Effects Of Organic Fertilizer Application On Main Physicochemical Properties Of Dryland Yellow Soil For 24 Consecutive Years

Yellow soil is the main soil type for agricultural land in Guizhou Province.The soil nutrient is poor,acidification is serious,and the texture is sticky.The main obstacles in production and utilization are the unreasonable application of chemical fertilizers this year.This has led to soil degradation problems such as soil compaction and soil acidification.Outstanding,further restricting the productivity of yellow soil arable land.Therefore,it is urgent to adopt reasonable fertilization measures to ensure the healthy and sustainable use of yellow soil arable land.Long-term positioning experiments can reveal the long-term change trend of the agricultural ecosystem and can evaluate the effect of fertilization more comprehensively.However,there are few systematic studies on the physical properties of yellow soil by long-term fertilization in the past.Therefore,this paper relies on the long-term positioning test of yellow soil fertility and fertilizer efficiency to study the effects of long-term different fertilization treatments（CK,NPK,1/4M+3/4NP,1/2M+1/2NP,M）on the soil texture and soil aggregate composition of dryland yellow soil.And the effects of stability,soil porosity,soil water-holding performance and corn yield,and comprehensive evaluation of the comprehensive soil fertility of long-term different fertilization through principal component analysis,aiming to provide a theoretical basis for rational fertilization in the yellow soil area.Research indicates:（1）The effects of long-term different fertilization on the main physical and chemical properties of the soil are mainly concentrated in the 0-20 cm soil layer,and have little effect on the deep soil.In the 0-20 cm soil layer,compared with the treatment without fertilization,the content of clay and powder in the single application of chemical fertilizer increased by 1.85%and 0.37%,respectively,and the content of sand decreased by 2.69%,with no significant difference.The clay content of each treatment（1/4M+3/4NP,1/2M+1/2NP,M）applying organic fertilizer decreased by 10.13%-23.60%,and the sand content increased by 8.42%-30.57%,the difference was significant.Compared with the single application of chemical fertilizer,the clay content of the organic fertilizer treatments（1/4M+3/4NP,1/2M+1/2NP,M）was significantly reduced by 11.76%-14.99%,and the sand content was significantly increased.11.40%-34.17%.Among the different ratios of organic fertilizer,single application of organic fertilizer has the best effect.It shows that long-term application of organic fertilizer can significantly reduce the clay content of the soil and improve the texture of yellow soil.The higher the amount of organic fertilizer,the more obvious the improvement effect,while the long-term single application of chemical fertilizer will aggravate the stickiness of yellow soil.（2）In the 0-20 cm soil layer,the content of soil mechanically stable aggregates and water-stable aggregates of different sizes in different fertilization treatments are both（>5）mm>5-2 mm>2-1 mm>1-0.5 mm>0.5-0.25 mm>（<0.25）mm,with the decrease of soil particle size,the content of soil aggregates keeps decreasing.Compared with the single application of chemical fertilizer,the water-stable aggregate content of each treatment（1/4M+3/4NP,1/2M+1/2NP,M）<0.25 mm with organic fertilizer was significantly reduced by 3.69-8.86%.Compared with the treatments without fertilization and single application of chemical fertilizers,the mean weight diameter（MWD）and geometric mean diameter（GWD）of the soil aggregates in each treatment with organic fertilizer were significantly increased by14.24%-66.81%and 53.36%-188.80%,respectively.Compared with single application of chemical fertilizer,percentage of aggregate destruction（PAD）and unstable aggregate index(E_LT)were significantly reduced by 42.12%-71.10%and 39.34%-67.69%,respectively,and the increase or decrease was the largest with single application of organic fertilizer.It shows that long-term application of organic fertilizer significantly improves the composition of soil aggregates and improves the stability of soil structure.（3）In the 0-20 cm soil layer,the soil bulk density of each treatment with organic fertilizer（1/4M+3/4NP,1/2M+1/2NP,M）decreased by 5.47 compared with the treatments without fertilization and single application of chemical fertilizers 15.40%,total soil porosity,maximum water holding capacity,capillary water holding capacity,field water holding capacity increased by 4.12%-20.97%、5.82%-39.94%、5.58%-18.25%、1.80%-27.73%,respectively.It shows that long-term application of organic fertilizer can increase soil porosity and increase soil water retention and soil aeration.（4）In the 0-20 cm soil layer,the p H,organic matter,and available potassium content increased by0.39-0.75,9.02%-28.71%,133.20%-423.18%,respectively,compared with no fertilization and single application of chemical fertilizers.The increase rate increased with the increase of the amount of organic fertilizer;soil alkali-hydrolyzable nitrogen and available phosphorus increased significantly by4.08%-13.11%and 41.94%-93.12%,respectively,and the combined application of organic and inorganic fertilizers was higher.It shows that the organic matter and p H of yellow soil are mainly affected by the fertilization structure.The application of organic fertilizer can increase the soil organic matter and p H,while the application of chemical fertilizers is the opposite.The soil available phosphorus and potassium nutrients are mainly affected by the application of phosphorus and potassium.（5）The results of principal component analysis showed that in the dry land yellow soil area,the comprehensive order of the treatments without fertilization was:M>1/2M+1/2NP>1/4M+3/4NP>CK>NPK,indicating the long-term The application of organic fertilizer improves the comprehensive soil fertility,especially the effect of single application of organic fertilizer is obvious,and the long-term application of organic fertilizer increases crop yield.In the yellow soil area of Guizhou,adding organic materials is one of the measures to improve the quality of cultivated land.In the future agricultural production,we should pay attention to the application of organic fertilizer.In summary,long-term application of organic fertilizers can significantly improve soil physical properties,increase soil nutrient content and crop yields.Among the different organic fertilizer application ratios,long-term single application of organic fertilizer has the best effect on soil physical properties improvement and fertilization,but it is not conducive to crop growth and yield formation.Long-term organic-inorganic combined application can improve soil physical and chemical properties while achieving higher The crop yield is a more suitable fertilization mode on yellow soil.