Assessment of rock phosphate enriched compost on phosphorus adsorption-desorption patterns under maize-wheat cropping system in Typic Haplustept

Aim: To investigate the effect of rock phosphate enriched compost (RPEC) on phosphorus (P) adsorption-desorption patterns under maize-wheat cropping system in Typic Haplustept. Methodology: Soil samples were collected from ongoing experimental field since 2017 located at the Research Farm 8B of the ICAR-Indian Agricultural Research Institute, New Delhi, India with six different treatments replicated four times each. The treatments involved a variety of organic and inorganic sources of P. The control was labelled as T1, while T2 consisted of 100% of the recommended dose of P using diammonium phosphate (DAP), T3 only 50% of the P was supplied through DAP and the remaining 50% P through RPEC. In T4, 25% of the P was from DAP and 75% from RPEC. In contrast, 100% P in T5 came from RPEC alone, and ordinary compost served as the sole source for 100% P in T6. Results: The bonding energy, binding affinity, maximum adsorption capacity, and maximum buffering capacity of P decreased with organic fertilizer application. The most significant effect was observed with supplementation of 50% P with RPEC. The desorption percentage and desorption index both increased with the application of RPEC, indicating an enhanced availability of P in the soil. Interpretation: The use of RPEC can positively influence the P dynamics in soil, thereby potentially leading to improved agricultural productivity. It can be an effective alternative for sustaining soil P and reducing foreign exchange spent on importing raw materials for P-fertilizer preparation.