Study On The Improvement Effect Of Combined Application Of Organic Materials And Biological Amendments On Loess Soil

The climate in the semi-arid area of the Loess Plateau is characterized by high temperature and little rainfall,which leads to the characteristics of alkaline calcification in the regional soil;however,the concentrated rainfall and loose soil in this area lead to poor soil water and fertilizer retention capacity and low organic matter content;In addition,the long-term excessive fertilizer input in agricultural production has resulted in excess soil fertility,which has seriously affected the healthy and green development of the Loess Plateau regional economy.Although it is known that both organic materials and biological amendments have the ability to improve soil fertility,there are few reports on special soil amendments for degraded soils in semi-arid areas.Therefore,this experiment aims at the problems of high soil p H,low phosphorus utilization rate,poor water retention capacity,and poor nutrient retention capacity of barren loess soil in arid regions of the Loess Plateau.Cinnamon japonica,rapeseed,and small crown flower)to replace some of the chemical fertilizers,and combined with bio-modifiers mainly made of a variety of functional microbial bacteria,a one-year field positioning experiment was carried out in mountain orchards in semi-arid areas..The purpose is to clarify the effect of the combined improvement of different organic materials and biological amendments and the effect of single application of biological amendments on soil fertility improvement in the area.The main findings of the test are as follows:(1)The combined application of different organic materials and biological amendments With the increase of soil depth,the soil p H first decreased and then increased.Among them,the soil treated with distiller’s grains(M3)showed better p H reduction effect.(2)The combined application of different organic materials and biological amendments can significantly improve soil water retention.Under different treatment conditions,the changes of soil water content and field water content were mainly manifested in the 20-40 cm soil layer,and the water retention index of the combined treatment was higher than that of the single application of soil amendment.It is distiller’s grains(M3),followed by rapeseed(M5)and mushroom residue(M2).(3)Under the condition of combined application of different organic materials and biological amendments,the release of available phosphorus in soil increased significantly.The activation coefficient(PAC)of soil phosphorus increased to33.29%-78.09%,among which 0-20 cm of fungus residue(M2),20-40 cm and40-60 cm of distiller’s grains(M3)had the largest PAC;for soil phosphatase For example,the phosphatase activity of the soil improved by the combined application of organic materials and amendments was significantly higher than the background value,while the phosphatase activity of the soil amendments alone increased by only 0.52 units compared with the background value.(4)Under the conditions of combined application of different organic materials and biological amendments,the content of available nutrients in soil varies greatly.Among different treatments,distiller’s grains(M3)showed the best overall effect on the release of available nutrients from soil,and the contents of nitrate nitrogen,ammonium nitrogen,alkali-hydrolyzed nitrogen,available potassium and easily oxidizable organic carbon reached 26.06 mg/kg,7.14 mg/kg,35.01 mg/kg,139 mg/kg,0.58 g/kg.The treatment effect of bacterial residue(M2)combined with biological modifier was the second.Compared with the control(CK),the increase range of total nitrogen and total phosphorus content in soil was 2.22%-52.32%,1.66%-18.62%.The content of total potassium,organic matter and CEC in soil increased by57.35%-23.70%,34.47%-150.10% and 14.81%-30.39%.There was a significant positive correlation between soil organic matter and total nitrogen and total phosphorus(P<0.05).For the exchangeable calcium and magnesium in the soil,its content gradually increases with the deepening of the soil layer,and the content of available metals(A-Fe,A-Cu,A-Mn,A-Zn)is concentrated in 20-40 cm and 40-60 cm two soil layers.(5)Under the combined application conditions of different organic materials and biological amendments,soil microbial biomass carbon and nitrogen decreased with the increase of soil depth,while soil microbial phosphorus first increased and then decreased with the deepening of soil depth.the trend of.Compared with the control(CK),the increase of soil microbial carbon under different treatment conditions was between 4.06% and 106.66%;the total amount of urease,glucosidase,catalase and phosphatase in soil after different treatments There are different degrees of increase,among which the various enzyme activities of the soil treated with the fungus residue(M2)and the soil amendment showed significant activity on the whole;the AI3 index of the soil increased by 4.96%-77.32%,and its main activity Concentrate on the0-20 cm soil layer.(6)The comprehensive fertility index(IFI)of soil increased to different degrees under the combined action of different organic materials and biological amendments;the increase of single application of biological amendments was the smallest,and the overall increase was in order from large to small.The order is: fungus residue(M2)>distiller’s grains(M3)> rapeseed(M5)> sheep manure(M4)> chinensis(M6)>small crown flower(M7)> single application of modifie r(M1)> control(CK);The maximum IFI value of the treatment with fungus residues combined with modifier was 0.56,while the IFI values of rapeseed and distiller’s grains were close,and the application amount of rapeseed was about half of that of distiller’s grains and fungus residues.Therefore,the combined improvement mode of organic materials and bio-improvers has a significant improvement effect on local soil quality;among them,the mode of combination of mushroom residue(M2)and bio-improvers has the best soil improvement effect,and the distiller’s grains have the best effect on soil improvement.The improvement effect of(M3)was second,and the combination of rapeseed(M2)and the modifier had better effect,but it was more economical to apply it in a large area.This study provides a scientific basis for the joint improvement of barren soils with organic materials and biological amendments in the region;it is of great significance for the improvement of soil fertility in the region and the resource utilization of agricultural wastes.