Soil Quality Evaluation Of Irrigated Sandy Soil After A Single Application Of Biochar For Ten Years

As a big grain country,my country is also one of the countries with the most serious soil desertification and erosion.Irrigated sandy soil is one of the main low-yield soils in Xinjiang.Biochar generated after carbonization of agricultural wastes such as straw is a new research direction for improving irrigated sandy soil from irrigation and farming.Research on the environmental behavior and environmental effects of biochar in my country are still in its infancy,and there is little research on barren soils in arid areas,such as irrigation and irrigated sandy soils.This study has important theoretical and practical significance for improving low-yield soil fertility in arid areas and improving irrigation and irrigated sandy soil with biochar.This paper mainly studies the changes of soil physical,chemical,and biological properties and soil quality evaluation of irrigated sandy soil after 10 years of application of biochar.By setting 7 treatments(Blank control（CK₁）,22.5 t·hm^-2farmyard manure（1%cow dung,CK₂）,22.5 t·hm^-2humic acid（1%humic acid,CK₂）,22.5 t·hm^-2biochar（1%BC）,67.5t·hm^-2biochar（3%BC）,112.5 t·hm^-2biochar（5%BC）,222.5 t·hm^-2biochar（10%BC）),one-time application of different amounts of biochar,after 10 years of long-term positioning test,by analyzing the differences of 22 biochar physicochemical indexes among different treatments,the effect of biochar on the physicochemical and biological properties of irrigated sandy soil and its soil quality evaluation were obtained.Through the above research,the following main conclusions are drawn:（1）After 10 years of application of biochar,biochar can still significantly improve the soil physical properties of irrigated sandy soil.Among them,there were no significant differences in soil specific gravity and water-stable aggregates in the 0-20 cm soil layer,and soil bulk density,soil water content,saturated water content,field capacity,and relative water content in the 0-10 cm soil layer,and 10%BC treatment could significantly reduce soil bulk density and increase soil water content,saturated water content,field water capacity,and relative water content in the 10-20 cm soil layer of irrigated sandy soil.Compared with CK₁treatment,10%BC treatment significantly decreased soil bulk density by 6.68%in the 10-20cm soil layer（P<0.05）,significantly increased soil water content by 27.31%,saturated water content by 18.60%,field water holding capacity by 15.50%,relative The water content was10.14%（P<0.05）.（2）After 10 years of application of biochar,biochar could still significantly increase the chemical properties of irrigated sandy soil,but some chemical properties had no difference or decreased significantly.In the 0-20 cm soil layer,there was no significant difference in soil p H,conductivity and total potassium,but total salt,CEC,total carbon,total nitrogen,alkali-hydrolyzed nitrogen,and available potassium showed a trend of first increasing,then decreasing and then increasing with the increase of biochar dosage,the content of total phosphorus and available phosphorus decreased.Compared with CK₁treatment,1%BC treatment significantly increased total salt by 114.69%,total carbon by 1.41%,total nitrogen by 11.32%,and alkaline hydrolyzed nitrogen by 75.87%（P<0.05）,and significantly decreased available potassium by 65.34%（P<0.05）;3%BC treatment significantly decreased total carbon by 7.76%,total phosphorus by 29.74%,and available potassium by 11.39%（P<0.05）;5%BC treatment significantly increased total carbon by 7.69%,total nitrogen by 15.75%,and alkaline hydrolyzed nitrogen by 118.92%（P<0.05）.significantly reduced total phosphorus by40.74%and available phosphorus by 29.06%（P<0.05）;10%BC treatment significantly increased CEC by 34.32%,total carbon by 11.40%,total nitrogen by 53.69%,alkaline hydrolyzed nitrogen by 64.54%,Available potassium was 17.09%（P<0.05）,and available phosphorus was significantly reduced by 32.08%（P<0.05）.（3）After the application of biochar for 10 years,the biochar would have a certain negative effect on the biological properties of irrigated sandy soil.In the 0-20 cm soil layer,there was no significant difference in soil microbial biomass carbon and catalase,the soil urease activity increased first and then decreased with the increase of biochar dosage,and the soil organic matter content decreased significantly.Compared with CK₁treatment,3%BC treatment significantly increased urease by 32.73%（P<0.05）and significantly decreased organic matter by 20.49%（P<0.05）;5%BC and 10%BC treatments significantly decreased organic matter by 61.77%and 20.15%（P<0.05）.（4）After application of biochar for 10 years,1%MA treatment could significantly increase the biological properties of irrigated sandy soil while significantly reducing some chemical properties,while 1%FA treatment could significantly increase the chemical properties of some irrigated sandy soils,The two have no effect on soil physical properties of irrigated sandy soil under irrigation.（5）After the application of biochar for 10 years,the soil quality evaluation score of irrigated sandy soil showed a trend of first decreasing and then increasing with the increase of biochar dosage,and the improvement effect of biochar decreases year by year from the 6th year.10%BC treatment has the highest score of 0.568,followed by CK₁treatment with 0.550,and 1%BC treatment with the lowest score of 0.489.The scores from high to low are10%BC>CK₁>CK₃>3%BC>CK₂≈5%BC≈1%BC.At the 6th year,the soil improvement effect of 3%BC treatment was the strongest.In conclusion,the application of 3%BC treatment and repeated application after 7 years had the highest cost-effectiveness,while on the time scale of 10 years,the fertilizer efficiency of the 10%BC treatment was longer,the fertilizer efficiency of the 1%BC treatment was the worst,and the fertilizer efficiency of CK₃treatment was second only to that of 10%BC and CK₁treatments.