Abstract
Abstract: A slope farmland has been one of the most serious land-use types of soil and water loss, as well as the non-point source pollution. Natural conditions and unreasonable farming have also posed great damage to the ecological environment, particularly on the quality degradation of slope farmland. Therefore, it is very necessary to construct the quality control system of slope farmland in recent years. Taking sloping farmland in Yunnan province of China as a research object, a factor analysis model was first established to diagnose the quality obstacle factors of slope farmland. The types of quality obstacles were then ranked to define in each region, thereby identifying the controllable factors, the regulation priority, and objectives of slope farmland quality. The quality regulation potential of slope farmland was calculated to determine the zoning regulation mode in different regions. The results showed that: 1) The main types of quality obstacles were erosion degradation, drought, and water shortage, as well as the nutrient poverty type in the sloping farmland. There was some difference in the combination and performance of obstacle factors in different regions. 2) The adjustable factors of slope farmland quality included the thickness of arable layer, soil bulk density, pH value, organic matter, the total nitrogen, available phosphorus, available potassium, irrigation assurance rate, and field slope, among which the field slope, soil organic matter, irrigation assurance rate, available phosphorus, available potassium and pH value were the priority adjustment and control factors. The goal of quality control in the sloping farmland was to make the controllable factors in the appropriate range under various control measures. An optimal range of factors were achieved, where the thickness of plough layer ≥17.35 cm, soil organic matter ≥28.89 g/kg, soil available phosphorus ≥32.44 mg/kg, soil available potassium ≥137.81 mg/kg, irrigation assurance rate ≥73.33%, soil bulk density ≤1.31 g/cm3, field slope ≤12.87°, and pH value 6.06-8.06. 3) The objectives of quality control in the sloping farmland included the ideal and actual state. In an ideal state, the potential of quality control in the sloping farmland was 0.347, indicating an upgrade from the "medium" to the "higher" level. In the actual state, the potential of quality control in the sloping farmland was 0.198, indicating that the quality level was improved from the current "medium" to "high". The potential of actual state control was used as the standard quality control of slope farmland. 4) According to the general idea of "erosion control, water regulation, and fertility enhancement", the integrated mode of quality control in the sloping farmland was constructed as follows. The tillage modes were utilized to promote soil and water conservation, such as ridge, contour, and reverse slope tillage, as well as the conservation tillage (rotary, subsoiling, and no tillage + deep tillage) in farming measures. The water engineering slope to ladder project and high-efficiency water-saving measures can be implemented to actively promote the straw returning, green and organic fertilizer application. The soil testing and formula fertilization among soil fertility measures can be used to increase the content of soil organic matter and nutrients in the slope cultivated land. This finding can provide a scientific guide for the quality cultivation and management of regional slope farmland at a provincial scale.
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