Study On The Relationship Between Soil Labile Organic Carbon Fractions And Soil Enzyme Activity With Different Tillage Measures In Rainfed Farmland

It is one of the important ways to reduce the global climate change and reduce the carbon loss for improve the ability of soil carbon sequestration and maintain the balance of soil carbon in the field of soil. Farmland Soil carbon pool as the core component of soil carbon pool. Due to frequent human activities interferences, The dynamic change was happened in labile organic carbon fractions in soil carbon pool. It is key to change the mineralization process of soil organic carbon on soil carbon pool under the action of soil enzyme. Long term transition of agricultural production activities, such as tillage measures, as a key factor in the change of soil organic carbon pool have adverse effects on sustainable development of soil ecosystem for promote soil organic matter input and organic carbon turnover rate and damage the balance of soil carbon pool and atmospheric carbon poo l. The ecological environment was deteriorated in Loess Plateau for their poor natural conditions, and the poor agricultural production activities of human transition, which makes the soil erosion in the region. Based on the long-term experiment of conservation tillage in region of the Loess Plateau in Dingxi, dynamic changes for Soil labile organic carbon fractions and soil enzyme activities and their correlation was studied with different cultivation conditions, the main conclusions are as follows: 1.Under different tillage measures, with the promotion of wheat growth stage, soil readily oxidized organic carbon increased first and reached the peak at the jointing stage and then decreased. Harvest period has picked up. Soil microbial biomass carbon in the growth stage was increased first and reached the peak at the jointing stage and then decreased. Compared with conventional tillage, no tillage combined with straw mulching could significantly increase the content of soil active organic carbon and microbial biomass carbon in 0-30 cm soil layer of wheat growth stage. no tillage and tillage with straw incorporation could improve the total organic carbon, soil readily oxidized organic carbon and soil microbial biomass carbon content in 0-30 cm of soil layer and all showed no tillage and straw mulching > tillage and straw returning > no tillage > conventional til age. 2.Under different tillage measures, soil sucrase activity increased first reached the peak at the filling stage and then decreased. diastase, cellulase, peroxidase and dehydrogenase activity increased first, then decreased gradually at the jointing stage, and then increased at the grain filling stage. Compared with conventional tillage, no tillage and straw mulching, tillage and straw returning, no tillage could increase sucrase, diastase, cellulase, and peroxidase and dehydrogenase soil enzyme activities on the whole wheat growth stage. It was significantly effected on soil enzyme activity of 0-10 cm. 3.Compared with conventional tillage, three kinds of conservation tillage measures include no tillage with straw, no tillage and tillage with straw returning could increase the carbon pool management index, MBC/TOC and ROOC/TOC. Especially it has obvious effects on 0-10 cm. 4.During the whole growth stage, soil readily oxidized organic carbon and different soil enzymes, soil organic carbon and soil microbial biomass carbon were significantly positively correlated in 0-30 cm.The total soil organic carbon, soil microbial bio mass carbon and soil enzyme were significantly positively correlated 0-5cm, The correlation between 5-10 cm and 10-30 cm soil layers was only related to some soil enzymes. Five kinds of soil enzyme in different soil layers showed significant correlation except soil sucrase in 5-10 cm and 10-30 cm. 5.For 0-10 cm soil layer, soil sucrase activity increased in favor of total soil organic carbon, readily oxidized organic carbon,soil microbial biomass carbon accumulation. Soil cellulase could increase soil total organic carbon, soil microbial biomass carbon. Soil dehydrogenase and diastase had significant effects on soil readily oxidized organic carbon.