Effects Of Planting Forage Grasses On Eco-Enviroment In A Peach Orchard

The cultivation of fruit trees is a major component of the Chinese agricultural structure. The cultivated area and production of fruit trees in China are over 8,700,000 hm2 and 72,000,000 tons, respectively. However, conventional clean tillage, which is still pervasive in China, can severely destroy the orchard's environmental quality and decrease the availability of nutrients in soils, such as soil compaction, soil erosion and decline in organic matter content, thereby reducing the growth and productivity of fruit trees. Moreover, clean tillage can not make full use of different land spaces in the orchard, resulting in wastes in land resources. Grass cover, which as a green ecological planting method in fruit garden, may solve the ecological and environmental problems caused by clean tillage. Grass cover may also improve the growth of fruit trees and the quality of fruits.In this study, I planted chicory (Cichorium intybus L.), alfalfa (Medicago sativa L.) and white clover (Trifolium repens L.) in a peach orchard located in Nanhui Xinchang Town, Pudong New District, Shanghai, in order to investigate the effects of different tillage methods and forage grasses on the microclimate, soil physicochemical properties, fruit tree growth, fruit quality and diffused pollution in the orchard. The primary results of my study are as follows:(1) The effects of grass cover on the microclimate of the peach orchard were demonstrated: during seasons of high temperature, i.e., July and August, grass cover significantly reduced soil temperature and increased soil water content. With forage grass cover, soil temperature (5 cm in depth) was reduced by 8.0-12.3℃in July and August, and soil water content (0-10cm in depth) was increased by 0.8-20.6%.2. Revealed the change law of soil physical and chemical properties in peach orchard under grass cover. Grass cover decreased bulk density of surface soil; it also increased organic mater content and PH of surface soil. Moreover planting alfalfa was more effective than planting chicory and white clover. During the periods of vigorous growth and nutrient accumulation in fruits (starting from June through August), grass cover decreased available P content in soils of 0-10 depth, despite non-significant statistical difference. In contrast, for the periods of fruit maturing and non-reproduction growth, plantation of alfalfa significantly elevated available P content and NH4+ in soils, but grass cover decreased soil NO3- content, the activities of soil urease and catalase and the decomposition of soil organic matter.3. The growth of fruit trees and qualities of peach can be improved by planting suitable grasses. Planting alfalfa significantly increased the growth of new braches, which were inhibited by planting chicory. The content of soluble sugar in peach was increased and the content of soluble protein were reduced by planting alfalfa and white clover.4. Grass cover in peach orchard could reduce amount of surface runoff and release non-point source pollution. It was proved that the amount of surface runoff was decreased by 41.6%, 35.0%, 58.4% compared with after planting chicory, alfalfa and white clover. When the fertilizer rate of N:P:K compound fertilizer were 30.0g/m2, 15.0g/m2 and no fertilizer, the loss amount of N and P were respectively reduced by 73.0%, 23.5%, 51.4% and 63.3%, 73.4%, 71.2%.5. Considering with microclimate in peach orchard, soil physical and chimerical properties, the growth of peach trees and the qualities of beaches, planting alfalfa was more effective, then was planting white clover, and there was a relatively poor effect of planting chicory.