Effects Of Different Patterns Of Straw Returning On Soil Physical And Chemical Properties And Rice Yield In North Rice Field

In order to explore the feasibility of different ways of straw returning and biochar based fertilizer in rice growing area of Northeast China.From 2017 to 2018,the field positioning test was set up in the Calima rice experimental station in Liaozhong,Liaoning Province for two consecutive years,compared with conventional fertilization(CK),the contrast research of the effects of direct straw returning(ST),equal amount of straw carbonization returning(SB),and biochar based fertilizer(CF)on soil physical and chemical properties,rice growth and yield.Based on the soil-rice system,comprehensive comparative analysis of two ways of straw returning to the field to improve soil fertility and promote yield.The effects of cumulative straw(direct,carbonized)on soil physical properties,soil nutrient content,rice growth and yield were determined.Based on the analysis of soil physical and chemical properties,rice agronomic characteristics and yield,the application of biochar based fertilizer in rice production was studied.In order to provide theoretical basis for straw resource utilization in northeast China,soil fertilization in rice field and stable yield improvement.The main test results are as follows:1.Field positioning experiments for two consecutive years showed that direct straw returning to the field and straw carbonization returning to the field could significantly reduce the soil bulk density of the paddy field,with an average two-year reduction of 6.2% compared with the control,increased total porosity of the soils,In 2017,the two methods increased10.5% and 9.88% respectively compared with the control,improved the stability of soil water stable aggregates,and changed the three(solid,liquid and gas)phase composition of soil,The cumulative effect of straw carbonization on improving soil physical properties is better than straw direct return.Both of them Both straw mulching methods can improve the physical properties of soil,coordinate the water,gas and heat conditions of soil,and provide a good soil micro ecological environment for rice growth.2.After the two crop growing seasons,compared with the control,the level of soil available nitrogen,available P,total P,total K and the content of soil organic matter were increased,in the first year it had no significant effect on the content of total N and available K,but in the second year,the effect was significant,and the soil fertility of paddy field increased,It is good for conservation and improve the quality of arable soil and provide sustainable nutrient supply to crops.3.During the main growth stage of rice,straw direct returning,straw carbonization returning and biochar based fertilizer treatment increased plant height,tiller number,SPAD value and dry matter accumulation.Compared with straw direct returning,straw carbonizationreturning was more effective in increasing SPAD value of rice during grain filling.In conclusion,compared with the control,each treatment improved the rice production capacity,and finally increased the spike number,grains per spike and the 1000-grains weight.Straw direct returning mainly through the promotion of rice tillering and then increase the number of effective ears,straw carbonization returning increase the number of grains per ear and the1000-grains weight.,and ultimately achieve the increase of rice yield.4.Biochar based fertilizer can improve soil bulk density,improve soil porosity and nutrient content,and promote rice growth and yield,with an average yield of 2% and dry matter accumulation of 5.14% in two years.Biochar based fertilizer can be used as a new fertilizer for soil improvement,improving soil fertility and rice production.5.The results of SEM image analysis showed that Soil,straw and biochar have changed their evolutionary forms after rice planting for two consecutive years,The soil becomes denser.When the decomposition level of straw is lower in the first year,it can be completely decomposed after two years,and the soil becomes denser.When the decomposition level of straw is lower in the first year,it can be completely decomposed after two years,biochar is relatively stable in the soil and can form a special composite structure with the soil,thus improving the physical properties of the soil and regulating the content of soil nutrients It provides theoretical basis for revealing the action mechanism of straw and biochar.