Supplementation of organic fertilizer for improving upland cropping systems of red-yellow podsolic soils

A study on supplementation of organic fertilizer for improving upland cropping systems on red yellow podsolic soils was conducted at Tamanbogo, Central Lampung. The study was started in 1986/1987 wet season up to 1992 dry season. In 1991/1992 a similar study in Serang-Jabar. The main objective of the study was to study the role of organic as well as inorganic fertilizers for improving and stabilizing food crop yields on upland cropping system. The cropping pattern evaluated upland rice, corn, soybean and cassava in related intercropping systems. A randomized block design with three replications and ten treatments was used. A check control plot without fertilizer, was used. The other treatment were combinations of NPK fertilizer, was used. The manure and green manures and lime. The rates of N, P, and K fertilizers were 250 kg Urea, 300 kg TSP and 180 kg KCl/ha. Organic fertilizer applied ranged from 10 to 30 t/ha and lime at a rate equivalent to 1,5 x exchangeable Aluminium. NPK fertilizer was found as a key input increasing corn, upland rice, soybean and cassava yields. With only an application of NPK all of the food crop yields were increased significantly. Application of green manure and animal manure when combined with NPK fertilizer increased crop yields by 64.94, 79.89, 54.14 and 31.29 percent for upland rice corn, soybean and cassava respectively. The yield stability of food crops could be maintained for six years. The crop yields stability were higher when NPK, green manure, and lime were combined altogether. Combined treatment included also soil pH, organic matter content and reduced exchangeable alumunium of the soil. In Serang podzolic soil, using of green manure, NPK, and lime altogether increased crop yields by 1.94 t/ha of rice grain, 1.37 t/ha of corn grain and 0.65 t/ha of soybean grain respectively. F. congesta and G. sepium as alley crops yielded 21.38 t/ha and 15.49 t/ha of organic matter in 7 months. Pot experiment indicated that of the animal manure gave the best organic fertilizer for soybean among the F. congesta and G. sepium using at 150 g/10 kg of soil gave the highest yield of soybean