Arid Region Of Xinjiang Research Articles

The Relationship between the Carbon Fixation Capacity of Vegetation and Cultivated Land Expansion and Its Driving Factors in an Oasis in the Arid Region of Xinjiang, China

The Relationship between the Carbon Fixation Capacity of Vegetation and Cultivated Land Expansion and Its Driving Factors in an Oasis in the Arid Region of Xinjiang, China

Identifying and mapping the spatial distribution of regions prone to snowmelt flood hazards in the arid region of Central Asia: A case study in Xinjiang, China

AbstractSnowmelt floods are highly hazardous meteorological disasters that can potentially threaten human lives and property. Hence, snowmelt susceptibility mapping (SSM) plays an important role in flood prevention systems and aids emergency responders and flood risk managers. In this paper, a method of identifying snowmelt flood hazards is proposed, and a large‐scale snowmelt flood hazard zonation scheme based on historical recordings and multisource remote sensing data is established. To assess the quality of our approach, the proposed model was tested in the cold and arid region of Xinjiang, China. Overall, 140 historical snowmelt flood events and 27 explanatory factors were selected to construct a geospatial dataset for SSM of the contemporary period. GridSearchCV was used to comprehensively search the candidate parameters from the grid of given parameters obtained with the random forest (RF) algorithm. Then, the geospatial dataset was divided into two subsets: 70% for training and 30% for testing. Next, SSM results were obtained with the RF algorithm using optimized parameters. The results indicate that our optimized RF classifier performs well for the task of SSM, with a high AUC value (0.975) for the test dataset. The validation and analysis suggest that the proposed method can efficiently identify snowmelt flood hazards in undersampled arid areas at a regional scale.

Methodology for Mapping the Ecological Security Pattern and Ecological Network in the Arid Region of Xinjiang, China

Xinjiang is an important arid region in the northwest of China and plays an important role in the field of ecological security protection in China. Because of its aridity, the identification of critical areas for ecological protection and the optimization of ecological space structure in Xinjiang are of great significance for promoting the harmonious development of the oasis economy, enhancing the ecological environment, and improving human well-being. This study applied an ecological security evaluation from the three dimensions of habitat quality, ecosystem service value, and soil-water conservation to identify the basic situation of the ecological security pattern. The core “source” area of ecological protection was extracted using the morphological spatial pattern analysis (MSPA) method, while the ecological corridor and important ecological nodes were identified using the minimum cumulative resistance model (MCR). The “point-line-plane” three-dimensional ecological network structure was then constructed, providing a case for the development of the ecological security and construction in the oasis. The results showed that in the arid regions of Xinjiang, the ecological land is extremely fragmented and is mainly distributed in the mountains and waters distant from human activities. Overall, there is a substantial geographical disparity with a low level of ecological security, particularly in the ecological marginal areas. The ecological network framework of Xinjiang is characterized by an uneven distribution of “sources”, broken corridor structure, and a low degree of networking. Therefore, this study proposed an ecological space layout system consisting of “7 ecological subsystems, 51 source areas, 87 ecological corridors, and 33 ecological nodes” by combining the regional physical and geographical characteristics with the overall development plan.

Microplastic Contamination in Urban, Farmland and Desert Environments along a Highway in Southern Xinjiang, China.

The different types of microplastics (MPs), including debris, fibers, particles, foams, films and others, have become a global environmental problem. However, there is still a lack of research and understanding of the pollution characteristics and main causes of MPs in the arid region of Xinjiang, China. In this survey, we focused on the occurrence and distribution of MPs in urban, farmland and desert areas along a highway in the survey area. Our results showed that the main types of MPs were polypropylene (PP) flakes, polyethylene (PE) films and both PE and PP fragments and fibers. The abundance levels of MPs in street dust of Korla, Alar and Hotan districts equaled 804, 307 and 1526 particles kg−1, respectively, and were positively correlated with the urban population. In farmland areas, there were only two types of MPs (films and fibers), of which the film particles dominated and accounted for 91% of the total on the average. The highest abundance rate of MPs reached 7292 particles kg−1 in the desert area along the highway. The minimum microplastic particle sizes were 51.8 ± 2.2 μm in urban street dust samples, 54.2 ± 5.3 μm in farmland soil samples and 67.8 ± 8.4 μm in samples from along the desert highway. Particle sizes < 500 μm were most common and accounted for 48–91% of the total in our survey. The abundance and shape distribution of the MPs were closely related to the different types of human activities.

Effects of water quality, irrigation amount and nitrogen applied on soil salinity and cotton production under mulched drip irrigation in arid Northwest China

Understanding the interaction effects of water, fertilizer, and salinity is of great environmental importance to mitigate soil salinization and improve crop production. Field experiments were conducted to evaluate the effects of water quality, irrigation amount, and nitrogen application rate on soil salt accumulation, root water and nitrogen uptake, lint yield, and water productivity during 2018 and 2019 growing seasons of cotton (Gossypium hirsutum L.) in arid region of Xinjiang, China. Four irrigation levels 75%, 100%, 125%, and 150% of crop water requirement (ETc) and four nitrogen levels 195, 255, 315, and 375 kg ha−1 were applied with groundwater and brackish water irrigation. Results demonstrated that, brackish water irrigation significantly increased the root-zone soil salt accumulation (SSA). Either increasing irrigation amount during the squaring stage or decreasing irrigation amount during the flower boll stage with higher nitrogen application rate can reduce the SSA. And with an increase in brackish water irrigation amount, a corresponding increase in nitrogen application rate is required to reduce the possible soil salt accumulation during the flower boll stage. Highest irrigation amount (150% ETc) and nitrogen application rate (375 kg ha−1) at the flower boll stage and during the whole growing season resulted in significant higher nitrogen uptake increment with an increasing rate of 25–74% and 39–65%, respectively. The integration of higher irrigation amount and highest nitrogen application rate with groundwater irrigation produced higher lint yield and water productivity. Considering soil salinity and lint yield as well as water productivity, the appropriate integration modes of water and nitrogen are higher irrigation amount and highest nitrogen application rate (125% ETc and 375 kg ha−1) for groundwater and lowest irrigation amount and lower nitrogen application rate (75% ETc and 255 kg ha−1) for brackish water.

Impact of agricultural residual plastic film on the growth and yield of drip-irrigated cotton in arid region of Xinjiang, China

Long-term and widespread use of plastic mulching has led to the accumulation of residual plastic film (RPF) in farmland soils of Xinjiang, China. However, there is no specific quantitative basis for RPF pollution or a clear understanding of the influence of residual film on crop growth. The aim of this study was to investigate the effect of RPF on the growth of cotton, an important cash crop of Xinjiang. Based on the field conditions and previous reports, various amount of residual film was applied in 0-30 cm soil layer. The growth index including emergence rate, dry matter, and yield of cotton was examined at different growth stages under different soil residual film levels. Results demonstrated a significant effect of RPF on soil moisture distribution and movement. Plastic residues had a significant effect on cotton growth at levels above 200 kg/hm2, and the yield decreased as the RPF amount increased. Based on these findings, 200 kg/hm2 was suggested as a threshold level to determine the effects of RPF on cotton. This study provided a basis to rate RPF pollution in farmland soils and help understand the impact of pollution on crop productivity. Keywords: residual plastic film, plastic film pollution, soil pollution, pollution control, cotton, production management DOI: 10.25165/j.ijabe.20201301.5084 Citation: Hu C, Wang X F, Wang S G, Lu B, Guo W S, Liu C J, et al. Impact of agricultural residual plastic film on the growth and yield of drip-irrigated cotton in arid region of Xinjiang, China. Int J Agric & Biol Eng, 2020; 13(1): 160–169.

Impact of agricultural residual plastic film on the growth and yield of drip-irrigated cotton in arid region of Xinjiang, China

Long-term and widespread use of plastic mulching has led to the accumulation of residual plastic film (RPF) in farmland soils of Xinjiang, China. However, there is no specific quantitative basis for RPF pollution or a clear understanding of the influence of residual film on crop growth. The aim of this study was to investigate the effect of RPF on the growth of cotton, an important cash crop of Xinjiang. Based on the field conditions and previous reports, various amount of residual film was applied in 0-30 cm soil layer. The growth index including emergence rate, dry matter, and yield of cotton was examined at different growth stages under different soil residual film levels. Results demonstrated a significant effect of RPF on soil moisture distribution and movement. Plastic residues had a significant effect on cotton growth at levels above 200 kg/hm2, and the yield decreased as the RPF amount increased. Based on these findings, 200 kg/hm2 was suggested as a threshold level to determine the effects of RPF on cotton. This study provided a basis to rate RPF pollution in farmland soils and help understand the impact of pollution on crop productivity. Keywords: residual plastic film, plastic film pollution, soil pollution, pollution control, cotton, production management DOI: 10.25165/j.ijabe.20201301.5084 Citation: Hu C, Wang X F, Wang S G, Lu B, Guo W S, Liu C J, et al. Impact of agricultural residual plastic film on the growth and yield of drip-irrigated cotton in arid region of Xinjiang, China. Int J Agric & Biol Eng, 2020; 13(1): 160–169.

Identifying pedogenic magnetic minerals in loess from China and Siberia using isothermal remanent magnetization acquisition curves

Aeolian loess is carried by wind and undergoes pedogenesis after deposition. Therefore, both detrital components from the source region and soil pedogenic components contribute to the magnetic properties of the loess. The pedogenic component can be identified by analyzing the coercivity spectra of loess with different degrees of pedogenesis. We used isothermal remanent magnetization acquisition curves to analyze the coercivity spectra of loess in China and Siberia and defined the low ( 100 mT) coercivity components, i.e., components 1, 2, and 3, respectively. In the arid region of Xinjiang, Northwest China, the Bole section, with negligible soil development has loess with only component 2 centered at ∼80 mT. In semiarid central China, the Xifeng section has both loess and paleosols with three coercivity components centered at ∼26 mT, ∼82 mT, and ∼960 mT. Component 1 has a pedogenic origin, and the remanence contribution increases in a positive linear relationship with the intensity of pedogenesis. In the humid region of Siberia, the Kurtak section has three coercivity components are centered at ∼23 mT, ∼78 mT, and ∼1014 mT. The remanence contribution of component 1 shows a low correlation with the intensity of pedogenesis. Component 3 is characterized by high-coercivity minerals and its remanence contribution is related to the intensity of pedogenesis. The soil development in the semi-arid Xifeng section tends to produce massive fine-grained ferromagnetic minerals, so the remanence contribution of component 1 is positively correlated with the intensity of pedogenesis. The humid pedogenic environment of the Kurtak section is prone to form high-coercivity minerals and destroys fine-grained ferromagnetic minerals, so the remanence contribution of component 3 increases with the degree of pedogenesis.

地表反照率不同计算方法对干旱区流域蒸散反演结果的影响——以新疆三工河流域为例

地表反照率不同计算方法对干旱区流域蒸散反演结果的影响——以新疆三工河流域为例

Effects of timing and duration under brackish water mulch drip irrigation on cotton yield in northern Xinjiang, China

The brackish water is an important potential water source and has frequently been utilized to drip-irrigate cotton due to the water shortage in the arid region of Xinjiang, northwestern of China. The brackish water is usually saline water with salinity ranging from 1 g/L to 5 g/L, which is widely distributed in this area, so the reasonable use of that brackish water may not only play a vital role in the local agricultural production, but also save plenty of freshwater. However, irrigation with brackish water usually causes the reduction of crop yield and soil salinization which can negatively impact plants through three major components: osmotic, nutritious and toxic stresses. Therefore, a field experiment, with eight different time-series irrigation modes using brackish water (3.5±0.2) g/L and freshwater, less than 1 g/L, beneath a combined film and drip-irrigation system was carried out to study the changes of soil salt content and cotton yield aiming to search for a balanced method during the 2 cotton growing seasons in 2012 and 2013. The results indicated that the time-series irrigation modes determined the soil salinity and moisture distribution based on observed spatio-temporal distribution of water content and electric conductivity, and soil salinity generally gathered at the depth of 0-10 cm and 60 cm of soil with the increase of irrigation quota. Moreover, the results demonstrated that the yields of cotton which was grown using brackish water and freshwater were better than those only using freshwater and the soil salinity with reasonable irrigation timing was not accumulated obviously. Keywords: brackish water, mulch drip irrigation, timing and duration for irrigation, irrigation scheduling, cotton DOI: 10.25165/j.ijabe.20171006.3108 Citation: Wang C X, Yang G, Li J F, He X L, Xue L Q, Long A H. Effects of timing and duration under brackish water mulch drip irrigation on cotton yield in northern Xinjiang, China. Int J Agric & Biol Eng, 2017; 10(6): 115–122.

Effects of water-fertilizer coupling on root distribution and yield of Chinese Jujube trees in Xinjiang

Water and fertilizer are the two main factors which promote the rapid growth of Jujube (Ziziphus jujuba) trees. Studies of root systems and the nutrition-use efficiency of dense, dwarfed fruit trees are limited, especially in an extremely arid region with drip irrigation. The experiment was conducted in a 12-year-old dwarf jujube planting basement in Hami from 2013 to 2015. In this experiment, root length density and root weight density were calculated and found to range from 75 cm to 275 cm in horizontal distance, and from 0 to 90 cm in vertical depth, treated with three drip irrigation quota gradients and three fertilizer rates with each treatment replicated three times. The results showed that, as the amount of nitrogen applied increased gradually, the jujubes’ growth amount increased, reaching a maximum when an optimal concentration was applied. However, the jujubes’ growth was inhibited, and the growth declined when the amount of nitrogen applied was more than the optimal concentration. At an appropriate level of nitrogen, the growth, yield and quality of jujube trees could be guaranteed. If the rate of nitrogen application was lowered, the jujubes’ growth would inhibit, and hence the yield wound be seriously impacted. The optimal irrigation quota and fertilization amount were found to be 900 mm and 1500-1800 kg/hm2, respectively. The research findings were of significance and hold great promise for the development of the forestry and fruit industries in the arid region of Xinjiang. At the same time, there was a further study on irrigation technique, focusing on the combined effect of the dwarfed-planting technique and drip irrigation on jujube trees; with this information, the application efficiency of water and fertilizer can be optimized, leading to higher profits and economic efficiency. Keywords: water-fertilizer coupling, root distribution, yield, dense dwarf trees, Ziziphus jujuba DOI: 10.25165/j.ijabe.20171006.3109 Citation: Liu H G, He X L, Li J, Li F D, Gong P, Zhang J, et al. Effects of water-fertilizer coupling on root distribution and yield of Chinese Jujube trees in Xinjiang. Int J Agric & Biol Eng, 2017; 10(6): 103–114.

Effects of timing and duration under brackish water mulch drip irrigation on cotton yield in northern Xinjiang, China

The brackish water is an important potential water source and has frequently been utilized to drip-irrigate cotton due to the water shortage in the arid region of Xinjiang, northwestern of China. The brackish water is usually saline water with salinity ranging from 1 g/L to 5 g/L, which is widely distributed in this area, so the reasonable use of that brackish water may not only play a vital role in the local agricultural production, but also save plenty of freshwater. However, irrigation with brackish water usually causes the reduction of crop yield and soil salinization which can negatively impact plants through three major components: osmotic, nutritious and toxic stresses. Therefore, a field experiment, with eight different time-series irrigation modes using brackish water (3.5±0.2) g/L and freshwater, less than 1 g/L, beneath a combined film and drip-irrigation system was carried out to study the changes of soil salt content and cotton yield aiming to search for a balanced method during the 2 cotton growing seasons in 2012 and 2013. The results indicated that the time-series irrigation modes determined the soil salinity and moisture distribution based on observed spatio-temporal distribution of water content and electric conductivity, and soil salinity generally gathered at the depth of 0-10 cm and 60 cm of soil with the increase of irrigation quota. Moreover, the results demonstrated that the yields of cotton which was grown using brackish water and freshwater were better than those only using freshwater and the soil salinity with reasonable irrigation timing was not accumulated obviously. Keywords: brackish water, mulch drip irrigation, timing and duration for irrigation, irrigation scheduling, cotton DOI: 10.25165/j.ijabe.20171006.3108 Citation: Wang C X, Yang G, Li J F, He X L, Xue L Q, Long A H. Effects of timing and duration under brackish water mulch drip irrigation on cotton yield in northern Xinjiang, China. Int J Agric & Biol Eng, 2017; 10(6): 115–122.

Random Forest Classification of Wetland Landcovers from Multi-Sensor Data in the Arid Region of Xinjiang, China

The wetland classification from remotely sensed data is usually difficult due to the extensive seasonal vegetation dynamics and hydrological fluctuation. This study presents a random forest classification approach for the retrieval of the wetland landcover in the arid regions by fusing the Pléiade-1B data with multi-date Landsat-8 data. The segmentation of the Pléiade-1B multispectral image data was performed based on an object-oriented approach, and the geometric and spectral features were extracted for the segmented image objects. The normalized difference vegetation index (NDVI) series data were also calculated from the multi-date Landsat-8 data, reflecting vegetation phenological changes in its growth cycle. The feature set extracted from the two sensors data was optimized and employed to create the random forest model for the classification of the wetland landcovers in the Ertix River in northern Xinjiang, China. Comparison with other classification methods such as support vector machine and artificial neural network classifiers indicates that the random forest classifier can achieve accurate classification with an overall accuracy of 93% and the Kappa coefficient of 0.92. The classification accuracy of the farming lands and water bodies that have distinct boundaries with the surrounding land covers was improved 5%–10% by making use of the property of geometric shapes. To remove the difficulty in the classification that was caused by the similar spectral features of the vegetation covers, the phenological difference and the textural information of co-occurrence gray matrix were incorporated into the classification, and the main wetland vegetation covers in the study area were derived from the two sensors data. The inclusion of phenological information in the classification enables the classification errors being reduced down, and the overall accuracy was improved approximately 10%. The results show that the proposed random forest classification by fusing multi-sensor data can retrieve better wetland landcover information than the other classifiers, which is significant for the monitoring and management of the wetland ecological resources in arid areas.

The occurrence, sources and spatial characteristics of soil salt and assessment of soil salinization risk in Yanqi basin, northwest China.

In order to evaluate the soil salinization risk of the oases in arid land of northwest China, we chose a typical oasis-the Yanqi basin as the research area. Then, we collected soil samples from the area and made comprehensive assessment for soil salinization risk in this area. The result showed that: (1) In all soil samples, high variation was found for the amount of Ca2+ and K+, while the other soil salt properties had moderate levels of variation. (2) The land use types and the soil parent material had a significant influence on the amount of salt ions within the soil. (3) Principle component (PC) analysis determined that all the salt ion values, potential of hydrogen (pHs) and ECs fell into four PCs. Among them, PC1 (C1-, Na+, SO4 2-, EC, and pH) and PC2 (Ca2+, K+, Mg2+and total amount of salts) are considered to be mainly influenced by artificial sources, while PC3 and PC4 (CO3 - and HCO3 2-) are mainly influenced by natural sources. (4) From a geo-statistical point of view, it was ascertained that the pH and soil salt ions, such as Ca2+, Mg2+ and HCO3 -, had a strong spatial dependency. Meanwhile, Na+ and Cl- had only a weak spatial dependency in the soil. (5) Soil salinization indicators suggested that the entire area had a low risk of soil salinization, where the risk was mainly due to anthropogenic activities and climate variation. This study can be considered an early warning of soil salinization and alkalization in the Yanqi basin. It can also provide a reference for environmental protection policies and rational utilization of land resources in the arid region of Xinjiang, northwest China, as well as for other oases of arid regions in the world.

Comparison of Two Dripper Line Designs to Assess Cotton Yield, Water Use, and Net Return in Northwest China

This study aimed to compare the effects of two types of drip irrigation line design on cotton yield, water use, and net returns. The experiments were carried out in the arid region of Xinjiang, Northwest China, during 2009-2010 growing years. The two types of lateral placement are commonly used by the local farmers in the area: double lines (two laterals controlling four rows) and single line designs (one lateral controlling four rows). The results indicated that less irrigation water was applied by single line compared with double lines design. This implies that more irrigation water could be saved using single line, by reducing the water consumption of cotton. The emergence rates for double lines were 2 and 6% higher than those for single line design in 2009 and 2010. The seed cotton yields for double lines design were 5.76 and 6.41 Mg ha−1 which were 13 and 9% higher than for single line design in 2009 and 2010, respectively. Single lines could however lower the investment cost compared to double lines, which produced 10 and 7% more net income in 2009 and 2010, respectively. By contrast, the double lines was more profitable and suitable for the farmers in Northwest China than single line design.