Change Characteristics Of Soil Organic Carbon Pools Under Different Management

With the the experiment of long-term fertilization and interplanting sod in the orchard, the effects of land management on the amounts and quality of soil organic carbon and its components were studied, Furthermore, the content, distribution, and temporal and spatial variations of these soil carbon pools under different land management were analyzed. Then the correlation between different soil organic carbon pools and carbon crop was determined. The main results and conclusion are given as follows:(1) that effect of different long-term fertilization on soil organic carbon and its components were investigated. The results showed that the contents of soil total organic carbon, soil microbial biomass carbon (SMBC), water-soluble organic carbon(WSOC), and the light fraction organic carbon (LFOC)as well as the ratios of SMBC/TOC, WSOC/TOC, LFOC/TOC Of the combined application of chemical fertilizers and manure were higher than only applying chemical fertilizers.Compared with no fertilization, the heavy fraction organic carbon (HFOC) as well as the ratios of HFOC/TOC were ignificant increased under all fertilization treatments, especially, under only applying chemical fertilizers. There are significant effects of different fertilization patterns on the amounts of different size aggregates and it's TOC. Furthermore, TOC in> 0.25mm water-stable aggregates was significantly higher under only applying chemical fertilizers and the combined application of chemical fertilizers, while TOC in< 0.25mm water-stable aggregates was higher under chemical fertilization, indicating extensive use of organic fertilizers or a combination of organic and inorganic fertilizers increased the contents of active organic carbon and aggregate stability, resulting in maintaining and increasing the quality indications of soil carbon pool, which will maintain soil sustainable productivity. The different organic carbon components was studied by correlation analysis, the results showed that SMBC, WSOC, LFOC and POM-C can be used as the early index reflecting soil organic carbon library change(2) The cropt nutrients and output under long-term fertilization were investigated. The results showed that the total Nand total P all followed the order:rice>barley, grain>stem.The total N, P and K of rice stem and grain were increased under the application of chemical fertilizers and manure, While the total N of barley was inversely related to fertilizer, and the total N and P of rice stem and grain under organic manure treatment were higher than single inorganic fertilizer, and the total of K. under under organic manure treatment was lower than single inorganic fertilizer. The total N and P of barley stem and grain were decreased under the application of chemical fertilizers and manure, while the total K was increased. The three the nutrient content organic fertilizer were higher than than chemical fertilizer. Compared to CK, the organic fertilizer were more sensitive to increasing rice biomass and grain output than chemical fertilizer, especially applying the higher level inorganic fertilizer and organic manure has the highest biomass and grain output level. The single N fertilization treatment decreased significantly the rice biomass, which suggested that the reasonable application of fertilizer has remarkable effect to increase rice biomass(3) The effect of interplanting sod in the orchard,on soil organic carbon and its components were investigated. The results showed that the total organic carbon followed the order: ryegrass>CK>vicia villosa. Compared to CK, the SMBC and WSOC were increased by ryegrass and vicia villosa, especially with ryegrass. The LFOC and HFOC were all dereased with 6.45% and 1.73% by ryegrass, while increased 11.13% with and dereased with 13.25% by vicia villosa, repectively. The amounts of different size aggregates ware increased by interplanting sod in the orchard, especially in (> 250μm) water-stable aggregates. The TOC of different size aggregate was also effected by interplanting sod in the orchard. The different size aggregate organic carbon fractions in the orchard soil was increased by ryegrass (except for< 74μm)and decreased by vicia villosa(except for> 2000μm). These results indicated that grasses have significant effects on increasing soil active organic carbon and stable organic carbon.(4) The effect of interplanting sod in the orchard,on the dynamic changes of soil organic carbon and its components were studied. The results showed that the total organic carbon was higher in Summer and autumn, while lower in Spring and winter with the development of planting grass year, which on account of the different temperature of organic decomposition. The SMBC was increased with the development of planting grass year by interplanting sod. The WSOC was in an order of Grass> Legume, appearing the change trend of increase-reduce-increase. The soil LFOC of ryegrass and CK experienced rise-down-up change, while vivia villosa had been rising. The HFOC increased firstly with the maximum in the earli sampling(9.35g/kg), and then has decreased. The vivia villosa had been rising firstly, then declined to the minimum in the peach decay stage. The effect of interplanting sod on different size aggregate organic carbon fractions was significant difference. The different size aggregate organic carbon fractions in the orchard soil was increased by ryegrass and vicia villosa, and increased to the maximum with grass firstly, which is related to their different decomposition rate.