Effects Of Organic Fertilizer Replacing Chemical Fertilizer On Soil Organic Carbon Stability And Rice Yield In Paddy Field

Organic fertilizers have a great impact on soil nutrients and crop yield,and at the same time,it will cause changes in soil organic carbon components and soil organic carbon mineralization,Soil organic carbon stability includes organic carbon fractions and organic carbon mineralization.In order to clarify the influence characteristics of replacing fertilizer with organic fertilizer on soil organic carbon stability and rice yield in paddy field,In this study,no fertilization(CK),single application of chemical fertilizer(NPK),replacement of 50% fertilizer with organic fertilizer(1/2NPKM)and replacement of 100% fertilizer with organic fertilizer(M)were taken as research objects,Based on the field experiment site in Xixiu District,Anshun City,through the combination of field experiment and laboratory culture,The relationship between soil active carbon,soil microbial biomass carbon and organic carbon mineralization under different treatments was investigated by alkali absorption and physico-chemical group,and the effect of organic fertilizer replacing chemical fertilizer on rice yield was studied;Identify the best method of organic fertilizer instead of chemical fertilizer.It provides scientific basis for rational fertilization of paddy soil,stability of organic carbon and yield increase of rice.The main results obtained are as follows:(1)Organic matter,total nitrogen and alkali-hydrolyzed nitrogen reached the highest value with 1/2NPKM treatment,available phosphorus and available potassium reached the highest value with NPK treatment,and available phosphorus with 1/2NPkm treatment had no significant level with NPK treatment.organic fertilizer instead of chemical fertilizer could improve soil organic carbon content.the organic carbon between each fertilization treatment was significantly higher than that of CK treatment,but there was no significant difference in organic carbon between each fertilization treatment.The coarse fraction of free active organic carbon in 1/2 NPKM treatment was significantly higher than that in CK and NPK treatments,There was no significant difference with M treatment;The composition of physically protected organic carbon in 1/2NPKM treatment was only significantly higher than that in CK treatment,There was no significant difference with NPK treatment and M treatment,but M treatment was significantly higher than CK treatment.There was no significant difference between the treatments of free active organic carbon fine particle composition,chemically protected organic carbon powder composition and biochemically protected organic carbon composition.he organic carbon pool of each component was in the order of free active carbon pool > chemically protected organic carbon pool > biochemically protected organic carbon pool > physically protected organic carbon pool,with an average proportion of 43.13%,36.28%,11.68%,8.64%.(2)SOC cumulative mineralization is an important index affecting SOC mineralization rate.Soil organic carbon mineralization rate during incubation in each treatment showed a downward trend on the whole.According to the decrease rate,it could be divided into the early stage(2-5 days),the first significant decline,the middle stage(5-26 days),the small decrease,and the late stage(26-60 days),and gradually stabilized.The cumulative SOC mineralization all treatments showed an increasing trend with time.The highest soil cumulative mineralization was obtained by M treatment(1497.39 mg/kg),followed by CK treatment(1421.68 mg/kg),NPK treatment and 1/2NPKM treatment(1386.40 mg/kg and 1384.03 mg/kg.The content of active organic carbon components(ROC,DOC and MBC in soil)before and after mineralization was only 1/2NPKM and significantly higher than that in CK treatment.(3)Replacing chemical fertilizer with organic fertilizer significantly affected rice yield.Compared with CK(8.31t/hm2)treatment,the rice yield of NPK treatment,1/2NPKM treatment and M treatment was significantly increased,There was no significant difference in rice yield between 1/2NPKM treatment,and the rice yield of M treatment decreased by 18.11 %.The substitution of organic fertilizer for chemical fertilizer had obvious effects on the effective panicle number,grain number per panicle,1000-grain weight,plant height and panicle length of rice,but had no obvious effect on seed setting rate and panicle height ratio,Replacing 50 % chemical fertilizer with organic fertilizer can ensure the accumulation of nitrogen accumulation and significantly improve the utilization rate of nitrogen fertilizer.In conclusion,organic fertilizer instead of 50 % chemical fertilizer can improve soil nutrients.soil organic carbon stability,organic carbon content and nitrogen utilization rate of rice,reduce soil organic carbon cumulative mineralization rate,thus reducing CO2 emission,promoting soil carbon seque stration ability and ensuring stable rice yield.