Effect Of Slope-land Ameliorating Measures And Land-use Patterns On Purple Soil Physical And Chemical Properties

Slope-land is the most important reason of water loss and soil erosion in China. How toprevent and control soil erosion caused by slope-land, and improve the soil fertility ofslope-land is an important issue that must be solved. In this paper, soil physical and chemicalproperties under different land-use patterns (paddy field, grapefruit soil, vegatable soil,woodland soil), different slope-land amelioration measures (terraced plowing, big transverseslope and small lengthways slope, return farmland to woodland and hedgerow), differentslope grades and slope locations in purple soil of Three Gorges Reservoir Area were studiedto find the best land-use patterns and slope-land amelioration measures of improving soilfertility, which was helpful to the regional water and soil conservation and thesustainable land utilization. The main results were as followed:1. Paddy field had the lowest soil bulk density, the biggest porosity and field capacityamong different land-use patterns. Paddy field had the lowest bulk density, the greatestporosity and field capacity; under the condition of dry sieve, vegetable field had the greatest>0.25mm soil aggregates and paddy field had the least; under the condition of wet sieve, theamount of>0.25mm soil aggregates showed as vegetable field> artificial woodland=paddyfield> orchard (P<0.05). Soil pH, organic matter and total nitrogen of paddy field wassignificantly higher than orchard soil, vegatable soil and artificial woodland soil; and soilalkali-hydrolyzable nitrogen of paddy field was significantly higher than orchard soil andartificial woodland soil (P<0.05); soil total phosphorus, available phosphorus and availablepotassium of orchard soil was the highest among these four land-use patterns.2. Compared with natural slope and return farmland to woodland measure, Bigtransverse slope and small lengthways slope measure can reduce soil pH and bulk density,increase the contents of soil organic matter, total nitrogen, total phosphorus andalkali-hydrolyzable nitrogen. The soil and water conservation effect of big transverse slopeand small lengthways slope measure was close to terraced plowing.3. In this study, soil pH, main nutrients, porosity,>0.25mm aggregates and water stable aggregate of0-10cm soil layer in different slope positions showed as lower slope＞middleslope＞upper slope, while the bulk density showed as upper slope＞middle slope＞lowerslope. In the uuper slope and middle slope, soil pH and organic matter, total nitrogen,alkali-hydrolyzable nitrogen, available phosphorus of0-10cm layer decreased as slope gradeincreased. In the lower slope, the alkali-hydrolyzable nitrogen and available phosphorus of0-10cm layer decreased as slope grade increased, while soil pH was just the reverse. Thecontents of soil total phosphorus and available potassium did not change significantly as theslope grade changed. The differences of soil nuturient in10-20cm layer were not as obviousas0-10cm layer in different slope grades.4. Soil pH, organic matter, total nitrogen, alkali-hydrolyzable nitrogen and availablephosphorus of hedgerow system showed as hedgerow＞slope-land between hedgerows. SoilpH, organic matter, total nitrogen, alkali-hydrolyzable nitrogen, available phosphorus,available potassium and porosity of hedgerow were higher than soil ridge and bare land,showing that hedgerow can prevent soil nutrient erosion and preserve soil fertility effectively,and meaning hedgerow is a better slope-land amelioration measures than soil ridge system topromote.