Wheat straw incorporation enhances paddy soil quality: Evidence from a pot experiment

Abstract

Evaluating soil quality under various management practices in agroecosystems is crucial for understanding soil functioning. In this study, a soil quality index (SQI) was developed to assess the impact of wheat straw incorporation on soil quality. Several soil attributes, either sensitive or insensitive to straw incorporation, were quantified in a pot experiment, and factor analysis was applied as a dimension reduction technique. Samples were taken from 0–20 cm depth in paddy soil, with treatments including no-fertilizer control and wheat straw incorporation at rates of 0%, 50%, 100%, and 150% under combined NPK fertilization. The wheat straw used in this study was obtained from a rice–wheat rotation system. Soil properties, including physical (mean weight diameter), chemical (organic carbon, total nitrogen, ratio of organic carbon and total nitrogen, and particulate organic carbon), and biological (microbial biomass carbon and nitrogen, and three enzymes) parameters, were measured to create a minimum data set for the SQI evaluation. Results suggested a significant improvement in SQI under 100%S treatment. While the 100%S treatment enhanced most soil microbial attributes, not all of them contributed to SQI due to their interrelationships. Only geometric mean of microbial biomass (GMB) and geometric mean of enzyme activity (GME) were critical for the SQI, collectively contributing 56.97%. Thus, GMB and GME were essential indicators for distinguishing between straw management systems and could be employed to monitor improvements in soil quality under 100%S treatment. Taken together, the 100%S treatment showed the highest SQI, indicating improved soil capacity and functions compared to the control. Smallholder farmers should consider the 100%S treatment for enhanced soil quality in paddy ecosystems.