Abstract: In order to understand the effects of land reclamation on soil inorganic carbon in 0-50 cm soil layer in arid zone, an investigation was carried out at a typical inland river basin namely the Sangong River watershed in Xinjiang, northwest China. The soil inorganic carbon content and storage in 0-20 cm and 20-50 cm soil layers were determined in crop growth season (from May to October) under different reclamation durations \[0 (non-reclaimed land), 5, 20, 50 and 100 years\]. The results showed that there was a similar change trend in soil inorganic carbon content for all reclamation durations, which was increased before June, and then followed by a decrease during crop growth season. For different soil layers, accumulation of soil inorganic carbon in the old oasis region was higher in non-reclaimed land than that in reclaimed land, but it showed an opposite trend for soil inorganic carbon accumulation in the new oasis region, with an increased carbon accumulation in 0-20 cm soil layer of nonreclaimed land and in 20-50 cm soil layer of reclaimed land, and a decreased inorganic accumulation in 20-50 cm soil layer of non-reclaimed land and 0-20 cm soil layer of reclaimed land. pH value decreased with the increase of reclamation duration after 5 years (P<0.05). The soil inorganic carbon content and storage increased from early reclamation before 20 years, and then decreased, being 1.8 times in 20 years as that in 100 years with soil inorganic carbon storage of 66.80 kg·m^-2 in 0-50 cm soil layers. In conclusion, soil inorganic carbon content and storage in the 0-50 cm soil layers began to decrease 20 years after reclamation.

Key words: maize, biomass, photosynthate allocation, model.