Comparative evaluation of changes in soil bio-chemical properties after application of traditional and enriched vermicompost

For nutrient-deficient soils, vermicompost is an excellent soil additive. We find biochemical fluctuations in soil by comparing enriched vermicomposts to regular vermicomposts in a carefully controlled pot experiment. Various rock minerals, including mica, dolomite, and rock phosphate (RP), were used to create the enriched vermicompost before it was applied to acid lateritic soil, and so we investigated how vermicompost’s biochemical impact on the soil evolves (15-day intervals). Our results suggested that traditional vermicompost (VC) prepared from water hyacinth effectively improves nutrient content, enzymatic activities, and soil microbial properties. However, enriched VC application significantly (p<0.05) augments the concentration of available P (60% higher than conventional VC) and exchangeable K (increased by 10% from conventional VC) in soil. Furthermore, we observed that enrichment of VC using a combination of rock minerals showed significantly higher urease (around 35%), acid phosphatase activity (by 93%), and enhanced microbial biomass carbon (about 25%) and nutrient content of soil compared to only rock mineral additions. Nevertheless, our study revealed that conventional VC shows better soil organic carbon build-up than rock-based enriched VC. Although, enrichment conferred differential benefits to the soil in terms of increased P in RP-based and raised K in MC-based VC

Biogenic link to the recent increase in atmospheric methane over India

Methane (CH4) is a prominent Greenhouse Gas (GHG) and its global atmospheric concentration has increased significantly since the year 2007. Anthropogenic CH4 emissions are projected to be 9390 million metric tonnes by 2020. Here, we present the long–term changes in atmospheric methane over India and suggest possible alternatives to reduce soil emissions from paddy fields. The increase in atmospheric CH4 concentrations from 2009 to 2020 in India is significant, about 0.0765 ppm/decade. The Indo-Gangetic Plains, Peninsular India and Central India show about 0.075, 0.076 and 0.074 ppm/decade, respectively, in 2009–2020. Seasonal variations in CH4 emissions depend mostly on agricultural activities and meteorology, and contribution during the agricultural intensive period of Kharif–Rabi (i.e., June–December) is substantial in this regard. The primary reason for agricultural soil emissions is the application of chemical fertilizers to improve crop yield. However, for rice farming, soil amendments involving stable forms of carbon can reduce GHG emissions and improve soil carbon status. High crop production in pot culture experiment resulted in lower potential yield–scaled GHG emissions in rice with biochar supplement. The human impact of global warming induced by agricultural activities could be reduced by using biochar as a natural solution

Climate-resilient agricultural ploys can improve livelihood and food security in Eastern India

Agricultural practices naturally interject greenhouse gases (GHGs) into the atmosphere; consequently, analyzing decadal variation in N2O, CO2, and CH4 is indispensable over a major rice cultivating area (West Bengal) in subtropical India. Analysis of EDGAR data shows an unremitting increase in GHGs in the study region over two decades. The increasing global warming makes us revisit climate-resilient strategies to mitigate the risk of climate change on paddy production in agrarian economies. However, adapting to these strategies and impact assessment is necessary to comprehend their productiveness and further policy recommendation. Therefore, this study identifies the determinants of adaptation and measures the impact of these strategies on farm performance (yield and net income) and food security of smallholder paddy farmers in India. We used primary data from 612 paddy farmers from 20 villages in the Hooghly district, West Bengal, India. The study used probit regression analysis to identify adaptation constraints and Multinomial Logistic Regression (MLR) to determine the change in the direction and magnitude of the determinants of adaptation strategies. The study also used the Propensity Score Matching (PSM) approach to estimate the causal impact of climate adaptation on paddy yield, net income, and food security. Probit model outcomes identified that education level, cooperative membership, access to extension services, and institutional credit adoption positively and significantly impacted climate change adaptation across smallholders. MLR analysis identified that the direction and magnitude of the discussed determinants changed with different combinations of adaptation choices. The PSM results estimated that adaptation of climate-resilient strategies impacted paddy productivity, net income, and food security positively and significantly. In addition, paddy farmers using a more significant number of climate adaptation strategies experienced better yield, revenue, and food security than those farmers using fewer adaptation strategies

The ozone hole measurements at the Indian station Maitri in Antarctica

International audienceStratospheric ozone is a trace gas of great importance as it filters harmful ultraviolet radiations reaching the earth surface. Since ozone influences temperature and dynamics of the stratosphere, it is also a climate-relevant gas by influencing tropospheric temperature. Significant changes in the stratospheric ozone are, therefore, a concern for human health and climate. India has a dedicated polar research programme with two stations in Antarctica; Maitri (70.4° S, 11.4° E, since 1989) and Bharati (69.2° S, 76.2° E). Semi-regular measurements of total column ozone (TCO) are carried out to monitor the changes in the ozone layer there. Here, we use the available TCO measurements from Maitri in the winters of 1999–2003 and 2006, to estimate the chemical ozone depletion for the first time there. We estimate the largest ozone loss (59% or 180 DU) in 2006, and smallest in 2002 and 1999 (44% or 160 DU) among the winters; consistent with the meteorology, as the winter 2006 was the coldest and 2002 was the warmest with the first-ever sudden stratospheric warming over Antarctica. The Maitri ozone loss analysis is found to be representative for the whole Antarctica as assessed from the comparison with the average TCO from all Antarctic stations and satellite overpass TCO observations. The study, henceforth, demonstrates the value and significance of continuous monitoring of the ozone hole at Maitri to assist the policy decisions such as the Montreal Protocol and its amendments and adjustments

Legume Biochar Fertilizer Can Be an Efficient Alternative to Compost in Integrated Nutrient Management of Paddy (Oryza sativa L.)

Continuous use of chemical fertilizers is detrimental to soil health and crop productivity. Therefore, we need to recycle the agroresidues in the valorized form (e.g., biochar or compost) to improve soil quality while maintaining crop yield. This study compares different nutrient management practices using varied dose combinations of biochar/compost for sustainable production of rice. We present the results from a controlled environment study under nine different nutrient management options to assess the effect of a novel legume biochar fertilizer compared with legume-derived compost. Our results suggest that a relatively smaller dose of soil test-based balanced fertilization (75% of required nutrients) added with novel biochar (25% nutrient equivalence) is the best combination in nutrient-poor vertisols of semi-arid tropics. The yield benefits from novel biochar fertilizer might find relevance to similar total–N content to compost, although there are noticeable differences in other macronutrients, secondary, and micronutrients. The surface area and C:N ratio are significantly higher for biochar (i.e., 4.47 m2g−1; 37.68) than that of compost (i.e., 0.87m2g−1; 10.5) which provides a boost to rhizospheric interactions resulting in higher plant nutrient uptake resulting in improved plant growth attributes at lower doses. In addition, integrated biochar with mineral fertilizers improves soil organic carbon at the harvest of paddy by 44–54% than sole mineral fertilizer compared to a meager increase (10–15%) in compost. This study suggests a novel alternative (as legume biochar fertilizer) to compost that can have policy implications for developing a carbon-negative fertilization technique in paddy farming

Biochar-based nutrient management as a futuristic scalable strategy for C-sequestration in semiarid tropics

Climate and agriculture experts emphasize the need to develop a carbon sink in the soil to help alleviate the effects of climate change. A 2-year field experiment in semiarid tropical drylands tested sustainable nutrient management approaches to sequester carbon in the soil. We analyzed nine different treatments, including chemical fertilizers (as blanket and soil test-based [STB] recommendations), sole organic (biochar and compost), and their combinations (with 75% and 50% STB recommendation) as integrated applications (integrated nutrient management [INM]) in the maize–chickpea cropping sequence. We report that biochar treatments show higher (24%–30%) organic carbon stock in the top layer of soil than the respective compost treatments. Furthermore, the biochar-based INM showed the maximum residual effect in chickpea (Cicer arietinum L.) crops. The system equivalent yield showed the best results (8 Mg ha−1) for 50% need-based fertilizer and 50% biochar. Although we observed that sole-biochar sequestered the highest amount of soil organic carbon (0.69%) in the topsoil compared to the other treatments, it was not scalable due to the lower yield for maize crops. Similarly, composts showed more labile carbon concentrations as microbial biomass but lagged behind biochar treatments for organic carbon storage. The system performance expressed as net returns and benefits–cost ratio also showed better results for biochar-based INM. The findings show that drylands facing widespread land degradation in terms of nutrient imbalances and low C levels will benefit from an integrated approach of need-based fertilizer with biochar application. Therefore, this might be a long-term sustainable strategy for C-sequestration and food security for semiarid tropical drylands

Assessing residue and tillage management options for carbon sequestration in future climate change scenarios

Soil carbon depletion is a major concern for food security in drylands. The objective of this study is to test tillage with residue management under sequential and intercropping systems for carbon sequestration in semi-arid tropical drylands of India. We report the findings from a long-term field experiment (9 years) used to simulate the effect of residue and tillage management in Maize-chickpea sequential and Maize-Pigeonpea intercropping systems for the four possible future climate projections using APSIM model. These findings demonstrate a sustainable route with inclusive growth, as pledged at the UN climate change summit. A comparison of results under SSP 2.6 and 4.5 Wm−2 with SSP 8.5 shows that demand pressure from competitive marketplaces inhibits the establishment of soil carbon sinks and significantly reduces crop yields, likely due to indiscriminate chemical fertilizer use. We observed that a better decision in selecting cropping system might improve soil organic carbon content (SOC). SOC content ranging from 0.9 to 1.2% in Maize-pigeonpea intercropping and 0.85–1.1% in maize-chickpea sequential cropping systems, demonstrate good potential in the climate change mitigation exertions. Early SOC saturation (20 years) led to a decreased carbon stock in topsoil without residue addition practises. The addition of crop residues significantly increased SOC levels under both conventional and minimum tillage and created additional income for farmers. Simulation analysis showed impact of SOC changes on crop yield which remained nearly stable for 85 years. Therefore, hardy straw biomass of crops covering a large tract in dryland tropics, can be a scalable and sustainable solution to yield losses, while mitigating climate change through carbon sequestration

Record high levels of atmospheric ammonia over India: Spatial and temporal analyses

International audienceAtmospheric ammonia (NH3) is an alkaline gas and a prominent constituent of the nitrogen cycle that adversely affects ecosystems at higher concentrations. It is a pollutant, which influences all three spheres such as haze formation in the atmosphere, soil acidification in the lithosphere, and eutrophication in water bodies. Atmospheric NH3 reacts with sulfur (SOx) and nitrogen (NOx) oxides to form aerosols, which eventually affect human health and climate. Here, we present the seasonal and inter-annual variability of atmospheric NH3 over India in 2008–2016 using the IASI (Infrared Atmospheric Sounding Interferometer) satellite observations. We find that Indo-Gangetic Plains (IGP) is one of the largest and rapidly growing NH3 hotspots of the world, with a growth rate of +1.2% yr−1 in summer (June–August: Kharif season), due to intense agricultural activities and presence of many fertilizer industries there. However, our analyses show insignificant decreasing trends in annual NH3 of about −0.8% yr−1 in all India, about −0.4% yr−1 in IGP, and −1.0% yr−1 in the rest of India. Ammonia is positively correlated with total fertilizer consumption (r = 0.75) and temperature (r = 0.5) since high temperature favors volatilization, and is anti-correlated with total precipitation (r = from −0.2, but −0.8 in the Rabi season: October–February) as wet deposition helps removal of atmospheric NH3. This study, henceforth, suggest the need for better fertilization practices and viable strategies to curb emissions, to alleviate the adverse health effects and negative impacts on the ecosystem in the region. On the other hand, the overall decreasing trend in atmospheric NH3 over India shows the positive actions and commitment to the national missions and action plans to reduce atmospheric pollution and changes in climate

Consortium of Management Practices in Long‑Run Improves Soil Fertility and Carbon Sequestration in Drylands of Semi‑Arid Tropics

A continuously declining carbon in soils of drylands has increasingly become a source of concern and needs integrated solutions to achieve global food security and sustainability goals. This study analysed the impact and sustainability of management practices for climate change mitigation and food security in dryland tropics using long-term field trials. We compared a consortium of interventions, comprised four treatments, viz. traditional farming, improved practice, and regenerative treatments. Additionally, we presented the results of regeneration practices aimed at maintaining the soil macro and micro-aggregates. Results showed significantly higher soil organic carbon (SOC) in the topsoil layer (0–15 cm) of regeneration areas compared to the precision farming area. Our long-term experiments with a consortium of interventions resulted in a promising increase in soil carbon and crop yields. We selected shared socioeconomic pathways for scenarios in future climates and simulated the effect of improved practices in the near and distant future. Our simulation results revealed that adopting improved practices enhanced soil carbon at the rate of 0.7% per year and provided additional income from the yield of pulses in the 2-year rotation. Similarly, we observed an increasing trend in SOC building for improved practices in all future climate scenarios. However, the traditional practice showed a clear decline (0.20–0.15%) in SOC stock for all shared-socio-economic pathways