Assessing village-level carbon balance due to greenhouse gas mitigation interventions using EX-ACT model

Under National Initiative on Climate Resilient Agriculture (NICRA) project, a range of climate smart agricultural practices were evaluated with on-farm demonstrations during 2011–2013 in eight climatically vulnerable villages of Andhra Pradesh, India. Proven climate smart practices viz residue recycling, soil, water and nutrient management, afforestation and feeding + breeding practices in livestock were implemented in annual and perennial crops, irrigated rice, horticulture, fodder, forestry and livestock. An EX-ante carbon-balance tool (EX-ACT) developed by the FAO was used with a combination of various climate smart interventions to know the mitigation potentials in eight climatically vulnerable villages of Andhra Pradesh, India. Based on our observations, EX-ACT model had shown that these practices were effective to mitigate CO2 emissions apart from enhancing soil productivity. In Nacharam, Yagantipalli, Sirusuwada and Matsyapuri villages, climate smart practices implemented in annual crops along with crop residue recycling, crop and water management practices resulted in negative carbon (C) balance by −16,410, −8851, −7271 and −6125 t CO2 e, respectively. The EX-ACT model predicted positive carbon balance with irrigated module in the rice-growing villages of Sirusuwada and Matsyapuri villages. The negative values suggest a sink, and positive values a source for CO2 emissions. In Chamaluru village, although there were CO2 emissions (source) due to livestock and non-forest and land use changes, there was a carbon sink due to other activities as predicted by the model. The results suggested that various climatic smart practices at the village level were successful in creating net sink of CO2 emissions (t CO2 e)

Decomposition of roots and shoots of perennial grasses and annual barley-separately or in two residue mixes

Little is known about the decomposition rates of shoot and root residues of perennial grasses. This knowledge is important to estimate the carbon sequestration potential of the grasses. An incubation experiment was carried out in a sandy clay loam with shoot and root residues of three native perennial grasses (Wallaby grass, Stipa sp. and Kangaroo grass) and the annual grass barley either separately or in mixtures of two residues. Respiration rate was measured over 18 days, and microbial C and available N were measured on days 0 and 18. Decomposition was lower for roots than for shoots and lower for residues of perennial grasses than for barley. Cumulative respiration was positively correlated with water-soluble C in the residues but not with residue C/N. In the mixtures, the measured cumulative respiration was higher than the expected value in five of the nine mixes usually where the differences in cumulative respiration between the individual residues were relatively small. Lower than expected cumulative respiration were found in two of the mixtures in which barley shoots (high cumulative respiration) were mixed with residues with low cumulative respiration. There was a negative correlation between the change in microbial biomass C concentration from day 0 to day 18 and cumulative respiration on day 18. In the amended soils, the available N concentration decreased from day 0 to day 18. It is concluded that the low decomposition rate of perennial grasses residues should favour C sequestration, but that mixing residues of similar decomposition rate may accelerate their decomposition.Andong Shi, Chris Penfold, Petra Marschne