International Journal of Plant & Soil Science

Low phosphorus availability can constrain the productivity of groundnut–maize cropping systems, while the direct effectiveness of rock phosphate may be limited by poor solubility. An in situ trial was conducted over two consecutive years (2021-2022 and 2022-2023 for groundnut; 2022 and 2023 for maize) to evaluate the effect of rock phosphate (RP) combined with organic amendments (vermicompost, FYM and humic acid) and phosphate-solubilising bacteria (PSB) on the quality, yield and economics of a groundnut-maize cropping system. Fourteen integrated nutrient management (INM) treatments were compared, ranging from an unfertilised control to a fully integrated package (100% RP + vermicompost + FYM + humic acid + PSB). The results showed that the quality parameters of groundnut (protein and oil content and yield, kernel yield and shelling percentage) and maize (protein content and yield) improved significantly and progressively with the successive integration of organic and microbial inputs. The fully integrated treatment (T14) recorded the highest values across the parameters, followed by T13 and T12, whereas the control recorded the lowest. Economic analysis revealed that, although the cost of cultivation increased progressively with input intensity, gross income and the benefit-cost ratio increased more sharply, with T14 giving the highest B:C ratio in both groundnut (2.33) and maize (2.44). The groundnut equivalent yield (GEY) of the cropping system also more than doubled under T14 (39.34 q/ha) relative to the control (17.95 q/ha). The combined application of rock phosphate, vermicompost, FYM, humic acid and PSB was the best-performing treatment under the study conditions.