Effects Of Different Rice Straw Returning Methods On Soil Organic Carbon Component And Combined Status In The Paddy Soil

The soil fertility of the coastal soil has decreased in northern China because of the poor soil management over the years.Rice straw returning,as a cheap and easy resource of organic fertilizer,has a positive effect for remaining soil fertility and reducing chemical fertilizer use.Studying the effects of straw application on soil organic carbon component and combined status is helpful to clarify the effect of different rice straw returning methods on fertility status in paddy soil.It is important for popularizing straw returning and increasing straw utilization efficiency.The paper observed the effects of different rice straw returning methods?rotted rice straw returning,direct returning of rice straw,rice straw-derived biochar returning?on soil organic carbon component and combined status in the paddy soil in Panjin city,Liaoning province.It is to explore the suitable way of rice straw returning,and to provide the basis for rational utilization of straw resources.the results have shown that as follows:?1?)It can increase the readily oxidable carbon content through all different rice straw returning methods?rotted rice straw,direct return of rice straw,rice straw-derived biochar?,and the best effect is rotted rice straw,which is 9.528g kg^-1.rice straw-derived biochar can increase oxidative stability index of soil organic carbon,which is 57.44.?2?Both rotted rice straw and direct return of rice straw increased the content of dissolved organic carbon,soil microbial biomass carbon,microbial entropy,and management index of carbon pool,and the best effect is rotted rice straw,which is 104.03 mg kg^-1,188.43mg kg^-1,1.82%and 148.13.Straw-derived biochar increased soil microbial biomass carbon content,which is 142.54 mg kg^-1.?3?The content of soil organic carbon and heavy fraction organic carbon increased with all different rice straw returning methods?rotted rice straw,direct return of rice straw,rice straw-derived biochar?.But they accelerated the decomposition rate,and rotted rice straw is the fastest,which is 18.6%and 22.1%.Straw biochar treatment slowed down the degradation rate by only 13.4%and 18.8%.?4?The loosely combined humus-C and firmly combined humus-C content inceased by applying rotted rice straw and direct returning of rice straw,and the best effect is rotted rice straw,which is 3.82 g kg^-1 and 0.91 g kg^-1.Straw-derived biochar can increase the tightly combined humus-C,which is 6.41 g kg^-1.?5?Three different straw returning methods increased the extractable humus-C and humic acid content,and the best effect is rotted rice straw,which is 4.09 g kg^-1 and 1.37 g kg^-1.The treatments of rotted rice straw and direct return of rice straw also can increase the accumulation of water soluble organic substances,direct return of rice straw is 0.31 g kg^-1In general,rotted rice straw returning and direct return of rice straw were more conducive to increasing the active organic component in the soil.It made soil nutrients more easy for absorption and utilization by plant.But they also accelerated the decomposition of soil carbon with a more rapid rate by rotted rice straw and a slow rate by direct return of rice straw.The straw-derived biochar is more conducive to the fix of soil nutrients,slowed down the rate of nutrient releasing and lossing,increased the accumulation of soil nutrients,and reducing the activity of soil carbon.Therefore,it might be reasonable for application of straw biochar combined with the application of rotted rice straw or direct return of rice straw in order to reduce its negative effects of reducing the nutrient activity.The results of this paper will provide the theoretical basis and data support for selecting reasonable rice straw returning method and for improvement of soil fertility by obtained dynamic rules from the effects of different rice straw returning methods on soil organic carbon component and complex status in paddy soil in northern China.