Phosphorus and molybdenum nutrition impacts soybean productivity and soil bio-chemical attributes

A field experiment was conducted during kharif 2021 at the CSKHPKV-experimental farm, Palampur, to evaluate the effects of graded phosphorus (0, 30, 60, and 90 kg P/ha) and molybdenum levels (0, 1, and 2 kg Mo/ha) on soil fertility, microbial activity, and soybean (Glycine max L.) productivity under acid soils. A factorial randomized block design involving two factors (P and Mo) was employed, generating twelve treatment combinations with three replications each. The results revealed that application of 90 kg P/ha and 2 kg Mo/ha produced the highest grain yields (2479 and 2211 kg/ha, respectively), while the lowest were under P- and Mo-devoid plots (1541 and 1874 kg/ha, respectively). Soil pH and organic carbon remained statistically unchanged, while available N, P, K, and Mo increased with higher doses, reaching maximum values of 319, 26.4, and 126 kg/ha and 0.194 mg/kg, respectively, with 90 kg P/ha and 318, 23.1, and 124 kg/ha and 0.200 mg/kg with 2 kg Mo/ha. P fertilization caused a proportionate increase in the microbial biomass carbon (MBC), microbial biomass nitrogen (MBN), viable bacterial, fungal, and actinomycetes counts, and urease activity, whereas the least was under P-omitted treatments. Application of 2 kg Mo/ha improved all these traits, except urease activity, which did not show any significant change. The interaction effect was non-significant for all the studied soil properties. Thus, the individual application of 90 kg P/ha and 2 kg Mo/ha came out as the most productive treatment in improving the soil chemical and microbial balance and soybean productivity under acidic soil conditions.