Improvement of growth and yield of several varieties of soybean following paddy rice using Rhizobium biofertilizer with reduced NPK doses

Abstract

In paddy fields, soybean is generally planted following harvest of paddy rice crops, and the average yield achieved by farmers is still low. This study aimed to examine the effect of applying Rhizobium biofertilizer with reduced NPK fertilizer dose on growth and yield of soybean grown following flooded rice crop. The experiment, conducted on farmers’ paddy fields in East Lombok (Indonesia) from August to November 2020 was arranged according to Randomized Block Design, with two treatment factors, namely soybean varieties (Anjasmoro, Grobogan, Biosoy-2) and biofertilizers (P0= without biofertilizer, P1= 50% NPK dose + Rhizobium biofertilizer). The results showed that application of Rhizobium biofertilizer did not significantly increase growth and yield of soybean except for weight of 100 grains, but the significant interaction effect on trifoliate number, pod number, unfilled pod number, weight of 100 grains, harvest index, and grain yield indicated that grain yields of Grobogan (2.03 tons/ha) and Biosoy-2 (2.31 tons/ha) were significantly higher with biofertilizer application while that of Anjasmoro variety (2.83 tons/ha) was higher under recommended NPK fertilization doses. It was concluded that the NPK fertilizer dose can be reduced by 50% of the recommended dose if it is accompanied by application of Rhizobium biofertilizer.