Effect of long-term tillage and diversified crop rotations on nutrient uptake, profitability and energetics of maize (Zea mays) in north-western India

The current cereal based systems of South Asia are under threat due to multiple challenges of declining water table, escalating energy and fuel prices, shortages of farm labour, deteriorating soil health with overarching effects of climatic variability making farming uneconomical and unattractive. Conservation agriculture (CA) based management practices together with cropping system optimization have demonstrated to produce more with less while restoring, conserving and sustaining natural resources. In north-western India, maize (Zea mays L.) based systems are beingadvocated as an alternate to rice-based systems to address the issues of resource degradation particularly water table and climate-change-induced variability in rainfall and temperature, etc. However, targeting maize systems without futuristic best-bet crop management practices suited to production systems and ecologies, may lead to other problems. Therefore, we attempted to evaluate the performance of maize in kharif 2014 under long-term CA-based [permanent bed (PB) and zero tillage (ZT)] practices with conventional tillage (CT) as main-plots and four intensified irrigatedmaize systems [maize-wheat-mungbean (MWMb), maize-chickpea-Sesbania (MCS), maize-mustard-mungbean (MMuMb) and maize-maize-Sesbania (MMS)] in sub-plots under an ongoing trial established in 2008. During seventh year of study, higher maize glucose equivalent yield (MGEY) was recorded in ZT (2 942 kg/ha) and PB (2 774 kg/ha) while, the lowest in CT (2 576 kg/ha). Similarly maize glucose equivalent yield under diversified maize-based rotations was invariably higher in MCS and MWMb systems compared to MMuMb and MMS rotations. The results revealed that the maximum total N, P and K uptake (134.7, 40.9 and 156.6 kg/ha) as well as the protein content (8.7%) in maize grain were recorded in ZT, and minimum in CT. However, among the cropping systems plots the kharif maize planted in MCS plots registered the highest N, P, K uptake in stover and grain and protein (8.96%) content in grain. Maize net returns and BC ratio were significantly higher under ZT and PB planting compared to CT. Net returns and BC ratio under ZT and PB were higher by 18-29% and 26-38%, compared to CT plots, respectively. The maximumgross output energy (210.1×103 MJ/ha), energy efficiency (16.4) and energy intensity (8.50 MJ/`) were recorded under ZT. Tillage and cropping system interactions significantly influenced maize cob and grain yield in 7th year of experimentation and maximum yield was in ZT-MCS. Overall, our long-term results suggest that adoption ofconservation agriculture-based tillage under MCS and MWMb systems can enhance crop productivity, profitability,nutrient uptake and energetics of kharif maize in north-western region of India and elsewhere under similar agroclimaticconditions.