Effects of different organic wastes incorporation on soil organic carbon and its fraction under wheat-maize cropping system in North China Plain

Abstract: There are large amounts of agricultural waste produced in China annually and China has become the world's largest agricultural waste generator with the rapid development of farming, breeding, and the agricultural processing industry. The vastmajority of these wastes are under utilized as a potential resource, which not only causes a huge waste of resources but also creates serious environmental pollution. Thus,acircular agriculture pattern of planting and animal farming and/or agro-processing industry which is good for reducing pollution, improving the use of natural resources and saving fossil energy are important to promote sustainable development of agriculture and the environment. Based on the conception of circular agriculture, five types of organic wastes were applied to the field at an equal rate of carbon in the study including crop straw (CS), biogas residue (BR), pig manure (PM), mushroom residue (MR) and wine residue (WR). The effect of different organic waste on soil total organic carbon and labile organic carbon fractions were investigated and analyzed in this paper. The field experiment was established from June 2010 in a wheat-maize rotation cropping system. The data analyzed in this paper were observed from 2010 to 2014. The main results showed that: (1)Soil total organic carbon (TOC), labile organic carbon (LOC), microbial biomass carbon (MBC) and dissolved organic carbon (DOC) were all increased graduallyunder different organic wastes amendments. Soil TOC, LOC, MBC and DOC content were 1.24-1.62, 2.07-3.19, 1.20-2.06 and 1.05-3.36 times of inorganic fertilizer treatment after applying organic material 5 years.The annual increase rate of soil TOC, LOC and MBC under organic wastes treatment were 15.57%-22.82%, 20.00%-38.31% and 16.30%-50.56%, respectively. (2) Among the five kinds of organic wastes, biogas residue and mushroom residue are more effectiveto the improvement of soil TOC content compared with crop straw. The areraqe annual increasing rate of soil TOC content of bioqas residue, mushroom residue, pig manure, wine residue and Crop straw were 22.82%, 21.88%, 16.42%; 16.13% and 15.57%, respectively.