Effects Of Tillage And Fertilization On Rice Growth And Soil Fertility In Cold Paddy Fields

Under the current rice production mode in cold regions,rice production is faced with some problems,such as the decline of soil fertility,the wandering of per unit yield and the difficulty of quality improvement.The effects of tillage and fertilization on soil fertility,yield and rice quality need to be further studied.Field experiments were carried out from 2019 to 2020,including five treatments:chemical fertilizer treatment(R0F),straw non-returning and conventional tillage;straw returning with chemical fertilizer(RF),others with R0F;optimized returning 1(OPT1),straw returning combined with non-stirring;optimized returning 2(OPT2),straw returning plus autumn counter-rotary tillage operation,non-stirring;optimized returning 3(OPT3)to optimize fertilization on the basis of OPT1.The physical properties and nutrients of paddy soil,the growth and development of rice,the accumulation of nutrients,the yield and quality of rice were determined,and the relationship between tillage and rice growth was clarified.It is expected to provide theoretical basis and technical support for paddy field fertilization,high yield and high quality.The main results are as follows:Straw returning combined with non-stirring slurry can improve the physical properties of soil.compared with R0F,straw returning can reduce the bulk density by 3.34-7.29%.Returning straw to field in 0-25cm plough layer soil can effectively reduce soil compactness.The effect of non-stirring of straw returning to the field on the reduction of bulk density and compactness is not obvious,but it can increase the content of large aggregates and increase the average weight diameter of aggregates.Straw returning had no significant effect on the formation of large aggregates.After returning to the field,the agitation-free slurry did not significantly reduce the bulk density and compactness,but could significantly reduce the damage to the aggregate structure.Compared with R0F,the aggregate size of R>0.25 could be increased by 29.28%-45.53%,and the particle size of aggregates>2mm could be increased by 98.82%-371.76%.Treatments such as returning straw to the field without stirring can improve the content of soil nutrients.Compared with R0F treatment,the content of mineralized nitrogen in soil increased by11.26%.The content of mineralized nitrogen was increased by 25.34%after returning to the field and non-stirring.After continuous straw returning combined with non-stirring,soil available phosphorus and available potassium increased significantly,but straw returning had no significant effect on other soil nutrients.Treatments such as straw returning and non-stirring had no significant effect on soil available zinc.Straw returning inhibited the growth and development of rice in the early stage,and non-stirring promoted the growth of rice in the whole growth period.Compared with R0F,the tiller decreased by 7.89%at jointing stage,and the dry matter accumulation of leaves was significantly affected by 28.51%.Compared with R0F,the dry matter accumulation of rice leaves at the heading stage increased by 10.69%-19.59%,the dry matter accumulation of rice at the mature stage increased by 10.00%-12.21%,respectively.Compared with R0F,the nitrogen accumulation,phosphorus accumulation and potassium accumulation of leaves at jointing stage of straw returning to field significantly decreased by 19.90%,25.58%and 26.14%,respectively.Compared with R0F,straw returning combined with non-stirring increased the nutrient accumulation of nitrogen,phosphorus and potassium.Tillage methods such as straw returning combined with non-stirring could significantly increase rice yield,but straw returning had no significant effect on rice yield.Compared with R0F,the yield of the returning and non-stirring can be increased by 5.28%-10.00%,counter-rotation after returning by 7.30-12.21%,and optimize fertilization by 4.88%-7.95%,respectively.Affected by precipitation and accumulated temperature,there is a large gap in the overall yield between the two years,with an average yield of 8.15 t/hm~2in 2019 and 10.12 t/hm~2in 2020.After returning straw to the field,the rate of brown rice increased significantly by 0.46%-1.2%,and the rate of milled rice increased by 1.80%-2.00%,but the difference was not significant,and there was no significant difference in rice quality among fertilization modes.Straw returning can also improve the milling quality of rice,and will not affect the eating quality of rice.After returning straw to the field,the rate of brown rice increased significantly by 0.46%-1.2%,and the rate of milled rice increased by 1.80%-2.00%,but it was not significant.The treatments of straw returning and non-stirring had no significant effect on amylose,protein and taste value of rice.In summary,the two treatments of non-stirring and counter-rotation after returning to the field can not only increase the yield,but also effectively prevent soil degradation and improve soil fertility,which is an excellent tillage and fertilization scheme in rice cultivation.