This is in a nutshell was the gist of a research paper from PhilRice [Philippine Rice Research Institute] that was adjudged the second best paper in the farm machinery and mechanization category during the recent 58th annual national convention of the Philippine Society of Agricultural Engineers at UP Los Banos. The paper was written by Dr. Manuel Jose C. Regalado, Engr. Paulino S. Ramos and Dr. Rolando T. Cruz.
The PhilRice researchers said that the continuing rise in the cost of farm labor cost is one of the major factors that should be considered in the adoption of innovative land preparation and crop establishment practices like reduced tillage and drum seeding. They added that 60 percent of the total input costs in rice production is spent for farm labor.
Traditionally, irrigated rice fields have been conventionally prepared by plowing and harrowing or puddling using implements drawn by an animal or hand tractor. However, studies by Dr. Basilio Mabbayad in the late 1960s have shown that excessive soil tillage in lowland rice fields could be reduced if weeds were controlled by herbicide spraying before planting and then complemented with good water control.
In another study Dr. Mabbayad and his co-workers found that yields from lowland rice fields subjected to reduced or minimum tillage and sprayed with herbicide before planting were comparable to those from conventionally prepared fields. They concluded that on flooded soils where weeds are predominant, the amount of labor needed in land preparation could be reduced without sacrificing yield provided effective weed control and low-cost herbicides are used.
A study that looked at alternative land preparation and planting techniques by another group of scientists noted that transplanting produced significantly higher yields than broadcasting pre-germinated seeds.
In their study, Dr. Regalado and his co-workers compared tillage methods for land preparation and planting techniques. They used two land preparation methods [conventional and reduced tillage] and two planting techniques [mechanical transplanting and drum seeding].
Conventional tillage was done in two weeks, while reduced tillage was performed in 10 days. In conventional tillage, one pass of 4-wheel tractor was made on dry field. After that irrigation water was brought into the field for wet preparation. This consisted of two passes [length-wise and cross-wise] of harrowing using a hand tractor with cage wheels and comb harrow, final harrowing, and leveling using a hand tractor-mounted ride-on leveler.
On the other hand, reduced tillage was done with two soil puddlings. First, an initial single pass of the PhilRice-improved floating tiller was made on water-soaked soil. A second double pass of the floating tiller was done before final leveling with a hand tractor-riding type leveler.
For mechanical transplanting method of crop establishment, the researchers raised 21-day old seedlings in plastic trays with soil 3 centimeters (cm) deep. The seeding rate was 40 kg/ha. The seedlings were transplanted using a 4-row mechanical transplanter. For drum seeding, pre-germinated seeds were sown directly at the rate of 40 kg/ha using a 12-row manually pulled drum seeder.
Both the transplanted and drum-seeded crops were fertilized with 147-42-42 kg nitrogen, phosphorus and potassium [NPK] per hectare in the dry season and 127-35-35 kg NPK/ha during the wet season. Nitrogen fertilizer application was based on the leaf color chart [LCC] technique wherein leaf color readings were first taken before split nitrogen fertilization was done.
Results
The average dry season grain yields of both transplanted (5,840 kg/ha) and drum-seeded (7,220 kg/ha) in thoroughly or conventionally prepared fields were significantly higher than those in reduced tillage fields (transplanted, 5,260 kg/ha; drum-seeded, 6,590 kg/ha).
The drum-seeded crops matured earlier than the transplanted crops by 13 days, resulting in significantly higher yields of drum-seeded crops during the dry season was due to the 13-day lead time in reaching maturity. Earlier maturity allowed the drum-seed crops to escape stemborer infestation, Dr. Regalado said.
On the other hand, there were no significant differences in the wet season yields of transplanted and drum-seeded crops in the conventional and reduced tillage fields. However, the yields of drum-seeded crops were numerically lower than those of the transplanted crops due to rain and strong winds in the last three weeks before harvest, resulting in the lodging of the crops.
The PhilRice researchers also found that mechanically transplanted crops in conventionally prepared fields had higher production costs (per kilogram yield) during the dry (PhP6.66/kg) and wet (PhP6.09/kg) than those in reduced tillage fields (PhP6.58/kg and PhP5.49/kg, respectively).
Similarly, the drum-seeded crops in conventionally prepared fields had higher production costs during the dry (PhP4.94/kg) and wet (PhP5.79/kg) seasons than those in reduced tillage fields (PhP4.73/kg and PhP5.20/kg, respectively).
It was also observed that rice production using through land preparation and mechanical transplanting was as efficient in the use of energy inputs as that of applying reduced tillage during the dry season. The reverse was observed during the wet season.
Likewise, although the establishment of drum-seeded crop in thoroughly prepared fields was as energy efficient during the dry season, it was more energy efficient during the wet season.
Based on their findings, Dr. Regalado and his co-workers concluded that the number of tillage operations could be reduced to decrease the unit production cost by 10-12 percent without reduction in yield, labor productivity, and energy efficiency.
Moreover, they said that drum seeding with either conventional land preparation or reduced tillage would be the better option to improve labor productivity in irrigated lowland rice farms in the Philippines to a level that can surpass the high farm labor productivity in the highly mechanized production system.
They added that the labor productivity and energy efficiency obtained in the study may still be improved by further mechanizing the harvesting operation.
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