Soil quality and carbon sequestration under conservation agriculture with balanced nutrition in intensive cereal-based system

Conventional tillage practices and imbalanced use of inorganic fertilizers is well known to result in poor soil health. Alternative tillage and precision nutrient management are important strategies for tackling the issues of soil health deterioration, particularly in cereal-based intensive cropping systems. Therefore, we conducted a 4-year study with the objective of (a) monitoring the changes in soil physical, biological and chemical properties and crop productivity, (b) development of soil quality index-SQI, and monitor its’ changes against system productivity as management goal, and (c) studying the changes in soil organic carbon-SOC in relation to annual C input. The experiment was laid out in a split-plot design with 3-tillage practices [zero tillage-ZT; permanent beds-PB; and conventional tillage-CT] and 4-nutrient management strategies [Control (unfertilized), farmers’ fertilizer practice-FFP, recommended fertilizers doses-Ad-hoc and site specific nutrient management-SSNM] under a continuous maize (Zea mays L.) - wheat (Triticum aestivum L.)- mungbean (Vigna radiata L. Wilczek) rotation in a sandy loam soil (Typic Haplustept) of north-western Indo-Gangetic plains (NW-IGP) of India. The ZT/PB with SSNM/Ad-hoc nutrient management resulted in higher values of a) physical parameters viz., water stable aggregates >250 μm, saturated hydraulic conductivity (Ksat) and mean weight diameter-MWD, b) chemical parameters viz., SOC, available N, P, and K, and c) biological parameters viz., microbial biomass carbon and enzyme activities (fluorescein diacetate hydrolase, dehydrogenase, ß-glucosidase and alkaline phosphatase) compared with CT and unfertilized treatments. The CA practices recorded an increase in WSA (12–21%), MWD (14–29%), and Ksat (11–14%) compared with CT at the 0-0.15 m and 0.15–0.30 m soil depths, respectively. The PB-SSNM registered (44.1%) higher SOC content as compared to CT-unfertilized plots. Values for MBC, FDA and βGA declined in the order SSNM=Ad-hoc>FFP > Control. While, the DHA declined in the order SSNM>Ad-hoc=FFP > Control. Principal component analysis included MWD, SOC and available K in the minimum data set (MDS) as the soil quality indicators. Adoption of PB/ZT resulted ∼22.5% higher SQI compared with CT. The SSNM plots improved SQI by ∼19.3% and ∼5.3% over unfertilized and FFP. The SSNM based CA practices attained a significantly higher annual C sequestration rate than other treatments. Therefore, adoption of CA with SSNM and Ad-hoc nutrient management in intensive cereal based systems of NW-IGP is essential for improving nutrient cycling, soil quality, crop productivity and C-sequestration potential

Enabling smallholder farmers to sustainably improve their food, energy and water nexus while achieving environmental and economic benefits

Traditional cropping practices in the Eastern Gangetic Plains, South Asia, are resource intensive, requiring large inputs of water, energy and human labor. They are also inefficient, with relatively low productivity for the inputs used although the climate, soil and water resources of the region indicate that greater productivity is achievable. In on-farm experiments conducted across three countries (Bangladesh, India, Nepal) we compared the performance of traditional and improved management practices to understand which better facilitated the production of food-grain crops while reducing energy and water demands, thus improving the sustainability of cropping system energy requirements. Benefits of improved over traditional management practices included increases of up to 10% in crop grain yields; up to 19% in water productivity; up to 26% in energy productivity; and reductions of up to 50% in labor. These metrics combined to reduce the cost of production under improved management by up to 22% and to increase gross margins by up to 100% (although in most instances gross margins increased by 12–32%). CO2-equivalent emissions reduced by 10%–17% compared to traditional practices. The principles behind the improved management practices, which we demonstrate improve the food-energy-water nexus while concurrently promoting more sustainable use of energy resources, are applicable across smallholder farming systems throughout South Asia and in many emerging-economy countries. These improvements to traditional management practices combined with our approach of supporting farmers through the implementation of new methods has widespread applications and the potential to assist many countries transitioning to low-energy, sustainable food production