Soil organic matter changes and organic matter decomposing microbiota abundance in long-term experiment of soil tillage systems integrated with straw and green manure

Abstract

Organic matter improves soil quality and in some cases reduces negative tillage impact in soil. Though, soil management variables are controlling the quality of organic matter as well as organic compound decomposers. Aim of this study was to evaluate long-term impact of tillage within application of straw and green manure on soil organic matter and organic matter decomposing microbiota. Surface (0-20 cm in depth) soil from long-term no-tillage and tillage plots in field experiment of Aleksandras Stulginskis University were characterized for soil biochemical and microbial parameters. It was estimated that long-term (15 years) straw application increased soil organic carbon content. Reduced tillage systems without primary tillage have been even effective, organic carbon content in soil increased by more than 20%. However, reduced tillage systems with primary tillage had no effect on soil organic carbon pools. Thus, no-tillage and catch cropping for green manure significantly increased the pools of organic carbon by 28.9-32.7% and 31.7-33.3%, respectively, in the plots with and without straw. Continuous straw application either has by 22.7% increasing the mobile humus substances. It was estimated that due to increased soil microbial abundance there have been the tendency to intensify soil organic matter decomposition in reduced tillage systems without primary tillage. Even though microbial abundance (especially abundance of micromycetes) has been higher, reduced tillage increased the total microbial biomass. Thus, reduced tillage leads to higher soil organic carbon potential turnover rates. Reduced tillage, especially without primary tillage and integrated with straw and green manure ones, in long-term period considerably reduce risks of soil organic matter lost compared with conventional ploughing.