The Effects Of Long-term Addition Of Corn Straw On Physical And Chemical Properties Of Meadow Black Soil

Long term application of inorganic fertilizers has adverse effects on the soil physical and chemical properties and has a certain impact on the growth and development of crops.In this paper,the effects of different amount of corn straw on soil physical propertiesand chemical properties in different fertilized meadow black soil were studied.（1）The results were as follows:the mechanically stable aggregates in soil were obtained by dry sieving method,because of long term application of inorganic fertilizers on the soil or long term farming on the soil,soil aggregates with the particle size is larger than ten millimeter were more than 20%,when add corn straw in this soil the amount begin to decrease.After adding corn straw in the soil,the percentage of each particle size in the range between 0.25mm and10mm has increased gradually,and the value of mean weight diameter and geometric mean diameter will increased of dry sieving soil,the value of fractal dimension will decrease.The experimental results show that after adding corn straw in the experimental soil could improve the soil aggregates mechanical stability and the soil physical properties.（2）The water-stable aggregates were obtained by wet sieving method,and get small amount of particle size which less than 5 milimeter.After adding corn straw 0.125 kg/m² and 0.25kg/m²in the single application of N and P fertilizer,combined application of N/P,P/K,N/P/K fertilizer,the percentage of each grade of aggregate were increased,and got smaller amount of soil aggregates with particle size which less than 0.25mm,this result indicating that the experimental soil has a strong water stability.Compared the MWD and GMD values with non-added corn straw soil,we concluded that adding 0.125kg/m² in the soil was the optimum amount to keep soil water stability.（3）The effect of different amount of corn straw on soil acidity and exchange performance was studied,due to long-term fertilization or unreasonable use of land the result shows that adding corn straw can alleviate soil acidification and alleviate the reduce of soil p H,reduce the amount of exchangeable acid,exchangeable H⁺,and exchangeable Al³⁺in the soil,the amount of cation exchange were increased,however,the adding amount of maize straw was determined by the different fertilization structure of soil.In summary,we found adding corn straw in the soil could improve soil chemical properties.（4）The soil chemical composition includes soil clay minerals and organic matter and so on.Test the soil minerals by X ray diffraction method,analysis the picture we found the Magnesium saturated sample diffraction peak has slightly offset at position of 1.42nm,after adding corn straw,the 550℃heated Potassium sample diffraction peak disappeared at the position of 1.2nm.After adding corn straw 0.125kg/m² in the single application of N fertilizer soil,the 300℃heated Potassium sample diffraction peak was shorter at the position of 0.71nm,the Magnesium saturated sample diffraction peak begin to slow down at the position of 1.41 nm.After comprehensive analysis,the result shows that the types of clay minerals of long-term fertilizing soil are kaolinite,smectite,Illite and a small amount of chlorite,vermiculite,mixed layer mineral of Illite with smectite.And the effects of adding straw on soil clay mineral composition is small.The experimental results shows that soil mineral chemical oxides mainly containing a large amount of Si O₂,Al₂O₃ and Fe₂O₃,the small amount of Ca O,Mg O,K₂O and Na₂O,Ti O₂,P₂O₅ and Mn O.and the result shows that after adding corn straw into the soil,the change of each chemical element was small.However after long term adding corn straw in soil,the amount of organic matter in meadow black soil was increased.Given all this,long term adding corn straw could enhance the water stability and mechanical stability of soil aggregates,improve the soil physical structure and chemical structure.Due to long term adding inorganic fertilization lead to soil acidification,adding corn straw can alleviate soil acidification,increased the amount of soil organic matter,and can also improve the soil chemical properties,but it does not change the amount of clay mineral chemical elements.So,long term addition of corn straw can improve soil physical properties and chemical properties.