| Because of the long-term submergence conditions and poor ventilation,the gleyed rice fields cause severe hypoxia in the soil,low microbial activity,accumulation of toxic and harmful reducing substances,and poisoning of crop roots.The amount of organic matter and total nutrients in the latent rice paddy soil is high,but its effectiveness is low.Therefore,the potential of the submerged rice paddy fields is considered as one of the low yield fields with the greatest potential for yield increase.This paper intends to study the potential of subtropical rice fields,and to improve soil microenvironment through the use of slow-release calcium peroxide,and explore the effects of slow release of calcium peroxide on rice physiological and yield changes,soil nutrients,and biological and soil reducing substances in the latent rice fields.The characteristics of the changes in order to provide a theoretical basis and a practical basis for the improvement of lagoon rice fields.In this experiment,a typical anaerobic rice field soil（Zhentou Town,Liuyang City,Hunan Province）was selected to carry out a simulation experiment under gleization environment and a rice pot experiment,and the soil physiochemical properties after the improvement were compared.The pot experiment was based on eight treatments:T1-conventionalfertilization（N-P2O5-K2O=0.25-0.15-0.25g/kgsoil）,T2-conventionalfertilization+calciumperoxidepowder,T3-conventional fertilization+non-envelopedperoxidationcalciumparticles,T4-conventional fertilization+I coated slow-release calcium peroxide,T5-conventional fertilization+II coated slow-release calcium peroxide,T6-conventional fertilization+Ⅲ coated slow-release calcium peroxide,T7-conventional fertilization+IV coated slow-release calcium peroxide,T8-conventional fertilization+urea peroxide powder.There are seven treatments in the simulation test,which are the T1,T2,T3,T4,T5,T6,and T7treatments in the above tests.Periodically measure the number of tillers,plant height,SPAD,net photosynthetic rate,stomatal conductance,and intercellular CO2concentration in pot experiments.During the harvest period,determine rice yield and sample and analyze N,P and K in rice straw and grain;Test and simulation test soil pH,redox potential,active oxygen concentration,reducing substances（total reducing substances,active reducing substances content,ferrous and manganous content）,effective nutrients(alkaline nitrogen,available phosphorus,available potassium And slow-effect potassium content,soil biological characteristics and soil total cadmium and effective cadmium and other changes.The results of the study are as follows:The use of calcium peroxide in the incubation of rice fields can increase rice yield and nutrient use efficiency,promote rice growth and development,reduce the content of reducing substances in soil,increase soil redox potential and culturable microbial activity and effective nutrient content,Uncoated calcium peroxide particles and sustained-release calcium peroxide are superior to calcium peroxide powder.The yield and nutrient use efficiency of rice treated with T2?T7 were significantly higher than that of T1 treatment.Compared with T2 treatment,the grain yield per plant,total biomass per pot,and nutrient use efficiency of nitrogen,phosphorus,and potassium were increased by 5.22%,respectively.4.44%and 0.17%,6.48%,9.48%,the difference was not significant;T4,T5,T6,T7 treatment per pot grain yield,total biomass per pot and nitrogen,phosphorus,potassium nutrient utilization rate increased by an average of 15.83 compared with T3 treatment%,6.03%and 37.17%,17.65%,5.37%.Among them,the T6 treatment had the most significant increase in efficiency.The grain yield per pot,the total biomass per pot,and the N,P,and K nutrient use efficiency were increased by 25.91%,17.10%,and 56.20%,32.05%,and 23.11%,respectively,compared with T3 treatment.T6 treatment The total biomass of each pot differed significantly from other treatments,with the highest number of tillers,plant height,and chlorophyll content.The effect of carbamide peroxide on rice yield,NPK utilization efficiency,and growth was not as significant as that of calcium peroxide powder treatment.The difference was not significant.The oxygen release time,soil reductive substance content,microbial activity,and effective nutrient content in the pot experiment and simulation experiment were basically the same.T6 treatment of active oxygen release time up to about 80 days,followed by T7,T5,T4,T3 treatment;simulation of the oxygen release time is shorter than the pot test;T3T7 treatment of reducing substances lower than T2 treatment,and each The oxygen release regulation tends to be consistent,and the reducing material content in the simulation experiment is higher than that in the pot experiment.The effective soil nutrient content in the order is T6>T7>T5>T4>T3>T2.The soil available nutrient content in the simulation experiment is smaller than the potted experiment.The changes of soil microbial biomass carbon and nitrogen were basically the same,followed by T6>T7>T5>T4>T3>T2.The soil microbial biomass phosphorus was T6,T4,T7,T5,T3,and T2 in that order.The biomass was lower than that of the pot experiment.The comparison of SMBN in each treatment in the simulation experiment was significantly different between T7 treatment and other treatments.The changes of soil enzyme activity and soil culturable microorganism amount were basically the same,followed by T6,T7,T5,T4,T3,and T2.The soil enzyme activity and the number of soil culturable microorganisms in the simulated experiment were lower than that in the pot experiment.There was no significant difference among the treatments;the total cadmium and effective cadmium levels in the pot experiment were lower than those in the simulation experiment.The treatment changes tend to be consistent,followed by T2>T3>T4>T5>T7>T6.The oxygen release time,reducing material content,microbial activity and effective nutrient content of treated urea were lower than those of calcium peroxide treatment.The application of Ⅲ-coated slow-released calcium peroxide in latent rice fields can significantly increase rice yield,photosynthetic performance,nitrogen,phosphorus and potassium nutrient use efficiency,soil microbial activity,effective nutrients,promote growth and development,and reduce rice soil reducibility.Material content.Ⅲ coated calcium peroxide sustained release is worth further study. |
