Soil inorganic carbon sequestration through alkalinity regeneration using biologically induced weathering of rock powder and biochar

Soil inorganic carbon(SIC)accounts for about half of the C reserves worldwide and is considered more stable than soil organic carbon(SOC).However,soil acidification,driven mainly by nitrogen(N)fertilization can accelerate SIC losses,possibly leading to complete loss under continuous and intensive N fertilization.Carbonate-free soils are less fertile,productive,and more prone to erosion.Therefore,minimizing carbonate losses is essential for soil health and climate change mitigation.Rock/mineral residues or powder have been suggested as a cheaper source of amendments to increase soil alkalinity.However,slow mineral dissolution limits its efficient utilization.Soil microorganisms play a vital role in the weathering of rocks and their inoculation with mineral residues can enhance dissolution rates.Biochar is an alternative material for soil amendments,in particular,bone biochar(BBC)contains higher Ca and Mg that can induce even higher alkalinity.This review covers i)the contribution and mechanism of rock residues in alkalinity generation,ii)the role of biochar or BBC to soil alkalinity,and iii)the role of microbial inoculation for accelerating alkalinity generation through enhanced mineral dissolution.We conclude that using rock residues/BBC combined with microbial agents could mitigate soil acidification and SIC losses and also improve agricultural circularity.

Assessment of ecosystem services of rice farms in eastern India

Background:Rice is a major cereal crop and staple food of eastern India,and most farmers depend solely on rice for their livelihood.Rice farming provides both tangible and non-tangible benefits to ecosystems which need to be maintained and enhanced.These benefits are provided through ecosystem services(ES)that include both marketable and non-marketable.Methods:In this study,the rice farms in eastern India were valued by quantifying the economic value of the services under conventional method of rice cultivation and the gap of ecosystem services value and farm income per unit area were assessed.A stratified random sampling technique was used in this study for selection of agro-climatic zones,districts,blocks,gram panchayat,and study units(households).Soil sampling was also performed for assessing the regulating services(biocontrol of pests,carbon flow,soil erosion,nitrogen fixation),provisioning services(food and by-products),and supporting services(soil fertility,hydrological flow,nutrient cycling,and soil formation).Results:The results indicated that the total economic value of ecosystem services ranged from US$1238 to 1688 ha−1 year−1.The marketed(primary production)and non-marketed ecosystem services values ranged from 66–89 to 11–34%of the total,respectively.Valuation of some of the ecosystem services such as cultural services,biodiversity,and gas regulation,which may play a significant role in total ecosystem services,has not been made due to non-availability of data and appropriate methodology for rice ecosystem.Different values of parameters can explain the variability in ecosystem services among the agro-climatic zones in eastern India.Clustering of locations based on variability of ecosystem services helps in identifying intervention points for sustaining and improving ecosystem services,while permitting sustainable agro-ecological intensification.The highest total economic gap between ES value and farm income was found in the north central plateau zone(US$1063 ha−1 year−1)and the lowest in the north western plateau zone(US$670 ha−1 year−1).Conclusion:We suggest various measures to reduce the economic gap,including payments for ecosystem services for rice farming for sustainability of the ecosystem and agricultural development,while ensuring reliable farm income.

GREENHOUSE GAS AND AMMONIA EMISSION MITIGATION PRIORITIES FOR UK POLICY TARGETS

Agriculture is essential for providing food and maintaining food security while concurrently delivering multiple other ecosystem services. However,agricultural systems are generally a net source of greenhouse gases and ammonia. They, therefore, need to substantively contribute to climate change mitigation and net zero ambitions. It is widely acknowledged that there is a need to further reduce and mitigate emissions across sectors, including agriculture to address the climate emergency and emissions gap. This discussion paper outlines a collation of opinions from a range of experts within agricultural research and advisory roles following a greenhouse gas and ammonia emission mitigation workshop held in the UK in March 2022. The meeting identified the top mitigation priorities within the UK's agricultural sector to achieve reductions in greenhouse gases and ammonia that are compatible with policy targets. In addition, experts provided an overview of what they believe are the key knowledge gaps, future opportunities and cobenefits to mitigation practices as well as indicating the potential barriers to uptake for mitigation scenarios discussed.