and Q.0211 to .0282 per kilogram for the labor intensive and commercial
Analyzing the data by quadratic regression produced a maximum yield of
4954 kilograms per hectare when 66 kilograms of nitrogen were applied. Most profit
per hectare resulted from an application of 65 kilograms of nitrogen per hectare and
the most efficient resulted from 61 kilograms per hectare (See figure 2).
Based on these data it is suggested that the general fertilizer nitrogen sugges-
tion for the medium and small farm unit in the Oriente be fixed at 60 kilograms per
hectare which is equivalent to 92.4 pounds per manzana or 2 quintales per manzana
Data for the most effective number of applications within the various overall
rates were not as significant as the amount of nitrogen applied. Often, the experi-
mental procedure was not of sufficient precision to statistically measure differences
and the magnitude of the differences were relatively smaller than the nitrogen rate
differences. Nevertheless, since the cost involved was nil to low and a definite
tendency was observed, the data will be treated.
In general, the data indicated that the number of applications giving the better
yield depended upon the quantity of nitrogen being applied and that for the series of
experiments, 1, 2, 3, and 4 applications were superior for the nitrogen rates of 30,
- 32 -
QUADRATIC REGRESSION ANALYSIS OF RESPONSE TO
NITROGEN APPLICATIONS TO CORN IN SIX MUNICIPIOS
IN JUTIAPA, GUATEMALA.
45, 60, and 75 kilograms per Ha., respectively. This tendency is true both for
number of cases and average yields of the series of experiments (See Table 9).
Average yield increases due to applications of the individual rates discussed
in the paragraph above, the value and cost of these corn yield increases, profit
produced, and benefit-cost ratios are presented in Table 12.
AVERAGE YIELD INCREASES DUE TO NUMBER OF
APPLICATIONS OF NITROGEN ON CORN GRAIN YIELDS,
VALUE OF INCREASES, COST OF INCREASES, PROFITS,
AND BENEFIT-COST RATIOS FOR EXPERIMENTS IN SIX
MUNICIPIOS OF JUTIAPA, GUATEMALA
Treatment-Appl. Average Value Inc. B/C
Yield Inc. Cost Profit Ratio
30-1 200 23.08 -1.50 24.58
45-1 139 21.41 -1.75 23.16
60-3 307 47.28 2.00 45.28 22.64
75-4 144 22.18 2.25 19.93 8.86
The general practice in this area is either 1 or 2 applications; however, these
are not applied at planting time. Evidently, about 30 kilograms per hectare of ni-
trogen are required at planting time for efficient growth; however, single applic-
ations of either the 60, or 75 kilogram per hectare nitrogen rates were detrimental
to plant growth as evidenced by reduced plant populations.
It is doubtful if the farmers will apply fertilizer four times; however, three
applications probably will be accepted. Benefit cost ratios indicate that increased
number of applications should be encouraged when higher nitrogen rates are used.
It was hoped that the farmers could substitute labor for fertilizer by increasing
the number of applications of a lesser quantity of nitrogen. In general, this is not
the case. The 15 kilogram per hectare increase in nitrogen applied produced a lar-
ger increase in corn grain yield than the number of applications. It is possible that
at rates of nitrogen higher than used in these experiments this could prove true, as
we can see in Table 13; the yield differences tend to decrease with increasing ni-
CORN GRAIN YIELDS (Kg/Ha) FROM VARIOUS RATES
AND NUMBER OF APPLICATIONS IN SIX MUNICIPIOS
IN JUTIAPA, GUATEMALA
30 Kg/Ha v45 Kg/Ha 45 Kg/ha v 60 Kg/ha 60 Kg/Ha vs75Kg/Ha
Location 2 Appl. 1 Appl. 3 Appl. 2 Appl. 3 Appl. 2 Appl.
Agua Blanca 3906
Atescatempa 3871 4861 4324 4250 5058 5281
Asunci6n Mita 3080 2876 3064 3711 3632 3656
El Progreso 4407 5590 4760 4640 4861 4958
Jerez 4001 4702 4596 4983 5842 5953
Yupiltepeque 4223 4742 5058 5281 5662 5512
Average 3913 4410 4315 4581 4925 4958
A 497 266 33
Yield component factors, shown in Table 4 indicate that 30 kilograms per hec-
tare of nitrogen is sufficient to stabilize the plant population; that 60 kilograms per
hectare stabilizes the number of ears per plant; but that 75 kilograms per hectare con-
tinues to increase the number of grains per ear and also the size of the grain. Nitrogen
fertilization in these experiments was most effective in increasing the number of grains
per ear and in decreasing the number of plants which did not produce ears.
COMPONENT OF YIELD FACTORS FOR NITROGEN
RATE AND TIMES OF APPLICATION TO CORN IN SIX EXPERIMENTS IN
Fertilizer Rate Number of Number of Number of Weight of
Kg/Ha "N" Plants per Ears per Plant Seeds per each Seed
0 .954 .826 .450 .896
30 .982 .941 .662 .880
45 .986 .949 .705 .882
60 .083 .971 .746 .923
75 .983 .971 .772 .939
Based on these data we are still 30.8 percent short of our goal of 6840 kilograms
per hectare of corn grain. Efforts must be directed toward increasing the number of grains
per ear and toward grain size. In the variety trials the hybrid H-5 produced 13 percent
more grains per ear than did the hybrid used in these experiments (H-3) without a decrease
in grain size and this should change the component product deficit from 30.8 to 25 percent.
Undoubtedly, component of yield factors for other agronomic practices will decrease this
value even more, but it is felt that better control of soil moisture and new hybrids
will probably be required to reach the present goal of zero deficit and still maintain
an economic advantage.
PLANTING RATE STUDIES IN CORN
The number of seeds to plant per unit area of land is a yearly problem for the
farmer. He most contend with the germination percentage of the seeds, insects damages
to the seeds while they are in the soil before germination and seed rots. In addition he
knows that losses of young plants will occur from seedling rots and insect damage. In
the older plants losses will occur due to the fall army worm, stalk borers and diseases
such as common smut and ear rots, especially Diplodia zea in the Oriente.
The situation is further complicated by the weather. If he plants a high popular -
tion to overcome the above stated losses and the weather turns dry, there will not be suf-
ficient moisture to develop the existing plants. Thus, he must try to obtain a population
of corn plants that not only takes all of these factors into account, but also considers the
management practices at his disposal.
The purpose of this series of experiments was to evaluate the factors affecting
yield in relation to seeding density and determine desirable seeding densities under con-
ditions of the medium and small sized farm unit.
Three initial corn populations of 30,000 ; 40,000; and 50,000 plants per hec-
tare were employed.
Yield data shown in Table 15 indicates that 40,000 plants per hectare were su-
perior to either 30,000 or 50,000 plants per hectare; however, these data cannot esti-
mate the effect of intermediate populations on yield.
CORN GRAIN YIELDS (Kg/Ha CORRECTED TO 13% MOISTURE)
PRODUCED BY THREE INITIAL CORN POPULATIONS
IN THREE MUNICIPIOS IN JUTIAPA, GUATEMALA
Original Santa Catarina Agua El
Population Mita Blanca Progreso Average
30,000 2873 4710 3927 3837
40,000 3820 5232 3922 4325
50,000 3946 4660 3773 4126
Yield component factors were used to graphically determine the effect of inter-
mediate populations by the following method.
1. Multiplying the yield component factors number of plants per hectare by number
of ears per plant gives the number of ears per hectare.
2. Multiplying the yield component factors grains per ear by average weight of each
grain gives the average weight of grain on each ear.
3. The values derived in 1 and 2 above were plotted graphically and intermediate va-
lues obtained from each curve.
4. The product derived by multiplying the intermediate values of number of ears per hec-
tare by the average weight of grain per ear produces the relative yield value which
can be converted to the real yield by multiplying by 6840.
5. Averaging the yield component factors from several experiments will generally pro-
duce a relative yield value plateau where yield component factor product differen-
ces are minimized and yields should be maximized.
Values for the yield component factors derived from the experiments are shown
in Table 16 and again the major factor limiting yield is the average number of seeds
per ear. Increasing the population from 30,000 to 50,000 plants per hectare drops the
average number of seeds per ear fifteen percent and causes a six percent decrease in
grain size. However, a thirty-four percent increase in the number of ears harvested
per hectare indicates the need to seed the maximum number of plants that the soil and
moisture availability permit.
YIELD COMPONENT FACTORS DERIVED FROM CORN POPULATION
STUDIES IN THREE MUNICIPIOS IN JUTIAPA, GUATEMALA
Number of Number of Number of Grains Weight of
Population Plants/Ha Ears per Stalk Per Ear each Grain
Santa Catarina Mita
30,000 .764 1.048 .548 .954
40,000 1.076 .966 .555 .966
50,000 1.076 1.109 .527 .916
30,000 .885 1.008 .837 .962
40,000 1.076 .966 .795 .923
50,000 1.190 .895 .703 .906
30,000 .981 .944 .643 .962
40,000 1.003 .941 .632 .959
50,000 1.286 .980 .493 .886
Average All Three Municipios
30,000 .877 1.000 .676 .959
40,000 1.052 .958 .661 .949
50,000 1.184 .995 .574 .903
Figure 3 shows the graphical representation of the number of ears per hectare
and the average weight of grain per ear for the combined experiments and Table 17
gives the relative yield values at populations between thirty to fifty thousand.
RELATIVE YIELD VALUES DERIVED FROM THREE CORN
POPULATION STUDIES IN THREE MUNICIPIOS IN JUTIAPA
Santa Agua El Progreso
Population Catarina Blanca Average
30,000 .419 .718 .573 .567
32,000 .451 .740 .563 .582
34,000 .481 .754 .561 .596
36,000 .510 .763 .562 .609
38,000 .536 .766* .565 .621
40,000 .557 .763 .572 .629
42,000 .575 .758 .582 .638*
44,000 .588* .747 .590* .640*
46,000 .590* .731 .591* .639*
48,000 .587 .710 .589 .630
50,000 .576 .678 .551 .609
- 42 -
FIGURE 3. YIELD COMPONENT PRODUCTS DERIVED FROM THREE CORN
POPULATIONS IN THREE MUNICIPIOS IN JUTIAPA, GUATEMALA.
PLANTS SEEDED PER HECTARE (X 1,000)
30 40 50
- 43 -
The data from Table 17 suggests several things. First, note the data from
Agua Blanca which suggests that at higher yield levels the extra plants must be fed.
Number of stalks increased 33.7 percent from 30 to 50 thousand initial plants, but
ears per stalk, seed per ear and seed weight decreased 11.2, 16.0, and 5.8 percent,
respectively; while, yields remained about the same and the high yield was produced
with 38,000 plants initial population. This field lost some of its yield potential by
the time it was four to six weeks of age.
Second, the fields in Santa Catarina Mita and El Progreso were grown under
less favorable climatic conditions, but still responded to populations up to 44-46
thousand plants per hectare. These trials were conducted using the hybrid H-3 and
data from the variety trial work (see Table 3) indicates that H-3 isn't especially adapt-
ed to dry climatic conditions and that any of the other varieties or hybrids tested would
stand the conditions under which these tests were performed better than H-3.
The existence of the relative yield value plateau for the average of the three
tests suggests an initial population of 44,000 plants per hectare. Thus, on deep soils
with average or better water holding capacity and average (60 Kg/Ha "N") or better
nitrogen fertilization it is recommended that the farmer plant in rows 90 centimeters
wide with a spacing of 25 centimeters between plants. This will produce an initial
population of 40 44,500 plants depending upon seed germination percentage. On
shallow soils, soils with low water holding capacity, or low fertility, increase the
plant spacing to 30-35 centimeters.
METHOD OF PLANTING CORN
Nearly all farmers in the Oriente plant corn by hand and all have one thing
in common planting in hills because it is easier and faster; however, it is not
better or even equal to single plant seedings.
In all of the experiments executed this year, it is seen that the yield component
factor most limit ing for yields was number of seeds per ear. It can also be seen
from the population studies that seeds per ear were low even at the lesser populations
and that seed per ear deficits increased with population increases. Thus, it seemed
reasonable to assume that the factor would be even more predominant in multiple
seed per hill plantings. In addition, compensation for lost plants should be much less
when seeding in hills.
This preliminary experiment was carried out cooperatively with the grain sorghum
program in the production center in Jutiapa. It consisted of surveying the planting
system experiment of that program for missing plants in hills from the varying system and
tagging the hill with the missing plant as well as the neighboring hills. Three adja-
cent complete hills in the same plot were tagged simultaneously. The three hill plots
were harvested separately for analysis.
Data was obtained on seeding of one, two, and three plants per hill and will here-
inafter be denoted as 1-1-1, 2-2-2, and 3-3-3 respectively. In like manner, 1-0-1,
2-1-2, and 3-2-3 denotes that one plant was missing from the center hill.
- 45 -
Since nine plants make up an experimental unit for the 3-3-3 planting system,
the data for the other two systems was adjusted to nine plants to allow comparisons.
This data is shown in table 18.
DATA ON NINE EAR COMPARISONS FOR CORN GROWN
UNDER THREE PLANTING SYSTEMS
Weight of Loss due to % Loss Due % Loss % Loss due
Grain in Plot Missing ear To Missing Relative to To system+
Treatment (gms) (gms) ear 1-1-1 System Missing
1-0-1 1342.0 113.3 7.78
2-2-2 1385.1 4.82 9.37
2-1-2 1216.2 168.9 12.19
3-3-3 1171.8 19.48
3-2-3 1042.4 129.4 11.04 22.32
First let us look al the effect of the three systems on yields. Again we note that
the 1-1-1 system is the more productive, yielding 4.82 and 19.48% more grain than
the 2-2-2 and 3-3-3 system, respectively.
Second, let us look at the affect of missing plants on yields within the three
planting systems. We note that there is less compensation for lost plants where higher
numbers of plants are seeded in each hill. Since two component yield factors number
of plants per hectare and number of ears per plant were fixed, it is obvious that this
- 46 -
reduction must come from either less seed per ear, or size of the seed. Data in table
19 shows that the loss of a plant from a hill increases the number of seeds per ear in
the remaining hills and that the seed size increased for single spaced plants, but
decreased when several plants were seeded in the same hill.
Finally, combining both system and plant loss it was found that at a plant loss
rate of one plant in nine (11.1%) individually seeded corn yields 9.37 and 22.32
percent more than corn seeded either two or three plants to the hill.
YIELD COMPONENT FACTORS FOR CORN GROWN UNDER THREE
SYSTEMS WITH AND WITHOUT PLANT LOSSES
NUMBER OF SEED PER EAR WEIGHT OF SEED REL.
Ears from Individual Nine Ear Ear from Indiv. Nine ear YIELD
Hills Plot Hills Plot VALUE
1-1-1 .938 .957
.960 993 .953
1-0-1 1.026 1.007
2-2-2 .860 .993
.863 .983 .848
2-1-2 .867 .967
3-3-3 .758 .953
.780 .930 .725
The overall affect on grain yield showed a decrease in both the number of seed
per ear and weight per seed and relative yield values of .953, .848, and .725 for
the 1-1-1, 2-2-2, and 3-3-3 systems, respectively. Where possible, the farmer
should consider single spaced plants. Two plants per hill would be the second best
alternative, followed by three and then four plants per hill.
PLANTING DATE STUDIES IN CORN
The general practice in the Oriente is to seed corn at the beginning of the
rainy season; however, some farmers plant in dry soil and await the first rains for ger-
mination of the seed. When climatic conditions are favorable, little difference is noted;
however, quite often the first rains of the season are followed by a dry spell that is of
approximately ten days to two weeks duration. Early planting under these conditions
should reduce yields. Very late plantings also either yield less than normal plantings,
or interfere with the second cropping cycle. For this reason a terminal planting date
of June 10th was suggested to all programs operating in the Oriente.
Results of the planting date studies can be seen in Table 20. In one case,
Atescatempa, the early planting was superior; however, in the other three experiments
later planting dates proved to be superior. It should also be noted that a sharp decline
in yields occurred after the June 6 planting date. There is no one best planting date as
it varies from region to region and year to year; however, under the growing conditions
of Guatemala it is very important for high yields that a plant never stops growing at a
rapid rate. For this reason, it is suggested that planting corn in the Oriente not be
initiated until the soil has been wet to a depth of 50 centimeters. In the soils having
a depth of less than 50 centimeters it is advisable to wait until the rainy season is de-
finite. This is one reason many of the farmers plant criolla varieties. If they plant
late they must use an early corn or suffer yield losses in the second growing season.
CORN GRAIN YIELDS (Kg/Ha) CORRECTED TO 13% MOISTURE
OBTAINED FROM 5 PLANTING DATES IN FOUR MUNICIPIOS IN
Agua Asunci6n Atesca- El
Seeding Date Blanca Mita tempa Progreso Average
16 May 1552 4253 3952 2698 3114
23 May 2356 4938 3509 2668 3368
30 May 2630 4965 3232 2780 3402
6 June 1847 4782 3264 3009 3225
13 June 136 2108 1582 2935 1690
The improved varieties and hybrids usually mature adequately in 100-110 days
to permit doubling in the field. The criollas can be doubled in 88-95 days. By using
the early dwarf criollas the farmer can gain 5-22 days for use by the second crop. Ge-
nerally, the rainy seasons commences around November 15; thus, the farmer has about
180 days in which to grow two crops. Rainfall in the second growing season is not well
distributed especially after the 20th of October. If the farmer is three weeks late in
planting his first crop of corn, then the later maturing hybrids may actually require 131
of the 180 growing season days and leave only 49 days of rain for the second crop.
CUADRATIC REGRESSIONS CURVES OF CORN GRAIN YIELDS
SEEDED ON FIVE DATES IN FOUR MUNICIPIOS iN JJTIAPA,
43 cm. depth
16 23 30 6
DATE OF SEEDING
50 cm. depth
DATE OF SEEDING
13 16 23
DATE OF SEEDING
DATE OF SEEDING
There are two approaches to solving this problem, (1) is to develop a higher
yielding early variety for the region or (2) conserve more of the early rainfalls in the
soil by permitting less runoff through the use of conservation practices. Both alterna-
tives are feasible and both can help fill a need.
- 52 -
WEED CONTROL IN CORN
Weed control is one of the more important cultural practices in any dry region,
yet it often does not receive recognition for its importance in the Oriente of Guatemala.
Many farmers weed their corn fields only one time during the growing season, usually 21
to 28 days after planting and all is done by hand. The use of herbicides is practically non-
existent in the region. There is a definite labor shortage during this period and it is dif-
ficult for the farmers to maintain control of the weeds. In these two preliminary experi-
ments the purpose was to obtain estimates of the effect of weeds under conditions of the
medium and small farm units and to evaluate the need for more intensive studies.
Data for these two tests are shown in Table 21. In these tests, the plots were
weeded 7, 14, 21, and 28 days after seeding. In addition one treatment was maintained
weed free while in another the weeds were not controlled.
EFFECT OF WEED CONTROL ON YIELDS OF CORN GRAIN
IN TWO MUNICIPIOS IN JUTIAPA, GUATEMALA (Kg/Ha 13% MOISTURE)
Treatment Agua Blanca Yupiltepeque Average
Clean after 7 days 4320 2596 3458
Clean after 14 days 5290 3266 4278
Clean after 21 days 5127 5355 5241
Clean after 28 days 4882 5380 5131
Maintain weed free 5412 5891 5654
Don't clean weeds 4502 2450 3476
If only one weeding is to be done, it should be accomplished about 21 days
after seeding; however, this is not the best method. Two cleaning were basically re-
quired to maintain the fields fairly weed free and the difference in yield of corn grain
was 413 kilograms per hectare. At present market prices, this grain is equivalent to
an increased value of Q63.60 per hectare. Where possible labor should be employed
to clean the corn fields at least twice. It would also be advantageous to study an
integrated weed control system employing both herbicides and manual labor.
CONTROL OF SOIL INSECTS IN CORN
Another question for which data was lacking, but which required an answer
concerned the advisability of applying a soil insecticide in the Oriente. Discussions
with public sector agricultural technicians and farmers produced mixed opinions.
There are known areas in the Oriente where soil insecticide applications are
a must for profitable crop production; however, should soil insecticides be a general
recommendation for the area? A series of experiments were executed to study this pro-
blem. The results are shown in Table 22.
CORN GRAIN YIELDS FROM PLOTS WITH AND WITHOUT
SOIL INSECTICIDES APPLICATIONS IN SEVEN
MUNICIPIOS IN JUTIAPA, GUATEMALA
YIELD IN Kg/Ha 13 MOISTURE
MUNICIPIO CHECK CYTROLAN E VALEXON
Agua Blanca 2585 2678 2611
Asunci6n Mita 1758 1568 1410
Atescatempa 5945 5165 5266
El Progreso 5275 5220 5433
Jerez 3770 3945 4160
Santa Catarina Mita 1959 2323 1676
Yupiltepeque 4337 4250 4652
AVERAGE 3661 3594 3601
Of these seven tests, only two Atescatempa and Jerez were significant
and one of these produced a positive effect while the other was negative. Similar
results were obtained with beans. Thus, it would seem that treatment of the soil
with an insecticide should not be recommended as a general practice. Soil insec-
ticides should be recommended only when the past history of the field indicates the
need, or when insect counts within a square meter of soil exceed six in number.
RECOMMENDED CORN PRODUCTION PRACTICES FOR THE ORIENTED
The following corn production practices are recommended for the Oriente.
They are based on research results and have been integrated into the existing farming
systems to produce a minimum of change to the existing systems. Alternative choices
are included where possible; however, unless otherwise stated each succeeding alter-
native is less desirable than the proceeding one.
Corn Variety Selection
Recommendation: The highest yielding and most adaptable corn for the Oriente is
H-5. It is taller and 5-10 days later than H-3. In the more humid regions such as
Atescatempa, Yupiltepeque and Jerez, H-3 is equal to H-5 when grows on deep soils
with good water holding capacity. The hybrid H-3 is also more desirable for inter-
planting with beans in the humid areas mentioned above.
1st. Alternative: Pioneer X 105-A can substitute for H-5 in the drier areas such as
El Progreso, Santa Catarina Mita, Asunci6n Mita and Agua Blanca. For interplanting
with beans in the above named areas ICTA B-1 is suggested. ICTA B-1 is similar in
characteristics and maturity to H-3. ICTA B-1 should also serve for those farmers who
will only plant an open pollinated variety.
Recommendation: Single, spaced plants are desirable, especially if the farmer intends
to apply a high level of technology. There is less competition between plants and the
spaced plants compensate more for skips or plant losses.
- 57 -
1st. Alternative: The first alternative is hill dropped corn with two plants per hill.
Three or more plants per hill is not recommended for the Oriente.
Recommendation: For the more humid areas such as Yupiltepeque, Jerez and Atesca-
tempa and in other municipios of the region when the soils are deeper than 70 centi-
meters and have a good water holding capacity, the better seeding rate is 44-45,000
plants per hectare. This can be accomplished by seeding single spaced plants 25 cen-
timeters apart in rows 90 centimeters wide.
1st. Alternative: For soils of less than 50 centimeters depth in the humid regions or
less than 70 centimeters depth in the more dry region, or sandy soils with low water
holding capacity, the population should be reduced to 38,000 40,000 plants per
hectare. This population can be obtained in 90 centimeter rows by increasing single
plant spacing to 30 centimeters.
Recommendation: Maintain the fields free of weeds. Clean the fields twice starting
12 to 14 days after seeding and again 25-30 days after seeding. Fields with high weed
populations may require three weedings. Consider using a herbicide when labor is in
short supply if the rotations permit. Don't allow weeds to go to seed and reinfest fields.
1st. Alternative: Cultiva or weed the corn 21-25 days after seeding and when hilling
at 40 days.
Control of Soil Insects
Do not apply a soil insecticide unless the field has a past history of insect damage or
unless there are at least 6 damaging insects per square meter to a depth of 20 centi-
Aldrin, cytrolane, and valexon used according to manufacturers' directions will ef-
fectively control soil insects where necessary.
Recommendation: In general, 60 kilograms per hectare of nitrogen will be profitable
in most cornfields in the Oriente and is the base recommendation for the area. Nitro-
gen responses are closely related to good management practices and the better the ma-
nagement, the greater the quantity of nitrogen that can be applied profitably. In
addition, nitrogen fertilization and phosphate fertilization must be considered jointly;
however, since corn utilizes about four parts of nitrogen for each part phosphorus, the
former is generally the more limiting and responses in yield are generally greater to
Take a soil sample for a soil test. If the "P" level is greater than 6 PPM do not apply
a fertilizer containing phosphorus unless one is aiming for very high yields. If the "P"
level is between 3-6 PPM, the first inversion should be in Nitrogen. After reaching
the base recommendation of 60 kilograms per hectare of nitrogen, the inversion should
be equally distributed between nitrogen and phosphorus. If the soil test "P" level is
less than 3 PPM the initial inversion in fertilizer should be equally divided between
nitrogen and phosphorus up to 30 Kg. per hectare each of "N" and "P205", followed
by an additional inversion in nitrogen only, up to a total nitrogen level of 60 kilograms
per hectare. Additional inversions in fertilizer should be equally distributed between
nitrogen and phosphorus.
All phosphorus applications should be applied at or before planting, preferably in a
band to decrease fixation. Nitrogen applications should include at least 30 kilograms
per hectare at planting time. Single applications of 45 kilograms per hectare of nitrogen
were nearly as effective as two applications; however, three applications are superior for
the 60 Kg/Ha rate and above.
For the 60 Kg/Ha rate apply one-half at planting and an additional one-fourth at
25-30 and 45-50 days after planting. For rates above the base rate, apply three-fourths
of the increase to the rate at 25 days after planting and the rest along with base rate at
45 days after planting.
At Planting 25-30 Days 45-50 Days
Base Rate 30 15 15
40 Kg. Extra 0 30 10
100 Kg. Total 30 45 25
Potash fertilization is not recommended for corn production in the Oriente.
STANDARD EXPERIMENTAL PROCEDURES
Black beans, the second most important crop in the Oriente, are the primary
protein source and thus cannot be evaluated on economics alone. However, bean
production is and probably will continue to be a problem in this region.
The climate isn't particularly suited to bean production. Temperatures are
high and beans do not tolerate drought. That beans have been accepted extensive-
ly in this region is probably related to their being a short season crop, usually re-
quiring 80-90 days until harvest.
The level of technology in bean production utilized in the region is rather low
and will be more difficult to increase than in either corn or sorghum. We at ICTA
know what a farmer must do in order to obtain high yields, but we cannot guaran-
tee that high yields will be obtained if he follows our suggestions.
Beans are very sensitive to soil conditions. Often we obtained greater varia-
tion between replications of the same treatment than between treatments.
The Transference of Technology team obtained excellent bean yields throughout
the region; however, we are still not sure that we can duplicate our research respon-
ses in the same fields in another year. Technology exists, but it is in a scrambled
condition and must be partitioned point by point.
To allow for comparisons between experiments within areas and within experiments
- 61 -
between areas, a standardized experimental design was employed. All factors
were held constant throughout the region with the exception of the factor being
studied. These were:
Rows per plot
Length of rows
Soil Insect Control
Foliar Insect Control
2 rows x 5 meters
15 plants per meter
*When soil analysis for "P" was less than 6 PPM, 60 kilograms per hectare of
P205 from triple superphosphate were applied.
- 62 -
BLACK BEAN VARIETY TESTS
There are numerous improved bean varieties produced by the Ministry of Agri-
culture on the Market. Included are Negro Jalpatagua, Jamapa, Turrialba-1,
San Pedro Pinula, Cuilapa-72, and Ipala-72. The bean research program of ICTA
stated that the two latter varieties were being dropped for lack of resistance to
The other varieties were placed in yield tests in the seven municipios of the
pilot region. Results of these yield tests are shown in Table 23.
SEED YIELDS OF FIVE BEAN VARIETIES GROWN IN
SEVEN MUNICIPIOS IN JUTIAPA, GUATEMALA
YIELD OF SEED IN Kg/Ha 13 MOISTURE
Negro Sn. Pedro Local
MUNICIPIO Jalpatagua Jamapa Turrialba-1 Pinula Variety
Agua Blanca 577 654 777 594 660
Asunci6n Mita 518 546 567 426 374
Atescatempa 453 397 428 430 402
El Progreso 226 219 123 181 299
Jerez 717 1118 1230 1090 649
Sta. Catarina Mita 508 480 606 581 553
Yupiltepeque 907 853 1076 583 712
AV ERAG E 558 609 687 555 521
Data on yields of improved black bean varieties for the Oriente are con-
flicting. To interpret the data in Table 23 knowledge of not only the climatic
conditions under which these tests were carried out, but also the relative matu-
rities of the materials are necessary. With regards to the weather, the first 20-
30 days after seeding was dry throughout most of the region. This drought would
have a greater effect on the early varieties such as Negro Jalpatagua and the
local criolla testigos than on the late varieties such as Jamapa, Turrialba-1 and
San Pedro Pinula. Thus, it is more correct to compare among the late varieties,
or between the two maturity groups and the local varieties.
Among the late varieties Turrialba-1 was definitely superior in yield, pro-
ducing average seed yields of 687 kilograms per hectare in comparison with 609
and 555 kilograms per hectare for Jamapa and San Pedro Pinula, respectively.
Likewise, among the earlier varieties, Negro Jalpatagua produced more than the
local criolla varieties; however, it should be stated that the criollas are earlier
than Negro Jalpatagua.
There also appears to be a relation between yield level in general and yield
of the local criolla varieties. The higher the yield level of the experimental site,
the more the advantage of the improved varieties. To study this relation, the
average yield level of each experimental site was determined as the average
yield of all of the improved varieties at each site. This value was then plotted
against the divident obtained by dividing the yield of Turrialba-1 by the local
criolla variety. Turrialba-1 was selected because it was the highest yielding va-
riety in the test. These data are presented in Table 24 and Figure 5.
AVERAGE EXPERIMENTAL SITE YIELDS AND DIVIDEND OBTAINED BY
DIVIDING THE YIELD OF TURRIALBA-1 AT EACH SITE BY THE
YIELD OF THE LOCAL CRIOLLA VARIETY AT THE
SAME SITE (Kg/Ha)
Average Yield at the
Sta. Catarina Mita
Since the criolla actually yielded more at the experimental site El Progreso,
the dividend value was placed at unity in Figure 5.
From these data it is evident that the improved varieties are very sensitive to
growing conditions and it is probable that they actually will yield less than the local
varieties under very unfavorable conditions.
Estimating seed costs of the improved varieties at Q28.00 per quintal and 19.00
per quintal for the local varieties, there is a Q12.87 differential in seed cost per
hectare, or the equivalent of 30.8 kilograms of bean seed per hectare before the
improved varieties offer a profit incentive to the farmer.
FIGURE 5. AVERAGE YIELD OF BEANS AT EACH EXPERIMENTAL SITE
PLOTTED AGAINST YIELD OF TURRIALBA CRIOLLA.
< 400 '/
0 p p
1.0 1.2 1.4 1.6 1.8 2.0
TURRIALBA-1 YIELD TESTIGO YIELD
- 66 -
Based on yields averaged over the seven experimental sites, only Turrialba-1
offered sufficient profit incentive to suggest that it might be acceptable to the farmer.
Turrialba-1 produced Q5.39 for each quetzal invested. All other varieties produced
less than Q2.00 for each quetzal invested.
Turrialba-1 proved superior to the other late varieties and is reported to be
the best variety for the lower altitudes of the Altaplain and Negro Jalpatagua, an
earlier variety has performed well in other years. It is suggested that ICTA produce
these two varieties and discard the rest.
- 67 -
Dates of seeding for beans is very similar to that mentioned in corn. The only
variation being the tendency to seed the beans early even if it means planting in
dry soil and again the farmer shows the preference for early bean varieties; how-
ever, in some years these practices can be detrimental.
Table 25 shows the results of a date of seeding trial in the municipio of Santa
Catarina Mita utilizing the variety Negro Jalpatagua. After the initial rains, there
was a drought for 27 days and this is reflected in the yield data where June 6 gave
the highest yield. Note also the sharp drop between the June 6 and June 13 plant-
ing date. As with corn, beans show a definite decline in yields when seeded after
YIELD OF BEAN SEED PRODUCED FROM FIVE
SEPARATE PLANTING DATES IN SANTA CATARINA MITA
Yield Difference Difference in Value over first
Planting Date Kg/Ha Kg/Ha Percent Seeding date
16 May 602 -
23 May 777 175 -29.07 Q73.15
30 May 1054 452 -75.08 188.94
6 June 1239 637 -105.81 266.27
13 June 724 122 -20.27 51.00
Note also that the yield from the first seeding data is very similar to the yield
from the variety trial for this same municipio. Also note that seeding date as it
reflects climate can increase and/or decrease yields up to 100+ percent. Again
this points out the need of having some measure other than date for determining
when to seed. Soil depth and moisture characteristics appear the most logical.
Based on limited experience it is suggested that the farmer wait until the soil pro-
file has been wet to a depth of 50 centimeters. On soils having a depth of less
than 50 centimeters or very sandy such as the series Suchitan, it is best to wait
until one is sure that the rainy season is definite.
There is always the possibility of encountering a drought period called the
Canicula which often occurs between the middle of July to the middle of August.
If late bean seedings will be in bloom during this period the farmer should consider
an alternative crop such as grain sorghum, broom corn, or possibly soybeans if a
market is secured or the soybeans can be marketed through animal feed.
Due to the drought patterns in the Oriente, it is not the ideal area for bean
cultivation. Beans are predominant in this area due to harvest date and less inci-
dence of bacterial and fungal diseases; however, it is possible that the insect trans-
mitted virus diseases may make the Oriente unsuitable for economic bean culture,
especially during the second growing season.
The recommendation of the bean research program for seeding rates in the first
growing season is to plant in 45 centimeter rows with 15 plants per linear meter.
The farmers usually plant in rows which vary in width from 40 to 50 centi-
meters. However, there is little agreement among the farmers concerning spacing
between plants or hills. Since nearly all beans are planted by hand, any increase
in planting rate requires not only the additional seed, but also the extra time to
plant. Time for the small farmer is critically limiting during planting season.
Four experiments on populations were seeded in the municipios of Asunci6n
Mita, Atescatempa, Santa Catarina Mita, and Yupiltepeque. Spacing was fixed
at 45 centimeters between rows and plant spacings were varied from 10 to 20 plants
per meter of row. Results obtained from these plantings are shown in Table 26.
EFFECT OF PLANT SPACING ON BEAN YIELDS (Kg/Ha) IN
FOUR EXPERIMENTS SEEDED IN THE ORIENTED
10 Plants 15 Plants 20 Plants
Location Per meter Per meter Per Meter
Asunci6n Mita 1412 1089 1174
Atescatempa 573 518 503
Sta. Catarina Mita 699 972 801
Yupiltepeque 1419 1448 1474
AVERAGE 1026 1007 988
For the area in general, there appears to be a tendency toward slightly higher
yields with the lower planting rate; however, this could readily be a climatic effect
for this season. There is also a tendency for higher populations to be the more pro-
ductive in areas receiving more rainfall. This would be expected, within limits.
However, when we consider that 65 kilograms of bean seed are required to plant
one hectare of beans when 15 seeds are planted per meter, increasing of seeding
rate of 20 plants per meter consumes about 24 kilograms of the commercial beans
produced just to pay for the seed. Increased planting costs can easily consume
another 12 to 15 kilograms per hectare, and if the weather is dry yields can be
reduced (see Atescatempa data).
Thus, it appears that in the areas that usually receive more rainfall the bet-
ter recommendation would be for 15 plants per meter except on the deep sandy
soils with low moisture holding capacity where ten plants per meter appear to be
indicated. In the drier areas within the region ten plants per meter of row ap-
pears best in general. Deep rich alluvial soils with high water holding capacity
could support 15 plants per meter.
NITROGEN FERTILIZATION OF BLACK BEANS
Nitrogen fertilization of black beans is somewhat of an enigma. Being a legume,
beans can utilize atmospheric nitrogen. In addition beans and their associated nitrogen
fixing bacteria can use either residual soil nitrogen, or applied fertilizer nitrogen. The
fixation of atmospheric nitrogen is related generally to the quantity of residual and/or
applied nitrogen, decreasing with increasing nitrogen levels in the soil. The levels of
plant available nitrogen in the soil are also in a constant flux being subject to uptake
by plants, fixation in the process of organic decomposition, loss from the soil profile by
leaching, and several other minor loss mechanisms.
In addition, there are variations in soil conditions which inhibit or enhance
nitrogen fixation by the bacteria. These include the soils acidity or alkalinity, aeration,
moisture content and nutrient status, and a host of other physical and chemical charac-
Third, there are the plant-symbiotic organism interactions. Not all strains are
equally effective in fixing atmospheric nitrogen. It is equally certain that not all host
varieties are equally effective in producing conditions favorable for the nitrogen fixing
Finally, there are all the climatic conditions and management factors which affect
the response of any crop to fertilizer applications.
- 72 -
Thus, just as there is no one variety suitable for all conditions, there will not
be one fertilizer recommendation that fits the requirements for all bean fields in the
Consider the data shown in table 27. The only thing is clear is that the three
experiments responded to nitrogen applications. The proper amount to apply, or how
to apply the nitrogen varies in each site and cannot be measured statistically utilizing
the existing technology under growing conditions experienced by the medium or small
The differences between the average bean yields for the plots receiving no
fertilizer and the average bean yields for the highest yielding plots receiving fertilizer
were 240, 247, and 489 kilograms per hectare for the experiments in Santa Catarina
Mita, Jerez, and Yupiltepeque, respectively; while the variation in yields within the
plots not receiving fertilizer were 458, 572, and 393, respectively. Thus the variation
within measured units is usually equal to or larger than the differences between the
treatments which we are trying to measure.
Average yield levels of all plots making up the experiments were 776, 1599,
and 1462 kilograms per hectare for Santa Catarina Mita, Jerez, and Yupiltepeque,
respectively. The yield at Santa Catarina Mita is excellent when viewed in terms of
growing conditions this year, and the yields at Jerez and Yupiltepeque are excellent
for any location during any year. Yet, with the high degree of variability it is not
certain that the results can be repeated on the same fields another years.
- 73 -
YIELD RESPONSE OF BLACK BEANS TO RATES AND
TIMES OF APPLICATION OF NITROGEN IN THREE
MUNICIPIOS IN JUTIAPA, GUATEMALA
Yield in Kg/Ha 13% Moisture
Total Quantity Number of Santa
of Nitrogen Applications Catarina
applied Yupiltepeque Mita Jerez Average
0 0 1237 618 1537 1131
30 1 1505 653 1681 1280
30 2 1303 656 1682 1214
45 1 1554 741 1518 1271
45 2 1426 858 1681 1322
45 3 1726 696 1616 1346
60 1 1418 806 1478 1234
60 2 1281 847 1667 1265
60 3 1483 773 1648 1301
60 4 1565 757 1346 1223
75 1 1629 730 1630 1330
75 2 1715 736 1784 1412
75 3 1245 794 1760 1266
75 4 1647 886 1355 1296
75 5 1208 1004 1597 1270
As a researcher, I am reluctant to treat these data further; however, as regional
coordinator of the Oriente charged with proving technology and suggesting crop pro-
duction practices for the region it becomes a must; thus the following treatment of the
data is presented.
One experiment responded to nitrogen applications up to 30 kilograms per hectare,
the second to 45 kilograms per hectare, and the third to 75 kilograms per hectare. Av-
erage response over all applications indicated the 45 kilograms rate gave the highest
yields. Evaluating yields based both on quantity of nitrogen applied an number of appli-
cations showed the following practices to be the more efficient.
1) 3 applications 45 Kg/Ha = 1346 Kg/Ha seed
2) 2 applications 45 Kg/Ha = 1322 Kg/Ha seed
3) 1 application 30 Kg/Ha = 1280 Kg/Ha seed
Average yield for the plots not receiving nitrogen was 1131 kilograms per hectare.
Nitrogen cost was estimated at Q.63 per kilogram (Urea at Q. 13.oo/qq). Application
cost was estimated at Q.2.oo per application per hectare. Beans were valued at Q19.00
per quintal. No costs were charged to harvesting or marketing. Based on these estimates
the data in table 28 was calculated.
ESTIMATES OF PRODUCTION, COSTS, PROFITS, AND BENEFITS
FROM APPLYING NITROGEN TO BEANS IN THREE MUNICIPIOS IN JUTIAPA
Production Value of Cost of B:C
Treatment Production Increase Increase Increase Profit RATIO
3 appl. 45 Kg/Ha 1346 215 89.87 34.35 55.52 1.62
2 appl. 45 Kg/Ha 1322 191 79.84 32.35 47.49 1.47
1 appl. 30 Kg/Ha 1280 149 62.28 20.90 55.17 2.64
From a profit motive there is little difference between the three treatments.
The risk factor suggests the single application at the 30 kilogram per hectare rate
which also gives the highest return on the money invested.
WEED CONTROL IN BLACK BEANS
Weed control in production of black beans is very important in the Oriente.
In an experiment in Atescatempa, yields of beans from plots maintained free of
weeds averaged 1551 kilograms per hectare. The plots where weeds were allowed
to grow for 20 days before cleaning and then weeded every twelve days thereafter
produced 1344 kilograms per hectare.
Similarly, in Asunci6n Mita, plots maintained free of weeds produced 2097
kilograms per hectare while plots produced under the farmers practice of weeding
at 21 days had an average yield of 1746 kilograms per hectare.
While yields are definitely higher, so are production costs to maintain the
fields free of weeds. The first weeding usually costs the farmer about Q40.00 per
hectare for manual labor. A second weeding would cost about half that value and
a third weeding about half the cost of the second weeding. Three weedings would
be somewhat equivalent to maintaining weed free and would cost in the neighborhood
of Q70.00 per hectare.
Table 29 shows the economics of these weeding practices. Maintaining the
fields free of weeds produced an increase in bean yields valued at Q116.72 and
Q66.53 per hectare for Asunci6n Mita and Atescatempa, respectively.
- 77 -
YIELDS, VALUES OF PRODUCTION, COSTS OF WEED CONTROL
AND IN-THE-FIELD PROFITS OBTAINED FROM MAINTAINING
BEAN FIELDS FREE OF WEED AS COMPARED TO THE FARMERS
PRACTICES IN TWO MUNICIPIOS IN JUTIAPA, GUATEMALA
ASUNCION MITA ATESCATEMPA
Weed Farmer's Weeds Farmer's
Free Practice Free Practice
Yield (Kg/Ha) 2097 1746 1551 1344
Value of Production 876.55 729.83 648.32 561.79
Cost of Weed Control 70.00 40.00 70.00 50.00
Marginal value 806.55 689.83 578.32 511.79
Marginal profit 116.72 66.53
Benefit-cost ratio 3.89 3.32
Overall B-C ratio 3.58
The benefits are high, but so are the costs. ICTA should make every effort to
bring these costs down. It is suggested that the weed control program initiate work
in 1976 toward this goal.
SOIL INSECT CONTROL IN BLACK BEANS
Soil insect control experiments in black beans showed results very similar to
the results for the experiments in soil insect control in corn. That is, soil insect
control should not be recommended as a general practice. In addition, it appears
that the soil applied insecticides could be toxic to black beans. Note that in two
of the four experiments, the plot where the insecticide was not applied produced
significantly higher yields.
YIELDS OF BLACK BEANS WHEN SOIL INSECTICIDES
WERE APPLIED IN FOUR MUNICIPIOS IN JUTIAPA
CHECK CYTROLANE VALEXON
Asunci6n Mita 1480 1134 1211
Atescatempa 749 842 756
Santa Catarina Mita 1386 1486 1465
Yupiltepeque 1631 1858 1821
AVERAGE 1362 1332 1313
It is recommended that soil insecticides be applied only to those fields having
a past history of soil insect problems or where the soil insect population exceeds
six insects in an area of 1 square meter of soil to a depth of 20 centimeters.
SUGGESTED BLACK BEAN PRODUCTION PRACTICES
The following suggestions for bean production during the first growing season in
the Oriente should be viewed as suggestions and not as recommendations. As often
as not, the suggestions are based on observed tendencies rather than on data which
was statistically significant.
If the farmer generally produces less than 580 kilograms per hectare and does
not plan a better management program, there is no advantage to using the improved
In the more humid areas and on well drained deep but not drought soils, there
is probably an economic advantage to seeding the improved varieties. Negro Jal-
patagua would be the first choice with Turrialba, the second choice.
For the more humid areas such as Yupiltepeque, Jerez and Atescatempa, and
on soils having a depth greater than 50 centimeters and a good moisture holding ca-
pacity, it is suggested that the beans be seeded in rows 45 centimeters apart with
15 plants per meter of row.
In shallow soils having low moisture retention characteristics it is suggested
that the number of plants per meter of row be reduced to ten.
Maintaining the fields free of weeds is very important. It is suggested that the
first weeding be done at 14 days after seeding followed by a second two weeks
later and a final weeding after an additional two weeks. The farmer should consider
using a herbicide such as Afalon to reduce weed control costs.
It is suggested that 30 kilograms per hectare of nitrogen be applied at time of
Phosphorus fertilization should be based on a soil test. If the analysis shows the
soil test level to be greater than 6 PPM, do not apply phosphorus. Soils having test
levels of 3-6 PPM should receive 30 kilograms of P205 per hectare and soils testing
less than 3 PPM should receive 45-60 kilograms per hectare of "P205".
Potash is not suggested for bean production in the Oriente.
Control of Soil Insects
Do not apply a soil insecticide unless the field has a past history of insect da-
mage, or unless the soil contains at least six damaging insects per square meter to
a depth of 20 centimeters.
DECISION MAKING CORN OR BLACK BEANS
There are three economic principles or basic rules in decision making, assuming
that the farmer is motivated by maximum profits.
The first rule is the added cost added return principle which states that it pays
to add variable resources to fixed resources as long as the added returns are greater
than the added costs.
The second rule is the opportunity cost principle. This principle states that
profits will be at a maximum when each unit of land, labor, capital and manage-
ment is used in the place where it adds most to returns.
The third rule is the substitution principle. This principle says that the cost of
producing a given quantity of product is reduced by substituting one resource for
another as long as the amount of the reseource added times its price is less than
the amount of some other resource replaced times its price.
Which rule or rules most applies to the medium and small farm unit in the Orien-
Obviously, the first rule will maximize profits, but it will not likely lower
average production costs and requires larger capital outlays. Since the medium
and small farm unit are of said size, they do not generate much capital and this is
often the most limiting factor. Where capital is most limiting, the opportunity cost
principle becomes the most important. The substitution principle is generally limited
- 82 -
to substituting a variable resource for land and in some cases labor.
Thus, of the three basic economic principles, the opportunity cost principle
is the one that must be given priority. Later when capital becomes less limiting
the substitution principle will become effective.
Two crops dominate the agriculture during the first growing season in the
Oriente corn and beans. The farmer when he decides how to divide his re-
sources must determine not only what is profitable, but also what resource utili-
zation is most profitable. The data accumulated in Table 31 was prepared to aid
in this decision making process. Included are the yields of the recommended prac-
tices, average increase in production due to the recommended practice, value of
the increase based on current INDECA princes, additional cost per hectare for
the improved practice, profit, and benefit-cost ratios.
SOME ECONOMIC DATA REQUIRED BY THE CORN BEAN FARMER
IN THE ORIENTED FOR RATIONAL DECISION MAKING
Recommended Yield due to Value of Cost per Profit Benefit-
Practice Kg/Ha Practice Increase Hectare Q/Ha Cost ratio
Kg/Ha Q/Ha Q/Ha
Number "N" Applic. 4961 307 47.28 2.00 45.28 22.64
Seeding single plants 5885 552 85.01 4.00 81.01 20.25
Use proper hybrid 4091 1256 193.42 11.80 184.62 15.39
(60 Kg/Ha 3 appl.) 4925 2322 357.59 39.80 317.79 7.89
Complete weed cont. 5954 413 63.60 10.00 53.60 5.36
Seeding rate 3543 123 18.94 3.07 15.87 5.17
Improved variety 687 166 69.39 12.87 56.52 4.39
Nitrogen fertilization 1280 149 62.28 20.90 41.38 1.98
Complete weed control 1824 274 114.53 25.00 89.53 3.58
Increased costs per hectare for a farmer that adopts all the recommended practi-
ces are Q68.76 and Q58.77 for corn and beans, respectively, or an additional Q127.53
for two hectares.
Benefit cost ratios indicate that there is more opportunity for increased profit
making in corn than in beans. The lowest benefit-cost ratio in corn was more than the
highest benefit-cost ratio in beans. This relation held for all Municipios in which we
worked. Thus, it appears that we have more reliable technology in corn than in beans.
Average yields of each crop were determined for each municipio. These ave-
rages contain data from all treatments in every experiment. Their value was estimated
using product prices of 15.4 and 41.8 9' per kilogram. These data shown in Table 32
indicate the yield differences between corn and beans obtained this year.
AVERAGE CORN AND BEAN YIELDS (Kg/H-a 13 MOSITURE)
AND VALUE OF YIELD BY MUNICIPIO
MUNICIPIO YIELD VALUE YIELD VALUE
Agua Blanca 3681 566.87 652 272.54
Asunci6n Mita 3246 499.88 1156 483.21
Atescatempa 4397 677.14 796 332.73
El Progreso 3923 604.14 210 87.78
Sta. Ca6arina Mita 2707 416.87 988 412.98
Yupiltepeque-Jerez 4454 685.92 1310 547.58
AVERAGE 3735 575.19 852 356.14
Early season drought affected bean yields more than corn yields. Recall also,
that bean are harvested in ninety days, whereas corn requires one-hundred twenty days,
or that beans occupy the land 25 percent less time. Reducing the value of the corn pro-
duced by 25 percent generated Q431.39 which is still 21 percent above the value of
Most of the arable land in the Oriente is currently in use. Production increase
in the future will have to come from increased yields on current acreages. Increased
bean production will come about only at the expense of corn production and it is doubt-
ful if this will happen beyond the immediate needs of the farmer, for if we apply either
the opportunity cost principle, or the substitution of resources principle, they both fa-
vor corn production over bean production.
In addition, the golden mosaic problem in the second growing season further
complicates the issue. To date, we have not encountered resistance to this disease in
any materials tested; thus, unless resistance is found rapidly, we will have to live with
a disease which is increasing rapidly in severity and bean production will become uneco-
nomic during the second growing season.
ICTA should initiate studies in bean production in other regions of the country,
especially in the Altiplain. Shifts in bean production to other parts of the country can
be expected. From a national point of view, these shifts can help stabilize total bean
production and free lands in the Oriente for increased production of corn and grain sor-
ghum where substituting variable resources such as fertilizer and varieties can bring
about large, per unit yield increases.
Continuing studies can possibly produce a "breakthrough" in bean production
practices such as varieties and disease resistance, but it will not solve the factor
most limiting bean yields in the Oriente climate.
GRAIN SORGHUM VARIETY TESTS
About 50,000 hectares of grain sorghum are grown each year in Guatemala.
Yields average about 800-900 kilograms per hectare for an annual production of 40-
50 thousand metric tons. Most of this production is localized in the Oriente. The
criolla varieties are late maturing, tall sorghum which offer limited production al-
Three new varieties were introduced by ICTA to replace the criolla sorghums.
These are, Guatecau, Guatex Blanco, and Guatex Rojo. Specifically, the variety
Guatecau in the North Oriente where much of the sorghum grain is utilized as human
food and the Guatex varieties for the Pacific Coastal Plain where disease is more pre-
valent. Data from various years of investigation by the grain sorghum program indica-
ted that the Guatex varieties were superior yielders under conditions of the experi-
ments; however, that Guatecau was equal under growing conditions of the medium
and small farm unit.
Yield data from variety tests in five municipios of Jutiapa, Guatemala are shown
in Table 33. Statistically, grain yields between the three varieties were not, different
in any of the seven variety test sites; thus, due to farmer preference of Guatexau as a
food source, it is suggested that the variety Guatecau be recommended for the North
Oriente and the Guatex varieties be limited to the Pacific Coast, or for silage and
- 88 -
YIELD OF THREE GRAIN SORGHUM VARIETIES DURING
THE SECOND GROWING SEASON IN 5 MUNICIPIOS
IN JUTIAPA, GUATEMALA
GUATECAU GUATEXBL. GUATEX R.
MUNICIPIO Kg/Ha Kg/Ha Kg/Ha
Asunci6n Mita 2957 2970 2845
Atescatempa 2428 2420 2426
El Progreso 3678 3416 3342
El Progreso 2380 1874 2005
El Progreso 2309 1828 2094
Sta. Catarina Mita 2150 1774 1780
Yupiltepeque 1849 1870 1983
X 2536 2307 2353
NITROGEN FERTILIZATION OF GRAIN SORGHUM
Most of the criolla grain sorghums are not fertilized. Being very late maturing,
their daily uptake rate of nitrogen is not as critical as for the earlier maturing im-
proved varieties. In addition, nitrogen fertilization of the criollas produces plants
three to four meters tall which are difficult to harvest; thus, the farmer is reluctant
to fertilize his sorghum crop. The earlier maturing, improved varieties will not yield
without an adequate nitrogen supply for rapid uptake at critical growth stages. Data
from the grain sorghum program indicated that the most economic rate of nitrogen fer-
tilization for grain sorghum production in the second growing season in the Oriente
was between 40-60 kilograms per hectare of nitrogen. Seven nitrogen rate experi-
ments were conducted in six Municipios in Jutiapa to evaluate nitrogen responses
and profitability under conditions of the small and medium farm unit. Yield results
from these experiments are presented in Table 34, and shown graphically in Figure 6.
Yield levels at the various nitrogen rates were significantly different in every experi-
Yield varied from 1168 kilograms per hectare of sorghum grain without ap-
plied nitrogen to 2301 kilograms per hectare of sorghum grain produced when 100
kilograms per hectare of nitrogen was applied. Yield responses of grain sorghum to
nitrogen applications are less than in corn (see Figure 1). This is due to (1) lack of
adequate soil moisture and (2) planting of the sorghum between corn rows.
YIELD RESPONSES OF SORGHUM TO LEVELS OF
APPLIED NITROGEN IN SIX MUNICIPIOS
IN JUTIAPA, GUATEMALA
YIELDS Kg/Ha AT VARIOUS NITROGEN LEVELS
MUNICIPIO 0 25Kg 50Kg 75Kg 100Kg
Agua Blanca 156 265 496 515 544
Asunci6n Mita 2098 2754 2887 3068 3507
Atescatempa 1028 998 1570 2245 2176
El Progreso 1715 2452 3082 2850 3672
El Progreso 2093 2007 2738 2934 3133
Sta. Catarina Mita 785 1193 1303 1295 1311
Yupiltepeque-Jerez 300 622 997 1824 1766
X 1168 1470 1868 2104 2301
YIELD RESPONSE OF GRAIN SORGHUM TO LEVELS OF
APPLIED NITROGEN IN SIX MUNICIPIOS IN JUTIAPA,
- 91 -
0 25 50 75 100
- 92 -
BENEFIT COST RELATIONS OF GRAIN SORGHUM TO
APPLICATIONS OF NITROGEN
PROD. PROD. PRICE PROFIT
RATIO Kg/Ha Kg/Ha Q/Ha Q/Ha Q/Ha B:C
0 1168 -
25 1470 302 39.86 16.00 23.86 1.49
50 1868 700 92.40 32.00 60.40 1.89
75 2104 936 112.32 48.00 64.32 1.34
100 2301 1122 149.56 64.00 85.56 1.34
- 93 -
PHOSPHORUS FERTILIZATION OF GRAIN SORGHUM
Phosphorus fertilization, with or without a soil test analysis is an enigma in
the Oriente. Often, soils with high soil test values for available "P" respond to
phosphorus applicat ions. More often, soils that test practically nil in available
soil phosphorus may or may not respond to soil phosphorus applications.
Another problem concerns the critical levels. Formerly, the critical level
was set at 19 PPM of extractable "P". An error of 3 PPM whether it came from
taking the sample in the field, or in laboratory procedure represented an analysis
error of 16 percent at the critical level. The same 3 PPM at the present critical
level of 7 PPM represents an error of 43 percent. Errors of this magnitude can be
In addition cultural practices can affect crop yield response to phosphorus
applications. Crops vary in their response to available soil phosphorus levels.
Weather conditions can also affect response to phosphorus applications.
The question before the transference of technology program can be stated:
"How do we go about recommending phosphorus fertilization for the crops in the
Experiments in grain sorghum fertilization with phosphorus were located in
four municipios in Jutiapa, Guatemala. Data from these experiments are presented
in Table 36. The value below the municipio is the soil test "P" level. Soil test
"P" levels were 1.5, 2.4, 5.2, and 26.0 PPM of "P". Three of these levels are
less than the critical value of 7 PPM; yet there was not a significant yield response
in any of the test sites. A tendency does exist toward a slight response up to rates
of application of 50 kilograms per hectare of "P2051 ; however, the profitability is
questionable as can be seen in table 37. Before, all cost ratios presented were be-
nefit-cost ratios; however, since the farmer would loose money in 3 of the four rates
applied, the relation presented in Table 37 is value of production-cost ratios. If
the farmer applied 25 kilograms per hectare of "P205" he would lose Q 0.28 per quel-
zal invested. At the 50 kilogram per hectare rate, he would earn Q0.26 per quet-
zal invested. Applications of additional "P205" above 50 kilograms per hectare would
cause additional losses.
These tests do not resolve the problem; however, it is hoped that they will
help point out the necessity for concentrated effort on the part of ICTA toward
solving this enigma.
YIELDS OF SORGHUM GRAIN (Kg/Ha) AT VARIOUS
LEVELS OF APPLIED PHOSPHORUS IN 4 SOILS
IN JUTIAPA, GUATEMALA
YIELDS Kg/Ha "P205" LEVELS
MUNICIPIO 0 25 50 75 100
Atescatempa 2471 2162 2024 2488 2165
El Progreso 1689 1556 1823 1748 1936
Jerez 4329 4485 4772 4692 4593
Sta. Catarina Mita 1183 1420 1523 1258 1796
X 2418 2406 2536 2546 2622
X 7.0 PPM 2400 2487 2706 2566 2775
VALUE COST RELATIONS TO APPLICATIONS OF VARIOUS
PHOSPHORUS LEVELS IN FOUR SOILS IN JUTIAPA, GUATEMALA
A PRICE COST PROFIT
RATIO Kg/Ha Kg/Ha Q/Ha Q/Ha Q/Ha V:C
0 2400 -
25 2487 87 11.48 16.00 -4.52 .72
50 2706 306 40.39 32.00 8.39 1.26
75 2566 166 21.91 48.00 -26.09 .46
100 2775 355 46.86 64.00 -17.14 .73
- 97 -
METHOD OF PLANTING GRAIN SORGHUM
As stated earlier, it appears that the new, "improved" varieties of grain sorghum
are slightly early in producing the embryonic seed head inside the sorghum plant. This
is more the case when seeding between the corn rows than when seeding alone. Head
differentiation during the short days of the second growing season is initiated about
28-30 days after emergence in the variety Guatecau. When the plants are seeded
between the rows of growing corn, the shading by the corn severely limits growth during
the early stages of plant development. The meristematic growing point remains small,
and when it differentiates into a sorghum head, the head is likewise small. In prior
years, the author has shown that about 75 percent of grain sorghum yield in Guatemala
is dependent upon the number of seed produced and only 25 percent on size of the seed.
It follows, then, that if the heads are going to be small, we must produce more heads per
hectare if we are to obtain increased yields.
A series of experiments were conducted in five municipios in Jutiapa, Guatemala,
to determine the effect of total population on yelds of sorghum grain. Row widths of
40, 60, and 90 centimeters were seeded with a constant per row population of 10 plants
per linear meter of row. Yields data from these tests are shown in table 38. In every
experimental site, highest yields were produced when the sorghum was seeded in 40 cm.
rows. The value of this practice is unquestionable. Production increases (see table 39)
of 359 and 862 kilograms of sorghum grain produced profits of Q. 37.83 and 90.58 for
the 60 and 40 centimeters rows, respectively, over the conventional one row, 90
centimeter system currently being employed.
Added cost values include all costs such as additional seed, additional labor
for planting, and labor plus expenses for harvesting. It is probable that the added
cost of Q. 23.20 per hectare for seeding in 40 centimeter rows is high; however,
the benefit-cost ratios remain fairly costant, and indicate that the farmer should
seed two rows of sorghum between each row of corn if he uses the variety-Guatecau.
YIELDS OF SORGHUM GRAIN (Kg/Ha
SEEDED AT VARIOUS ROW WIDTHS
MUNICIPIO 40 cm. 60 cm. 90 cm.
AGUA BLANCA 1768 1372 1532
ASUNCION MITA 1720 1506 1511
EL PROGRESO 4155 3637 2839
YUPILTEPEQUE- JEREZ 1824 1395 542
STA.CATARINA MITA 2526 1570 1261
X 2399 1896 1537
BENEFIT- COST RELATIONS FOR SORGHUM SEEDED IN
VARIOUS ROW WIDTHS
PRO D PRICE I
Treatment Kg/Ha PRO D CO ST PROFIT
Kg/Ha Q/Ha Q/Ha Q/Ha B:C
90 cm. 1537 -
60 cm. 1896 359 47.39 9.56 37.83 3.96
40 cm. 2399 862 113.78 23.20 90.58 3.90
______ I _
BLACK BEAN VARIETY TESTS
Black beans are also seeded entensively throughout the Oriente during the
second growing season. Major production problems center around a lack of soil
moisture and golden mosaic disease.
Varieties are usually early maturing local varieties which are drought
escaping, but not drought resistant and they show little if any resistance to golden
The varieties recommended by ICTA are later maturing and also have little
resistance to golden mosaic.
Variety tests were planted in four municipios in Jutiapa, Guatemala. These
tests contained the four varieties suggested by ICTA and the farmers variety. Results
of these experiments are presented in table 40. Unfortunately, the farmer harvested
the plot containing his local variety in Agua Blanca, and the farmers seed in Atesca-
tempa were of low germination.
The only experimental site that was statistically different was Agua Blanca
where Negro Jalpatagua yielded less. In general, the varieties showed similar
yielding abilities. There is no clear evidence that the ICTA varieties are definitely
superior to the local varieties.