Study On The Effects Of Measures Of Soil Conservatoin And Water Closure In Slope Farmland Area Of Chao Lake Basin

The non-point source pollution made by soil and water loss, the unreasonable tillage and fertilizer management made become more and more serious in Chao lake. The effect of the unreasonable tillage measures was particularly serious on Chao lake environment, which not only leaded to land degradation, declining water quality, but also a great barrier to the sustainable development of ecological system in Chao lake area. In this paper, soil water flow and nutrient loss characteristics were observed with the treatments of soil conservation tillage(CK-conventional slope tillage, PH-hedgerows, HM-hedgerow+zone coverage, CT-contour) in slope cultivated land by the position test in runoff plots near Long linhe town in Chao lake basin. These studies were to explore the difference between the traditional tillage and soil conservation closure tillage in soil erosion and nutrient loss and select the reasonable cultivation way. Meanwhile, it provided a theoretical basis for the source control of non-point source pollution. The main conclusions were presented as follows:1. The treatment of soil conservation and water closure could effectivity reduce surface runoff and sediment yield. The runoff of HM, PH, CT and CK were0.8m3,0.89m3,0.94m3and1.41m3respectively during the test period. The Runoff were reduced43.00%,36.52%and33.11%respectively in the treatments of HM, PH and CT compared with the conventional tillage treatment. The sediment yield of HM, PH, CT and CK were971.17g,1122.16g,1161.75g and1886.60g respectively. The sediment yield were decreased by48.52%,40.52%and38.42%in the treatments of HM, PH and CT respectively compared with conventional tillage. Evidently, measures of soil conservation and water closure could effectively reduce the effect of rainfall on slope erosion and scouring the runoff and sediment erosion to some extent. The effect of hedgerow+zone coverage between soil and cover processing intercepting was best which had significant differences with conventional tillage treatment during the treatments.2. The treatments of soil conservation and water closure could effectivity reduce the loss amounts of N and P of slope land. The total nitrogen loss in runoff of HM, PH, CT and CK were1.43kg/hm2,1.51kg/hm2,1.65kg/hm2and2.81kg/hm2during the test period. Nitrogen loss in treatments of HM, PH and CT in runoff accounted for50.73%,53.54%and58.95%of conventional tillage treatment CK. The loss amount of nitrate nitrogen was2.4-4.9times higher than ammonium nitrogen in runoff. The treatment of hedgerow+zone coverage treatment could control nitrogen loss effect best and nitrogen loss accounted was only50.73%of conventional loss. The nitrogen concentration increased after HM treatment in straw decay runoff. The total phosphorus loss of HM, PH, CT and CK in runoff were0.24kg/hm2,0.25kg/hm2,0.27kg/hm2and0.53kg/hm2. The phosphorus loss of treatments of HM, PH and CT of in runoff accounted for44.88%,46.98%and50.53%of conventional tillage treatment CK. The total phosphorus loss of conventional tillage treatment in runoff and particle state was higher than the other treatments of soil conservation and water closure, moreover, the water-soluble phosphorus loss in runoff were similar among the four treatments, and that measures of soil conservation and water closure can effectively reduce the loss of farmland phosphorus removal. The treatment of hedgerow+zone coverage treatment could control phosphorus loss effect best and phosphorus loss accounted for only44.88%of the conventional loss. The phosphorus concentration increased after HM treatment in straw decay runoff.3. The measures of soil conservation and water closure could effectively improve the soil nutrient content. The contents of of soil organic matter, available nitrogen, available phosphorus, effective potassium content were:HM> PH> CT> CK in arable layers of four treatments, and nutrient content were higher in the layer of0-10cm than10-20cm. Alley cropping had interception effect on nutrients in the soil and could make the nutrients in the soil enrichment before plant hedge. Furthermore, the soil nutrients of upper slope and middle slope were lower than the foot slope.