Study On Soil Nutrient&Enzyme Activity Under Different Intercropping Mode Of Walnut Forest On Loess Plateau

The economic forests themselves can get more economic benefit than the soil and waterconservation forests. For many years, our country has treated the construction of economicforests seriously. It dramatically increases utilization of land and farmers’ income to planteconomic forests in sloping land of the mountains. Meanwhile, it takes about two or three yearsfor fruit tree from planting to bearing fruits, even about four or five years to fruiting well. Duringthese few years, we have found some important means to make full use of land resources andkeep soil fertility, by intercropping other crops with fruit tree seeding scientifically.The poor soil quality leads to perennial low production of maize and low income. Moreimportantly, it prevented the ecological restoration of soil erosion of sloping fields in FangzhiVillage, Chengguan Town, Xunyi County, Shaanxi province. Recently, there has been planned toplant walnut trees according to the Grain for Green Program. Because walnut trees grow slowlyin the short term, we seeked for a solution to solve the problem of poor vegetation cover and noharvest by tree-crop intercropping. This paper chiefly studied the soil nutrients and soil enzymeactivity of walnut forest under different intercropping patterns, in order to explore the relationbetween soil enzyme nutrients, soil enzyme activity and season, intercropping patterns before theeconomic trees bear the fruit. The main conclusions were as follows:(1) Soil nutrient status of loess slope land was inferior in the research area. In addition, apartfrom soil available phosphorus, the rest of soil indicators were lacking even extremely lacking.To some degree, soil nutrients were improve after tree-crop intercropping, and the most obviousone was walnut-soybean intercropping.(2) There were significant differences among average determination of the soil nutrients andsoil enzyme in0-60cm by different intercropping patterns. Compare results was as follows:walnut-soybean intercropping with plastic mulching＞walnut-soybean intercropping withoutplastic mulching＞walnut-maize intercropping with plastic mulching＞walnut-maizeintercropping without plastic mulching＞walnut monoculture without plastic mulching.(3) Spatial distribution of the soil nutrients and soil enzyme also presented significantdifferences. Soil nutrients and soil enzyme activity decreases with the soil layer increases. (4) Under the same intercropping pattern, determination of the soil nutrients and soilenzyme of every layer were significant differences in different seasons. Generally speaking:harvest season in the second year under the intercropping pattern＞harvest season in the firstyear under the intercropping pattern＞planting season in the second year under theintercropping pattern＞planting season in the first year under the intercropping pattern＞walnut monoculture.From the point of soil quality assessment, we got the results above by modeling integratedsoil quality index and scientific calculation. So we draw a conclusion: the soil quality of thewalnut-soybean intercropping was improved better than that of walnut-maize intercropping; thesoil quality at harvest season was superior to that at planting season; also, the quality of soil inthe second year have an advantage over that in the first year.