Improvement Of Sandy Soil Quality And The Mutual Feeding Mechanism With Legume Growth By Water And Fertilizer Cultivation Methods

The fragile ecological environment and soil erosion in Loess Desert area seriously affect the regional ecological protection and high-quality development.According to the low soil fertility,poor agricultural and ecological utilization potential of aeolian sandy soil.The study took the top soil of Shenmu County,Yulin City,Shaanxi Province,Setting three water gradients:normal water supply（75%-80%field water）,moderate drought（55%-60%field water）,severe drought（30%-35%field water）.Feldspatnic sandstone was mixed with aeolian sandy soil by volume ratio 1:1,1:2,1:5.Coal fly ash was mixed by 1%,5%,10%dry weight of aeolian sandy soil.Organic fertilizer was mixed by 0.4%,0.6%,1%dry weight of aeolian sandy soil.Control tests were also set up at the same time.Exploring the distribution of soil particles,chemical properties and growth parameters of Astragalus adsurgens,seeking the best proportion and dosage of different fertilization measures.On this basis,the optimal proportion and dosage of arsenic sandstone,coal fly ash and organic fertilizer were tested separately.On this basis of optimal proportion and dosage,feldspathic sandstone,coal fly ash and organic fertilizer were single and dispensing tested.Exploring the best combination of agronomic measures to improve soil quality through two pot experiments.The results obtained were as follows:（1）The fractal dimension was highest when feldspathic sandstone and aeolian sandy soil with a volume ratio of 1:1 and 1.51,2.11 and 2.03 times of control under three water gradients,respectively.Under three water gradients,the total phosphorus content of feldspathic sandstone and aeolian sandy soil increased by 130%,100%and 98%than the control,respectively.The results of the principal component analysis indicated that the combination of feldsapthic sandstone and aeolian sandy soil had certain effect on improving soil fertility.The fertility of aeolian sandy soil was limited by nitrogen nutrient.The addition of feldspathic sandstone had no obvious effect.（2）Under each water condition,the fly ash with 10%of the dry soil weight had the highest value,and 1.54,2.07 and 1.97 times of the control,respectively.The content of organic carbon and total nitrogen in the windy sand were highest at 10%compound condition.The values were 93.38,59.69,63.42 g·kg-1 and 32.76,20.51 19.63 times of the control respectively.The total nitrogen content was 1.01,0.79,0.92 g·kg-1 and 4.59,3.953.54 times of the control respectively.The addition of coal fly ash could increase organic carbon and total nitrogen content of aeolian sandy soil.The fertility of the aeolian sandy soil was highest under 10%compound conditions,and the addition of coal fly ash could promoted the plant growth.（3）The addition of organic fertilizer did not significantly promote the formation of fine particles in aeolian sandy soil and drought had a limited effect on the formation of clay and silt particles.The addition of organic fertilizer could promote the increase of total nitrogen and total phosphorus content in the soil.The results of principal component analysis showed that organic fertilizer has certain effect on improving the fertility of aeolian sandy soil and was applicable in drought situation.N:P was higher than the national level,C:P was lower than the national level.This indicated that organic fertilizer facilitated the accumulation of nitrogen and phosphorus elements.Organic fertilizer was most conducive to plant growth under the condition of 0.4%of dry weight.（4）Under each water condition,the organic carbon content in the aeolian sandy soil was higher than 100 g·kg^-1when the coal fly ash was added,more than 20 times the control;the total nitrogen content was higher than 0.74 g kg^-1,more than 2.96 times of the control.The total nitrogen content was highest under（coal fly ash+organic fertilizer）,the values were 1.07,0.98 and 1.08 g·kg^-1and was 4.86,4.08 and 4.32 times of the control.under three water gradients respectively.Single application of organic fertilizer need more water,it showed that the organic fertilizer needs more water participation to play the fertilizer effect.The results of principal component analysis combined with the cluster analysis results indicated that mixed of feldspathic sandstone+coal fly ash+organic fertilizer had a better effect on improving the fertility of aeolian sandy soil and had a certain applicability on the case of drought.During the experiment time,plant height,stem thickness and leaf area had the highest value under the condition of single organic fertilizer.Drought had an inhibitory effect on plant growth,and plant growth was limited by nitrogen.To sum up,feldspathic sandstone,coal fly ash and organic fertilizer had a good effect on improving the fertility of aeolian sandy soil,and have certain applicability in drought cases.