Impact of different cropping systems on the land nutrient index, microbial diversity, and soil quality

Abstract

AbstractIn the last two decades, the productivity of the rice–wheat growing system (RWGS) in the upper Indo‐Gangetic Plains of India has come to a plateau, and, as a result, farmers are now shifting to other crop growing systems (cropping sysytems) to achieve a higher net productivity. Inclusion of other cropping systems in place of the rice–wheat system affects overall crop productivity; however, there is dearth of information with respect to nutrient index (NI), microbial diversity, and soil quality. This study was carried out to assess how NI, microbial diversity, and soil quality changed after replacement of rice–wheat by a vegetable growing system (VGS), pulse growing system (PGS), potato growing system (PoGS), and a mustard growing system (MGS). An analysis of 307 soil samples from these crop growing systems revealed a soil pH range of 6.58–8.87 with 75.3% soils falling within the low category of mineralized N, and low NI (<1.67). The highest NI, enzymatic activity, and microbial diversity was recorded under PGS, which restored 34.2, 24.1, and 10.2% greater soil organic carbon (SOC) than other systems, and had a better carbon substrate oxidation rateand mineralized N than PoGS. The diversity indices peaked under PGS followed by VGS due to greater SOC, mineralized N, higher microbial counts, and more soil enzymes. Among the different crop growing systems the soil quality index (SQI) ranged from 0.647 (for PoGS) to 0.783 (for VGS) . The silt content, SOC, Zn, TN, acid phosphatase activity, available P, and total culturable fungi were the key soil indicators across all the crop growing systems. SOC is the most important and viable indicator for all the crop growing systems that affected microbial dynamics and soil quality. The greater SQI under VGS was due to the addition of organic manure and augmented SOC, P, and Zn availability. In contrast, the highest microbial and enzymatic activities, and functional diversity was recorded under PGS mainly due to greater edaphic variables. It is concluded that the pulse growing system (PGS) is the best for maintaining higher NI, and improving microbial and functional diversity.