Effects of Diverse Habitat Biofertilizers on Yield and Nitrogen Balance in Plant–Ratoon Crop Cycle of Sugarcane in Subtropics

Abstract

Three nitrogen fixing biofertilizers of diverse habitat; endophytic Gluconacetobacter diazotrophicus, free living Azotobacter chrococcum and associative Azospirillum brasilense were tested in field condition for a complete sugarcane crop cycle of one plant and a ratoon crop at different levels of N input for enhancing crop productivity and soil N balance. Different biofertilizers increased the crop yield at all nitrogen levels but the maximum increase was recorded at N75 as compared to N150. G. diazotrophicus based biofertilizer was found to be the best in terms of crop yield production followed by its combination with A. chrococcum and A. brasilense. PFP for nitrogen was more in plant crop (9–38%) than the ratoon crop (4–24%) due to different biofertilizers. Apparent N balance indicated a contribution of 52.3–216.7 kg N ha−1 in plant crop and from 65 to 225.3 kg N ha−1 in ratoon crop due to biological nitrogen fixation in different biofertilizer × N treatments. The maximum N contribution was recorded with G. diazotrophicus and minimum with A. brasilense in a plant-ratoon cycle of sugarcane crop. Overall field inoculations of sugarcane by diazotrophic biofertilizers are highly beneficial and of tested biofertilizers G. diazotrophicus based biofertilizer is most efficient in terms of higher cane yield, commercial cane sugar production, efficient N utilization and maintaining positive N balance.