Temporal changes in rhizosphere biological soil quality indicators of wheat in response to nitrogen and straw incorporation

Abstract

Soil health and sustainability of rice-wheat cropping system (RWCS) in the Indo-Gangetic plains (IGP) in South Asia are possibly adversely influenced due to in-situ burning of large quantities of rice residues. Instead of burning, it is increasingly being advocated to incorporate the crop residues into the soil. In a field experiment, effects of four nitrogen (N) levels (0, 90, 120 and 150 kg N ha− 1) as main-plots and four levels of rice straw (RS) incorporation (to a depth of 0.10–0.15 m) (0, 5, 7.5 and 10 t ha− 1) as sub-plots in split plot design were studied on soil enzymatic activities at two stages i.e. maximum tillering (MT) and flowering (FL) of wheat, and crop yield after 7 years. Activities of dehydrogenase, fluorescein diacetate, alkaline phosphatase, acid phosphatase, phytase, urease, l-asparaginase, cellulase, xylanase, β-glucosidase, peroxidase and phenol oxidase enzymes and grain yield of wheat in the treatment receiving 120 kg N ha− 1 and 10 t ha− 1 RS incorporation were significantly higher than in the control (without N and RS incorporation). The enzyme activities except peroxidase and phenol oxidase were dominated in rhizosphere than in the bulk soil, and at MT rather than at FL stage. Principal component analysis revealed that l-asparaginase, and phenol oxidase activities can be used as the most sensitive and reliable indicators for assessing soil quality under RWCS when rice residues are incorporated into the soil.