Semiarid Region Of Northwest China Research Articles

Suitable furrow mulching material for maize and sorghum production with ridge-furrow rainwater harvesting in semiarid regions of China

In order to select environmentally friendly mulching materials and to increase rainwater utilization in a semiarid region of Northwest China, a field experiment was conducted using a randomized complete design to determine effects of three furrow-mulching materials (liquid film (LF), maize straw (MS) and biodegradable film (BF)) on soil temperature, moisture, evapotranspiration (ET), crop (maize and sorghum) yields and water use efficiency (WUE) with no-mulching (NM) as a control, during three consecutive crop growing seasons in years 2013-2015. Silage, grain, and biomass yields and WUE for maize were 1.75, 1.87, 1.82 and 1.76 times greater than corresponding yields and WUE for sorghum during the study period. BF increased topsoil temperature and soil water storage, while MS decreased topsoil temperature but increased soil water storage. Compared with NM, the increase in average topsoil temperature at the furrow bottoms of BF was 1.05–1.37 ºC during the growing seasons for maize, while it was 1.07–1.25 ºC during the growing seasons for sorghum. During the growing seasons, the decrease in topsoil temperature at the furrow bottoms for MS was 1.22–1.81 ºC for maize, while it was 1.34–1.59 ºC for sorghum. BF and MS decreased furrow soil evaporation but increased crop transpiration, while they did not shift the total water loss from ET. BF resulted in high soil temperature and moisture, increased crop yields, and WUE. Although low temperatures impaired emergence and crop development, high soil moisture increased crop yields and WUE with MS. Compared with NM, BF treatments resulted in increased mean silage, mean grain and mean biomass yields for maize of 17.0%, 17.7% and 13.7%, respectively, while corresponding yields for sorghum increased by 12.9%, 17.0% and 11.7%, respectively. The mean silage, grain, and biomass yields for maize with MS increased by 9.3%, 12.1% and 8.0 %, respectively, while corresponding yields for sorghum increased by 5.6%, 14.3% and 6.7%, respectively. Mean WUEs for maize and sorghum with BF significantly increased by 4.8 and 2.6 kg ha−1mm−1, respectively, while those values with MS significantly increased by 3.8 and 2.8 kg ha−1mm−1. MS provided a lower increase (12.1 %–14.3 %) in grain yields compared with BF (17.0 %-17.7%) in the study. LF had similar soil temperature and water moisture as with no mulching, and did not significantly increase either crop yields or WUE.

Lag effect of air temperature on the incidence of respiratory diseases in Lanzhou, China.

Previous studies have found that ambient temperature was associated with respiratory disease. However, little evidence is available in Lanzhou, a semi-arid region in northwest China, and respiratory disease is not well understood. This study evaluated the risk of outpatient visits for respiratory diseases associated with ambient temperatures from 2007 to 2016 in Lanzhou. We used a distributed lag non-linear model coupled with a generalized additive model to estimate the association between daily temperature and hospital visits for respiratory diseases in age- and sex-specific groups. Over 10years, 1,042,656 hospital visits were recorded for respiratory disease, the ratio between males and females was 1.21:1. The peak period of onset occurs from November of the current year to March of the following year. Both low and high temperatures were associated with an increased risk of hospital visits for respiratory illness. The results showed that a large temperature decrease was associated with a significant risk for respiratory disease, the maximum effect of a temperature drop was reached at lag 1~2days, the extreme low temperature (- 16°C) had the maximum RR at lag 1, and the RR value was 1.082 (95% CI 1.025-1.142). The high temperatures (23°C) had maximum RR for respiratory disease on the current day, and the RR value was 1.099 (95% CI 1.049-1.152). The high temperatures had acute and short-term effects and declined quickly over time, while the effects in low-temperature ranges were persistent over longer lag periods. Females suffered more from cold-associated morbidity than males. The effects of both hot and cold temperatures were greater among adolescents aged 6-14years. Our study suggests that ambient temperatures are associated with hospital visits for respiratory illness in Lanzhou, particularly for those who are female and young. Caregivers and health practitioners should be made aware of the potential threat posed by cold and hot temperatures.

Responses of soil organic carbon and nitrogen to land-use changes in a semiarid region of northwest China

Currently, we lack a clear understanding of how climate influences the responses of soil organic carbon (OC) and nitrogen (N) to land-use changes in semiarid regions. Thus, to clarify the mechanisms involved, we measured the soil OC and total N (TN) concentrations and stocks in the 0–100 cm soil layer in adjacent grassland, farmland, and woodland at five sites on the Loess Plateau in China, which varied in terms of the mean annual precipitation (MAP) and mean annual temperature (MAT). The farmland or woodland was converted from grassland at each site. Conversion of grassland to farmland significantly reduced the soil OC and TN, with greater decreases in sites with relatively lower MAP and MAT (–0.60 Mg OC ha−1 yr−1 and –0.22 Mg TN ha−1 yr−1, respectively) than sites with relatively higher MAP and MAT (–0.35 Mg OC ha−1 yr−1 and –0.04 Mg TN ha−1 yr−1). Conversion of grassland to woodland increased OC and TN at sites with higher MAP and MAT, but decreased them at sites with lower MAP and MAT. OC and TN increased to a depth of 100 cm with MAP and MAT after this land-use change. OC and TN decreased at relatively drier and colder sites, but increased at relatively wetter and warmer sites. These findings provide insights into the effects of land-use changes on the soil OC and TN under different climate conditions, thereby facilitating the sustainable management of grasslands in semiarid regions.

Spatial associations between NDVI and environmental factors in the Heihe River Basin

The Heihe River Basin is located in the arid and semi-arid regions of Northwest China. Here, the terrestrial ecosystem is vulnerable, making it necessary to identify the factors that could affect the ecosystem. In this study, MODIS-NDVI data with a 250-m resolution were used as a proxy for the terrestrial ecosystem. By combining these with environmental factors, we were able to explore the spatial features of NDVI and identify the factors influencing the NDVI distribution in the Heihe River Basin during the period of 2000–2016. A geographical detector (Geodetector) was employed to examine the spatial heterogeneity of the NDVI and to explore the factors that could potentially influence the NDVI distribution. The results indicate that: (1) the NDVI in the Heihe River Basin appeared high in the southeast while being low in the north, showing spatial heterogeneity with a q-statistic of 0.38. The spatial trend of the vegetation in the three sub-basins generally increased in the growing seasons from 2000 to 2016; (2) The results obtained by the Geodetector (as denoted by the q-statistic as well as the degree of spatial association between the NDVI and environmental factors) showed spatial heterogeneity in the associations between the NDVI and the environmental factors for the overall basin as well as the sub-basins. Precipitation was the dominant factor for the overall basin. In the upper basin, elevation was found to be the dominant factor. The dominant factor in the middle basin was precipitation, closely followed by the soil type. In the lower basin, the dominant factor was soil type with a lower q-statistic of 0.13, and the dominant interaction between the elevation and soil type was nonlinearly enhanced (q-statistic = 0.22).

Transport pathways of PM10 during the spring in northwest China and its characteristics of potential dust sources

Abstract Dust storms that occur frequently during the spring in the arid and semiarid regions of northwest China can significantly increase PM10 loadings in the local area and its surroundings, and impair environmental ecology, human activity and health. Based on the monitoring data of PM10 and backward trajectories of air parcels calculated by the Hybrid Single Particle Lagrangian Integrated Trajectory model in Jiayuguan, Jinchang and Lanzhou during the spring seasons from 2014 to 2017, trajectory cluster analysis was used to identify the major transport pathways of PM10, and concentration-weighted trajectory and trajectory sector analysis were applied to identify the potential sources and quantify regional transported contributions. The results showed that there were major transport pathways coming from three directions: the northwestern pathways (for Jinchang and Lanzhou), the western pathways (for Jiayuguan and Lanzhou), and the northern pathways (for Jiayuguan and Jinchang). The corresponding potential dust sources for these pathways were the northwesterly sources, the westerly sources and the northerly sources, respectively. In addition, the northern Tibetan Plateau was another important source affecting Jiayuguan. There were distinct differences among the regional transport contributions from various directions. The PM10 concentrations (percentages) that exogenous dust sources contributed to Jiayuguan, Jinchang and Lanzhou decreased in a sequence from west to east at 47 μg/m3 (29.8%), 40 μg/m3 (27.1%) and 26 μg/m3 (17.3%), respectively, which were attributed predominantly to the long-range transport of dust sources with the remainder coming from local or nearby emissions. The above decreasing tendency was in accordance with the distance effect from the dust sources to the receptor sites.

Interactive Effects of Water and Fertilizer on Yield, Soil Water and Nitrate Dynamics of Young Apple Tree in Semiarid Region of Northwest China

Exploring the interactive effect of water and fertilizer on yield, soil water and nitrate dynamics of young apple tree is of great importance to improve the management of irrigation and fertilization in the apple-growing region of semiarid northwest China. A two-year pot experiment was conducted in a mobile rainproof shelter of the water-saving irrigation experimental station in Northwest A&F University, and the investigation evaluated the response of soil water and fertilizer migration, crop water productivity (CWP), irrigation water use efficiency (IWUE), partial factor productivity (PFP) of young apple tree to different water and fertilizer regimes (four levels of soil water: 75%–85%, 65%–75%, 55%–65% and 45%–55% of field capacity, designated W1, W2, W3 and W4, respectively; three levels of N-P2O5-K2O fertilizer, 30-30-10, 20-20-10 and 10-10-10 g plant−1, designated F1, F2 and F3, respectively). Results showed that F1W1, F2W1 and F3W1 had the highest average soil water content at 0~90 cm compared with the other treatments. When fertilizer level was fixed, the average soil water content was gradually increased with increasing irrigation amount. For W1, W2, W3 and W4, high levels of water content were mainly distributed at 50~80 cm, 40~70 cm, 30~50 cm and 10~30 cm, respectively. There was no significant difference in soil water content at all fertilizer treatments. However, F1 and F2 significantly increased soil nitrate-N content by 146.3%~246.4% and 75.3%~151.5% compared with F3. The highest yield appeared at F1W1 treatment, but there was little difference between F1W1 and F2W2 treatment. F2W2 treatment decreased yield by 7.5%, but increased IWUE by 11.2% compared with F1W1 treatment. Meanwhile, the highest CWP appeared at F2W2 treatment in the two years. Thus, F2W2 treatment (soil moisture was controlled in 65–75% of field capacity, N-P2O5-K2O were controlled at 20-20-10 g·tree−1) reached the best water and fertilizer coupling mode and it was the optimum combinations of water and fertilizer saving.

Analyses of mitochondrial genomes of the genus Ammopiptanthus provide new insights into the evolution of legume plants

The genus Ammopiptanthus is mainly distributed in the semi-arid regions of northwest China. It only contains two species: A. mongolicus and A. nanus. They exhibit similar morphological characteristics, but little is known about their genetic differences. We performed de novo sequencing and mitochondrial genome assembly and found that both species contain 36 protein-coding genes, 3 rRNA, and 16 tRNA genes. The comparison of A. mongolicus and A. nanus mitogenomes revealed a 6.5-kb region loss in A. nanus mitogenome, which was replaced by a 1.5-kb different sequence element. Other small variations between the two species include 25 SNPs, 4 deletions, and 2 insertions. Meta-analyses indicated that 34% of the A. mongolicus mitogenome was unique to Ammopiptanthus and has no similarity with any other known legume mitogenomes. These unique sequences are mainly distributed in intergenic regions. Gene gain and loss analysis showed that this mitogenome gained two genes, rps7 and sdh4, during evolution, with rps7 transferred from the chloroplast genome. Selective pressure analysis implied that the atp8 gene was under positive selection. Our study established high-quality reference mitogenomes for the genus Ammopiptanthus, revealed novel genetic differences between A. mongolicus and A. nanus, and provided new insights into the evolution of legume plants.

Spatial Characteristics of Deep-Developed Boundary Layers and Numerical Simulation Applicability over Arid and Semi-Arid Regions in Northwest China

The spatial distribution and long-time variation of the deep-developed boundary layer are not well understood in arid and semi-arid regions of northwest China. ERA-Interim (ECMWF Reanalysis data, ECMWF: European Centre for Medium-Range Weather Forecasts) were used to study the deep-developed boundary layer in the five representative areas in summer and then the Weather Research Forecast (WRF) model was applied to simulate and verify its applicability. The results show that the boundary layer heights in the five representative areas are higher in late spring and summer (the highest is 2485~3502 m in June) and lower in autumn, winter and early spring (the lowest is 758~907 m in December). The seasonal variations of the boundary layer height are smaller at 02:00 BJT and 08:00 BJT, while the variations are relatively larger at 14:00 BJT and 20:00 BJT. The atmospheric boundary layer, with heights over 4000 m, generally exists in late spring and summer. The boundary layer heights are higher in the arid region than in the semi-arid region and the deep-developed boundary layer lasts longer in the arid region. The boundary layer heights present reductions from the northwest to the southeast, except for Minqin in the middle north. The numerical simulation results show that there is a significant difference between different combinations of parameterization schemes to simulate the deep-developed boundary layer in these areas. The combination Goddard+SLAB+ACM2 performs better in the extreme arid area, Dunhuang, and the arid areas, Jiuquan and Minqin, whereas the simulation effect of the combination Dudhia+Noah+ACM2 is better in the semi-arid areas, Yuzhong and Lanzhou. The difference between the schemes is related to the determination of the boundary layer height.

Plant Feedback Aggravates Soil Organic Carbon Loss Associated With Wind Erosion in Northwest China

AbstractSoil organic carbon (SOC) loss caused by wind erosion can profoundly impact carbon (C) balance in arid and semiarid regions. Nevertheless, previous researches mainly focused on the direct effect of wind erosion through removing surface soil only but ignored its indirect effects associated with soil nitrogen (N) loss and subsequent reductions of plant productivity. To better understand the wind erosion effect on SOC storage, we conducted a large‐scale field experiment by manipulating wind erosion at 371 sites in arid and semiarid regions of northwest China from 2014 to 2016. We further integrated an observation‐based empirical equation of wind erosion process into a terrestrial biogeochemical model to evaluate the direct and indirect effects of wind erosion on SOC storage in northwest China. The observed results showed that direct SOC losses increased linearly with the square of wind speed but decreased nonlinearly with soil water content. Over the 34 years (1980–2013), simulated cumulative SOC losses associated with wind erosion in northwest China were 27.47 Tg C, among which the indirect effects contributed to 2.68 Tg C (9.76%). The indirect effect of wind erosion initially enhanced SOC storage by decreasing heterotrophic respiration from 1984 to 1988 but decreased SOC pool by reducing net primary productivity due to soil N loss under the long‐term wind erosion scenario. This work, for the first time, quantified the indirect impact of wind erosion on SOC storage via feedback of suppressed plant productivity, which is crucial for the convincing assessment on SOC storage in arid and semiarid regions.

Photosynthetic characteristics and grain yield of winter wheat (Triticum aestivum L.) in response to fertilizer, precipitation, and soil water storage before sowing under the ridge and furrow system: A path analysis

The ridge and furrow (RF) system can improve the soil moisture and temperature conditions, as well as increasing the grain yield and water use efficiency. However, the combined effects of the fertilizer amount, precipitation during the growing season (PGS), and soil water storage before sowing (SWSS) on the photosynthetic characteristics and yield under this system are still unclear in winter wheat. Thus, in this study, we used path analysis to determine the effects of these three factors based on a field experiment conducted for five years in a semiarid region of Northwest China. Path analysis showed that precipitation during the sowing to filling stage (PSF) in winter wheat had the greatest influence on the photosynthesis gas exchange characteristics of flag leaves in the filling stage, followed by the fertilizer amount. And the determination coefficients of PSF on the photosynthetic rate (Pn), transpiration rate, stomatal conductance (Gs), leaf instantaneous water use efficiency (WUE) and relative chlorophyll content (SPAD value) were 0.331, 0.868, 0.864, 0.820, and 0.414, respectively. The most important factor for the grain yield was SWSS, where the coefficient of determination was 0.838, followed by the fertilizer amount and PGS, and the indirect effect of the fertilizer amount on SWSS was negative. Therefore, our results suggest that SWSS has an important effect on the grain yield in winter wheat under the RF system in semiarid regions, and thus improving the SWSS can obtain better increases in the grain yield compared with fertilizer amount.

Water-conserving mining influencing factors identification and weight determination in northwest China

Water-conserving mining is an effective way to alleviate the contradiction between fragile ecological environment and high-intensity coal mining in the arid and semi-arid region of northwest China. It needs to consider the engineering and geological conditions, hydrogeological conditions and mining methods of coal seams. From the three aspects, this paper systematically analyzes the influencing factors and establishes an identification model with multi-level structures. The model includes three primary factors (including the engineering and geological conditions, hydrogeological conditions and mining methods), nine secondary factors (including overlying strata thickness, aquiclude, mining parameters and etc.), sixteen third-tier factors (including the faults, aquiclude thickness and effective mining height and etc.) and twelve fourth-tier factors (including the fault throw exponent, aquiclude permeability and coal pillar sizes and etc.). On the basis, the analytic hierarchy process is used to build the judgment matrix and obtain the weight of each influencing factor. The results indicate that the overlying strata thickness, aquiclude and effective mining height are the most important factors among the primary factors of engineering and geological conditions, hydrogeological conditions and mining methods, respectively. The research results could provide theoretical references for the water-conserving mining of coal resources in northwest China.

Increased drought and atmospheric CO2 positively impact intrinsic water use efficiency but do not promote tree growth in semi-arid areas of northwestern China

This work studied the response of tree growth to the increased drought and carbon dioxide in semi-arid areas of northwestern China. Forests ecosystems play a key role in the global carbon cycle. However, effects of increased drought and rising atmospheric carbon dioxide (Ca) on it are complex and there are many uncertainties. In this study, we evaluated this issue through dendroecology in semi-arid regions of northwest China. Results found the basal area increment of trees decreased by 28% (from 7.59 to 5.43 cm2 year−1) as the intrinsic water use efficiency increased 32% (from 98.61 to 130.28 µmol mol−1). Despite both Ca and drought positively affected intrinsic water use efficiency, they did not promote tree growth. Meanwhile, values of intercellular [CO2] increased 14% (from 158.83 to 180.89 ppm) while the ratio of intercellular [CO2] to Ca decreased 7% (from 0.50 to 0.46). Our study advances understanding of the variability of the global carbon cycle under climate change.

中国西北半干旱区净初级生产力驱动因子空间计算分析

中国西北半干旱区净初级生产力驱动因子空间计算分析

Caragana korshinskii phenylalanine ammonialyase is up-regulated in the phenylpropanoid biosynthesis pathway in response to drought stress

Drought is one of the most severe abiotic stresses, the damage due to which, various plant species mitigate by activating mechanisms that are not yet well understood. Caragana korshinskii is a xerophytic shrub found in the semi-arid regions of northwest China with high tolerance to several abiotic stresses, including drought. Based on the de novo transcriptome data from C. korshinskii leaflets collected along a precipitation gradient on the Loess Plateau (China), most of the differentially expressed genes were explored using trend analysis along the precipitation gradient. Gene ontological analysis showed that “phenylpropanoid biosynthesis process → secondary metabolite biosynthetic process” terms were the most significant gene ontologies, whereas Kyoto Encyclopedia of Genes and Genomes-based analysis indicated that the biosynthesis of secondary metabolites was a significant metabolic pathway. Real-time polymerase chain reaction and enzyme activity analyses confirmed the increased transcription of the phenylalanine ammonialyase (PAL) gene in C. korshinskii under drought stress in field and laboratory conditions. These results suggested that C. korshinskii adjusts its secondary metabolism to water-deficit environments and activates PAL by drought stress. Therefore, further studies on the obtained data can expand the current understanding of the molecular and genetic mechanisms responsible for the drought endurance in C. korshinskii.

Effects of film mulching and nitrogen fertilization on rhizosphere soil environment, root growth and nutrient uptake of winter oilseed rape in northwest China

The ridge film mulching and furrow planting (RFMF) pattern has been increasingly applied to the production of wheat, maize, and potato in arid and semiarid regions of northwest China because it can significantly improve crop yield. How RFMF affects the productivity and whether it can improve the rhizosphere soil environment of winter oilseed rape (Brassica napus L.) is not clear. The main objective of the present study was to determine whether RFMF can improve rhizosphere soil environment and winter oilseed rape productivity in comparison to the conventional flat planting (FP) pattern in a three-year (2014-2017) field experiment. In combination with each planting pattern, we determined an optimal nitrogen (N) application rate among six levels: 0 (N0), 60 (N60), 120 (N120), 180 (N180), 240 (N240) and 300 (N300) kg N ha−1. Results showed that the RFMF pattern significantly improved the rhizosphere soil environment by increasing soil moisture by 0.3–5.6% and soil temperature by 0.6–3.0 °C. However, soil oxygen concentration decreased by 0.03–5.66% during the flowering stage of winter oilseed rape. In addition, the RFMF pattern markedly improved rhizosphere soil enzyme activity and microorganism abundance and thus promoted root growth, nutrient uptake, and seed yield of winter oilseed rape. The resulting optimal N application rates remarkably improved rhizosphere soil enzyme activity, microorganism abundance, root growth, nutrient uptake, and yield of winter oilseed rape in both RFMF and FP treatments. In the RFMF treatment, N240 obtained significantly greater rhizosphere soil enzyme activity, microorganism abundance, root growth parameters, nutrient uptake, and seed yield than N0, N60, N120, and N180, with no significant differences observed between N240 and N300. In conclusion, the RFMF pattern in combination with the optimal N-application rate of 240 kg ha−1 has great potential to improve rhizosphere environment and winter oilseed rape productivity in arid and semiarid regions of northwest China.

Effect of film mulching and microbial inoculation on maize growth and water use efficiency under drought stress.

To resolve the problem of soil nutrient and water deficiency in arid and semiarid regions of Northwest China, and considering the symbiotic relationship between microbes and crops, we set up two water regimes: drought stress (35% of the soil water holding capacity) and normal water supply (75% of the soil water holding capacity), two film mulching patterns (non-film mulching and film mulching), and four levels of microbial inoculation [single inoculation with AM fungi (AM), single inoculation with phosphate solubilizing bacteria (PSB), co-inoculation of AM fungi with phosphate solubilizing bacteria (AM+PSB) and the control (CK)]. This study aimed to evaluate the effects of microbial inoculation on maize growth, nutrient absorption, and water use efficiency under different treatments of water regime and film mulching. Results showed that drought stress significantly increased the mycorrhizal colonization of inoculated plants, but significantly decreased soil external hyphal length, T-GRSP and EE-GRSP content. Under drought stress, AM inoculation showed the best promoting and mycorrhizal effect on maize growth by increasing biomass and water use efficiency, soil organic carbon content, the absorption and transportation of soil N, P, K, and thus increasing the N, P, K uptake. Under normal water supply, the inoculation effect of AM+PSB was better than that of AM or PSB treatment, especially combined with film mulching. Results from correlation analysis showed that plant biomass, leaf SPAD value, and nutrient uptake of maize aboveground were significantly positively correlated with soil external hyphal length, whereas water use efficiency was significantly negatively correlated with soil external hyphal length.

Effect of straw belt-mulching on soil temperature and yield of winter wheat in rain-fed semiarid region.

To evaluate the effects of straw belt-covering on soil temperature and yield of winter wheat in rain-fed semiarid region in Northwest China, five mulching modes, including flat field planting without any mulching (CK), whole plastic film mulching (PM), straw mulching by 30 cm covering belt with an interval of 30 cm planting belt with three-row sowing (SM1), straw mulching by 40 cm covering belt with an interval of 40 cm planting belt with four-row sowing (SM2), and straw mulching by 50 cm covering belt with an interval of 50 cm planting belt with five-row sowing (SM3), were set by two-year fixed-site trails in 2013-2015. The results showed that soil temperature significantly varied among different growth stages and soil layers in all treatments. SM1, SM2 and SM3 significantly decreased soil temperature by 1.0-1.3 ℃, 0.7-0.9 ℃ and 0.7-1.1 ℃ in the 0-25 cm soil layer, respectively. The mulching had double effects with increasing and decreasing soil temperatures. The straw mulching significantly increased soil temperature in the duration of seedling to overwintering stage, but greatly decreased soil temperature in the duration of reviving to mature stage. The temperature-increasing effect of film mulching was stronger than that of straw mulching, which was opposite to the temperature-decreasing effect. Straw mulching significantly reduced in the effective accumulated temperature and the daily temperature variations during the whole growth stages. The effective accumulated temperature under straw mulching decreased by 3.4-33.5 ℃·d, and the soil temperature difference decreased by 0.6-2.0 ℃. During over-wintering stage, the straw mulching showed a higher average soil temperature (0.2-0.3 ℃) and negative accumulated temperature (0.4-17.0 ℃·d) than those under the CK. The straw mulching significantly increased grain yield by 11.9%-19.5%. The variations of spikes per unit area were the main factor responsible for yield difference. The findings indicated that that straw mulching method is suitable for winter wheat production in rain-fed region of Northwest China.

Goaf water storage and utilization in arid regions of northwest China: A case study of Shennan coal mine district

In arid and semiarid regions of northwest China, there are abundant shallow coal reserves throughout the region, yet during the mining process, the shallow water resources available are typically depleted due to the formation of fractures in the shallow subsurface. Water-preserved mining is the only option for coal mining in arid regions of northwest China. Based on the geological and hydrogeological conditions of the study area, this paper investigates the basic conditions and mechanisms of goaf water storage. A time series model for goaf water storage is proposed, along with a method for estimating the quantity of goaf water storage. Finally, hydrochemical characteristics of mine water and water quality characteristics after purification in the study area were analyzed. As indicated by the analysis results, after simple purification, the goaf water can meet industrial, ecological and agricultural water consumption standards. In the end, combined with current monitoring results of goaf water pressure and the status of goaf water utilization in the study area, this paper describes the quantity and the effect of utilizing goaf water storage. Goaf water storage can effectively alleviate the scarcity of local production and domestic water, and provides the most effective approach of large-scale water-preserved mining of shallow coal seams in the arid regions of northwest China.

Remediation of heavily saline-sodic soil with flue gas desulfurization gypsum in Arid-Inland China

ABSTRACTSoil salinity is a major limiting factor for crop production in arid and semi-arid regions of northwest China. Flue gas desulfurization gypsum (FGDG) is valuable waste resource which can be used to improve saline soil. Monolith lysimeter leaching experiment was conducted with FGDG in heavily saline-sodic soil of northwest China. The four FGDG treatments with nine replicates for each treatment were applied when the FGDG rate was 0, 15, 30, and 60 t ha−1, respectively. Undisturbed sodic-saline soil was carefully collected in the 40-cm deep soil column. The results indicated that improvement effect on the depth of 0–10 cm soil layer was the best when the rate of FGDG was 60 t ha−1. It can reduce pH by 1.85, exchangeable sodium percentage (ESP) by 44%, and exchangeable Na+ by 7.37 cmol/kg in top soil layer. The values of the above soil parameters fell in the normal range due to FGDG treatment. At the same time, FGDG application reduced soil bulk density and increased saturated hydraulic conductivity. But from the maize growth, the emergence rate, plant height, shoot, and root weight were the best when the FGDG rate was 30 t ha−1. The results also showed that the FGDG application increased soil electrical conductivity value. Therefore, it is quite necessary to move saline ions into the deep soil layer through leaching process. Although effect of FGDG treatment of 60 t ha−1 on top soil was the best, considering the improvement effects of entire soil profile, we recommend that the optimum rate of FGDG was 30 t ha−1.

Enlargement of the semi-arid region in China from 1961 to 2010

Due to spatial and temporal heterogeneity in moisture conditions, the responses of arid/humid climate regions (AHCR) to climate change are complex. In this study, we delineated the AHCR of China using information about the balance of the atmospheric water supply and demand collected from 581 meteorological stations over the past 50 years. We also analyzed inter-decadal shifts and linear trends in the AHCR and examined the influence of precipitation and reference evapotranspiration. The results indicate that the semi-arid region expanded significantly over the last five decades, mainly in northwest China, northern China, and the Tibetan Plateau and, by the 2000s, had increased by 33.53% relative to its extent in the 1960s; in contrast, the arid region shrank by 20.75%. The semi-arid region grew mainly because of transfers from the arid region in western China and the sub-humid region in eastern China. The decreased reference evapotranspiration and significantly increased precipitation together contributed to the expansion of the semi-arid region in northwest China and the Tibetan Plateau over the last 50 years. In contrast, the expansion of the semi-arid region in Inner Mongolia and northern China reflects the counteractive influence of decreased reference evapotranspiration and decreased precipitation.