Effects Of Four Soil Managements On Soil Physical,Chemical,Biological Properties

This experiment,using plum tree as experimental matter, studied the difference of soil physical, chemical, biological properties, the growth potential and physiological functions of plum trees among four soil management ways. It had been done by the way of field investigation and analysis in laboratory , whose results showed:1. Among four soil managements, the quantity of cellulose-decomposing bacteria was the largest in the management of mowing and covering .obviously larger than the other three managements; and yet the managements of mowing and burying, returning the livestock's feces to orchard were significantly larger than cleaning tillage. The quantities of silicate bacteria under the managements of mowing and covering, mowing and burying, returning the livestock's feces to orchard were near, and larger than cleaning tillage. The sequence of the quantities of the two kinds of microorganism from much to little in four seasons were summer, autumn, spring, winter.The trends of change of enzyme activity in four seasons were consistent with soil microorganism. The activity of sucrase, urease, catalase under the managements of mowing and covering, mowing and burying, returning the livestock's feces to orchard were significantly or extremely significantly higher than cleaning tillage. The activities of the three enzymes in 2004 are all higher than those in 2003. And those under the two treatments of mowing and covering, mowing and burying are significantly or extremely significantly higher than those in 2003, yet those under the treatment of returning the livestock's feces to orchard, cleaning tillage had no significant difference during the two years.2. The new shoot length, the content of chlorophyll and root activity of plum tree under three soil managements of mowing and covering, mowing and burying, returning the livestock's feces to orchard were all higher than those of cleaning tillage. Among these managements, the content of chlorophyll of the treatment of returning the livestock's feces to orchard was the highest (2.952 mg·g^-1 FW), and significantly higher than those of mowing and covering, mowing and burying. The root activity of mowing and burying was significantly higher than the treatment of returning the livestock's feces to orchard, which was significantly higher than mowing and covering.3. The water content of the treatment of returning the livestock's feces to orchard was the highest (19.665%), 5.715% higher than that of cleaning tillage (13.950%), but the water content among thethree treatments of mowing and coverings mowing and burying, returning the livestock's feces to orchard had no significant difference. The soil density of mowing and covering was the least (1.301 g-cm"3), decreased 0.177g-cm"\ 0.118 g-cm"3 and 0.043 g-cm"3 than cleaning tillage , mowing and burying, returning the livestock's feces to orchard respectively. Under the soil managements of mowing and covering, mowing and burying , returning the Jivestock's feces to orchard, the soil temperature was extremely significantly lower than cleaning tillage in summer, and a little higher than cleaning tillage in winter. The effect of decreasing temperature in summer and increasing temperature in winter under the management of mowing and covering was the finest, the ranges of change comparing with cleaning tillage were respectively 3.4°C⁵.2°C and 1.2°C².rC.4. The contents of all soil nutrients increased to some extent under the treatments of mowing and covering, mowing and burying, returning the livestock's feces to orchard comparing with cleaning tillage; and the contents of organic matter, total K increased extremely significantly; rapidly available K increased significantly. Especially organic matter increased 56.3%⁷1.8% than cleaning tillage. The contents of most nutrients in 2004 had a rise on the base of those in 2003, especially the effects of mowing and covering, mowing and burying were apparent. The rest of nutrients except alkaline hydrolytic N under the management of mowing and covering had a significant increase. Under the management of mowing and burying, organic matter increased a little, alkaline hydrolytic N increased significant, the rest increased extremely significantly. There was little change of the contents of nutrients during two years under the managements of returning the livestock's feces to orchard, cleaning tillage, even alkaline hydrolytic N and organic matter of the latter had a negative rise with the increase of age.5. A correlation exists among soil microorganism, soil enzyme activity and soil nutrients. Except that total P had a negative correlation with cellulose-decomposing bacterium, cellulolytic enzyme and polyphenol oxidase, the rest of nutrients had a positive correlation with microorganisms and enzymes. Organic matter had a significant correlation with cellulose-decomposing bacterium, polyphenol oxidase, had a extremely significant correlation with the other organisms and enzymes. Total K. had a extremely significant correlation with all organisms and enzymes. Rapidly available P and rapidly available K were extremely significantly correlated with silicate bacterium, sucrase, urease respectively, were significantly correlated with cellulolytic enzyme. Alkaline hydrolytic N had a extremely significant correlation with sucrase, urease, catalase, had a significant correlation with silicate bacterium. Total Nhad a extremely significant correlation with silicate bacteriurrK sucrase> catalase and cellulolytic enzyme, had a significant correlation with polyphenol oxidase. Total P was extremely significantly correlated with urease.Silicate bacterium had a extremely significant correlation with all enzymes; cellulose-decomposing bacterium had no significant correlation with urease, a significant correlation with sucrase, a extremely significant correlation with the rest of enzymes.6. Pathway analysis had been done among soil microorganisms x soil enzymes and soil nutrients, whose results showed: ureasex silicate bacteriunu cellulolytic enzyme were main factors that promoted the deposit of organic matter; sucrase was the most important factor affecting the rapidly available nutrients of N> P, K, but catalasen polyphenol oxidasex cellulose-decomposing bacterium affected them in part.7. Soil physicak chemical x biological properties and the growth potential - physiological function of plum trees had a apparent improvement and enhancement under the managements of mowing and coverings mowing and buryingx returning the livestock's feces to orchard comparing with cleaning tillage, but the former three treatments had little difference. Therefore the three managements were all good models in the hilly area of the middle of Sichuan province, which could improve soil properties, resist drought, protect ecological environment, enhance sustainable and comprehensive development of agriculture.