Areas Of Chinese Loess Plateau Research Articles

Spatiotemporal patterns and driving factors of soil protection in the wind-water erosion area of Chinese Loess Plateau

Spatiotemporal patterns and driving factors of soil protection in the wind-water erosion area of Chinese Loess Plateau

Contributions and Resistances to Vulnerability of Rural Human Settlements System in Agricultural Areas of Chinese Loess Plateau since 1980

The vulnerability evolution of human settlements system on the micro-scale is a direct indicator of the local impact of global environmental change. Traditional agricultural areas are most vulnerable to climate and market changes. Due to the lack of historical statistics, micro-scale quantitative studies on the historical evolution of vulnerability are extremely scarce. From the perspective of the socio-ecological system, this study conducted field investigations along with quantitative assessment and an ethnographic approach to explore the vulnerability change of rural human settlements system since 1980 in Jia County, an agro-pastoral interlocking area. The study found that the vulnerability of natural, dwelling and social systems has continued to decrease, while human system vulnerability increased. At present, the RHSS is characterized by the poor quality of the river, a depressed rural population and a large gap between the rich and poor as weaknesses, and is characterized by sandstorm disaster reduction, more robust rural roads, adequate water for domestic use and high social security as strengths. Results revealed that ecological projects, increased precipitation, market changes, urbanization siphoning and farmer behaviors are key drivers to the vulnerability change since 1980. The study findings can be directly applied to rural revitalization strategies, vulnerability mitigation and adaptive management practices in China. In addition, the vulnerability evolution under multiple perturbations can provide guidance for settlement planning and construction in traditional agricultural areas among developing countries under global changes.

Effects of different forms and application methods of selenium fertilizers on wheat selenium uptake and utilization and its residual availability

<p id="C3">A two-year positioning field experiment was conducted to determine the reasonable regulation measures of selenium (Se) fertilizer for improving wheat grain Se nutrition, and to explore the feasibilities of different Se application approaches in Se agronomic biofortification of wheat grown in the typical Se-deficient soils of Yongshou County, Shaanxi Province. To study the effects of different forms and application methods of Se fertilizers on wheat yield, Se concentration and its accumulation and utilization, with the goal of producing wheat grain with Se concentration of 100 μg kg ^-1, five Se application rates of 0, 15, 18, 700, and 45 g hm^-2 were calculated for the treatments of no Se application (control), soil- and foliar-sodium selenate, and soil- and foliar-sodium selenite in the first year, respectively. In the following wheat season, for further investigating the residual Se availability, no Se fertilizer was applied and each plot was divided into straw removal and straw return. These results showed that the wheat grain yield and straw biomass were not influenced by Se forms and application methods. For the first wheat season, grain Se concentration reached the expected target value with a range of 109-397 μg kg ^-1, and the flour Se concentration varied from 101 μg kg ^-1 to 356 μg kg ^-1 for all the Se application treatments. In the next year, both grain and white flour Se concentrations were 100 μg kg ^-1 higher than under the treatment of soil-sodium selenite, and there was no significant difference of straw removal and straw return. Grain Se biofortification index was 4.7, 16, 0.3, 8.0 (μg kg^-1) (g hm^-2)^-1 for soil- and foliar-sodium selenate, and soil- and foliar-sodium selenite, respectively. The Se use efficiency was the highest for foliar-sodium selenate (7.3%), whereas its cumulative use efficiency was only 0.3% in soil-sodium selenite treatment with the long-term residue effects. At wheat harvest, the highest soil available Se was observed for soil-sodium selenite, with 91 μg kg ^-1 and 107 μg kg ^-1 for the straw removal and straw return, respectively. In conclusion, both soil- and foliar-sodium selenate /selenite were beneficial for producing wheat grain with target Se concentration of 100 μg kg ^-1, and the sodium selenite requirement was the highest, and its residual availability should be taken into consideration for Se biofortification in wheat production in the Se-deficient area of Chinese Loess Plateau.

Spatial and temporal characteristics of surface soil moisture in a disturbed coal mining area of Chinese Loess Plateau.

Soil water content is an important variable in hydrology and many related disciplines. It affects runoff from precipitation, groundwater recharge, and evapotranspiration. This research used the coal mining area of the Changhe River Basin in the Loess Plateau as a study and using SAR (Synthetic Aperture Radar) data, the surface soil water in 24 days (From Jan 25, 2018 to Dec 10, 2019) was estimated using a radar signal change detection algorithm. The temporal and spatial variation characteristics of surface soil water inside and outside the disturbed area were compared and analyzed. An empirical orthogonal function (EOF) analysis method was used to analyze the potential temporal and spatial variation of surface soil water, and to detect the regional soil water variation under coal mining disturbances to better understand the different potential modes of spatial variation of soil water in the unobserved time. The results showed that the average surface soil water content in the study area changed with season, showing a dry-wet-dry variation. Moreover, it was significantly affected by precipitation factors, and its response to precipitation had a hysteresis effect. From the perspective of spatial variation, the influence of coal mining disturbance on surface soil moisture was not obvious. From the perspective of time series change, moving from wet to dry conditions, the soil in the disturbed area dried faster than the soil in the undisturbed area after soil wetted. When moving from drying to wetting, the soil in the disturbed area was quickly wetted. The EOF analysis showed that most observed spatial variability of soil moisture was stable in time. The study was conducted in a disturbed area and an undisturbed area for single EOF analysis, and the results showed that the EOF mode of the disturbed area was closer to that of the whole study area. By comparing the two subregions and the entire study area, it was found that the changes of correlation values were related to soil texture, bulk density, altitude and slope, indicating that the soil texture of the two subregions may be different at different elevations, and may also be related to the change of the original soil structure in the disturbed area. Overall, the EOF mode of the disturbed area determined the EOF mode of the entire study area.

Seasonal dynamics of soil water content in the typical vegetation and its response to precipitation in a semi-arid area of Chinese Loess Plateau

Seasonal dynamics of soil water content in the typical vegetation and its response to precipitation in a semi-arid area of Chinese Loess Plateau

Quantitative assessment of check dam system impacts on catchment flood characteristics – a case in hilly and gully area of the Loess Plateau, China

The purpose of this study is to investigate the impact of check dams on catchment hydrological response in a small catchment on the hilly and gully area of Chinese Loess Plateau by applying a numerical model at 2 m resolution DEM. The results showed that check dams significantly increase the so-called runoff lag times (lag to generation, lag to peak and lag to end of runoff) at the channel outlet compared to catchments without check dams. Furthermore, the peak runoff discharge at the catchment outlet without check dams decreased by 93.0% compared to with check dams. The total outlet discharge, surface water stored, and infiltration were, respectively, 20.1%, 74.9% and 5.0% of the total precipitation in the check dam catchment, while 75.4%, 22.6% and 2.0% in the system without check dams. Installation of check dams also altered the spatial water distribution of maximum discharge, moving the occurrences of maximum discharge further upstream and, thus, increasing safety downstream. In conclusion, implementing check dams significantly and effectively mitigated flood processes and increased runoff infiltration upstream.

Ridge-furrow with full plastic film mulching improves water use efficiency and tuber yields of potato in a semiarid rainfed ecosystem

A planting pattern of alternate ridges and furrows with plastic film mulching has been viewed as a best management practice for crop production in the arid and semiarid regions, but there is a lack of insight into the underlying changes in soil–crop water relations on mulching areas and ridge-furrow shapes for potato (Solanum tuberosum L.) production. A field study with comparisons of three mulching areas and two ridge-furrow shapes was conducted for two years (2009 and 2010) to assess evapotranspiration, water use efficiency, and tuber yields in the semiarid Northwest China. The experiment included five mulching area and ridge-furrow shape combinations: (1) full mulching on double ridges and furrows (DRFFM), (2) full mulching on both ridges and furrows (RFFM), (3) half mulching only on ridges (RFHM), (4) no mulching on ridges and furrows (RFNM), and (5) traditional-flat planting and without mulching as the control (CK). The two full mulching treatments had the best effect on topsoil temperature–moisture, improved emergence rate by 9.3–14.4% and advanced emergence by 8.1–11.7 days (P<0.05). Full mulching treatments reduced evapotranspiration by about 24.0–45.0% during emergence, but increased it by up to 18.7% thereafter, primarily due to rapid increase of LAI under faster development, and also enhanced root/shoot ratio (P<0.05). Full mulching produced the highest tuber yields (57.4–78.2% higher than the CK) with higher cost of mulching material and labour than the half or no mulching treatments. The full mulching also resulted in the highest water use efficiency (increased by 56.8–70.3% than the CK). The beneficiary effects became smaller with the decrease of mulching areas. However, the difference between the two full mulching treatments was not significant (P>0.05) despite there was slightly higher WUE in DRFFM than RFFM. Our results revealed that the full mulching on ridge-furrow planting strategy was effective to increase potato productivity and water use efficiency in the semiarid area of Chinese Loess Plateau.