Yield constraints and fertilizer management in shallow rainfed transplanted and broadcast seeded lowland rice in the Philippines
1988
De Datta, S.K. | Garcia, F.V. | Abilay, W.P. Jr. | Alcantara, J.M.
Yields of transplanted rice (TPR) with researchers' inputs at the Tarlac and Nueva Ecija [Philippines] sites averaged 4.9 t/ha; in Camarines Sur [Philippines], the average was 5.0 t/ha. Farmers' inputs gave yields 1.1-1.6t/ha than did researchers' inputs. Broadcast seeded rice (BSR) yielded lower than did TPR, but yield gaps were similar to those in TPR. Low N fertilizer level and inefficient timing of application were the major yield constraints in TPR in Tarlac, and in TPR and BSP in Camarines Sur. In Nueva Ecija, the major constraints were poor insect control for TPR and poor weed control for BSR. Among the improved rices tested, only the early-maturing, promising breeding line IR32307-107-3-2-2 was superior to farmers' varieties-predominantly IR60 (Tarlac) and IR36 (Camarines Sur). The Tarlac and Nueva Ecija sites responded significantly to N application. Applying 30-45 kg N/ha produced high yields when the fertilizer was applied basally and thoroughly incorporated into mud without standing water. The Camarines Sur sites needed N and P fertilizers to increase yields. Across sites, response to applied Zn, either by dipping seedling roots into 2% ZnO suspension or basal incorporation of 20 kg ZnSO4/ha, was not observed in IR36, IR50, IR56, and IR60 grown on soils with pH below 7.0, although the available Zn content was below the 1.0 ppm critical level. Researchers split-applied prilled urea was as efficient as deep hand-placed urea supergranules. Yields with researchers' split were superior to those with farmers' method and machine deep placement.
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