scholarly journals The Ecological Relationship of Groundwater–Soil–Vegetation in the Oasis–Desert Transition Zone of the Shiyang River Basin

Water ◽  
2021 ◽  
Vol 13 (12) ◽  
pp. 1642
Author(s):  
Le Cao ◽  
Zhenlong Nie ◽  
Min Liu ◽  
Lifang Wang ◽  
Jinzhe Wang ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Soil Water ◽  
Soil Salinity ◽  
Shallow Groundwater ◽  
Water Source ◽  
Northwest China ◽  
Soil Salinization ◽  
Arid Areas ◽  
Important Indicator ◽  
Vegetation Growth

Groundwater is an important ecological water source in arid areas. Groundwater depth (GWD) is an important indicator that affects vegetation growth and soil salinization. Clarifying the coupling relationship between vegetation, groundwater, and soil in arid areas is beneficial to the prevention of environmental problems such as desertification and salinization. Existing studies lack research on the water–soil–vegetation relationship in typical areas, especially in shallow groundwater areas. In this study, the shallow groundwater area in Minqin, northwest China, was taken as study area, and vegetation surveys and soil samples collection were conducted. The relationships between vegetation fractional coverage (VFC) and GWD, soil salinity, soil moisture, and precipitation were comprehensively analyzed. The results showed low soil salinity in the riparian zone and high soil salinity in other shallow-buried areas with salinization problems. Soil salinity was negatively correlated with VFC (R = −0.4). When soil salinity >3 g/kg, VFC was less than 20%. Meanwhile, when GWD >10 m, VFC was usually less than 15%. In the areas with soil salinity <3 g/kg, when GWD was in the range of 4–10 m, VFC was positively correlated with soil moisture content (R = 0.99), and vegetation growth mainly depended on surface soil water, which was significantly affected by precipitation. When GWD was less than 4 m, VFC was negatively correlated with GWD (R = −0.78), and vegetation growth mainly relied on groundwater and soil water. There are obvious ecological differences in the shallow-buried areas in Minqin. Hence, it is reasonable to consider zoning and grading policies for ecological protection.

scholarly journals Understanding the Role of Shallow Groundwater in Improving Field Water Productivity in Arid Areas

Water ◽  
2020 ◽  
Vol 12 (12) ◽  
pp. 3519
Author(s):  
Xiaoyu Gao ◽  
Zhongyi Qu ◽  
Zailin Huo ◽  
Pengcheng Tang ◽  
Shuaishuai Qiao
Keyword(s):  
Soil Water ◽  
Soil Salinity ◽  
Water Productivity ◽  
Shallow Groundwater ◽  
Irrigation Scheduling ◽  
Crop Growth ◽  
Groundwater Depth ◽  
Groundwater Salinity ◽  
Arid Areas ◽  
Soil Water And Salt

Soil water and salt transport in soil profiles and capillary rise from shallow groundwater are significant seasonal responses that help determine irrigation schedules and agricultural development in arid areas. In this study the Agricultural Water Productivity Model for Shallow Groundwater (AWPM-SG) was modified by adding a soil salinity simulation to precisely describe the soil water and salt cycle, calculating capillary fluxes from shallow groundwater using readily available data, and simulating the effect of soil salinity on crop growth. The model combines an analytical solution of upward flux from groundwater using the Environmental Policy Integrated Climate (EPIC) crop growth model. The modified AWPM-SG was calibrated and validated with a maize field experiment run in 2016 in which predicted soil moisture, soil salinity, groundwater depth, and leaf area index were in agreement with the observations. To investigate the response of the model, various scenarios with varying groundwater depth and groundwater salinity were run. The inhibition of groundwater salinity on crop yield was slightly less than that on crop water use, while the water consumption of maize with a groundwater depth of 1 m is 3% less than that of 2 m, and the yield of maize with groundwater depth of 1 m is only 1% less than that of 2 m, under the groundwater salinity of 2.0 g/L. At the same groundwater depth, the higher the salinity, the greater the corn water productivity, and the smaller the corn irrigation water productivity. Consequently, using modified AWPM-SG in irrigation scheduling will be beneficial to save more water in areas with shallow groundwater.

scholarly journals Incorporation of Manure into Ridge and Furrow Planting System Boosts Yields of Maize by Optimizing Soil Moisture and Improving Photosynthesis

Agronomy ◽  
2019 ◽  
Vol 9 (12) ◽  
pp. 865 ◽  
Author(s):  
Anzhen Qin ◽  
Yanjie Fang ◽  
Dongfeng Ning ◽  
Zhandong Liu ◽  
Ben Zhao ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Soil Water ◽  
Loess Plateau ◽  
Cropping System ◽  
Northwest China ◽  
Chemical Fertilizer ◽  
Arid Areas ◽  
Grain Yields ◽  
Semi Arid ◽  
Planting System

A sustainable management strategy of soil fertility and cropping system is critical to guaranteeing food security. However, little is known about the effects of soil amendment strategies on crop growth via regulating soil moisture and photosynthesis in a ridge and furrow cropping system. Here, field experiments were carried out in 2017 and 2018 in semi-arid areas of Loess Plateau, northwest China to investigate the effects of integrated use of ridge and furrow planting and manure amendment on grain yields of maize. Four treatments were designed: CK (flat planting with 100% chemical fertilizer), RFC (ridge and furrow planting with 100% chemical fertilizer), RFR (ridge and furrow planting with 100% control-released fertilizer), and RFM (ridge and furrow planting with 50% manure fertilizer + 50% N fertilizer). On average, RFM increased photosynthetic rates (Pn) by 74%, followed by RFR by 47%, and RFC by 26%, compared to CK. Also, stomatal conductance (Cd), transpiration rates (Tr), and intercellular CO2 concentration (Ci) were highest with RFM, followed by RFR and RFC. Averaged across the two years, RFM conserved 10% more soil water storage (SWS) than CK did at harvest, followed by RFR with an increment by 8%. However, RFC consumed more soil water than CK did, with its ETc 8% higher than CK. Consequently, spring maize treated with RFM suffered less drought stress, especially in 2017 when precipitation was insufficient. On average, grain yields and water use efficiency of RFM were increased by 18% and 27%, compared to CK. Structural equation modeling analysis showed that there existed significant positive correlation between SWS in top layers and grain yields, while SWS in deep layers had negative effects on grain yields. In conclusion, the incorporation of manure into ridge and furrow planting system can be an efficient agronomic practice to improve plant photosynthesis, optimize soil moisture, and boost grain yields in semi-arid areas of Loess Plateau, northwest China.

Revealing the spatial pattern of subsurface soil salinity over the Argentinean Dry Chaco

2021 ◽  
Author(s):  
Michiel Maertens ◽  
Veerle Vanacker ◽  
Gabriëlle De Lannoy ◽  
Frederike Vincent ◽  
Raul Giménez ◽  
...  
Keyword(s):  
Soil Salinity ◽  
Land Surface ◽  
Large Scale ◽  
Hydrological Cycle ◽  
Regional Scale ◽  
Shallow Groundwater ◽  
Soil Salinization ◽  
Dry Forest ◽  
Surface Model ◽  
Subsurface Soil

&lt;p&gt;The South-American Dry Chaco is a unique ecoregion as it is one of the largest sedimentary plains in the world hosting the planet&amp;#8217;s largest dry forest. The 787.000 km&amp;#178; region covers parts of Argentina, Paraguay, and Bolivia and is characterized by a negative climatic water balance as a consequence of limited rainfall inputs (800 mm/year) and high temperatures (21&amp;#176;C). In combination with the region&amp;#8217;s extreme flat topography (slopes &lt; 0.1%) and shallow groundwater tables, saline soils are expected in substantial parts of the region. In addition, it is expected that large-scale deforestation processes disrupt the hydrological cycle resulting in rising groundwater tables and further increase the risk for soil salinization.&lt;/p&gt;&lt;p&gt;In this study, we identified the regional-scale patterns of subsurface soil salinity in the Dry Chaco. &amp;#160;Field data were obtained during a two-month field campaign in the dry season of 2019. A total of 492 surface- and 142 subsurface-samples were collected along East-West transects to determine soil electric conductivity, pH, bulk density and humidity. Spatial regression techniques were used to reveal the topographic and ecohydrological variables that are associated with subsurface soil salinity over the Dry Chaco. The hydrological information was obtained from a state-of-the-art land surface model with an improved set of satellite-derived vegetation and land cover parameters.&lt;/p&gt;&lt;p&gt;In the presentation, we will present a subsurface soil salinity map for a part of the Argentinean Dry Chaco and provide relevant insights into the driving mechanisms behind it.&lt;/p&gt;

Water exchange process and water uptake for irrigated maize cropland in a desert-oasis transition area, Northwest China

2020 ◽  
Author(s):  
Yongyong Zhang ◽  
Wenzhi Zhao ◽  
Chun Zhao
Keyword(s):  
Soil Moisture ◽  
Stable Isotope ◽  
Water Potential ◽  
Soil Water ◽  
Water Exchange ◽  
Exchange Process ◽  
Northwest China ◽  
Transition Area ◽  
Desert Oasis ◽  
Water Stable Isotope

&lt;p&gt;Soil water and groundwater convert frequently under cropland in a desert-oasis transition area, Northwest China. Crops variedly utilize soil water and groundwater during different growth periods under the cropland with shallow groundwater. The study of water exchange process under irrigated cropland has important significance for regulating the contradiction between water saving and groundwater recharge in the desert-oasis transition area. Soil moisture and soil matric potential at depths ranging from 0 to 70 cm were measured using HydraProbe II and TEROS-21 soil sensors in maize (Zea mays L.) fields in 2019. Stable isotope (&amp;#948;&lt;sup&gt;2&lt;/sup&gt;H&amp;#12289;&amp;#948;&lt;sup&gt;18&lt;/sup&gt;O) in different water sources (precipitation, irrigation water, soil water, crop stem, and groundwater) was also measured. The results showed that the groundwater depth varied between 0.57-1.07 m during the maize growth periods. The groundwater depth increased in summer due to the influence of pumped well, while the depth decreased in autumn resulting from the irrigation return water. In the maize growing season, soil moisture and water potential at depths from 10 cm to 30 cm responded to three irrigation times, while soil moisture and water potential below the depth of 50 cm were greater and kept a steady state, which were affected by upward capillary rise of groundwater. The relationship of soil water stable isotope values &amp;#8203;&amp;#8203;was &amp;#948;&lt;sup&gt;2&lt;/sup&gt;H=2.45&amp;#948;&lt;sup&gt;18&lt;/sup&gt;O-31.41, which was lower than the slope of the local atmospheric precipitation line due to the evaporation effect. The soil water stable isotope values at depth of 10 cm varied, while the variation of soil water stable isotope values decreased with the increase of soil depth. The soil water stable isotope values at the depths from 70 to 90cm were close to the groundwater isotope values, which were affected by the groundwater. The stable isotope values in crop stem water were relatively scattered, indicating that the maize used multiple water sources and the water use strategy changed during the growth periods.&lt;/p&gt;

scholarly journals Precipitation alters plastic film mulching impacts on soil respiration in an arid area of northwest China

2018 ◽  
Vol 22 (5) ◽  
pp. 3075-3086 ◽  
Author(s):  
Guanghui Ming ◽  
Hongchang Hu ◽  
Fuqiang Tian ◽  
Zhenyang Peng ◽  
Pengju Yang ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Soil Respiration ◽  
Drip Irrigation ◽  
Northwest China ◽  
Arid Area ◽  
Arid Areas ◽  
Plastic Film ◽  
Soil Co2 ◽  
Plastic Mulch ◽  
Film Mulching

Abstract. Plastic film mulching (PFM) has widely been used around the world to save water and improve crop yield. However, the effect of PFM on soil respiration (Rs) remains unclear and could be further confounded by irrigation and precipitation. To address these topics, controlled experiments were conducted in mulched and non-mulched fields under drip irrigation from 2014 to 2016 in an arid area of the Xinjiang Uygur Autonomous Region, northwest China. The spatio-temporal pattern of soil surface CO2 flux as an index of soil respiration under drip irrigation with PFM was investigated, and the confounded effects of PFM and irrigation/precipitation on soil respiration were explored. The main findings were as follows. (1) Furrows, planting holes, and plastic mulch are three important pathways of soil CO2 emissions in mulched fields, of which the planting hole efflux outweighs that from the furrow, with the largest values of 8.0 and 6.6 µmol m−2 s−1, respectively, and the plastic mulch itself can emit up to 3.6 µmol m−2 s−1 of CO2. (2) The frequent application of water (i.e. through irrigation and precipitation) elevates soil moisture and soil respiration and enhances their variation. The resultant higher variation of soil moisture further alleviates the sensitivity of soil respiration to soil temperature, leading to a weak correlation and lower Q10 values. (3) Soil CO2 effluxes from furrows and ridges in mulched fields outweigh the corresponding values in non-mulched fields in arid areas. However, this outweighing relation attenuates with increasing precipitation. Furthermore, by combining our results with those from the literature, we show that the difference in soil CO2 effluxes between non-mulched and mulched fields presents a linear relation with the amount of precipitation, which results in negative values in arid areas and positive values in humid areas. Therefore, whether PFM increases soil respiration or not depends on the amount of precipitation during the crop-growing season.

scholarly journals Response of Four Shrub Species to Different Water Source Components in an Arid Environment

2018 ◽  
Vol 8 (3) ◽  
pp. 166 ◽  
Author(s):  
A. Wagner ◽  
D. A. Devitt ◽  
B. Bird ◽  
R. Jasoni ◽  
J. A. Arnone III
Keyword(s):  
Soil Water ◽  
Great Basin ◽  
Vadose Zone ◽  
Soil Salinity ◽  
Water Source ◽  
Arid Environment ◽  
Water Diversion ◽  
Sarcobatus Vermiculatus ◽  
Shrub Species ◽  
Growing Period

Shrubland species in the Great Basin (USA) depend on soil water recharged from precipitation and/or groundwater for survival and growth. Climate warming and possible basin water diversion could alter the amount and timing of water availability to these plants. The objective of this study was to quantify the extent to which each of four co-occurring shrub species, big sage [Artemisia tridentata], rabbitbrush [Ericameria nauseosus], greasewood [Sarcobatus vermiculatus] and shadscale [Atriplex confertifolia)) acquired water from different sources (precipitation, soil vadose zone and/or groundwater) during a growing season. Soil salinity increased linearly with depth over the upper 1.5 m of soil, with salinity ranging from 0.84 to 31.70 dSm-1 in saturation extracts (R2=0.78, p&lt;0.001). Changes in soil water both with depth and time during the growing period indicated that all species accessed soil water from precipitation recharge. Evapotranspiration totals for the growing period exceeded total precipitation by 137 mm, indicating that plants also used water stored deeper within the vadose zone and/or from groundwater (particularly) by the phreatophyte greasewood. Delta18O in the soil solution declined linearly with depth over the upper 100 cm (R2=0.80, p&lt;0.001). Delta18O values in greasewood corresponded closely to Delta18O values measured deeper in the vadose zone and groundwater. Output from a mixing model indicated a decrease in groundwater reliance for greasewood from 30% in July to 2% in September, with a major shift to deeper soil water in the vadose zone (180 cm depth) (38% in July to 97% in September). Our data suggested that the four shrub species at our site were able to coexist because of their different spatial, temporal, and physiological uses of available soil water, reflecting possible water resource partitioning based on differences in response to precipitation, ability to extract water at deeper depths and variable tolerance to elevated levels of soil salinity to access groundwater.

scholarly journals Quantitative Retrieval of Soil Salinity Using Landsat 8 OLI Imagery

2021 ◽  
Vol 11 (23) ◽  
pp. 11145
Author(s):  
Ruolin Dong ◽  
Xiaodong Na
Keyword(s):  
Soil Moisture ◽  
Soil Salinity ◽  
Vegetation Index ◽  
Normalized Difference Vegetation Index ◽  
Soil Salinization ◽  
Landsat Tm ◽  
Landsat 8 ◽  
Entire Study ◽  
Field Samples ◽  
Spatial Differences

Soil salinization is the main reason for declining soil quality and a reduction in agricultural productivity. We derive the spatial distribution of soil moisture from the temperature vegetation dryness index (TVDI) of Landsat TM-8 OLI images to analyze the effect of spatial heterogeneity of soil moisture on the retrieval accuracy of soil salinity. We establish five soil salinity inversion models for different soil moisture levels (drought levels) based on the canopy response salinity index (CRSI), normalized difference vegetation index (NDVI), and automatic water extraction index (AWEI) derived from Landsat TM-8 OLI images. The inversion accuracy of soil salinity is assessed using 42 field samples. The results show that the average accuracies of the five inversion models are higher than that of the traditional soil salinity inversion model of the entire study area. The proposed model underestimates soil salinity in high-moisture areas and overestimates it in drought areas. Therefore, inversion models of soil salinization should consider spatial differences in soil moisture to improve the inversion accuracy.

scholarly journals Tracking Sustainable Restoration in Agro-Pastoral Ecotone of Northwest China

2021 ◽  
Vol 13 (24) ◽  
pp. 5031
Author(s):  
Lixiao Yang ◽  
Stéphanie Horion ◽  
Chansheng He ◽  
Rasmus Fensholt
Keyword(s):  
Soil Moisture ◽  
Soil Water ◽  
Ecological Restoration ◽  
Water Resource Management ◽  
Vegetation Index ◽  
Northwest China ◽  
Water Dynamics ◽  
Anthropogenic Activity ◽  
Contribution Rate ◽  
Change Type

Large-scale ecological restoration (ER) projects have been implemented in northwest China in recent decades as a means to prevent desertification and improve ecosystem services. However, previous studies have demonstrated adverse impacts in the form of widespread soil water deficit caused by intensive ER activities. Understanding the role of climate change and ER efforts in vegetation dynamics and soil moisture consumption is essential for sustainable ecosystem management. Here, we used the break for additive season and trend (BFAST) method to analyse spatial patterns in the normalized difference vegetation index (NDVI) variation over the agro-pastoral ecotone of northwest China (APENC) for 2000–2015. From the combined use of generalized additive modelling (GAM) and residual-trend analysis (RESTREND), we distinguished and quantified the effects of climate and human management on vegetation and soil water dynamics. Approximately 78% of the area showed vegetation variations representing a significant change in NDVI, of which more than 68% were categorized as abrupt changes. Large areas of the abrupt change type, interrupted increase and monotonic increase in NDVI were observed before 2006, and small areas of the change type of negative reversals were observed after 2012. Anthropogenic activity was found to be the major driving factor of variation in vegetation (contribution rate of 56%) and soil moisture (contribution rate of 78%). The vegetation expansion, which was mainly related to the large number of ER programs that started in 2000, was found to increase soil moisture depletion. By comparing areas where anthropogenic activities had a high contribution rate to vegetation increase and areas where soil moisture consumption was severely increased, we identify and discuss hotspot areas of soil moisture consumption caused by the ER programs. The current methodological workflow and results represent a novel foundation to inform and support water resource management and ecological-restoration-related policy making.

scholarly journals Water track modification of soil ecosystems in the Lake Hoare basin, Taylor Valley, Antarctica

2013 ◽  
Vol 26 (2) ◽  
pp. 153-162 ◽  
Author(s):  
Joseph S. Levy ◽  
Andrew G. Fountain ◽  
Michael N. Gooseff ◽  
J.E. Barrett ◽  
Robert Vantreese ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Soil Salinity ◽  
Shallow Groundwater ◽  
Dry Valleys ◽  
Solute Content ◽  
Ecological Zones ◽  
High Soil Moisture ◽  
Taylor Valley ◽  
High Soil ◽  
Soil Ecosystems

AbstractWater tracks are zones of high soil moisture that route shallow groundwater down-slope, through the active layer and above the ice table. A water track in Taylor Valley, McMurdo Dry Valleys, was analysed for surface hydrogeological, geochemical, and biological characteristics in order to test the hypothesis that water tracks provide spatial structure to Antarctic soil ecosystems by changing the physical conditions in the soil environment within the water tracks from those outside the water tracks. The presence of the water track significantly affected the distribution of biotic and abiotic ecosystem parameters: increasing soil moisture, soil salinity, and soil organic matter within the water track relative to soils outside the water track, and reducing soil phosphate, soil pH, and the population of nematodes and other invertebrates in water track soils relative to off track soils. These results suggest that water tracks are distinct and extreme ecological zones in Taylor Valley that provide long-range (kilometre to multi- kilometre) structure to Antarctic hillslope ecosystems through physical control on soil moisture and solute content. Contrary to expectations, these high soil-moisture sites are not hotspots for faunal biological activity because high soil salinity makes them suitable habitats for only the most halo-tolerant organisms.

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