C. P. Nath

Greenhouse gases emission, soil organic carbon and wheat yield as affected by tillage systems and nitrogen management practices

ABSTRACT Agricultural activities are responsible for greenhouse gases (GHGs) emission in the environment. Strategies are required to enhance the soil organic carbon (SOC) and nitrogen (N) sequestration to adapt and mitigate the climate change. We investigated GHGs emission, SOC and N enhancement under conventional tillage (CT) and zero tillage (ZT) with N management in wheat (Triticum aestivum L.). Seasonal carbon dioxide (CO2) emission and global warming potential (GWP) reduced for ZT treatments over CT without residues and 100% of required N with a blanket split application (CT – R + 100N). The ZT with 5 t ha−1 maize (Zea mays L.) residues retention and 75% of required N and GreenSeekerTM (GS)-aided N management (ZT + R + 75N + GS) reduced yield-scaled GHGs emission and increased total organic carbon (C) stock over CT – R + 100N. However, nitrous oxide (N2O) emission was lower in CT. The GS-based N management saved 26–35 kg N ha−1 in different tillage systems in both years over blanket application with higher N uptake and associated reduction in N2O emission. The study recommends that ZT with residues retention and GS-based N management can minimize the GHGs emission and improve the SOC.

Organic rice: potential production strategies, challenges and prospects

Organic farming is rapidly gaining recognition worldwide as a promising means to offer healthier food and to ensure environmental sustainability. Currently, organic produce including organic rice is in huge demand owing to its potential to fetch premium price in the global market. Despite the fact that rice performs well under organic production system, a set of constraints including nitrogen stress at critical growth stages, unavailability of rapidly mineralizable organic amendments, lack of appropriate varieties and intense crop–weed competition pose major challenges to realize the potential yield. Use of diverse organic nutrient sources including the split application of fast mineralizable nutrient-rich manures (vermicompost, poultry manure), green manures and bio-fertilizers can supply optimum nutrients in organic rice system. In parallel, development and deployment of rice varieties having response to organic nutrient inputs, resistance to diseases/insects and ability to compete with weeds can help minimize the risk of crop failure. Further, higher emission of greenhouse gases (GHGs) in organic rice field deserves greater attention in view of environmental sustainability. Strategic water management and selection of appropriate organic amendments could help address this issue. However, a substantial research gap still exists demanding a deeper understanding of the organic rice system in order to register higher yield gains. This review article outlines the latest advances in organic rice production system with an emphasis on nutrient supply and ensuing dynamics, the outflow of GHGs, pest dynamics, produce quality and key attributes of rice cultivars for organic cultivation. We underscore the urgency for alignment of modern agricultural techniques with organic rice production to improve both the system productivity and the produce quality along with effectively avoiding the risks associated with in discriminate use of chemicals in agriculture.

Grain Legumes for Resource Conservation and Agricultural Sustainability in South Asia

Degradation of natural resources is a major environmental concern that threatens the agroecosystem health and food security in South Asian countries. About 1.8 billion people (24% of world population) are living in this region in an area of 5.03 km2. The higher population pressure on agricultural land (7 person ha−1) has further threatened the existing resources to a great extent. Thus, conserving natural resource base is essential to feed the burgeoning population. Continuous practice of cereal-cereal rotation including rice-wheat in Indo-Gangetic plains have emerged several soil- and environmental-related issues. Diversification of cereal-cereal cropping systems is warranted to mitigate those issues and to adapt to the changing climatic condition and to enhance the resource-use efficiency on a sustainable basis. Grain legumes are the suitable candidate crop for diversification because of its inherent capacity to build up soil health and in conserving natural resources. There exists a large scope to introduce pulses as the second crop in 22.2 million hectare areas of rice fallows in India, Bangladesh, and Nepal. System intensification with inclusion of mungbean in summer fallows of rice-wheat cropping system could add an additional pulse crops area of 1.0 m ha in Indo-Gangetic plains. Several alternative grain legume inclusive crop rotations have been identified for the different agro-zones that certainly could play an important role in popularizing the conservation of agriculture in cereal-dominated production systems of South Asia. Endowed with an inherent potential biological N-fixation (30–150 kg N ha−1), of the deep root system, the root exudates mediated P-solubilization, and nutrient-rich residues of grain legumes improve the soil fertility and enhance the soil profile nutrient cycling. Crop diversification with grain legumes has additional benefits associated with improving water productivity, reducing input cost, and minimizing incidence of diseases and pests. Besides this, the low application rate of the N fertilizer to grain legumes has the advantage of reducing greenhouse gas emissions and groundwater pollution. Thus, grain legumes would play a crucial role in resource conservation, ecosystem balance, and in the sustainability of agricultural systems of South Asia.

Tillage and nitrogen management effects with sequential and ready-mix herbicides on weed diversity and wheat productivity

ABSTRACT In this experiment, weed management was studied in zero tillage (ZT) and conventional tillage (CT) wheat with and without crop residue and nitrogen (N). The treatment ZT with crop residue retention (R) and 75% of required N plus GreenSeeker™ (GS)-aided N management (ZTRNGS) resulted in a reduction of density and dry weight of weeds compared to CT and ZT without residue. Sequential application of pendimethalin and sulfosulfuron (PMT-SSF) reduced the weed density and dry weight compared to the weedy check (WC). Importantly, the richness and diversity indices were high in ZTRNGS and in WC treatments. Greater wheat grain (5.11 t/ha) and biomass yield (13.31 t/ha) were observed in ZTRNGS than CT without residue and blanket split application of N (CTN). The treatment ZTRNGS recorded 14.1% and 16.9% higher gross and net returns, respectively, over CTN. This study demonstrates that surface retention of crop residue in ZT is more useful than residue incorporation under CT for effective weed control, improving crop yield and profitability.

Improving soil organic carbon pools through inclusion of summer mungbean in cereal-cereal cropping systems in Indo-Gangetic plain

ABSTRACT Long-term effect of mungbean inclusion in lowland rice-wheat and upland maize-wheat systems on soil carbon (C) pools, particulate organic C (POC), and C-stabilization was envisaged in organic, inorganic and without nutrient management practices. In both lowland and upland systems, mungbean inclusion increased very-labile C (Cfrac1) and labile C (Cfrac2) in surface soil (0–0.2 m). Mungbean inclusion in cereal-cereal cropping systems improved POC, being higher in lowland (107.4%). Lowland rice-based system had higher passive C-pool (11.1 Mg C ha−1) over upland maize-based system (6.6 Mg C ha−1) indicating that rice ecology facilitates the stabilization of passive C-pool, which has longer persistence in soil. Organic nutrient management (farmyard manure + full crop residue + biofertilizers) increased Cfrac1 and carbon management index (CMI) over inorganic treatment. In surface soil, higher CMI values were evident in mungbean included cropping systems in both lowland and upland conditions. Mungbean inclusion increased grain yield of cereal crops, and yield improvement followed the order of maize (23.7–31.3%) > rice (16.9–27.0%) > wheat (lowland 7.0–10.7%; upland 5.4–16.6%). Thus, the inclusion of summer mungbean in cereal-cereal cropping systems could be a long-term strategy to enrich soil organic C and to ensure sustainability of cereal-cereal cropping systems.