IRRI Saturday Seminar
August 11, 1973
Comparison of Power Sources in' Multiple Cropping
Gordon R Bahinta
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 p6wer 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 improve.
"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 land, When considering the resources 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 centered on four main points in favor and four main points, against. The advantages of mechanization are 1) it reduces drudgery of the work,
1/ Johnson, Lloyd. Promotion of Agricultural Mechanization on an Energy Basis. Agricultural Mechanization in Southeast Asia, p. 50. Spring 1971.
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 cropping work has been centered on achieving maximum production, the hand.tractor:was the logical.power source to use; In reviewing the .situation in Southeast Asia it appears that it will be.a long. time in the future before a majority of the small.farmers will.be using hand tractors. Twenty-seven percent of the farms under two hectares in Thailand and the Philippines.have only hand labor while sixtyseven 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 I). With this :information and our objectives of developing technology for the small. farmer consistent with making optimum use of his resources it becomes evident. that more work would have to be done on hand labor and animal :power cropping patterns.
This paper is a summary of the experiments run from 1971 to 1973, with a few moments spent at the end discussing the direction of further research in these areas.
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 js the major difference of the power sources was obtained. The carabao waste 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 to get a proper seedbed. This was'not a weakness ':n 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 preparation under different soil conditions. The first 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 power for 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 cultivation 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 .(Figure l)f 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
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.
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 ad P90 with the tractor. Looking at land preparation alone, the tractot replaced 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 labors 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.
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 andcosts 2.3 times asmuch 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-sere kept at' a
.fairly high level (Table::7). -The phosphorus and potassium levels appear high. However, up to the present time the fertility requirements 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
yields were low due to insect damage. All of the treatments were sprayed 8 times 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 loweriin the hand tractor treatment as well as the corn they were grown with. In the cornmung interplant the yields were indefinite and no pattern developed.
Reviewing plant populations and some of the other agronomic 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 considerably 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 appoint 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 primarily 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 primarily 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 P0.80/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 balanced by the higher cash requirements of the hand tractor operation. 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 90.70 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 91,000, the carabao system would require P1,300 assuming the man had to hire a carabao to do his land preparation, and the tractor system would require R1,400 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 addition to the higher cost there is the risk the farmer faces of borrowing P1,400 compared with P1,O00.whed the expected net return is equal, a prospect that many farmers are not likely to be interested in.
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.
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.
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 combine 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. Seedbed preparation with three power sources 1971.
Hand labor Carabao Hand tractor
Crop Manhours Cost Manhours Cost Manhours Cost
.per ha (P/ha) per ha (P/ha), per ha (P/ha) 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. Compariso three soil condition
on of three power sources for seedbed preparation for ns.
Hand labor/ .:Carabao b/ Hand tractor/
Soil Man; CoSt. Man Cost Man Cost
condition hrs/ha (P/ha) hre/ha (P/ha) hre/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
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 cost.
Hand labor-a Carabao-b/ and 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 = #1.75 c/ One hour= P7.50,
Table 6. Labor use in three power sources.
Hand Hand Labor hours reCrop/power source labor Carabao tractor placed by carabao (Hre./ha) (Hrs/ha) (Hrs/ha) and tractor
Labor 660 390 200
Carabao 65 4.2
Tractor 25 18.6
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
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
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 (gm) 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
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 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
Hung and corn 7.50 1.50 1:50
Total pattern 3.50 2.80 2.00
1 hand tractor
I Corn Corn
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
1 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.