Assessment of Soil Chemical Quality, Soil Microbial Population and Plant Growth Parameters Under Organic and Conventional Rice–Wheat Cropping System

Abstract

Low-input organic agriculture is preferred over conventional agriculture for its sustainability and environmentally friendly nature. In this investigation, a field trial experiment was conducted to unravel the effect of conventional and organic farming practices on soil health and productivity under rice–wheat cropping system. Moreover, the dynamics of microbial communities was analyzed under both the farming systems using denaturant gradient gel electrophoresis (DGGE) and qRT-PCR techniques. This study found that the soil organic carbon was significantly higher under the organic farming system (0.63 ± 0.3% in wheat and 0.88 ± 0.2% in rice) than the conventional farming system (0.2 ± 0.1% in wheat and 0.63 ± 0.3% in rice). Quantification of 16S rDNA and nifH genes revealed higher abundance of total bacteria (2.52 × 1011 in rice and 2.40 × 1011 in wheat) as well as diazotrophs (8 × 106 in rice and 1.8 × 107 in wheat) under the organic farming system. Therefore, higher copy number of nifH genes in organic soil indicated that the diazotrophs played a significant role in supplying N for plant growth. DGGE band pattern authenticated that the bacterial diversity was higher under organic farming system. This study also showed that conventional practice gives comparatively more yield i.e. 0.29 t ha−1 extra rice and 2.86 t ha−1 more wheat than in organic farming. All other plant growth parameters are found higher in organic except nitrate reductase activity. This study signifies that organic farming is sustainable and can substitute the conventional practice for cost-effective, beneficial soil health and environmental sustainability for the long term.