Effect of cropping pattern and biomass return on n and c labile fractions and cassava (manihot esculenta l.) yield at typic hapludults

Legume biomass has advantages in maintaining soil organic matter and increasing soil nutrient content. The field research was conducted at Typic Hapludults of East Lampung, Lampung Province, Indonesia, which continuously has been planted with cassava in monoculture for more than 30 years. The experimental design used a split plot with three replications. The main plot was cropping pattern, i.e. 1) intercropping and 2) relay cropping. The sub-plot was type of organic matter, i.e. 1) groundnut biomass, 2) maize biomass, 3) groundnut-maize biomass with ratio of 1:1, 4) groundnut-maize biomass with ratio of 2:1, 5) groundnut-maize biomass with ratio of 1:2, and 6) without organic matter. The result indicated that planting cassava in monoculture continuously for more than 30 years reduced the soil macro nutrients and increased the micro nutrients, particularly Al saturation and Fe. The application of organic matter from groundnut and maize biomass did not affect total N and C organic in the soil, but increased the concentration of the labile fraction of N and C. The labile fraction of N and C in intercropping pattern was higher than that in relay cropping. Intercropping pattern also resulted in the higher cassava yield compared to that in relay cropping.