Li Zhanbin

Down-scale analysis for water scarcity in response to soil–water conservation on Loess Plateau of China

Water scarcity is one of the most prominent issues of discussion worldwide concerned with sustainable development, especially in the arid and semi-arid areas. On the Loess Plateau of China, population growth and fast-growing cities and industries have caused ever-increasing competition for water. The present paper shows a down-scale analysis on how the region wide mass action of soil–water conservation ecologically influenced regional water scarcity on the Loess Plateau, the Middle Reaches of the Yellow River of China. Result shows a great progress has been achieved in erosion control and food production since the 1980s. About 24% of erosion area has been controlled. Grain yield has increased greatly and sediment in the Yellow River has decreased by about 25%. However, various sources of evidence show that the soil–water conservation measures might have played a significant role on regional hydrocycles, leading to the depletion of deep soil water and reduced runoff in the Yellow River and consequently ecological problems. The study implies that cropland and forest plantations are increasingly suffering water stress. Advancing sustainable development further, or even maintaining the current situation, will be a great challenge given the burgeoning socio-economic development of the area combined with global climatic change.

Distribution characteristics of available trace elements in soil from a reclaimed land in a mining area of north Shaanxi, China

Through field and laboratory tests we studied the temporal and spatial variation in the soil content of four available trace elements :copper(Cu), iron(Fe), manganese(Mn) and zinc (Zn), to analyze their distribution characteristics in reclaimed mining land under different reclamation conditions. The available trace elements content varied considerably with different land reclamation patterns. Extended reclamation time was helpful for the recovery of the available trace element content in the soil, and after more than eight years of soil reclamation, the content of available trace elements was closer to or greater than that in soil under natural conditions. Various treatment measures significantly influenced the content and distribution of available trace elements in the soil, and reasonable artificial treatments, including covering the soil and growing shrubs and herbaceous plants, increased the content of available trace elements.

Effect of Covering-Soil Thickness on Crop Growth on Bare Rock and Gravel Land in an Ecological Restoration Project

Abstract: To study the mechanism by which the thickness of covering soil effects crop growth in an ecological restoration project of bare rock and gravel land, the physiological characteristics of summer maize were observed during 2010–2015. This experiment was set up on exposed rock land, which had been covered by soil with six different thicknesses: 30 (C30), 40 (C40), 50 (C50), 60 (C60), 80 (C80) and 100 cm (C100). During the experiment, soil physical properties and the physiological traits and yields of crops were recorded. The results indicated several effects. 1) With the same thickness level, soil bulk density of the covering soil increased in successive planting years. There was a logarithmic relationship between soil bulk density and covering thickness. There was also a strong algorithmic relationship between covering thickness and sedimentation coefficient (R2=0.91). 2) The thickness of covering soil had a significant influence on both the height of summer maize, and soil and plant analyzer development (SPAD) values. In each treatment, the growth rates of the crops during the jointing and booting stages were higher than that in the booting to grain filling stage. After two years of land-use, the mean height of the crop in the C50 treatment was 8.16%, 3.32%, 3.31%, 9.86% and 7.55% higher than that for the C30, C40, C60, C80 and C100 treatments, respectively. The differences between treatments were significant (p < 0.05). SPAD values were highest at the heading stage. The highest value for the C50 treatment was 298.41 after two years of land-use. 3) Soil thickness significantly affected yields and the water use efficiency (WUE) of summer maize. The highest average crop yield and WUE value during the experimental period for the C50 treatment were 4614.12 kg hm-2 and 13.57 kg hm-2 mm, respectively. For the C50 treatment the multi-year average water use efficiency was significantly higher than that of the other treatments in 2010–2015. In conclusion, a soil thickness of 50 cm covering the bare exposed rock was adequate as a tillage layer for the crop, and all crop growth indexes in this treatment were better than for other soil thicknesses. The results provide a scientific basis for the land remediation and ecological restoration of bare rock and gravel land. At the same time, for Africa, where one-third of the land is desert, arable land resources are relatively scarce and agricultural ecology is fragile, can serve as a significant reference to improve the ecological environment, develop arable land resources and increase agricultural income.

Runoff and Soil Erosion on Slope Cropland: A Review

Abstract: Soil erosion has become a serious environmental problem worldwide, and slope land is the main source of soil erosion. As a primary cover of slope land, crops have an important influence on the occurrence and development of runoff and soil erosion on slope land. This paper reviews the current understanding of runoff and soil erosion on slope cropland. Crops mainly impact splash detachment, slope runoff, and sediment yield. In this review paper, the effects of crop growth and rainfall on the splash detachment rate and the spatial distribution of splash detachment are summarized. Crop growth has a significant impact on runoff and sediment yield. Rainfall intensity and slope gradient can influence the level of erosive energy that causes soil erosion. Furthermore, other factors such as antecedent soil water content, soil properties, soil surface physical crust, and soil surface roughness can affect soil anti-erodibility. The varying effects of different crops and with different influence mechanisms on runoff and soil erosion, as well as changes in their ability to influence erosion under different external conditions should all remain focal points of future research. The effect of crop vegetation on runoff and soil erosion on slope land is a very important factor in understanding large-scale soil erosion systems, and in-depth study of this topic is highly significant for both theory and practice.