Cropping systems influence microbial diversity, soil quality and crop yields in Indo-Gangetic plains of India

Abstract

Wheat-rice cropping system has several negative effects on sustainability factors like underground water, soil structure, nutrient availability, soil organic carbon and productivity. In order to alleviate the obstacles of intensive cultivation of wheat-rice system, the impact of different cropping systems, viz., wheat-rice (W-R), lentil-rice (L–R), potato-green graM–Rice (P-Gg-R), mustard-rice (M–R) and wheat-green gram-pearl millet (W-Gg-Pm) on microbial diversity, soil quality and crop yields in Indo-Gangetic Plains of India was assessed. The W-Gg-Pm compared to first year, exhibited an increasing patterns of wheat and green gram yields by 6.51 and 7.04 % in second year, and 8.99 and 26.8 % in third year cropping sequence. The P-Gg-R system recorded the highest rice equivalent yield (17.4 t ha−1), N and K uptake, partial factor productivity and microbial diversity. Significant changes in most of the microbial activities, soil enzymes, water holding capacity, soil organic carbon, total C and N, C: N ratio and cation exchange capacity was recorded. Inclusion of legumes in rice or wheat -based cropping systems recorded significantly higher microbial and enzymatic activities, soil quality and crop yields. The highest physical, chemical and biological properties were observed in L–R system, closely followed by W-Gg-R, and the lowest in M–R system. The L–R system enhanced SOC by 11.6, 4.64, 4.64 and 2.48 % over M–R, W-R, W-Gg-Pm and P-Gg-R, respectively, while P-Gg-R system recorded the highest substrate oxidation rates (0.076 OD h−1), which was 22.4 % better to M–R system. The L–R system had the highest (0.844) soil quality index, while it was the lowest (0.727) in M–R system. Share of the minimum data set towards the improvement of soil quality index was in the order of water holding capacity (29.2 %)>total carbon (25.4 %)>soil pH (12.9 %)>total culturable fungi (12.3 %). A non-significant correlation was recorded between soil quality index and rice equivalent yield that could be due to different yield potentials of test crops. It is concluded that potato-green gram-rice and wheat-green gram-pearl millet could be an alternate system to alleviate continuous cropping obstacles of wheat-rice system.