Six years of conservation agriculture and nutrient management in maize–mustard rotation: Impact on soil properties, system productivity and profitability

Conservation agriculture (CA) is being advocated as an alternative to conventional tillage based systems, as it not only holds the potential to enhance soil biological properties, but could also sustain production in the long-run. The impact of long-term tillage and nutrient management on soil biological properties, crops performance, yield and returns were evaluated under maize-mustard rotation. Three tillage practices viz. zero tilled flatbed (ZTFB), permanent bed (PNB) and conventional tillage (CT) along with three nutrient management practices; farmer's fertilizer practices (FFP), recommended dose of fertilization (RDF) and nutrient expert assisted: site-specific nutrient management (NE®) were tested under the field conditions for six years (2013–2019). ZTFB produced the highest average maize grain yield, which was statistically similar to PNB; however it was 28.4% greater than CT. NE® and RDF recorded 27.4% and 24.8% higher yield over FFP, respectively. Similarly, ZTFB and PNB produced 8.0% greater mustard seed yield than CT, while NE® and RDF had 23.5% and 22.3% greater seed yield compared to FFP. Average of six years indicates, ZTFB and PNB produced 9.7% and 8.9% greater maize grain equivalent yield (MGEY) than CT. Furthermore, NE® and RDF had similar MGEY, but 24.9% and 23% greater than FFP. ZTFB and PNB gave the maximum economic benefits in comparison to CT plots. CT was 18.7% and 19.3% costlier than PNB and ZTFB, while RDF was more expensive than NE® and FFP. Plots under ZTFB and PNB had 13.9% and 17.8% (0.0−0.15 m soil profile) and 14.6% and 12.5% (0.16−0.30 m soil profile) greater soil organic carbon (SOC) than CT plots. These practices also had significant (p<0.05) positive impact on soil biological properties, such as, soil microbial biomass carbon (SMBC), dehydrogenase (DH), alkaline phosphatase (AP) and urease (UA) activities. In 0.0−0.15 m soil layer, NE® had greater values for SOC and SMBC than FFP, but not significantly different to RDF. This study clearly demonstrated that the adoption of conservation tillage (ZTFB / PNB) coupled with NE® and RDF in maize-mustard rotation would definitely improve system MGEY, net returns and soil biological properties in semi-arid regions of the north-west India.