Response of Long-Term Application of Fertilizers and Manure on P Pools in Inceptisols

Soil phosphorous (P) can limit plant growth due to its fixation which stipulates the changes occuring due to imbalanced fertilization in pearl millet-wheat system. The study was aimed to identify the long-term effect of fertilizers and manures on availability of P due to changes in soil inorganic (Pi) and organic P (Po) pools at 0–15, 15–30, 30–60, and 60–90 cm. A sequential methodology was used to determine the effect of fertilizers and manures w.r.t. control (CK) on pools of P and their distribution in soil profile. Fertilizers and manures significantly increased the total and available P concentration. Labile (LOP) and moderately labile (MLOP) organic phosphorous concentrations significantly (P < .05) impacted throughout the soil profile. However, moderately and highly stable organic P pools (MSOP & HSOP) were significantly higher at surface soils. Integrating manures with fertilizers (NPKM) for 10 years increased the LOP and MLOP by 121.5 and 50.0%, while the concentration of MSOP and HSOP was higher under fertilizer treatments (NPK and BFSTCR) at surface soils. The Pi associated with Saloid-P, Aluminium-P, and Iron-P showed decreasing concentration, while calcium-phosphorous concentration increased at all soil depths. The increase in residual-P was more pronounced at lower depths. The proportion of Pi to the total P increased to 16.8% in fertilizer treatments at 30–60 and 60–90 cm soil, while Po proportions increased to 21.0% at 0–15 cm soil. Integrating manures with fertilizers could be a viable nutrient management practice of enhancing the Po and Pi and their availability to plants in sandy soils of Inceptisols.