An adventure in applied science - IRRI books - International Rice ...

Early research and training results 133By 1967, Pathak had worked out an excellent method for rapid screening ofvarieties at the seedling stage for resistance to both leafhoppers and planthoppers,a method still being used by IRRI.AGRICULTURAL ENGINEERINGJohnson got his research under way (as mentioned in Chapter 2) in early 1963,after the construction of IRRI’s 80-ha experimental farm had been completed.During the next 4 years he worked principally on:• testing and modifying equipment for wetland preparation,• modifying the design of a cone thresher,• measuring irrigation water use and losses, and• studying the relationships between spacing and yield components.Johnson realized that heavy-textured rice soils in Asia were normallyplowed and harrowed while flooded because animal-drawn equipment requiredtoo much draft to prepare the land when dry. He felt, however, thatanimal power was inefficient and that ways should be found to do the job withtractors. He devoted a great deal of effort to testing and redesigning existingequipment for wetland preparation. Working with tractors ranging in sizefrom small Japanese 2-wheeled power tillers to 36-hp 4-wheeled tractors, hedetermined the optimum ratio for traction and flotation for various sizetractors and designed and tested some 10 different types of lugs. He measuredthe physical soil constants for the Maahas clay soil on the IRRI farm. He testedthe scheme of using two 36-hp tractors together by removing the front wheelsof each unit and hitching the front of one to the back of the other in a pivotarrangement. In this way he had a power source with 4-wheel drive, centerpivoting action, power steering, and weight balance to prevent the elevationof the front end. He also developed wide rotary tillers driven from the powertakeoff of 4-wheeled tractors.From farmers and extension workers, Johnson learned of the demand in therice belt of Central Luzon for a simple, low-cost, high capacity contractor-typethresher. He was attracted by a cone-type thresher developed by W.F. Buchleleat Michigan State University. As reported earlier, Johnson and Prince Devakul,the visiting engineer from Thailand, worked on improving the cone thresher.They attempted to reduce choking, to increase the feeding rate, and to simplifythe construction of the thresher so that it could be mounted on a tractor andoperated from the power takeoff.Although three separate models incorporating those features were builtbetween 1963 and 1965, it was impossible to improve the thresher sufficientlyto recommend its use in the humid tropics, largely because of poor separationof straw and grain and, also, high power requirements. The project wastherefore dropped.A substantial grant from USAID and the arrival of Khan in 1967 renewed theeffort to develop rice threshing equipment. In 1967, prototypes of both tableanddrum-type threshers were built, paving the way for later superior models.