Tillage, crop residue management and nitrogen application impacts on soil properties under maize–wheat (Zea mays–Triticum aestivum) cropping system

Tillage intensity, crop residue retention and nitrogen application can significantly impact the soil properties and crop productivity. We studied the effect of tillage (deep tillage [DT] vs. shallow tillage [ST]) in main plots and residue management viz. conventional tillage without residue (CT-R), conventional tillage with residue (CT+R), minimum tillage without residue (MT-R) and minimum tillage with residue (MT+R) in sub plots and fertilizer-N at 75, 100 and 125% N (viz. N75, N100 and N125) in sub-sub plots. Field treatments were established in maize-wheat (Zea mays-Triticum aestivum) cropping system during 2016-2019 at two different locations in north-western India and were arranged in split-split plot design. The soil penetration resistance was significantly lower under deep tillage (3.4 to 3.7%) as compared to shallow tillage. CT+R recorded lowest penetration resistance as compared to other tillage and residue combinations but other soil properties like OC, available NPK, soil aggregation, infiltration rate did not differ significantly. The addition of crop residue both under minimum and conventional tillage significantly increased the soil microorganism count and dehydrogenase enzyme activity at both locations. CT-R recorded lowest microorganism count and dehydrogenase enzyme activity. The available soil nitrogen, microorganism count and dehydrogenase enzyme activity significantly increased with increasing nitrogen doses at both locations and were highest under 125% N level as compared to 75% and 100% levels. In both crops, the grain yield was not significantly affected by tillage and crop residue combinations while the different levels of nitrogen fertilizer significantly affected the grain yield. From soil health and sustainability point of view, CT+R treatment with 100% recommended dose of nitrogen in maize-wheat crop rotation seemed beneficial.