Effects Of Different Modes Of Straw Returned On Soil Biological Properties

With the rapid development of China’s agriculture, fertilizer application rate increased year after year, many ecological and environment problems have caused government and the public’s attention. The technology of straw returning can reduce pressure oflacked fertilizer and negative effects from excessive fertilizer application. Besides, straw returning can increase soil porosity, reduce soil bulk density, increase the quantityof microorganism, and improve soil enzyme activity. The research of straw returned technology has a great significance under today’s “green and low carbon economy” background. In this paper, the experiment is located in SanYuan long-term experimental field of Northwest A&F University. In order to work out the influence of9kinds of straw returned（WH+MC、WH+MM、WH+MN、WC+MN、WC+MM、WC+MC、WN+MC、WN+MM、WN+MN） to soil properties, the object of straw returning under wheat-maize rotation were studied throμgh laboratory simulation, including the measurement of soil enzyme, Carbon credits and nylon mesh bag decomposition. We also studied the influence of straw decomposition to soil enzyme and Carbon credits throμgh Pot experiment by control different C/N and fertilizations. The main conclusions were as follows:1. The activity of soil enzyme were increased after straw returning, including soilInvertase, Ployphenol oxidase, FDA hydrolase,β-glucosidase,Phosphatase,Dehydrogenase. Compared with blank, the TEI were increased significantly in straw returned managements.2. All straw returning treatments had increased SOC and soil readily oxidizable organic carbon significantly, while the largest increases of SOC by34.71%appeared inWN+MC, and the largest increases of soil readily oxidizable organic carbon by27.02%in WC+MN.3. Correlation analysis showed that the relative coefficient between FDA hydrolase and SOC, readily oxidizable organic carbon,Kos,carbon on level difference reached0.945**,0.750**,0.761**,0.794**respectively, so FDA hydrolase has Close connection with soil carbon accumulation, and it can reflect The degree of straw decay to some ex tent.4. After3years of wheat-maize rotation, WN+MC is the optimized straw management under comprehensive consideration.5. Straw decomposing presents the features that fast in early days,then slow down,and nearly stop in later period. The management of WC+MC was most conduciveto straw decomposing, reduce the time of release25%and50%of dry matter needed,it is3,45days respectively.6. The difference of activated carbon between high and low fertility soil was significant, but it differs little to the improved content,2.04g/kg in high fertility management,while2.06g/kg in low; The effect of fertility on the activity of Invertase,Ployphenol oxidase, FDA hydrolase,β-glucosidase,Phosphatase,Dehydrogenase was significant.The soil enzyme activity in different fertility under4straw returning present a rule ofT2.0>T1.0>T0.5>T0. activated carbon present a rule of T1.0＞T2.0、T0.5＞T0in earlier stage and T2.0>T1.0>T0.5>T0in later stage7. The difference of activated carbon between different C/N was significant， compared with regulate C/N management, the content of improved activated carbon in without regulate C/N was greater,it was2.04g/kg and2.81g/kg respectively. The effect ofC/N on the activity of Invertase, Ployphenol oxidase, FDA hydrolase,β-glucosidase,Phosphatase,Dehydrogenase was significant. The soil enzyme activity in different C/N under4straw returning present a rule of T2.0>T1.0>T0.5>T0. activated carbon presenta rule of T1.0＞T2.0、T0.5＞T0in earlier stage and T2.0>T1.0>T0.5>T0in later stage.