Effects Of Modified Biochar On Saline Alkali Soil Improvement And Growth Characteristics Of Winter Wheat

Biochar is a good soil remediation material,known as the "black gold”of degraded soil,which has the characteristics of water and fertilizer conservation,promoting the formation of soil benign structure.The application of modified biochar in saline alkali soil improvement can provide a new way for the comprehensive utilization of agricultural wastes,the improvement of soil quality and the promotion of crop growth.In this paper,three kinds of modified biochar,namely nano modified biochar(NBC),acidification modified biochar(HBC)and composite modified biochar(HNBC),were used to carry out infiltration test and pot experiment on saline alkali barren soil in lubotan,Shaanxi Province.This paper analyzed the,effect of modified biochar on soil water infiltration characteristics,clarified the improvement status of modified biochar on saline alkali soil quality,and revealed the influence mechanism of modified biochar on physiological salt tolerance of winter wheat.The main results are as follows:(1)The modified biochar has larger specific surface area and micropore volume,which enhances its adsorption capacity.One-dimensional soil column infiltration test showed that modified biochar reduced the infiltration capacity of saline-alkali soil compared with BC,and HNBC had the greatest effect on reducing soil infiltration capacity.However,HBC increased the contents of C,H and O elements in biochar,the O/C value and(O+N)/C value increased,which enhanced the hydrophilicity of biochar,increased the cumulative infiltration amount of soil in the same infiltration time,and enhanced the soil water holding capacity.(2)Pot experiment results show that the addition of modified biochar can effectively enhance soil water retention capacity,significantly reduce soil soluble salt content,and improve soil aggregate structure.The content of water-soluble sodium in 0-50 cm soil layer decreased by 1.63%-52.26%.Compared with CK,HBC increases soil organic matter content by 1.33-3.28 times,ammonium nitrogen content 1.10-22.74 times and total nitrogen content 1.18-2.32 times,and reduces soil nitrate nitrogen content by 43.77%-95.60%,available phosphorus content 8.88%-99.17%and The content of available potassium is 8.88%-83.68%.(3)Shannon index and Simpson index showed that the addition of modified biochar improved the diversity and evenness of soil bacteria in saline alkali soil.Modified biochar significantly increased the relative abundance of Proteobacteria and decreased the relative abundance of Halomonas.Among them,HBC also increased the relative abundance of Actinobacteriota,Acidobacteriota,Sphingomonas and Bacillus,and promoted soil nutrient cycling.HBC improves functional genes such as amino acid metabolism,carbohydrate metabolism and lipid metabolism,and enhances the metabolic activity of soil bacteria.(4)Compared with CK,the leaf area and chlorophyll content of winter wheat were increased by 76.27%and 15.16%,respectively,enhanced photosynthesis,and increased the plant height and above-ground dry matter weight of winter wheat by 1.35%-25.80%and 8.97%-31.01%,respectively,it has a certain promoting effect on the growth of winter wheat.The application of modified biochar increases the leaf area and chlorophyll content of winter wheat,enhances photosynthesis,increases the plant height of winter wheat and the dry matter weight of the above ground,and has a certain promoting effect on the growth of winter wheat.Under the action of modified biochar,the ability of winter wheat to absorb potassium and sodium secretion is enhanced,the total potassium content of winter wheat is increased by 14.51%-27.55%,and the total sodium content is reduced by 23.09%-43.74%.HBC increases the content of Amino acids and derivatives,Phenolic acids,Flavonoids and Organic acids in leaves,strengthens the biosynthesis of amino acids,arginine and proline metabolism and other pathways,alleviates the osmotic stress of winter wheat,and enhances the salt tolerance of winter wheat.In summary,the acidified modified biochar has the best improvement effect on saline-alkali soil and promotes the growth and metabolism of winter wheat under salt stress.