Comparison of power sources in multiple cropping

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Comparison of power sources in multiple cropping
Banta, Gordon R.

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IRRI Saturday Seminar
August 11, 1973

Comparison of Power Sources in Multiple Cropping

Gordon R. Bahita


The type of power that a small Asian rice farmer has is a
major factor in his decision on the type of cropping pattern to
use. There are four major types of power available to him: hand
labor, animal power, hand tractor, and four-wheel tractor.

When discussing multiple cropping these-sources of power
must be considered. There "is no doubt that mechanical power which
receives the most attention has certain advantages and will play
an increasing role .'n Asian agriculture as standards of' living

"Life cannot exist without food, but neither can
a high standard of living be developed on food
alone. Non-food energy sources must somehow be
introduced in Southeast Asia if the standards of
living are to improve."1/

A high standard of living appears to be a long way off for
the small Asian rice farmer. In starting these farmers on the road
to a better standard of living it appears to us that more effort
should be placed in combining the resources that the farmer has
with new technology suited tc these resources. Two of. the most
important resources are men and lan,: When considering the re-
sources the farmer has, we must look not only at the present but
also, and more important, the future. The man/land ratio is going
to continue decreasing and farm size is also decreasing. Thus, we
have more labor available on smaller farms., Animal and human labor
are the main power sources the farmer has available while tractors
are starting to come into effect in some countries. A great deal
has been written on the advantages and disadvantages of tractors
for the small Southeast Asian farmer. Generally, the arguments are cen-
tered on four.main points in favor and four main points, against. The
advantages of mechanization are 1) it reduces drudge-ry of tne work,

1/ Johnson, Lloyd. Promotion of Agricultural Mechanization
on an Energy Basis. Agricultural Mechanization in Southeast Asia,
p. 50. Spring 1971.

2 -

2) it speeds up the time of operation which may be dependent on
weather, 3) it speeds up turn around time allowing an extra crop
to be planted, and 4) it uses non-food energy.. The disadvantages
are 1) labor replacing, 2) high capital costs, 3) high cash cost
of operation, and 4) the unsuitability of the machines introduced.

All of the multiple cropping work at IRRI has been based
on a small hand tractor as the main power source with-hand labor
used whenever necessary. Since a majority of the multiple crop-
ping work has been centered on achieving maximum production, the
hand.tractor:was the logical.power sourceto use; In reviewing the
...situation in Southeast Asia it .appears that it will be a longtime
in the future before a majority of the using
hand tractors. Twenty-seven percent of the farms under two hectares
in Thailand and the Philippines. have only .hand labor while sixty-
seven percent of the same group have animal power. ..Seventy-two
percent of all farms in these countries use animal power and.
eighteen percent..use only hand labor (Table 1).. With this ;informa-
tion and our objectives of developing technology for the small.
farmer consistent with making optimum use of his resources it be-
comes evident that more work would have to be done on hand labor
and animal Ipower cropping patterns.

SThis paper is a summary .of the experiments run from 1971
to 1973, with a few moments spent at the end discussing the direc-
tion of further research in these areas.

Seedbed preparation.

In 1971 some initial studies were done on the comparison
of the three power sources. Due to a typhoon all of the crops were
lost after 60 days, but the' seedbed preparation data which is the
major difference of the power sources was obtained. The carabao
was'the cheapest way to prepare a seedbed for rice, soybeans, sweet
potato, sorghum, and corn (Table 2). This was our first attempt
at using the carabao and in each crop additional man-hours were
required. o get a proper seedbed. This was not a the
carabao but rather in our knowledge of how to use the carabao and
his implements. With this information and the data.obtained from
the agricultural economics and agricultural engineering departments
of IRRI it became evident that more work would have to be done on
'the carabao. In many cases it was proving to be a cheaper means of
seedbed preparation as well as being the main power source of Asian
rice farmers.

An additional study. was made in'comparing seedbed prepa-
ration under different soil conditions. The fi-st comparison made

- 3 -

was on wet soil coming out of puddled rice. Again, the carabao
had the cheapest cost of seedbed preparation (Table 3). The
second test was done on soil which had been plowed during the
harvest of sweet.potatoes.. The carabao was nearly as efficient
as hand labor. The third test was on very hard soil after puddled
.rice which had dried. Again, the carabao was the cheapest source
of powerfor seedbed preparation. Soybeans and corn were planted
on the 3 soils (Table 4). In both crops the yield from the hand
tractor treatment was the lowest. Soybean yields are extremely
low as they were infected by rust. It was assumed that the main
reason for the small yield of the hand tractor was due to the cul-
tivation done 30 days after seeding with the hand tractor. Many
of the roots were cut off and the plants from that point were less
vigorousthan in the other two treatments,

Power source comparison on a cropping pattern

The cropping pattern chosen for the power source study in
1972-1973 was rice relay interplanted with sweet potatoes 30 days
before the harvest of rice followed by a corn-cowpea interplant,
followed by:mung-corn interplant. This gave us six crops in one
year. The.experiment was laid out on a quarter hectare block with
each treatment 25 m long and 8 m wide with four replications .(Fi-
gure.;l) The varieties grown were rice (IR20), sweet potato
(BNAS 51),,. field corn (DMR-2) interplanted with cowpea (E.G.#2),
and mung (MG50-10a yellow) interplanted with sweet corn (Hawaiian
68). Our usual management practices.,were followed with the-rice
grown direct-seeded in a broad furrow, rows being 25 cm.apart with
90 kg/ha seeds used. The sweet potatoes were interplanted:.on the
ridge between the rice 30 days before-the-harvest of rice, 25 cm
between plants and 1 m between the rows:..;..The corn was planted 25cm
between plants:and 1 m between rows, thinned down to 1 plant per
hill 30 days after seeding. A row of cowpea was planted on each
side of the corn, 50 cm apart and 10 cm between plants., Two rows
of mung were planted 50 cm ppart and 5 cm between plants, between
the.corn which has the same spacing as before. Weeds were kept to
. a minimum and insect management was at a relatively high level.
. Downy mildew did become a problem. in the Hawaiian 68 sweet corn
(Table 9).

The results of land preparation in the 1972-1973 experiments
were very similar to those obtained in 1971 (Table 5). However,
with a better understanding of the carabao and his potentials far
less hand work was required. In all cases the carabao was the
cheapest means of seedbed preparation. The final sweet potato
land preparation was all done by hand as they were interplanted
into the. rice and no carabao or tractor could perform this work.

4 -

In this experiment total land preparation for six crops using hand
labor cost P1,300, the carabao, P750, and the hand tractor, P840,
thus saving about P500 compared with the hand labor and P90with
the tractor. Looking at land preparation alone, the tractor re-
placed 16.9 hours of hand labor in this cropping pattern, the
carabao replaced 4.5 hours of hand labor, and the tractor replaced
3.9 hours of carabao work. The tractor thus prepared the soil more
economically than hand labor, however, the tractor did 390 percent
more work than the carabao but it costs 430 percent more.

The low'amount of labor required to prepare the seedbed for
sweet potato indicates a definite advantage of relay interplanting.
Although it all had to be done by hand five men could prepare the
ridges for sweet potato in one day. A very small amount of soil
is moved when compared with the amount moved in planting the other
crops. A farmer with only hand labor will find. this a definite
advantage economically and physically. In addition weeds do not
get a chance to compete with the second crop as they do when one crop
is planted after the harvest of the first.

S In the total labor use pattern from the:three power sources,
in a cropping pattern designed for the landmaster tractor, the tractor
proves more economical and efficient:than hand labor. The tractor
did 20;.times as much work and only'costs: 10 times as much as hand
labor:. The carabao did!3 times as much work and:costs 2.3 times
as.much as hand labor. The tractor did 6.5 times as much as the
carabao and only costs 4.3 times as much in the total system
(Table 6). The main reason for the increase in efficiency of the
tractor over the carabao, when comparing land preparation with the
total cropping pattern, was the seeding operation. There are no
suitable carabao seeders-available so the carabao plots were seeded
by hand. The tractor plots were seeded with Planet Jr. seeders
pulled behind the landmaster tractor. There is a definite advantage
in seeding by a tractor.

The fertility rates on the experiments.: rere kept at' a
.fairly high level (Table:7). -The phosphorus and potassium levels
appear high. However, up to the present time the fertility re-
quirements of intercropping are not known and for the purposes of
this experiment it was desired to have an adequate fertility level.
Although the rates appear high it should be remembered that six
crops were grown, two of these being corn with high nitrogen
requirements as well as rice. An average of'50 .kg/ha-of potassium
was applied to each crop:and an average of 42 kg/ha of-phosphorus.
The nitrogen applied averaged 32 kg/ha per crop.." ''

The yield from the different power sources did riot show
the marked difference found in the 1971 experiments, but there is
a lower yield pattern for the hand tractor (Table 8). The rice

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yields were low due to insect damage. All of the treatments were
sprayed 8 time's but hopper burn did occur. The yield of sweet
potato in the hand tractor treatment was 1 ton below those in the
other 2 treatments. Cowpea yields were lower:in the hand tractor
treatment as well as the corn they were grown with. In the corn-
mung interplant the yields were indefinite and no pattern developed.

Reviewing plant populations and some of the other agrono-
mic characteristics from the 3 power sources the same pattern does
appear (Table 9). The sweet potato yields were lower in the hand
tractor treatment, but the number of plants at harvest was about
the same. The corn population was the same. However, the height
30 days after seeding was lower, the weight per ear of the green
corn was also lower as was the total number of ears harvested. The
cowpea population at harvest interplanted with the corn was con-
siderably lower in the hand tractor treatment. In the corn which
was interplanted with mung, downy mildew came in on both the hand
labor and the carabao treatments in all four replications but did
not appear to any significant extent in the any of the hand tractor
replications. However, the higher population in the hand tractor
treatment still did not give the highest height of plants at 30
days after seeding, and the weight per ear was down considerably.
The mung population was down in the interplant with corn in the
hand tractor treatment, perhaps due to the higher corn population.
There is a general trend for the hand tractor to give slightly
lower yields due to a variety of agronomic characteristics. The
only explanation that would seem to justify this lower hand tractor
yield is the fact that we may be over working the soil with the
hand tractor to a-point where we are lowering the tilth.

The cost and returns from the 3 power sources indicate
little difference (Table 10). The carabao treatment showed a
slight advantage. The hand labor and carabao treatments have the
same total returns but hand labor had slightly higher cost prima-
rily due to the added cost of soil preparation. In the carabao
treatment compared with the hand tractor treatment the cost of the
hand tractor was lower but the income from the lower yields was also
lower giving a slight advantage to the carabao system. It is pri-
marily the yield and return from sweet potato which gave the hand
tractor a disadvantage. Thus, no one system had a definite advantage
in net return, meaning that the choice of power source can be made
on other basis.

The return over variable cost per hour of labor vary from
P9/hour to PO.80/hour (Table 11). The.treatment with hand tractor
showed a definite advantage giving an average return of P3.70/hour
of labor. This is P1.00/hour higher than carabao and P1.50/hour


higher than the hand labor operation. Sweet potato with its high
labor requirements and low cash requirements showed a high return
per hour of labor, but this high return per hour of labor is ba-
lanced by the higher cash requirements of the hand tractor opera-
tion. Return over variable cost per peso of cash expense varied
from P7.50 to 0 (Table 12). It was assumed in figuring these
data thatall the farmer had available to him was hand labor and
was hiring all of the other work done. In this situation hand
labor had an advantage of P0.70 over carabao system and P1.50 over
the hand tractor.

The general cash flow picture of these 3 patterns showed
that the farmer starting to plant in June would not be able to pay
back his loan until sweet potatoes were harvested in mid-January,
a period of six months. Assuming that the farmer Had to borrow
the cash requirement, the hand labor treatment for one hectare
would require credit of P1,000, the carabao system would require
P1,300 assuming the man had to hire a carabao to do his land pre-
paration, and the tractor system would require P1,400 assuming the
man hired all of the tractor work done. The cost of this money for
six months at 13 percent per annum would be P65 for the hand labor,
P85 for the carabao, and P91 for the tractor treatment. In addi-
tion to the higher cost there is the risk the farmer faces of
borrowing P1,400 compared with P1,00.whed the expected net return
is equal, a prospect that many farmers are not likely to be interested

Throughout the experiment, the assumption was made that
adequate labor was available to conduct whatever work was needed
immediately. If we look at the more realistic farm situation and
assume that only 3 man units of labor are available, we get a very
different picture. In Figure 2.the same cropping pattern is shown
using three different power sources. The one hand tractor plus
3 men would be very similar to what we did conduct at IRRI, ending
in early July. However, if the power source was one carabao plus
3 men this cropping pattern would not be finished until late July,
and if only 3 men are available the cropping pattern would not be
done until late August, on into the next rainy season. With the
1 hand tractor and 3 men the land would be idle 7 percent of the
time over the cropping patterns; with 1 carabao and 3 men, 16
percent of the land will be idle over the cropping pattern, and
22 percent for only three men. The assumption in this' figure is
that good weather prevailed for up to one month while the hand
labor system was preparing the seedbed and planting. This is not
possible. The result is only two crops would be produced on part
of the land. A cropping pattern designed for a hand tractor is
unsuited if the power source is not available and other cropping
patterns must be developed for carabao and for hand labor.

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On the basis of these epxeriments we have demonstrated that
the carabao and in certain instances the hand labor is economically
competitive with the hand tractor even in systems designed for the
hand tractor. However, the time element makes it unrealistic. A
farmer with only hand labor will require cropping patterns with more
relay interplanting to reduce soil preparation to a minimum. Our
knowledge of the capabilities and techniques for the carabao are
weak. His potentials in intensive cropping patterns cannot be
evaluated, but they certainly appear to be strong. These experiments
have also allowed us to gather data on each activity that was carried
out. These data are now being compiled and can be used in designing
other cropping patterns for carabao and hand labor.

Future program

More data on carabao operations and techniques are needed.
To gather these data cropping patterns using carabao will be studied
in farmers' fields. Initially these data will be collected by
surveys. After the initial surveys, experiments will be conducted
with farmers and at IRRI. One of the basic assumptions in these
experiments will be that the farmer can farm better than he is now
but won't because of risk and lack of resources. The experiments
will be designed to remove these constraints and learn the best
technology the farmer knows. Research will then be started based
on the best technology the farmer knows, to find methods to com-
bine his resources and new technology to give him a high standard
of living.

size for Thailand and Philippines.a/

Farm Hand Animal Mechanical Mechanical and
size power power power animal power
(ha) 1000 1000 1000 1000
Farms % Farms % Farms % Farms %

( 1 355 40 495 55 19 2 27 3

1 2 263 19 1026 75 23 2 62 4

2 5 267 14 1484 76 40 2 166 8

5 < 76 7 852 74 31 3 190 16

Total 961 18 3857 72 113 2 445 8

a/ Compiled from:

National Statistical Office. Statistical Yearbook
Thailand No. 29. 1970-1971. .Bangkok

Bureau of Census and Statistics. Census of the
Philippines 1960 Agriculture Vol. II. 1965,

Table 1. Power source by farm

Table 2. Seedbbd preparation with three power sources 1971.

SHand labor_ Carabao and tractor
Crop Manhours Cost Manhours Cost Manhours Cost
per ha (P/ha) per ha (P/ha) per ha (P/ha)
., -. : ~ ,j.
Rice 149 112 14+59 69 25 188

Soybeans 160 120 20+60 80 25 188

Sweet potato 165 124 22+70 91 45 338

Sorghum 138 104 24+30 65 23 172

Corn 160 120 20+60 80 21 158

X 116 77 209

Table 3. Comparison
three soil condition

n of three power sources for seedbed preparation for

Hand labor .:Carabao b/ Hand tractoC-/
Soil Man, Cost. Man Cost Man Cost
condition hrs/ha (P/ha) hre/ha .P/ha) hrs/ha (P/ha)

Wet soil after
puddled rice 404 303 108 189 100 750

Plowed soil after
sweet potato 129 97 60 105 20 150

Hard soil after
rice 1352 1014 251 439 75 562

a/ One hour

b/ One hour

c/ One hour


- 1.75

- P7.50

Table 4. Yield per hectare from three power sources 1971.

Crop Hand'labor Carabao Hand tractor

Soybean (infected with rust) (kg/ha) 500 400 200

Corn (1000 marketable ears/ha) 30 35 25

Table 5. Land preparation -- time and coet.

a/ b/ Hand tractor~-c
Hand labor-- Carabao- Hand tractor_
Crop Man Cost Man Cost Man Cost
hrs/ha (P/ha) hrs/ha (P/ha) hrslha (P/ha)

Rice 355 210 65 120 25 185

Sweet potato .35 30 45 35 35 25

Cowpea-Corn 560 420 125 220 .25 195

Mung-Corn 840 630 240 420 60 455

a/ One hour P0.75

b/ One hour Pi.75

c/ One hour P7.50,

.. ::

Table 6. Labor use in three power sources.

Hand Hand Labor hours re-
Crop/power source labor Carabao tractor placed by carabao
(Hrs./ha) (Hrs/ha) (Hrs/ha) and tractor


Labor 660 390 200
Carabao 65 4.2
Tractor 25 18.6

Sweet potato

Labor 980 ... 420 .370.
Carabao : 245 2.3
Tractor 15. 35.8

Cowpea and corn.

Labor 1140 530 390
Carabao 130 4.7
Tractor 45 16.2

Mung and corn

Labor 2040 1500 1265
Carabao 520 1.1
Tractor ....75 10.1

Table 7. Fertilizer used on power source cropping pattern 1973.

Crop N P K

Rice 120 50 50

Sweet potato 75 100 150

Corn and cowpea 150 50 50

Corn and mung 150 50 50

Total 495 250 300

I -


Table 8. Comparison of yields from three power sources.

Crop. Hand labor Carabao Hand tractor

Rice (t/ha) 2.3 2.4 2.4

Sweet potato (t/ha) 9.4 9.4 8.3

Cowpea with corn (t/ha) 1.2 1.1 0.8

Corn with cowpea
(1000 marketable ears/ha) 32 31 30

Mung with corn (kg/ha) 230 400 430

Corn with mung
(1000 marketable ears/ha) 32 30 33

Table 9. Plant population and characteristics from three power sources.

Hand labor Carabao Hand tractor

Sweet potato
Plants at harvest (1000/ha) 39 37 37
Total yield (t/ha) 36 35 31

Corn interplanted with cowpea
Plants at harvest (1000/ha) 34 ... 34 34
Height at 30 DAS (cm) 145 147 143
Weight per ear (gn) 310 304 302
Ears (1000/ha) 35 35 33
Weight of ears (t/ha) 10.9 10.6 9.9

Cowpea interplanted with corn
Plants at harvest(1000/ha) 137 136 117

Corn interplanted with mung
Plants at harvest(1000/ha) 32a/ 33a/ 43
Height at 30 DAS (cm) 124 116 106
Weight per ear (gm) 220 202 184
Ears (1000/ha) 32 30 33
Weight of ears (t/ha) 7 6.1 6.1
Mung interplanted with corn
Plants at harvest (1000/ha) 148 187 134

a/ infected with downy mildew


Costs and returns from three power sources.

Hand labor Carabao Hand tractor
(P/ha) (P/ha) (P/ha)


Total return 1000 1100 1100
Variable costs 1000 900 900
Return over variable costs 0 200 200

Sweet potato

Total return 4700 4700 4100
Variable costs 1200 1000 .900
Return over variable costs 3500 3700 3200

Cowpea and corn

Total return 3100 .3000 2700
Variable costs 1600 1300 1100
Return over variable costs 1500 1700 1600

Mung and corn

Total return 3800. 3800 4300
Variable costs 1800 2200 2300
Return over variable costs 2000 1600 2000

Total return over.variable cost 7000 7200 7000

Table 10.



Table 11. Return over variable cost per hour of labor in P.

Crop Hand labor Carabao Hand tractor

Rice 0.80 1.20 1,70

Sweet potato 4.30 6.40 9.00

Cowpea and corn 2.10 3.30 4.40

Mung and corn 1.70 1.50 2.20

Total pattern 2.20 2.60 3.70

Table 12. Return over variable cost per peso of cash expense.

Crop Hand labor Carabao Hand tractor

Rice 0 0.30 0.30

Sweet potato 7.50 5.10 5.10

Cowpea and corn 2.00 1.90 2.00

Mung and corn 7.50 1.50 1:50

Total pattern 3.50 2.80 2.00

Sweet potato

i Rice I

Sweet potato





3 men

1 carabao
3 men
3 men


1 hand tractor
3 men F

S Sweet potato

Rice I

j Corn Corn

Cowpea Mung

1 1 1 1. 1. 1 1 1 1 1 1
Jun Jul Aug Sept Oct Nov Dec Jan Feb Mar Apr

Fig. 1. Time requirement of a cropping pattern with three power sources.

1 1 1
May Jun Jul



1 1
Aug Sept





Sweet potato

Corn Corn

Cowpea Mung

1 1 1 1 1 1 1 1 1 1 1 1

Jun Jul Aug Sept Oct Nov Dec Jan Feb Mar Apr May Jun Jul

Fig. 2. Cropping pattern for power source study, 1973.