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Phosphorus (P) loss from arable sloping land due to water erosion causes off‐site environment pollution in the Three Gorges area in China. This study aims to estimate the effects of agricultural practices on the reduction of P losses during water erosion processes under natural precipitation conditions: contour culturing with organic matter addition (CT + OM), contour culturing with wheat straw mulching (CT + SM), contour culturing with straw mulching and organic matter addition (CT + OM + SM) and conventional downslope culturing framework as a control (CK). Results demonstrated that CT + OM + SM could viably diminish runoff, sediment yields and P losses from arable sloping land. Compared with CK, CT + OM, CT + SM and CT + OM + SM lessened the surface runoff depths by 19%, 34% and 50%, respectively. A high curve number value induced a notable runoff potential from the plot. The surface‐runoff‐related total P (TP) loads for CK with yearly measures of 1·56 kg ha−1 were significantly higher than those for CT + OM, CT + SM and CT + OM + SM at 1·07, 0·77 and 0·51 kg ha−1 (p < 0·05), respectively. With all things considered, the particulate P losses represented a significant division of TP losses, adding up to almost 80% in 2014 and 79% in 2015. The outcomes demonstrated that surface protection and organic matter addition are two of the greatest agricultural protection practices that lessen P losses in the surface runoff from sloping farmland by water erosion. Copyright © 2017 John Wiley & Sons, Ltd.

Vegetative coverage is commonly used to reduce urban slope soil erosion. Laboratory experimental study on soil erosion under grass covered slopes is conventionally time and space consuming. In this study, a new method is suggested to study the influences of vegetation coverage on soil erosion from a sloped loess surface under three slope gradients of 51, 151, and 251; four rye grass coverages of 0%, 25%, 50%, and 75%; and three rainfall intensities of 60, 90, and 120 mm/h with a silt-loamy loess soil. Rye grasses were planted in the field with the studied soil before being transplanted into a laboratory flume. Grass was allowed to resume growth for a period before the rain simulation experiment. Results showed that the grass cover reduced soil erosion by 63.90% to 92.75% and sediment transport rate by 80.59% to 96.17% under different slope gradients and rainfall intensities. The sediment concentration/sediment transport rate from bare slope was significantly higher than from a grass-covered slope. The sediment concentration/transport rate from grass-covered slopes decreased linearly with grass coverage and increased with rainfall intensity. The sediment concentration/transport rate from the bare slope increased as a power function of slope and reached the maximum value at the gradient of about 251, whereas that from grass-covered slope increased linearly and at much lower levels. The results of this study can be used to estimate the effect of vegetation on soil erosion from loess slopes.

Sloping farmland is an essential type of the farmland resource in China. In the Sichuan province, livelihood security and social development are particularly sensitive to changes in the sloping farmland, due to the region's large portion of hilly territory and its over-dense population. In this study, we focused on spatiotemporal change of the sloping farmland and its driving forces in the Sichuan province. Sloping farmland areas were extracted from geographic data from digital elevation model (DEM) and land use maps, and the driving forces of the spatiotemporal change were analyzed using a principal component analysis (PCA). The results indicated that, from 2000 to 2015, sloping farmland decreased by 3263 km 2 in the Sichuan province. The area of gently sloping farmland (<10 • ) decreased dramatically by 1467 km 2 , especially in the capital city, Chengdu, and its surrounding areas. However, the steep sloping farmland (>25 • ) decreased by 302 km 2 , and was still the largest portion of total farmland in the area. The PCA analysis indicated that the main driving forces behind the changes were social and economic factors. The influence of agricultural intensification factors, such as the multiple cropping index and sown areas of crops, was relatively weak. Given the decrease in the overall slope cultivated area and the increased portion of moderately steep slope land (10-25 • ) in the cultivated area, special attention should be paid to the scientific conservation of sloping farmland during rapid social and economic development.Sustainability 2019, 11, 906 2 of 16 has significantly decreased because of degradation and the conversion of farmland into building land [17,18], where the increasing speeds of construction and forest land are faster than other land use types [19].Slope cropland is an ecosystem involving the interaction of both natural and social factors [20][21][22]. The evolution of the sloping farmland system has not only been influenced by natural conditions, but also by social and economic factors [23,24]. The decrease in human-induced cultivated land has become a serious problem, particularly with the increasing global population growth and the unreasonable utilization of water and soil resources by human beings [25][26][27][28]. Humans' social and economic activities have played a decisive role in changing cultivated land, where the impact of socio-economic and related industrial policies has been felt over a short period of time, including population growth, agricultural structure adjustment, urbanization, GDP per capita, output value, etc. [29,30]. Nowak and Scheifder found that sloping farmland was seriously affected by agricultural activities, and that the degradation areas were mainly located at the agriculturally intensive areas [31]. The International Geosphere-Biosphere Programme (IGBP) and the International Human Dimensions Program on Global Environmental Change (IHDP) have identified the main driving forces of land-use and land-cover, which are natural environments, land-use management, a...

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