Biomass Production and Carbon Stock in a Silvi-Horti Based Agroforestry System in Arid Region of Rajasthan

A study was conducted to compare carbon accumulation in both tree biomass and soil (0-30 cm in depth) in a six year old agri-silvi-horti system grown on a farmer field in arid region of Rajasthan. Silvicultural species were Prosopis cineraria (PC), Ailanthus excelsa (AE) and Colophospermum mopane (CM) along with Zizyphus mauritiana (ZM), Cordia myxa (COM) and Emblica officinalis (EO) horticultural species planted alternate plant to each other. These were intercropped with wheat (Triticum aestivum). In addition, there were controls for each tree species as well as crop alone. Biomass production of horticultural and silvicultural species was higher in agroforestry plots as compared to respective control plot. P. cineraria showed the highest biomass (14.02 kg per tree) and Z. mauritiana tree (2.07 kg per tree) lowest biomass in agroforestry system, whereas biomass was one and half time low in sole tree plot (control). Maximum reduction was in A. excelsa tree. Carbon content (%) was highest in leaf and lowest in ischolar_mains. The highest carbon content was 45.84% in C. mopane and lowest was 43.61% in A. excelsa trees. Both biomass and soil carbon stock varied (P<0.05) among the horti-silvi combinations. Average carbon stock was highest in P. cineraria based agroforestry than other two silviculture species. It was more in agroforestry than in sole horti- and silvi-species as well as agriculture plots. Our results show that the main carbon sink in horti-silvi is the wooden parts of trees which increased with stand age, whereas the soil carbon pool remained stable.