The High Phosphorus Incorporation Promotes the Soil Enzymatic Activity, Nutritional Status, and Biomass of the Crop

Abstract

Phosphorus (P) application in the soil improves soil fertility and thus contributes to reproductive organ development, resulting in a higher cotton yield. However, the effect of increasing phosphorus rate on soil nutrient status, phosphorus-related enzyme activities, and its effects on crop productivity needs excellent attention. A consecutive two-year (2017-2018) field experiment containing three phosphorus levels [0 (P1), 100 (P2), and 200 (P3) kg P2 O5 ha-1] was accomplished by maintaining three replications. During both cropping years, soil samples were gathered from the topsoil (0-20 cm) and subsurface (20-40 cm) during the harvesting stage of the cotton crop. Soil collected at topsoil showed a significant increase in available and total phosphorus contents and urease and acid, alkaline, and neutral phosphatase enzyme activities compared with the sub-soil. The soil nutrients, viz. ammonium, nitrate, total nitrogen, available potassium, and total potassium, were significantly higher in P3 at the topsoil compared to other treatments. Soil enzymes viz. urease and acid, alkaline, and neutral phosphatase activities in the P3 were improved compared to the P1 and P2 applications. On average, the activities of these enzymes were maximum in 2017 at both soil depths. Moreover, the maximum biomass accumulation was observed in vegetative (root, stem, and leaves) and reproductive (bur, lint, and seed) organs with P3 incorporation in the soil. Similarly, an increase in the phosphorus application rate significantly enhanced the plant biomass and seed cotton yield during the 2017 and 2018 cropping seasons. Conclusively, the findings of this study showed that the P3 (200 kg P2 O5 ha−1) rate enhanced cotton productivity by improving the soil physicochemical properties, which alternately enhanced the phosphorus availability to the crop. Thus, changing these properties of the soil resulted in the enhancement of soil enzyme activities by increasing the cotton yield under field conditions.