Study On Straw Maturity Returning To Field And Its Effect On Black Soil Fertility

Because a large amount of cultivated land has not been scientifically utilized,the proportion of fertilizer nutrients applied is seriously out of balance,only "using" not "raising",resulting in a continuous decline in the fertility of black soil and the gradual degradation of cultivated land quality and so on.As an effective agricultural measure to protect cultivated land,improve soil structure and improve soil fertility,straw return has been popularized and applied in a large area.However,in the process of straw returning,how to evaluate the dynamic decomposing effect of different straw maturing agents and the effect on cultivated soil quality and crops after returning to the field has become an urgent problem to be studied.In view of this,nylon net bag method was used to study the decomposition dynamics of corn straw treated with five kinds of maturing agents,and the best maturing agent was determined.Under the condition of conventional fertilization,the effects of returning straw directly to the field,returning maturing to the field and returning the field with organic fertilizer on the physical,chemical and biological properties of cultivated soil,the growth and development of crops,and the formation of yield were studied.In order to provide a theoretical basis for the protection and utilization of black soil cultivated land,improve the utilization efficiency of straw resources and increase the economic and ecological benefits of returning straw to farmland.The main results of this paper are as follows:(1)The degradation rates of corn straw treated with crude fiber maturing agent were 39.44%,49.31%,53.75%,56.97% and 58.57% at 12,24,36,48 and 60 days,respectively,which were higher than those of other treatments,and had significant difference with CK.The residual matter weight,dynamic degradation rate and dynamic cumulative degradation rate of corn straw treated with different straw maturing agents have the same trend with time.Their degradation can be divided into three stages: fast degradation(0-12 d),medium degradation(12-48 d)and slow degradation(48-60 d).Crude fiber maturing agent(T4)has the best degradation rate,while BM organic material maturing agent(T1)and HM maturing agent(T3)are not suitable for application in this soil environment.(2)Conventional fertilization + straw returning + straw maturing agent(F3)and conventional fertilization + organic fertilizer + straw returning(F4)can significantly improve soil moisture content,the proportion of water-stable macroaggregates,the content of available nutrients and microbial enzyme activity.Among them,there were no significant differences in soil aggregates,water content,alkali-hydrolyzed nitrogen content,sucrase activity,alkaline phosphatase activity,organic matter content,humin carbon content and total humus content.(3)With the growth of corn,the net photosynthetic rate of leaves increased first and then decreased,and the dry matter content of shoots increased continuously.corn straw decomposition(F3 and F4)can effectively increase net photosynthetic rate during plant growth,delay the aging process of corn,and has significant effect on the accumulation of dry matter in the shoot of plant.Compared with CK,the yield of F2,F3 and F4 treatments increased by 34.77%,38.42% and42.75% respectively.The essence of straw returning to field is that it can improve soil fertility and soil health quality.The yield of corn was related with soil moisture content,alkaline nitrogen content and alkaline phosphatase activity positively,and positively correlated with soil organic matter content.(4)Corn straw decomposition can significantly reduce nitrogen surplus,improve crop nitrogen use efficiency,and effectively reduce the contribution of basic soil fertility to yield.Compared with CK,the net income of each treatment increased by 15.75%,20.20%,26.83% and 32.23%respectively,indicating that corn straw decomposition and returning to the field could significantly improve the economic benefits of farmland soil and increase income on the premise of ensuring yield.On the whole,the measure of returning corn straw to field has obvious regulating and promoting effect on soil quality and effectively improving the productivity of cultivated land,and from the point of view of long-term sustainable development of agriculture,it is of great significance for the protection of black soil arable land.