Comparison of carbon footprint of traditional agroforestry systems under rainfed and irrigated ecosystems

Untenable expansion of cultivated lands and intensive agriculture accentuating the release of greenhouse gases (GHGs) into the atmosphere are warranting need for effective strategies to reduce the emission of green house gases associated with land use. Tree-based land use system has been emphasized as an effective strategy across ecological regions and farming situations as the most effective farmer-friendly technology limiting GHGs emission. The present study, therefore, was aimed to assess footprint and the annual fluxes of C in different traditional agroforestry systems in contrasting ecosystems to seek a way forward to mitigate climate change. The study revealed higher net C gain in rainfed ecosystem in agricultural system (3925.85 kg CE ha⁻¹) followed by agroforestry systems with trees grown on the boundary (3868.03 kg CE ha⁻¹) followed by trees scattered on farm land (3763.78 kg CE ha⁻¹) and on field bunds (3752.53 kg CE ha⁻¹). However, higher C sustainability index was with scattered planting of trees (30.35) followed by boundary planting (30.31), bund planting (29.54) and agricultural system (26.96). In irrigated ecosystem, higher C gain was in boundary planting of trees (6579.46 kg CE ha⁻¹) followed by silvihorti (6539.96 kg CE ha⁻¹) and bund planting (6051.59 kg CE ha⁻¹), but was the lowest in crops alone (5850.46 kg CE ha⁻¹) and in tree blocks (5121.59 kg CE ha⁻¹). However, higher C sustainability index occurred with block plantation (537.28) followed by boundary planting (40.99), bund planting (37.15), agricultural system (36.56) and silvihorti system (18.58). Further, it was observed that among the inputs used chemical fertilizers contributed more towards GHGs emission in both the ecosystems (76% of the total emission). In the contrasting ecosystems, bund and boundary planting agroforestry systems were more sustainable in terms C efficiency and offered better food security unlike block plantation, and partial substitution of chemical fertilizer helped reduce C emission. Overall, the agroforestry land use systems proved highly sustainable on long-term basis and hence need promotion.