Study On Habitat Condition And Liquid Manure Utilization Mode Of Ecological Mulberry Fields In Loess Hilly Region Of Northern Shaanxi Province

The ecological mulberry field in northern Shaanxi province is the fastestdeveloping mulberry forest resource since the policy of returning farmland toforest (grassland) was carried out, which is scattered in the counties locatedin loess hilly region of the Loess Plateau such as Suide, Qingjian, Wubao, Zizhou,Mizhi, Jiaxian, Hengshan, Zichang,and Yanchuan, and the mulberry fields hadreached41.9thousand hm2. The ecological mulberry fields in Northern Shaanxiprovince aim at comprehensively controlling soil erosion, targeting on maximizedeco-benefits, and no silkworm or less silkworms are rearing here, which breaksthe tradition of planting mulberry trees to rear silkworms. The loess hillyregions are arid and short of rainfall, the problems of soil depletion and soilerosion are severe, therefore most of the ecological mulberry trees are runtish.The government’s subsidy for returning farmland to forest has guaranteedfamers’ benefits, stabilized the acreage of the ecological mulberry fields,but its follow-up industry lagged behind. The ecological mulberry trees exerteda significant effect on water and soil conservation, but the overall economicbenefits were low, and there still exists serious problems in the sustainableutilization of it. Based on the knowledge of returning farmland to forest projectin northern Shaanxi and "transferring the mulberry trees in eastern area towestern area" project as well as the twists and turns history of developingsericulture, the study began with the natural environment, economic atmosphereand technological environment in northern Shaanxi sericulture area, analyzedthe restriction and effect of environment on mulberry trees’ growth, revealedthe relation between the habitat environment and ecological efficiency ofmulberry trees, and summarized and proposed the extension measures for liquidmanure utilization technology in the ecological mulberry fields in northernShaanxi province.It is believed that establishing ecological mulberry fields in large scalein northern Shaaxi is a product of reaping benefits from returning farmland to forest policy, resulting from "transferring the mulberry trees in eastern areato western area" project; there is abundant light and heat in loess hilly region,and a big day-and-night temperature difference, which suits for rearing highquality cocoons, but a mulberry tree has a short growth cycle and low biologicalyield, therefore the global benefits of cocoon production are not so high; thereis little rain in the loess hilly regions, leading to the severe shortage ofwater in soil, in addition, the nutrition in soil run off year by year, and theliquid manure condition restricted the growth and economic efficiency ofmulberry trees; if the ecological mulberry fields intercropping with alfalfa,there will be high vegetation coverage, but mulberry trees will compete withalfalfa on water and manure, resulting in severe soil desiccation.The ecological function of a mulberry tree is its natural property, the deeproots and lush leaves of a mulberry tree are the precondition and base to realizeits ecological function and economic efficiency. The major conclusions of thestudy include:1. The ecological mulberry fields in northern Shaanxi is small in economicland use, the subsidy from ecological forest policy is the main income sourceof returning land; the ecological mulberry trees don’t fit for cultivating theecological forest, economic forest management measures should be taken so asto develop into mulberry economic forest.2. The ecological mulberry trees in northern Shaanxi are superior in plantingin large scale and ecological resources, so measures such as establishingmini-type irrigation facilities, effectively collecting rainfall andpopularizing the water saving irrigation technology of water storage on slopingland can improve the fact of soil desiccation and ensure the healthy growth ofmulberry trees.3. The technology of green manuring should be carried out in mulberry fieldin which grasses are intercropped, and the forage grasses such as millet arerecommended to intercrop in the fields for which can transform organic nutrientsinto soil available nutrients and bring the soil fertilization in to full play.