Effects Of Organic Materials On The Ability Of Soil Carbon Sequestration Of Dry Farmland Of The Loess Plateau In Central Gansu

A nylon mesh bags method was conducted in field to study the effects of different organic materials(maize stubble, pig manure, compost)and addition level(CK:0g material+500g soil, T3:low-material +500g soil, T2:mid-material+500g soil, T1:high-material+500g soil) on the ability of soil carbon sequestration which involved the soil organic carbon(SOC) content, readily oxidizable organic carbon(ROC) content, microbial biomass carbon(MBC) content, total nitrogen(TN) content, microbial biomass nitrogen(MBN) content, material organic carbon residual ratio and soil carbon pool management index(CMPI) during all observation period(540 days) in dry farmland of the Loess Plateau in central Gansu. The main results were as follows:Adding maize stubble, pig manure and compost can all enhance the ability of soil carbon sequestration. Within the 0~540d, the soil organic carbon contribution ratio presented compost>maize stubble>pig manure. Compared with the treatment without materials, adding different organic materials can promote content of soil organic carbon, readily oxidizable organic carbon, microbial biomass carbon, total nitrogen, microbial biomass nitrogen and carbon pool management index, the effect of compost treatment is the best, SOC was increased by 137.72%, ROC was increased by 177.73%, MBC was increased by 174.33%, TN was increased by 312.27%, MBN was increased by 188.89%, CPMI was increased by 184.09%. The material residual ratio presented compost>maize stubble>pig manure, the changes of material organic carbon residual ratio had a relation to the chemical makeup of organic material.In the range of organic materials addition level, compared with the control treatments, the accumulation of soil organic carbon are all promote under different additive amounts of maize stubble, pig manure and compost, and the improvement of C retention increases with the increasing of addition. The material organic carbon decomposition ratio had a little relation to the different material additive amounts, the same kind of materials with different additive amounts material organic carbon decomposition ratio was no significant difference.In the loess soil(layland), gray calcareous soil, fluvo-aquic soil and dark loessial soil, adding maize stubble is conducive to the accumulation of soil organic carbon. In the range of maize stubble addition level, the accumulation of soil organic carbon increases with the increasing of addition. There are differences among ability of soil carbon sequestration of the same maize stubble additive amounts under various soil types, the changes had a relation to the soil structure.Taken together, the maize stubble, pig manure and compost with added amount of 6%, 11% and 9.6% can promote soil carbon pool lability, material organic carbon residual ratio and soil quality; The ability of soil carbon sequestration of loess soil(layland), gray calcareous soil, fluvo-aquic soil with 8% maize stubble addition level are better, while dark loessial soil with 6% maize stubble addition level can increase SOC, ROC, MBC and CPMI significantly.The research results show that adding maize stubble, pig manure and compost can all obviously enhance the content of soil organic carbon, promote the sustainable development of soil productivity. It illustrates that organic materials returning to field has significance to soil carbon sequestration.