[Effect of long-term fertilization on soil plough layer carbon storage in a reddish paddy soil].

With a reddish paddy soil as test materials, soil profile nitrogen storage in long-term different fertilization system (1990-2006) have been investigated. The result indicated that recycling of organic matter significantly increased the soil profile C storage (ranged from 57.7 to 66.2 t/hm2), and it was increased by 18.7-27.2 t/hm2 compared with the soil profile C storage of 1990. But it was increased by 5.4 t/hm2 with only application of chemical fertilizers. Saturated carbon storage of paddy soils was 84.0 t/hm2, and the C sequestration potential ranged from 17.8-43.7 t/hm2 compared with the current soil profile carbon storage. The result showed that there was a significant relationship between soil bulk density and depth changes of profile soil. The organic C storage would be greatly underestimated by 20.6% or 11.3% if we only take 20 cm or 23 cm as the standard depth in the estimating method for organic C storage, it also would be underestimated the difference of treatments. The combined application of chemical fertilizer and organic matter is optimal for agricultural field based onsoil organic C storage and the carbon sequestration potential.