Response of wheat yield and soil fertility to tillage and plant residue management

Tillage has been used for centuries for ensuring favorable growing conditions for good germination and crop stand and to release nutrients from the soil through accelerated mineralization of organic matter and to incorporate nutrients found in manures and crop residues. Incorporation of crop residue in the soil increases soil organic matter content that provides a substrate for soil microorganisms and increases the organic component of the soil, recycles nutrients removed by a growing crop, improves crop yield, and soil aggregate stability, and enhances soil life. In order to investigate the effects of residue incorporation with various tillage practices on wheat productivity and soil fertility, field experiments were conducted at Agronomy Research Farm, the University of Agriculture Peshawar, Pakistan during winter 2016-17 and 2017-18. The study was carried out in RCB design with split plot arrangement having four replications. Sesbania (Sesbania aculeate L.) and parthenium (Parthenium hysterophorus L.) residues were applied as N sources with and without urea with different tillage practices i.e. minimum, conventional and deep tillage. Sesbania and parthenium residues were analyzed for N content and were applied at such rate that 60, 120 and 180 kg N ha(-1) was obtained from each treatment. Minimum tillage increased grain yield by 8.6% and biological yield by 4.3% as compared to deep tillage. Minimum tillage also increased soil total N by 6.8% and soil phosphorus by 1.6%. Similarly, minimum tillage increased soil organic matter from 0.82 to 0.87% while reduced bulk density from 1.47 g/cm(3) to 1.42 g/cm(3) as compared to deep tillage practices. Application of 120 kg N ha(-1) from sesbania residue and 60 kg N ha(-1) from urea increased grain yield by 62% and biological yield by 44.1% as compared to control treatments. Similarly, application of 120 kg N ha(-1) from sesbania residue and 60 kg N ha(-1) from urea increased soil total N by 62%, soil phosphorus by 27% and increased soil organic matter from 0.58 to 0.98% but reduced bulk density from 1.49 g/cm(3) to 1.41 g/cm(3) as compared to control plots. It was concluded that minimum tillage and application of 120 kg N ha(-1) from sesbaina residue along with 60 kg N ha(-1) from urea is a sustainable approach for increasing wheat yield and soil fertility.