Effects Of Soil Managements On Soil In Plum Orchards

To study different soil managements in the plum orchards, soil's physical and chemical properties, microbial quantities ,enzyme activities and relations among them are studied, whose results show :1. During the summer drought period, as far as water-containing soil layers , ranging from zero to 20 cm deep and from 20 cm to 40 cm deep, are concerned, among different soil management modes, mowing and covering contains the highest moisture content. In terms of the soil's thermal retardation and cooling, mowing and burying and returning the livestock's feces to the orchard are not as effective as mowing and covering, but more effective than clean tillage. Among these managements, the soil's bulk densities vary much. Compared with clean tillage, in the soil layer ranging from zero to 20 cm deep, the soil's bulk density is 0.45 g/cm3 less when returning the livestock's feces to the orchard, whose absolute quantity of porosity increases by 17.0% and relative quantity increases by 29.0%.There are commonly variant levels of improvement in all the soil's nutrient indexes when compared with those before the treatments. All the processed nutrient indexes are best in returning the livestock's feces to the orchard, followed by mowing and burying and then by mowing and covering, and they are lowest in clean tillage.2. Among all the management modes, the quantities of bacterium, fungi, and antinomyces are highest in returning the livestock's feces to the orchard, followed by mowing and burying and then by mowing and covering, and they are lowest in clean tillage. Together with the soil layer's deepening, the quantities of the three major microbes are reducing, appearing a tendency of deeper soil layer, lower quantity of microbes. And the quantities also change in different seasons-highest in summer, then in autumn, in spring and lowest in winter. The bacteria's quantity shows significant positive correlations with available nitrogen, total nitrogen, and available phosphorus, whose correlation coefficients are 0.994**, 0.992** and 0.996** respectively; it also shows significant positive correlations with available potassium, total potassium and organic matters, whose correlation coefficients are 0.952 , 0.954** and 0.958** respectively. The fungi's and the antinomyces' quantities show significantpositive correlations with ail the available nitrogen, total nitrogen, available phosphorus, available potassium, total potassium and organic matters. The quantities of bacteria, fungi and antinomyces show negative correlations with total phosphorus ,whose correlation coefficients are -0.994, -0.980* and -0.979* respectively.3. The activities of catalase, invertases and urease are also highest in returning the livestock's feces to the orchard, followed by mowing and burying and then by mowing and covering, and they are lowest in clean tillage. Invertases and urease have an apparent gradation in the soil profile, while catalase's vertical distribution does not show a clear gradation in the profile. The activities of these three major enzymes are highest in summer, then in autumn, in spring and lowest in winter.The urease's activity shows significant positive correlations with available nitrogen and available phosphorus(r= 0.996**, 0.999**), a linear function correlation with total nitrogen and significant positive correlations with organic matters, total potassium and available potassium. The correlations between the invertases and the soil's fertility are similar to those between the urease and the soil's nutrient. The catalase's activity shows certain correlations with soil organic matters.total nitrogen, total potassium, available nitrogen, available phosphorus and available potassium, but not reaching a significant level. The activities of urease, invertases and catalase all show negative significant correlations with total phosphorus, whose correlation coefficients are -0.961',-0.953*,-0.977* respectively.4. The catalase's activity shows significant correlations with the fungi's and the antinomyces'...