Article

Soil quality changes due to flood irrigation in agricultural fields along the Rio Grande in western Texas

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Abstract

Growing populations demand more food, putting more pressure on soil productivity and sustainability around the world. In western Texas along the Rio Grande Valley, the low natural rainfall requires frequent irrigations for sustaining agriculture. To investigate the impacts of irrigation on soil quality, we collected and modelled geochemical data (major elements and nutrients) on irrigation water, soil pore water, drainage water, and soil samples, and monitored soil moisture, temperature, and electrical conductivity with sensors from two pecan, one cotton, and one alfalfa fields in western Texas. This study showed that flood irrigation with both surface (Rio Grande river) and ground waters significantly increased the root-zone salinity, soil sodicity, and nutrient leaching from soils to the underlying aquifers and Rio Grande river from agricultural fields of the arid southwest. The water used for irrigation was high in total dissolved solids (>500 ppm generally), dominated by Na⁺, Cl⁻, Ca²⁺ and SO4²⁻. After flood irrigation, infiltrating water dissolved salts such as gypsum that have accumulated in the soils due to previous irrigations, or/and mixed existing concentrated soil waters, and approached saturation with respect to these evaporite minerals. Soil water was supersaturated with respect to carbonates as pedogenic calcite precipitated out and reached concentrations of ∼10 wt% of total soil mass. This suggested that pedogenic carbonate is an important carbon reservoir and precipitation kinetics and controls of such secondary calcite need further investigation for the irrigated agricultural fields in arid regions of the world. Chemistry of agricultural return flow samples collected from drainage ditches was similar to that of irrigation water, suggesting that most of the irrigation water had taken a shallow and short flowpath through the fields to drains. Between irrigation events, soil water became more concentrated as water was lost through evapotranspiration that led to precipitation of evaporite salts. As a result, sodicity and salinity of soils, especially clayey soils, frequently exceeded the tolerance levels of major crops grown in the region. Here in these fine-textured soils, combination of high evapotranspiration rates, intensive irrigation with water of elevated salinity, and limited infiltration stunted crop growth, decreased soil porosity and permeability, led to poor aeration, and accelerated salt buildup via a positive feedback mechanism. During initial irrigation where soils were saturated, soil water also percolated and recharged to underlying aquifers, and thus salts, nutrients, and trace metals from agricultural practices (i.e., application of fertilizers, irrigation, soil amendments, and pesticide) could be mobilized to shallow groundwaters. This implied that chemistry of Rio Grande river, groundwater, and soil was closely linked. Thus the sustainability of agriculture depended on appropriate water, soil and crop management practices.

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... Soil and dust sample collection and characterization. These three sites have been previously studied for soil texture, salinity and sodicity [12][13][14]33 . Soil salinity is measured as electrical conductivity (EC) and sodicity as sodium adsorption ratio (SAR), the ratio of sodium concentration over the square root of the sum of calcium and magnesium concentrations in a soil slurry. ...
... However, the Pecan_Fine and Pecan_Coarse soils are characterized by visually distinct pecan growth, mainly due to different amounts of salt buildup. A 60-cm deep soil core was previously collected and characterized in an alfalfa field (as alfalfa) 12 and as Alfalfa_Fine_D 14 in El Paso, Texas. These soils are silty clay loam alluvium of Harkey-age (NRCS Custom Soil Report). ...
... The Ca 2+ /DIC molar ratios are variable in the Rio Grande river water, and much greater than 2 in the local groundwater (Appendix Table 2) 14 ; overall there should be a Ca 2+ -surplus after all DIC precipitates out of soil water according to Reaction (1). This is consistent with the presence of water-soluble and Ca-bearing evaporite salts in these soils 12,14 . ...
Article
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Agricultural fields in drylands are challenged globally by limited freshwater resources for irrigation and also by elevated soil salinity and sodicity. It is well known that pedogenic carbonate is less soluble than evaporate salts and commonly forms in natural drylands. However, few studies have evaluated how irrigation loads dissolved calcium and bicarbonate to agricultural fields, accelerating formation rates of secondary calcite and simultaneously releasing abiotic CO 2 to the atmosphere. This study reports one of the first geochemical and isotopic studies of such “anthropogenic” pedogenic carbonates and CO 2 from irrigated drylands of southwestern United States. A pecan orchard and an alfalfa field, where flood-irrigation using the Rio Grande river is a common practice, were compared to a nearby natural dryland site. Strontium and carbon isotope ratios show that bulk pedogenic carbonates in irrigated soils at the pecan orchard primarily formed due to flood-irrigation, and that approximately 20–50% of soil CO 2 in these irrigated soils is calcite-derived abiotic CO 2 instead of soil-respired or atmospheric origins. Multiple variables that control the salt buildup in this region are identified and impact the crop production and soil sustainability regionally and globally. Irrigation intensity and water chemistry (irrigation water quantity and quality) dictate salt loading, and soil texture governs water infiltration and salt leaching. In the study area, agricultural soils have accumulated up to 10 wt% of calcite after just about 100 years of cultivation. These rates will likely increase in the future due to the combined effects of climate variability (reduced rainfall and more intense evaporation), use of more brackish groundwater for irrigation, and reduced porosity in soils. The enhanced accumulation rates of pedogenic carbonate are accompanied by release of large amounts of abiotic CO 2 from irrigated drylands to atmosphere. Extensive field studies and modelling approaches are needed to further quantify these effluxes at local, regional and global scales.
... Evaporative water loss, limited water infiltration, and irrigation water of high salinity lead to the accumulation of evaporite salts near impermeable soil horizons. These secondary salts clog soil pores, decreasing salt leaching, facilitating future evaporation and accelerating future salt buildup (e.g., Assouline et al., 2015;Cox et al., 2018). Soil salinization from irrigated agriculture has been recorded worldwide, including in countries like the United States, Argentina, Zimbabwe and China (e.g., Falasca et al., 2014;Shrivastava and Kumar, 2015;Chemura et al., 2014;Wang et al., 2015), and it has been responsible for lowering crop yields and deteriorating overall soil quality (Pannell and Ewing, 2006;Shrivastava and Kumar, 2015;Cox et al., 2018). ...
... These secondary salts clog soil pores, decreasing salt leaching, facilitating future evaporation and accelerating future salt buildup (e.g., Assouline et al., 2015;Cox et al., 2018). Soil salinization from irrigated agriculture has been recorded worldwide, including in countries like the United States, Argentina, Zimbabwe and China (e.g., Falasca et al., 2014;Shrivastava and Kumar, 2015;Chemura et al., 2014;Wang et al., 2015), and it has been responsible for lowering crop yields and deteriorating overall soil quality (Pannell and Ewing, 2006;Shrivastava and Kumar, 2015;Cox et al., 2018). Altogether, soil salinization affects more than 830 million ha of land globally, or 8.3 million km 2 , or ~10% of the world's arable land (Szablocs, 1989;Martinez-Beltran and Manzur, 2005). ...
... Although atmospheric deposition, high evapotranspiration and salt accumulation are naturally occurring, it is important to determine if secondary salt formation is enhanced by agricultural management practices, outpacing the natural processes. Cox et al. (2018) collected 60-cm soil profiles from three major regional crops (cotton, alfalfa, and pecan) along the Rio Grande valley and reported high soil sodicity and salinity as a result of 90 years of cultivation with flood irrigation. Soil texture was identified to strongly impact water flow paths, residence time and to control the magnitude and location of salt accumulation (Cox et al., 2018). ...
Article
Soil salinization is a global problem affecting approximately 10% of agricultural soils, particularly in irrigated aridlands. This study quantified salt-loading by flood irrigation and soil fertilizers/amendments versus atmospheric deposition, studied controls of solute transport and salt buildup, and evaluated the effectiveness of gypsum application in improving soil sodicity in the arid southwestern United States. Study sites include one natural site and two agricultural sites in fields of dominant crops of the region, a pecan orchard and an alfalfa field near El Paso, Texas. The salt-loading rate in agricultural soils was dominated by the quantity and quality of irrigation waters rather than by dust. Salt loadings by irrigation waters were estimated ~ 306 g Na⁺ m⁻² yr⁻¹, 129 g Ca²⁺ m⁻² yr⁻¹, 361 g Cl⁻ m⁻² yr⁻¹, 419 g SO4²⁻ m⁻² yr⁻¹, and 284 g HCO3⁻ m⁻² yr⁻¹, followed by soil amendments. Whereas dust and fertilizer loadings were negligible in agricultural soils. Soil texture variability physically governs water movement and solute transport; coarser soils retained significantly less water than finer soils upon irrigation (p < 0.005) facilitating salt leaching. More salts accumulated around low-permeability layers. Some soils have approached salinity thresholds after only 90 years of cultivation. The Rio Grande river flow is projected to decrease due to reduced snowfall in Colorado, leading to more groundwater of higher salinity, to be used. If ground water were to be the sole water source, the salt loading rate would almost double. Soil amendments temporarily reduce soil sodicity induced by high Na⁺ concentrations in irrigation water. Their application is needed annually to prevent soil dispersion, to improve infiltration, and to stop even faster salt accumulation. This study highlighted the challenges that the Rio Grande valley in southwestern United States and other irrigated drylands are facing.
... Irrigated farming of the Rio Grande valley with relatively saline water from the Rio Grande and local groundwater (e.g., with total dissolved solids, or TDS, at~1000 mg/kg) has prevailed for the past 100 years (Ellis et al., 1993;Moore et al., 2008;Miyamoto, 2012). In this region, high evapotranspiration rates and intensive irrigation using water with high TDS have combined to cause excessive salt accumulation, including calcite and most soluble evaporite minerals such as halite and gypsum (Cox, 2012;Cox et al., 2017). At a global scale, 4% of dryland surfaces (~2 million km 2 ) are currently managed as irrigated agriculture, and almost 20% of irrigated drylands (0.4 million km 2 ) have become salt affected, impacting crop growth and soil fertility (Dregne, 1991;Ghassemi et al., 1995). ...
... Soil samples were collected from a pit at the Alfalfa field as previously described by Cox (2012) and Cox et al. (2017). Briefly, soil samples were collected at 10 cm intervals from the wall of the pit until 60 cm depth where a change from silt/clay to sandy soil texture was observed (field and sample photos in Appendix Fig. 1). ...
... Indeed, the Alfalfa site is irrigated intensively with Rio Grande water that has high U concentrations (e.g., 3.3 to 5.6 ppb) and high ( 234 U/ 238 U) ratios (1.6 to 2.2) (Szynkiewicz et al., 2015;Nyachoti, 2016). Intensive water loss through evapotranspiration makes soil water oversaturated with respect to calcite, leading to precipitation of pedogenic carbonates in the agricultural fields (Cox, 2012;Cox et al., 2017). Dissolved U has a high affinity for bicarbonate ions (e.g. ...
Article
Natural accumulation of pedogenic carbonates has been well documented but few studies have focused on carbonate formation in agricultural drylands. This study aims to determine accumulation rates of pedogenic carbonates in intensively irrigated soils, and to define key linkages between flood irrigation, salt loading and soil-atmosphere CO2 exchange in cultivated drylands of the southwestern United States. We used a combination of elemental chemistry (CaO, soil organic and inorganic carbon contents), mineralogy, and U-series (²³⁸U-²³⁴U-²³⁰Th) disequilibrium dating technique to investigate calcium sources, ages and formation rates of pedogenic carbonates. Study sites include an irrigated alfalfa field near El Paso in western Texas and a non-irrigated natural dryland site on the USDA Jornada Experimental Range of southern New Mexico. Our results showed that large amounts of dissolved calcium and inorganic carbon along with other soluble elements were loaded onto agricultural fields through irrigation waters in El Paso, TX while dust and rainfall were important for salt loading in natural soils of the Jornada. U-series activity ratios, (²³⁴U/²³⁸U) and (²³⁰Th/²³⁸U), in bulk soils suggested eolian deposits added U and modified U isotopes in shallow soils at both the irrigated and natural sites. Mobility of ²³⁴U within the soil profile is related to leaching of U (and by inference other soluble ions) and carbonate accumulation at depth. The U-series dating technique in pedogenic carbonates revealed the presence of much younger carbonates at the irrigated site compared to the natural site. Pedogenic carbonate formation rates in the irrigated soils were also much higher than those in the non-irrigated soils, likely a result of influxes from dissolved Ca and inorganic carbon in water used for irrigation. This study demonstrates the potential for agricultural expansion and land use change in drylands to increase rate of pedogenic carbonate accumulation. Such changes may have important implications to global carbon cycling since drylands are forecast to become the most expansive terrestrial biome by mid-century and dryland agriculture is expanding quickly.
... It provides irrigation water for the intensive agriculture practiced throughout the region. It also supplies some drinking water to municipalities and ecosystems throughout the basin (Sheng, 2013;Szynkiewicz et al., 2015;Chavarria et al., 2018;Randklev et al., 2018;Cox et al., 2018). ...
... The Rio Grande River is the fourth largest river in North America and runs through the region from north to south. This river starts as a snow Szynkiewicz et al., 2015;Randklev et al., 2018;Cox et al., 2018). ...
... Further, perusal of the findings indicates that soils of Murshidabad (Domkal block: 100%), Malda (56.4%) and Nadia (49.5%) districts were mostly alkaline (pH ≥7.5). Flood irrigation could be one of the reasons for increase in sodicity and pH of the soils (Christine et al., 2018;Shin-ichi, 1991). Prevalence of acidic (67.5% in pooled samples) and alkaline (>49% in some districts) reaction of soils in the studied area can be detrimental in terms of availability of nutrients for mulberry plantations and might lead to disparity in leaf productivity. ...
... The normal EC in the soils might be attributed to leaching of salts below root zone due to high rainfall (Prasenjit et al., 2018;Kar et al. 2011). The quality of ground water used to flood irrigate the fields could also be one of the factors behind occurrence of slightly saline soils (Christine et al. 2018). Earlier, CGWB (2016) has reported the presence of high EC (up to 5.17 dS m -1 ) in ground water of inland districts of West Bengal. ...
Article
Full-text available
Soil nutrient status of mulberry growing fields in West Bengal, India.
... Flood irrigation can have a major impact on soil properties by varying salinity, redox potential, compaction and/or porosity [7][8][9][10]. Furthermore, hop fields which are Flood irrigation can have a major impact on soil properties by varying salinity, redox potential, compaction and/or porosity [7][8][9][10]. ...
... Flood irrigation can have a major impact on soil properties by varying salinity, redox potential, compaction and/or porosity [7][8][9][10]. Furthermore, hop fields which are Flood irrigation can have a major impact on soil properties by varying salinity, redox potential, compaction and/or porosity [7][8][9][10]. Furthermore, hop fields which are floodirrigated need to be frequently tilled to control summer weeds and to reduce soil compaction and superficial crusts in the short term. ...
Article
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In hops (Humulus lupulus L.), irrigation by flooding the inter-row can carry away suspended particles and minerals, causing gradients in soil fertility. The effect of more than 20 years of flooding irrigation on soil and plants was evaluated in two hop fields by measuring soil and plant variables in multiple points along the rows. In a second experiment 1000 kg ha−1 of lime was applied and incorporated into the soil to assess whether liming could moderate any gradient created by the irrigation. At different sampling points along the rows, significant differences were recorded in soil properties, plant elemental composition and dry matter yield, but this was not found to exist over a continuous gradient. The variations in cone yield were over 50% when different sampling points were compared. However, this difference cannot be attributed to the effect of irrigation, but rather to an erratic spatial variation in some of the soil constituents, such as sand, silt and clay. Flooding irrigation and frequent soil tillage resulted in lower porosity and higher soil bulk density in the 0.0–0.10 m soil layer in comparison to the 0.10–0.20 m layer. In turn, porosity and bulk density were respectively positively and negatively associated with crop productivity. Thus, irrigation and soil tillage may have damaged the soil condition but did not create any gradient along the row. The ridge appeared to provide an important pool of nutrients, probably caused by mass flow due to the evaporation from it and a regular supply of irrigation water to the inter-row. Liming raised the soil pH slightly, but had a relevant effect on neither soil nor plants, perhaps because of the small amounts of lime applied.
... Pre-study soil sample analyses indicated that salinity was probably associated with chlorides and sulfates of sodium and calcium (Table 2). Salinity in the study region is caused by both geological deposits of CaCO 3 , CaSO 4 , halite (NaCl) as well as upwelling of brackish groundwater rich in sodium salts (Moyer et al. 2009;Cox et al. 2018). Since the study site soils had fine texture, low drainage, elevated salinity and sodicity, the addition of irrigation water in amounts far less than PET demand resulted in evapo-concentration of sodium salts in the surface soil ( Figure 3a) (Ganjegunte et al. 2017). ...
... CaCO 3 ), gypsum (CaSO 4 ) in the upper 75 cm (USDA-NRCS 2012;Cox et al. 2018). . Thus, fine texture, limited drainage, and high evapo-transpiration rates may cause native salts in the soils to become soluble and accumulate in the root zone upon irrigation(Johnston et al. 2013;Ganjegunte et al. 2017). ...
Article
This column study evaluated the effects of irrigation with two water qualities (WW and FW) to produce bioenergy sorghum on SOC balance, nutrients availability and salt constituents in two soils (TX and NM) amended with gypsum & elemental sulfur (S) and un-amended. Study results indicated that SOC concentration was higher in freshwater irrigated columns (7.41 g kg⁻¹) than wastewater irrigated soils (7.32 g kg⁻¹) across growth year-soil type-amendments-depth. Soils amended with gypsum and sulfur registered significantly higher value of 7.52 and 7.41 g kg⁻¹ compared to 7.30 and 7.23 g kg⁻¹ in non-amended soils under fresh and wastewater irrigation, respectively. Lower SOC in WW irrigated columns could be due to the combined effects of increased salinity and priming effects. Although SOC content initially increased in gypsum and S amended soils to about 10g kg⁻¹, at the end of the study SOC in all treatments decreased to levels significantly below the pre-study. WW irrigation added 2.00, 1.10 and 4.40 times the N, P and K added by fertilizers and was able to meet 65%, 87%, and 210% of bioenergy sorghum uptake of respective nutrients. Sulfates and chlorides of sodium and calcium were dominant salts, which significantly affected SOC and nutrients. Abbreviations: FW: freshwater; WW: treated wastewater; G + S: gypsum and elemental sulfur; NA: no amendment, TX: Texas soil and NM: New Mexico soil
... This indicates that the amount of water transported to the region was not enough to replenish the lost water (especially in the northeast portion of the study area). The main possible reasons are water infiltration fast and soil water supersaturation (Cox et al., 2018) and surface evaporation and loss caused by the climate (Lang et al., 1974). From the perspective of evapotranspiration, the northeast regions were much larger than the southwest after the movement of water; from the water saturation point of view, when the northeast regions reached saturation, the southwest maybe the time when SM increased sharply; from the perspective of water infiltration, the difference in DEM were caused SM gathers and disperses in a local region. ...
Article
Full-text available
Soil moisture (SM) plays an important role in regulating the global water cycle, especially in arid areas, and is one of the main indicators of ecological environmental health. Although traditional methods can accurately measure SM at a single sample site, they are limited in large-scale and dynamic SM monitoring. Therefore, we used the Landsat images as the data source and the soil adjusted vegetation index (SAVI) to build the adjusted SAVI (aSAVI) index by modifying the soil adjustment parameter L and introducing the short-wave infrared band. According to the theory of temperature vegetation dryness index (TVDI) and feature space, we introduced a model, combined the measured SM data (Minqin Basin, China) through a comparative analysis of four vegetation indices (NDVI, SAVI, MSAVI, aSAVI) determine the optimal model. Taking the Minqin Basin as the study area, the spatiotemporal variation characteristics of SM in three sub-regions (the entire study area, irrigated region, and periphery of the irrigated regions) were quantitatively analyzed and compared in four different periods: pre-Comprehensive Treatment Program of the Shiyang River Basin (pre-CTSRB) (2000–2005), CTSRB I (2006–2010), CTSRB II (2011–2016), and CTSRB-end (2017–2021) to evaluate the ecological restoration effects of treatment programs from the SM perspective. The results showed that: 1) SM values derived from TVDI inversion and the aSAVI were more accurate, and the model sensitivity decreased with soil depth; 2) the mean value of SM fluctuated across the four periods but decreased slightly over the entire time series. The spatial variations of the SM were characterized by a “descending then ascending” trend. Soil moisture increased in 21.35 % of areas at 0.00-0.10 m in the past 22 years, and 59.66 % at 0.10-0.20 m. There was a negative correlation between the mean variation trend of SM and the percentage of area where SM fell in different periods; 3) the treatment program positively affected the ecological restoration of the Minqin Basin from the SM perspective. The area where SM increased was larger than that of decreasing SM, especially in 0.10-0.20 m soil layer. The increase can promote growth and confer resistance to desertification. Keywords: soil moisture; adjusted SAVI (aSAVI); time series; arid / semi-arid regions; ecological restoration project
... For example, Mohammed et al. (2017) explained that irrigation water used in agricultural soils in Provence (SE France) was supersaturated with respect to calcite. The resulting increase in carbonates with irrigation water can accelerate the precipitation of pedogenic carbonates (Hannam et al., 2016;Cox et al., 2018). ...
Chapter
Carbonate-rich soils are common in many arid and semiarid areas. Many of them are cultivated, and agriculture is expanding by the spreading of irrigation. Although the soil mineral fraction has been usually considered little or not affected by agricultural management in the short term, increasing evidence suggests that this is not the case for carbonates in the tilled layer. The consequences of management can be intense and depend on the modifications induced in inorganic carbon cycling, which can result in gains or losses of total inorganic soil C, and in changes in its type (pedogenic vs. lithogenic), size and distribution. Net soil CO2 emissions and interactions with organic C cycle can be affected by these changes, thereby altering soil organic matter dynamics. This chapter summarizes the major observed effects of agricultural practices potentially altering soil carbonates, includes a case study in a newly irrigated area, and identifies the most important knowledge gaps and research perspectives.
... Soil texture governs the water and solute transport. Under irrigation conditions, finer soils limit water infiltration, and coarse-grained soils retain significantly less water than fine-grained soils [71,72]. The accumulation of soil salts is dominated by sodium salts originated from the irrigation water. ...
Article
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To explore the impact of artificial shelterbelt construction with saline irrigation on the soil water characteristic curve (SWCC) of shifting sandy soil in extreme arid desert areas, three treatments including under the shelterbelt (US), bare land in the shelterbelt (BL) and shifting sandy land (CK) in the hinterland of the Taklimakan Desert were selected. The age of the shelterbelt is 16, and the vegetation cover is mainly calligonum mongolicum. The soils from different depths of 0–30 cm were taken keeping in view the objective of the study. The SWCCs were determined by the centrifugal method and fitting was performed using various models such as the Gardner (G) model, Brooks–Corey (BC) model and Van Genuchten (VG) model. Then, the most suitable SWCC model was selected. The results showed that electrical conductivity (EC) and organic matter content of BL and US decreased with the increasing soil depth, while the EC and organic matter content of CK increased with the soil depth. The changes in soil bulk density, EC and organic matter of 0–5 cm soil were mostly significant (p < 0.05) for different treatments, and the differences in SWCCs were also significant among different treatments. Moreover, the construction of an artificial shelterbelt improved soil water-holding capacity and had the most significant impacts on the surface soil. The increase in soil water-holding capacity decreased with increasing soil depth, and the available soil water existed in the form of readily available water. The BC model and VG model were found to be better than the G model in fitting results, and the BC model had the best fitting result on CK, while the VG Model had the best fitting result on BL with higher organic matter and salt contents. Comparing the fitting results of the three models, we concluded that although the fitting accuracy of the VG model tended to decrease with increasing organic matter and salinity, the VG model had the highest fitting accuracy when comparing with BC and G models for the BL treatment with high organic matter and salinity. Therefore, the influence of organic matter and salinity should be considered when establishing soil water transfer function.
... Crop Residual water content pH pH of the soil z Soil layer depth farmers pump saline groundwater to make up the deficit. However, direct use of highly saline groundwater results in the accumulation of salts in the soil profile (Cox et al., 2018). Elevated salinity levels lead to a less effective soil volume in the root zone and negatively impact pecan root water uptake and plant development (Miyamoto et al., 1995;Ganjegunte et al., 2017). ...
Article
Water scarcity and soil salinization in arid regions have made desalination a competitive alternative source for irrigation. Perceptions of a higher cost and other misconceptions about desalinated water have limited its broader usage in agriculture. In this study, we have focused on understanding the suitability of using desalinated water as a substitute for saline water in the pecan (Carya illinoinensis) orchards of southwest Texas. Pecan is a perennial high-value nut crop that cannot be easily replaced. Therefore, it represents a perfect case study for the application of desalinated water. A recently developed system dynamic model, SMITUV (System Dynamic Modeling of Infiltration, Solute Transport, and Root Water Uptake in Vadose Zone), was modified to assess the effects of irrigation with desalinated water when soil-water salt content increased above pecan tolerance levels. This model simulated five irrigation scenarios with different fractions of river water and saline groundwater. As expected, to sustain the same level of pecan production, a higher amount of desalinated water was needed with increasing amounts of groundwater in the irrigation mix. Soil texture had a significant influence on the amount of desalinated water required. For sandy and silty soils, the 100% river water scenario required no additional desalinated water. Clayey soils could not sustain high production even in a 100% river water scenario. An economic analysis showed that pecan operations might be viable in non-clayey regions for some irrigation mixture even after factoring in the cost of using desalinated water. However, current desalination techniques and associated costs were economically unviable for sustaining pecan in regions with saline groundwater and clayey soils. This study also demonstrated the application of SMITUV and system dynamic modeling as a decision-making tool to assist growers in understanding the farm-scale applicability of desalinated water.
... However, assessment of soil erosion in natural 92 lands has been limited due to the lack or absence of climatic and soil characteristics data on local and global 93 measures (Bosco et al. 2015;Akbari et al. 2016b). In the long run, assessing soil erosion requires reliable long-94 term data, which is costly in terms of time and money (Salvati et al. 2013;Cox et al. 2018). In answer, semi-95 empirical tactics have been established to incorporate existing knowledge with logical necessities with the target 96 of generating results which can be utilized to inform policy (Borrelli et al. 2020 is not uncommon in this area and annually incurs damages to natural and man-made features, as well as claiming 115 the lives of people and livestock, the occurred floods in this period were particularly destructive. ...
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Floods cause great damage to ecosystems and are among the main agents of soil erosion. Given the importance of soils for the functioning of ecosystems and development and improvement of bio-economic conditions, the risk and rate of soil erosion was assessed using the RUSLE model in Iran’s Lorestan province before and after a period of major floods in late 2018 and early 2019. Furthermore, soil erosion was calculated for current and future conditions based on the Global Soil Erosion Modeling Database (GloSEM). The results showed that agricultural development and land use change are the main causes of land degradation in the southern and central parts of the study area. The impact of floods was also significant since our evaluations showed that soil erosion increased from 4.12 t ha ⁻¹ yr ⁻¹ before the floods to 10.93 t ha ⁻¹ yr ⁻¹ afterwards. Field surveying using 64 ground control points determined that erodibility varies from 0.17 to 0.49% in the study area. Orchards, farms, rangelands and forests with moderate or low vegetation cover were the most vulnerable land uses to soil erosion. The GloSEM modeling results revealed that climate change is the main cause of change in the rate of soil erosion. Combined land use change-climate change simulation showed that soil erosion will increase considerably in the future under SSP1-RCP2.6, SSP2-RCP4.5, and SSP5-RCP8.5 scenarios. In the study area, both natural factors, i.e. climate change and human factors such as agricultural development, population growth, and overgrazing are the main drivers of soil erosion.
... In general, with regard to environmental aspects, studies have shown a concern for soil fertility, water quality, erosion, climate change, and the use of energy from renewable sources. According to Cox et al. [65], soil and water quality are determining factors for agricultural productivity. The study demonstrated that sustainability in agriculture depended on adequate water, soil, and crop management practices and that monitoring by indicators was indispensable for managing the farm and for obtaining a history of its evolution based on the decisions made. ...
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Actions that promote the sustainability of small-scale agricultural activities are fundamental to maintaining the supply and diversification of products, generating income, and minimizing their environmental impact. This study aimed to identify the main economic, environmental, and social indicators used in studies focused on food production by family farming. A systematic literature review was performed in the Scopus database, where 22 original articles were identified. The largest number of publications was observed in Italy and the United States of America, followed by Brazil, India, Poland, and the United Kingdom. The main aspect observed in the publications was the interrelationship of the three spheres of sustainability, highlighting the importance of integrated monitoring. Some indicators identified were: in the economic sphere, financial planning, productivity, and profitability; in the environmental sphere, soil use and quality, water, erosion, temperature, and energy; and in the social sphere, food security, job and income generation, and government subsidies. A holistic approach to the use of monitoring indicators as a tool for sustainability is fundamental, but there are few studies that evaluate these three spheres; mainly in the field of agribusiness, due to its greater diversity of activities and aspects to be monitored.
... Secondary salinization of soil and water, waterlogging and soil sodi cation are known as environmental challenges against sustainable irrigation-based food production (van der Laan et al., 2017;Singh, 2018;Minhas et al., 2019). These emerge especially in (semi-)arid regions over the world in the presence of excessive ( ood) irrigation (Cox et al., 2018), inadequate drainage (Wichelns and Qadir, 2015), shallow saline groundwater table (Huang et al., 2016) due to clearing native vegetation (Pannell and Ewing, 2006), and irrigation with brackish water (Liu et al., 2019), wastewater (Elgallal et al., 2016) or produced water Abbreviations: DHmC, Dry Hydro-meteorological Condition; DI, de cit irrigation strategy; EC, Electrical Conductivity; ETA, actual evapotranspiration depth; EVoW, economic value of water; FSD, the First (short-term) Stage of Development; GoF, goodness-of-t measures; ha, hectare; HmC, hydro-meteorological conditions; HRB, Helleh River Basin; IRG, irrigation depth; IRR, Iranian Rial; IU, irrigation unit; LKG, leakage depth; MIT, irrigation units with micro irrigation technology; NHmC, Normal Hydro-meteorological Condition; NSE, Nash Sutcliff Ef ciency measure; OI, over-irrigation strategy; PBIAS, percent bias measure; PRC, precipitation depth; PSO, Particle Swarm Optimization; SA, stress avoidance irrigation strategy; SoD, stages of development; SSD, the Second (short-term) Stage of Development; TIANB, total irrigated agriculture's net bene t; TSD, the Third (short-term) Stage of Development; VARS, a global sensitivity analysis algorithm developed by Razavi and Gupta (2016); WEAP, Water Evaluation And Planning; ZSD, the Zeroth (short-term) Stage of Development; 1stR, The rst main region (division) of HRB; 2ndR, The second main region (division) of HRB; 3rdR, The third main region (division) of HRB; 4thR, The fourth main region (division) of HRB; 5thR, The fth main region (division) of HRB. (Echchelh et al., 2018) to alleviate the freshwater shortage. ...
Article
Helleh River, a southern vital agricultural ecosystem in Iran, has been suffering from both water shortage and quality degradation in recent decades. To deal with the problems, different stakeholders have been suggesting the central government some compartment development plans including construction of dams and irrigation districts, installation of modern irrigation technologies, and modification of crop patterns and irrigation–leaching strategies. Accordingly, this paper proposes a generic novel hydro-economic methodology for basin-scale optimal planning of an integrated development scheme for Helleh River Basin. Mentioned measures in different spatial scales from farm-level to basin-level as well as distinct time horizons of short-term and long-term are holistically evaluated and optimized based on technical, hydrologic, agronomic, and economic aspects. In this regard, a water allocation simulation model, i.e. WEAP software, improved here by some extra modules for salt routing and economic evaluation in Python Programming Environment is coupled with an optimization algorithm, i.e. Particle Swarm Optimization, which results in a new holistic hydro-economic simulation–optimization tool. Results demonstrate the economic efficiency of constructing three new dams, improvement and development of 19930 ha (ha) of irrigation area, irrigation technology, and strategy change, and crop pattern modification. Furthermore, results show that optimizing irrigation–leaching schedule leads to significant improvement of the economic value of water compared to the status quo, while construction and operation of structural projects result in a dramatic decrease in the economic value of water due to increase in both costs and leaching-related water usage. We discuss how irrigation technology improvement in salinity-affected basin may lead to a decrease in the economic value of water. Moreover, we advocate for the application of deficit irrigation strategy while respecting salt leaching requirements and cultivation of lower water-consuming crops. Results demonstrate how reservoirs’ operation takes a minor role in the regulation of rivers’ salinity, while we anticipate a significant increase in salt concentration of crops’ root zones due to more efficient water use.
... Traditionally, flood irrigation is widely applied for agricultural irrigation. However, flood irrigation not only results in water loss via surface runoff, soil evaporation, and deep percolation (Kharrou et al., 2011) but also causes soil salinity, sodicity, and nutrient leaching (Cox et al., 2018). Although sprinkler irrigation systems are a preferred method of irrigation in arid and semi-arid regions, a fraction of water is still lost by wind drift and evaporation before water reaches deeper soil during and after irrigation events (Al-Ghobari et al., 2018). ...
Article
Water shortage is a common environmental stressor encountered by agricultural production in arid and semiarid areas of the world. Under this situation, the impacts of different irrigation methods on the forage yield, select soil physiochemical properties, and soil microbial community structures were identified after alfalfa was planted for three years in Ningxia, northern China. The experiment consisted of five irrigation methods/treatments with three replicates for each treatment, including flood irrigation (FL), sprinkler irrigation (SP), and three subsurface drip irrigation systems, with drip tapes buried at a depth of 10 cm (SSL), 20 cm (SSM) and 30 cm (SSD). The results showed that all water-conserving irrigation methods increased the soil water content compared with FL, but only SSM and SSD presented higher potential in increasing alfalfa yield by improving soil water content, pH value and available P. Moreover, compared with FL, SSM and SSD also presented greater effects in altering microbial community structures, such as the α-diversity, β-diversity, and bacterial composition at the order level, but did not significantly affect microbial taxon composition at the phylum level. Among all determined parameters, alfalfa yield was detected as the strongest factor, which simultaneously associated with the bacterial and fungal community composition, α-diversity, and β-diversity. Moreover, the abundance changes of predicted microbial functional genes revealed that improved alfalfa growth also resulted in more nutrient exhaustion and organic matter depletion in those soils under SSM and SSD treatments. In addition, the changes in bacterial community structure were more sensitive than those in the fungal community structure to soil physicochemical properties and alfalfa growth. In conclusion, the SSM and SSD treatments have great potential to improve alfalfa growth and alter soil microbial community structures in the arid and semiarid areas of northern China.
... Traditionally, flood irrigation is widely applied for agricultural irrigation. However, flood irrigation not only results in water loss via surface runoff, soil evaporation, and deep percolation (Kharrou et al., 2011) but also causes soil salinity, sodicity, and nutrient leaching (Cox et al., 2018). Although sprinkler irrigation systems are a preferred method of irrigation in arid and semi-arid regions, a fraction of water is still lost by wind drift and evaporation before water reaches deeper soil during and after irrigation events (Al-Ghobari et al., 2018). ...
Article
Water shortage is a common environmental stressor encountered by agricultural production in arid and semiarid areas of the world. Under this situation, the impacts of different irrigation methods on the forage yield, select soil physiochemical properties, and soil microbial community structures were identified after alfalfa was planted for three years in Ningxia, northern China. The experiment consisted of five irrigation methods/treatments with three replicates for each treatment, including flood irrigation (FL), sprinkler irrigation (SP), and three subsurface drip irrigation systems, with drip tapes buried at a depth of 10 cm (SSL), 20 cm (SSM) and 30 cm (SSD). The results showed that all water-conserving irrigation methods increased the soil water content compared with FL, but only SSM and SSD presented higher potential in increasing alfalfa yield by improving soil water content, pH value and available P. Moreover, compared with FL, SSM and SSD also presented greater effects in altering microbial community structures, such as the α-diversity, β-diversity, and bacterial composition at the order level, but did not significantly affect microbial taxon composition at the phylum level. Among all determined parameters, alfalfa yield was detected as the strongest factor, which simultaneously associated with the bacterial and fungal community composition, α-diversity, and β-diversity. Moreover, the abundance changes of predicted microbial functional genes revealed that improved alfalfa growth also resulted in more nutrient exhaustion and organic matter depletion in those soils under SSM and SSD treatments. In addition, the changes in bacterial community structure were more sensitive than those in the fungal community structure to soil physicochemical properties and alfalfa growth. In conclusion, the SSM and SSD treatments have great potential to improve alfalfa growth and alter soil microbial community structures in the arid and semiarid areas of northern China.
... Although the fertilization pattern of the M-FI treatment enhanced maize vegetative growth, it probably led to an insufficient supply of water and nutrients during the midto late-growth stages, which resulted in premature leaf senescence and weakened assimilation, and in turn caused a decrease in economic yield and resource utilization efficiency (Tables 2, 3, 4). In addition, excessive and incorrect use of water and fertilizers in field leads to soil degradation, water eutrophication, high-nitrate leaching and high greenhouse-gas emissions, which possibly induce irreparable environmental damage (Conley et al. 2009;Cox et al. 2018;Zhang et al. 2019;Azad et al. 2020;Li et al. 2020). ...
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Drip irrigation is now commonly used for maize cultivation in China and other regions of the globe. The goal of this study was to compare water and fertilizer use as well as economic benefits for surface and subsurface drip irrigation and for mulched and non-mulched maize production in northeast China. An experiment was conducted during 2015 and 2016 in Chifeng in Inner Mongolia, China that included the following treatments mulched surface drip irrigation (M-DI), non-mulched surface drip irrigation (NM-DI); non-mulched subsurface drip irrigation (NM-SDI), and mulched furrow irrigation (M-FI). The results indicated that film mulching obviously improved the soil temperature and water content during the early growth period, which hastened maize emergence and growth. Compared with the M-FI treatment, the DI techniques significantly decreased the cost of field management and improved water and nitrogen use. The water use efficiency (WUE) and nitrogen partial factor productivity for DI treatments increased by 13.9–39.2% and 16.3–28.1%, respectively, on average for two years, compared to those for the M-FI treatment. The advantages of M-DI were film mulching and in-season fertigation, which improved maize development and achieved the highest yield and net output values, which were 9.2–10.1% and 4.7–19.1% higher than other techniques. The NM-SDI technique is a competitive viable alternative for maize cultivation given the lack of film residue, the ease of field management, which made the annual allocated cost of system decrease by 13.2–24.1% compared with others, and the highest WUE among the treatments. Therefore, the DI techniques showed potential to enhance maize production, but decisions regarding the use of DI should take both economic benefits and environmental impact into consideration.
... Moreover, large amounts of irrigation water are needed to sustain the current crops due to high evaporation rates. The annual average irrigation requirements of the three major crops pecan, alfalfa, and cotton grown in the region are 152, 152, and 84 cm, respectively (Cox et al., 2018). Therefore, during periods of drought more than half of agricultural fields are fallowed (mostly under annuals such as cotton) because the irrigation water allotted by the district is not enough to grow any of the three aforementioned crops. ...
... (1) Prevalence of irrigation by gravity (surface) and persistence of the practice of uncontrolled flooding (Fig. 12.1), involving severe water losses by runoff, seepage, and deep percolation, as well as high soil sodicity and salinity, as it has been demonstrated in very similar climate conditions (Cox et al. 2018); (2) Inadequate planning of irrigation-mainly based on the resource availability, without considering the characteristics of the soil, the needs of the crop, etc., and motivated by an insufficient extension of work with the farmers and poor dissemination of the best practices, derived from technical and scientific results; (3) The poor state of the irrigation water delivery infrastructure, which leads to a bad delivery performance that, coupled with the low application efficiency, gives a considerable decrease in the total efficiency of irrigation; (4) Insufficient infrastructure for the harvesting and conservation of rainwater, useful practice that increases the resilience of farming systems to the effects of drought; (5) Lack of incentives for water saving and responsible use of irrigation, leading to little awareness in this regard; and (6) Insufficient knowledge about irrigation water quality impairment (organic contaminants, pollution with nitrates, salinization, etc.). As a consequence, the irrigation water withdrawal exceeds the irrigation water requirement due to significant losses in distribution and application, with a water requirement ratio of about 44% in 2009 (Frenken and Gillet 2012). ...
Chapter
Urban and agricultural drainage ditches (DD) are important structures for the drainage of runoff. While agricultural DD remove the excess of irrigation water to lowlands areas, urban DD prevent the damage of civilian infrastructure caused by stormwater runoff. The drainage ditches in Mexico are generally unattended sites, where all type of waste is deposited. Moreover, they can be receiving bodies of clandestine domestic or industrial wastewater, which could contaminate the adjacent environment. The abandonment of urban and agricultural DD deteriorates the landscape and cause water contamination which could be derived in public health problems. This chapter presents a review of the current scenario of agricultural and urban DD in Mexico. The importance of these sites, as well as the associated environmental problems, is described. Finally, the vegetated urban and agricultural drainage ditches are presented, and their potential in the mitigation of environmental pollution and the improvement of the agricultural and urban landscape are discussed.
... Moreover, large amounts of irrigation water are needed to sustain the current crops due to high evaporation rates. The annual average irrigation requirements of the three major crops pecan, alfalfa, and cotton grown in the region are 152, 152, and 84 cm, respectively (Cox et al., 2018). Therefore, during periods of drought more than half of agricultural fields are fallowed (mostly under annuals such as cotton) because the irrigation water allotted by the district is not enough to grow any of the three aforementioned crops. ...
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Growers in the arid regions of the world constantly face freshwater scarcity and salinity. It is essential to develop information on crops that can tolerate water and salinity stress for ensuring long-term viability of agriculture in these extreme environments. Guar (Cyamopsis tetragonoloba L.) is a multipurpose crop mainly grown in arid regions of south Asia and the United States is a major importer of this crop. If guar can be produced on saline soils in the arid west, it can improve farm income of local growers. This controlled environment study evaluated germination, physiological response, seedling growth parameters, and ions uptake of 15 guar accessions under different salinity (0.9-control, 4.5 and 9.0 dS m-1 ). Results indicated that while one accession (PI 268229) recorded 100% germination at 9.0 dS m-1 , two accessions (PI164476 and PI 43359) showed 100% germination at 4.5 dS m-1 . Across all accessions the chlorophyll content and assimilation of CO2 decreased as salinity level of irrigation water increased, but the chlorophyll fluorescence (Chl F) remained higher at all three salinity levels. Accession PI 549164 had maximum leaf area and shoot biomass (OD weight) at 9.0 dS m-1 . Although the Na and Cl contents increased, K content and K/ Na ratio decreased in all accessions with increasing salinity. This could indicate that selective ion uptake to be the dominant salinity tolerance mechanisms in early stages of guar.
... Agriculture in the Rio Grande Project area that covers parts of New Mexico (NM) and Texas (TX) is totally dependent on irrigation because the annual precipitation is far less than the potential evapotranspiration. A significant proportion of irrigated area in the region suffers from salinity (Ganjegunte, Ulery, Niu, & Wu, 2017;Cox et al., 2018). In recent years, TX, like many other parts of the United States, has experienced severe drought, and as a result, freshwater (FW) available to agriculture is declining. ...
Article
Land degradation due to elevated salinity and sodicity is a serious problem affecting many irrigated regions of the world. Salinity coupled with freshwater scarcity has forced many farmers in arid regions to abandon agricultural lands. This study evaluated irrigation potential of marginal quality treated urban wastewater to produce bioenergy sorghum on saline soils collected from an abandoned degraded salt affected lands in Texas and New Mexico under greenhouse conditions. Study results indicated that the energy sorghum biomass production and quality under wastewater irrigation were comparable to that irrigated with freshwater on non-saline soils. Soil salinity especially in the subsurface increased over time under wastewater irrigation compared to that under freshwater irrigation. Soil sodicity (measured by sodium adsorption ratios) increased over time in all water-soil treatment combinations. Sodicity values were higher in treatments that received wastewater irrigation with no addition of calcium to counter sodium. Although sodicity exceeded the threshold value, no impairment in soil permeability was observed. Study results indicated a great potential for marginal quality water irrigation to improve degraded saline land productivity. Further field studies are required to confirm our greenhouse study results, potential of bioenergy crops especially on saline soils, and to highlight treated wastewater as a potential irrigation source.
Chapter
Cereals are essential human foods in both developed and developing countries. They are a significant source of energy, carbohydrates, protein, and dietary fiber and contain a range of micronutrients. However, salinity is one of the main abiotic barriers to their productivity. Salt stress threatens 10% of the world’s total land area (950 Mha), 20% of the world’s arable land (300 Mha), and 50% of the total irrigated land (230 Mha). Further, it is expected to affect 50% of total cultivated land in 2050 at an alarming rate due to environmental changes and various inappropriate irrigation practices, especially in arid and semiarid climatic areas. The continuous rise in worldwide salinization makes these areas soil one of the most critical categories of degraded soils, with profound effects ranging from loss of biodiversity to total disappearance of vegetation and a loss of soil fertility. The high concentration of salts in the environment can also induce a series of alterations, from the genetic level to the morphological level of the cultivated plants.Recently, biostimulants have gained considerable attention as natural and eco-friendly tools to maintain soil health and improve crops tolerance to (a)biotic stress such as salinity. The application of arbuscular mycorrhizal fungi (AMF), plant growth-promoting rhizobacteria (PGPR), organic amendment, algae extracts, and other active compounds as biostimulants has been recommended due, among others, to their capacity to enhance soil structure and porosity, fix atmospheric nitrogen for plant accessibility, improve nutrient uptake and solubilization, promote water absorption, and produce phytohormones. This chapter will explore plant biostimulants’ potential roles in sustainable agricultural production systems, their protective effects against salinity stress, as well as the underlying mechanisms that control these effects in cereals.KeywordsCerealsPlant biostimulantsStress toleranceOrganic componentsMicroorganismsNutrient uptakeProductivitySustainable agriculture
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Amaranthus palmeri S. Watson (Palmer amaranth) is an invasive agricultural weed that has quickly risen from a state of relative obscurity to now being globally regarded as one of the most economically destructive and difficult to manage weed species. It is now found in more than 45 countries where it poses a serious threat to agricultural production systems. Amaranthus palmeri is known to aggressively compete against crop plants for resources such as light, space, nutrients and soil moisture, all of which can result in significant crop yield reduction or even lead to crop failure. It has also been reported that A. palmeri is highly prone to evolve herbicide resistance; this makes management exceedingly challenging. Whilst there have been several control approaches introduced to manage the spread and impact of A. palmeri, many of them require more specific and focused research for their successful local and widespread application. In this regard, this global review explores the species’ biology and global distribution patterns, together with previous and current management strategies. It also explores and identifies promising areas of research that still require further investigation to more confidently assist in the control and containment of this globally concerning weed.
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Soil contamination due to chlorinated organics prompts an important environmental problem; however, the iron-based reduction materials and complicated ground environment are the main barriers to implementation and promotion of in situ soil remediation. Therefore, this study aims to evaluate the reductants zero-valent iron (ZVI) and its activated carbon composite (AC-ZVI) in terms of their self-oxidation and selectivity in soil experiments. The results indicated that saturated moisture conditions were beneficial for degradation due to the dispersal of the pollutants from soil particles. Particularly, increasing the water/soil ratio to the over-saturated state would decrease the selectivity of ZVI and AC-ZVI. Meanwhile, increasing the reductant loading decreased the selectivity of ZVI and AC-ZVI, whereas the high initial concentration increased the selectivity of AC-ZVI. In addition, the self-oxidation of ZVI (3.0 ×10-3 h-1) is 4.2 times higher than that of AC-ZVI (0.7 ×10-3 h-1), and the selectivity of AC-ZVI (48%) is 6.9 times higher than that of ZVI (7%), which confirmed that AC-ZVI is a superior iron-based amendment in saturated moisture conditions. Therefore, this study provides a reliable and feasible evaluation method for in situ remediation process, and deepens the understanding of the effects of moisture contents.
Article
Treated urban wastewater (TWW) is seen as a potential alternative for agricultural irrigation in arid west Texas region, due to scarcity of Freshwater (FW) supplies. However, TWW can potentially cause soil salinization and affect soil quality and crop productivity. Therefore, crops that are salt-tolerant and less water-intensive are needed to sustain agriculture in this region. Canola (Brassica napus L.) as an edible oilseed and biodiesel/biofuel crop, is salt-tolerant and relatively less water-intensive than crops that are traditional to this area. This two–year field study evaluated the performance of canola under TWW irrigation in terms of its seed yield potential and seed quality (oil content, oil yield and salt constituents), along with quantifying changes in soil salinity and sodicity. Experimental design included a randomized block split-plot with water quality (FW and TWW) as the main-plot and soil amendment (gypsum + sulfur and no-amendment) as the subplot factor. Results show that TWW application did not significantly affect canola seed yields in any of the two years. On average, seed yields were 1975 kg ha⁻¹ across all treatments and years. Seed oil content, oil yield and mineral constituents were also not affected by TWW irrigation. Nevertheless, average seed oil content was 42 % and oil yield was 849 kg ha⁻¹. Other than the effects on soil salinity and sodicity, Gypsum + Sulfur application did not influence canola seed productivity and quality. Changes in soil salinity and sodicity were more prominent under TWW irrigation but the levels were below the thresholds after two years. Gypsum + Sulfur application significantly reduced soil sodicity, especially in TWW irrigated soils. These results highlight that TWW can be successfully used to grow canola as a biofuel feedstock in this arid region while following appropriate soil management practices to alleviate sodicity hazard of TWW in the long-term.
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z Tarımsal üretimin üzerindeki baskılar gün geçtikçe artmaktadır. Tarım alanları sınıra dayanmış ve birim alandan daha çok üretim talep edilmektedir. Bunlara ek olarak iklim değişikliklerinin neden olduğu kurak dönem sayısındaki artış nedeniyle yarı kurak bölgelerde sulama ihtiyacını arttıracaktır. Ancak sulama kısa vadede üretimi arttırsa da uzun vadede başta tuzlanma olmak üzere toprak yapısını bozma, bitki besin elementlerinin yıkanmasının aralarında olduğu birçok olumsuz sonucu beraberinde getirmektedir. Toprakların sürdürülebilir kullanımı için uygulanan tarımsal yöntemlerin toprak kalitesini ne düzeyde etkilediği yapılacak detay çalışmalarla ortaya konulması toprak kalitesinin korunması hatta arttırılması için ön koşuldur. Adıyaman ilinin içinde yer aldığı Güneydoğu Anadolu Projesi kapsamında Atatürk Barajı göl havzasından yapılan sulama faaliyetleri 25 yıllık bir sürece dayanmaktadır. Sulu tarımın 25 yıllık süreçteki etkisi değerlendirmek için Adıyaman ili Kahta ilçesinin kuzeydoğusunda yer alan çalışma alanında 4 farklı noktadan 0-30 cm derinlikten toprak örnekleri alınmıştır. Örneklerde bazı fiziksel, kimyasal, mineralojik ve mikromorfolojik parametreleri araştırılmıştır. Çalışma alanındaki toprakların smektitin baskın kil minerali olduğu kil tekstürlü, kireçli, nötr ve hafif alkali pH'ya sahip oldukları belirlenmiştir. Mikroyapısal açıdan topraklarda sulama sonrası herhangi bir kireç birikimi veya yıkanma olgusu (kaplama/kütan) saptanmamıştır. Buna karşın kuru tarımdan sulu tarıma geçişle birlikte organik madde, organik karbon, azot ve C/N düzeyleri azalma eğilimi gösterirken, elektriksel iletkenlik düzeyi kabul edilebilir sınırlar içinde olsa da artma eğilimi göstermiştir. Sonuç olarak, inceleme alanındaki elektriksel iletkenlik düzeyindeki artış eğilimi ve organik maddedeki azalma sulamanın tarımsal üretkenliği tehdit edebileceğini göstermektedir. Bunun önlenmesi için etkin sulama ve besleme programlarının saptanıp olası en hızlı süreçte hayata geçirilmesini gerektirmektedir. Abstract The pressures on agricultural production are increasing day by day. The agricultural lands have reached their limit and more production is demanded from per unit area. In addition to these, many studies have shown that the need for irrigation in semi-arid regions will increase due to the increase in the number of dry periods lead by climate change. However, although irrigation increases production in the short term, it brings many negative consequences, among which the destruction of soil structure, especially salinization, and leaching of plant nutrients in the long term. It is a prior condition to reveal the effect of agricultural management applied for the sustainable use of soils on soil quality through detailed studies to protect and even increase the soil quality. The irrigation activities carried out in the Atatürk Dam lake basin within the scope of the Southeastern Anatolia Project, which includes the province of Adıyaman, date back to 25 years. Soil samples were taken from 0-30 cm depth from 4 different points in the study area located in the northeast of Kahta district of Adıyaman province in order to evaluate the effect of irrigated agriculture in the 25 years. Some physical, chemical, mineralogical, and micromorphological parameters were determined in the samples. It has been determined that the soils in the study area have clay-textured, calcareous, neutral and slightly alkaline pH, where smectite is the dominant clay mineral. In terms of microstructure, no
Chapter
The largest volume of water that humanity uses is dedicated to agricultural irrigation, vital to ensure food for the growing population of our planet. This poses many challenges since the concentration of the population in urban areas confers a new dynamic on the relations between the countryside and the city. Additionally, climate change creates scenarios that imply the need for improved irrigation water management, which cannot be achieved only through irrigation technologies, but with a global approach to the problem that also includes economic aspects such as incentives for producers to adoption of the most appropriate technologies for each region, as well as the conscious intervention of producer associations. Considering the mentioned conditions, in the present work the situation of the use of the irrigation water in the valley Atlixco-izúcar of the State of Puebla, Mexico is shown. The demonstration of the profits of technified irrigation was performed in three plots dedicated to sugar cane which led to increases in yields and savings of 50% and more of the irrigation water used.
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Salinity and sodicity are the dual problems affecting soil productivity, lint yield, and fiber quality in the irrigated pima cotton (Gossypium hirsutum L.) fields in far west Texas. This field study evaluated the effects of S burner-treated blended irrigation water on sodicity and salinity of the root zone, cotton lint yield, and fiber quality. Results indicated that pre-study soil salinity and sodicity exceeded the threshold levels in many areas within the 9.2-ha study site. One year of irrigation with S burner-treated water resulted in 19% reduction in salinity of the upper 0- to 30-cm depth and redistribution of salts at deeper depths. Average sodium adsorption ratio (SAR) of study site soils decreased by 3 to 5% at 0- to 15-, 30- to 45-, and 45- to 60-cm depths and reduction in the SAR range for 15- to 30- and 60- to 75-cm depths indicated redistribution of Na. Irrigation with S burner-treated blended water increased annual cotton lint yield by 20% compared with long-term average and improved fiber quality. However, 1 yr of irrigation with S burner-treated water did not reduce the maximum soil ECe and SAR values below the threshold levels at different depths. Multiyear studies are needed to confirm our results and quantify the duration required to restore soil quality, cotton yield, and fiber quality.
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El Paso County, located in the far west part of Texas in USA, is experiencing record water shortages due to prolonged drought conditions. County irrigation district caters to about 24,000 ha and of which about 6000 ha is under pecans, a water intensive tree crop. The current method of irrigation scheduling depends on farmer’s intuition or counting number of days since previous irrigation. This has resulted in over irrigation and wastage of precious freshwater. This study evaluated the potential for freshwater conservation by scheduling irrigation based on real-time soil moisture data and its effects on pecan yields and soil salinity. Real-time soil moisture conditions in five mature pecan orchards were monitored and irrigation was scheduled when the levels reached threshold value. Both frequency and amount of irrigation were lower under irrigation scheduling based on soil moisture than the traditional method. While the results of this 3 year study indicated that irrigation scheduling based on soil moisture conditions could save significant amounts of freshwater without adversely affecting pecan nut yields and soil salinity, long-term studies are needed to confirm these results. It is estimated that improved irrigation scheduling can potentially save 1820 ha-m of precious freshwater across the irrigation district.
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Thoroughly updated and now in full color, the 15th edition of this market leading text brings the exciting field of soils to life. Explore this new edition to find: A comprehensive approach to soils with a focus on six major ecological roles of soil including growth of plants, climate change, recycling function, biodiversity, water, and soil properties and behavior. New full-color illustrations and the use of color throughout the text highlights the new and refined figures and illustrations to help make the study of soils more efficient, engaging, and relevant. Updated with the latest advances, concepts, and applications including hundreds of key references. New coverage of cutting edge soil science. Examples include coverage of the pedosphere concept, new insights into humus and soil carbon accumulation, subaqueous soils, soil effects on human health, principles and practice of organic farming, urban and human engineered soils, new understandings of the nitrogen cycle, water-saving irrigation techniques, hydraulic redistribution, soil food-web ecology, disease suppressive soils, soil microbial genomics, soil interactions with global climate change, digital soil maps, and many others Applications boxes and case study vignettes bring important soils topics to life. Examples include “Subaqueous Soils—Underwater Pedogenesis,” “Practical Applications of Unsaturated Water Flow in Contrasting Layers,” “Soil Microbiology in the Molecular Age,” and "Where have All the Humics Gone?” Calculations and practical numerical problems boxes help students explore and understand detailed calculations and practical numerical problems. Examples include “Calculating Lime Needs Based on pH Buffering,” “Leaching Requirement for Saline Soils,” "Toward a Global Soil Information System,” “Calculation of Nitrogen Mineralization,” and “Calculation of Percent Pore Space in Soils.”
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The authors kindly acknowledge C. Williams and M. Menne for providing the adjusted monthly temperature values used in the computation of all temperature-related normals, and J. Crouch and B. Korzeniewski for providing valuable feedback on an earlier version of this manuscript. We also commend T. Whitehurst and N. Guttman for pioneering work on prior installments of NOAA's Climate Normals. Most importantly, we thank the legion of individuals-many of them volunteers-who perform the diligent and often thankless job of recording weather observations every single day. There could be no climate normals without their dedication.
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Aquifer overexploitation could significantly impact crop production in the United States because 60% of irrigation relies on groundwater. Groundwater depletion in the irrigated High Plains and California Central Valley accounts for ∼50% of groundwater depletion in the United States since 1900. A newly developed High Plains recharge map shows that high recharge in the northern High Plains results in sustainable pumpage, whereas lower recharge in the central and southern High Plains has resulted in focused depletion of 330 km3 of fossil groundwater, mostly recharged during the past 13,000 y. Depletion is highly localized with about a third of depletion occurring in 4% of the High Plains land area. Extrapolation of the current depletion rate suggests that 35% of the southern High Plains will be unable to support irrigation within the next 30 y. Reducing irrigation withdrawals could extend the lifespan of the aquifer but would not result in sustainable management of this fossil groundwater. The Central Valley is a more dynamic, engineered system, with north/south diversions of surface water since the 1950s contributing to ∼7× higher recharge. However, these diversions are regulated because of impacts on endangered species. A newly developed Central Valley Hydrologic Model shows that groundwater depletion since the 1960s, totaling 80 km3, occurs mostly in the south (Tulare Basin) and primarily during droughts. Increasing water storage through artificial recharge of excess surface water in aquifers by up to 3 km3 shows promise for coping with droughts and improving sustainability of groundwater resources in the Central Valley.
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This study was carried out to analyze the response of two Sicilian Typic Haploxererts to ESP values up to 15, at a low cationic concentration. Almost linear relationships were found between the investigated soil properties and ESP, indicating no critical ESP threshold; furthermore, the results obtained indicate that an effective hazard of soil quality degradation can be forecast even in a 2 to 5 ESP range at a low cationic concentration. -from Authors
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Chemical characteristics of groundwater and the composition of newly formed precipitates are critical in the management of modern irrigated agriculture in arid regions. Water samples representing the main aquifers in Riyadh region, Saudi Arabia, and solid samples fromthe newly formed precipitates were studied. Results showed that water temperature varied between 30.3-69°C, being higher in the deep aquifer and low in the relatively shallow aquifers. Initial water pH ranged from 6.39-7.92, increasing to 7.65-8.20 at atmospheric conditions. Shallowaquifer waters were categorized into sulfate-type and Cl- or no-dominant type waters, while the deep aquifers were characterized as Cl-type and no-dominant type. Soluble H 4 SiO 4 , soluble Fe and Mn ranged from 3.15 to 18.82, 0.10 to 17.30, and 0.01 to 4 0.32 mg L-¹, respectively. Calculation of saturation indices from water composition at initial, closed and equilibriumconditions indicated that changes in pH and water temperature cause major chemical changes in the water favoring the precipitation of carbonates and Fe-silicates. Data of total chemical analysis indicated that carbonates are present in all samples and constituted up to 976 g kg-¹ of the precipitates formed from the deep aquifer water in the irrigation tubes. Amorphous and/or crystalline Fe compounds were the dominant fractions in the surface crust precipitates, while crystalline Fe compounds was the dominant form in the precipitates in irrigation tubes and in the cooling reservoir. XRD data confirmed that aragonite was the dominant carbonate mineral in the precipitates formed fromthe deep aquifer water. Calcite and Mg-calcite were detected in considerably low quantities. Poorly crystalline Fe-oxide minerals were present in all the precipitate samples. Results suggested that formation of precipitates either in cooling reservoirs or in irrigation systems can be minimized by controlling the degassing through keeping the system closed, lowering the pH through the injection of inorganic acids in the system or both.
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Drylands cover about 40% of the terrestrial land surface and account for approximately 40% of global net primary productivity. Water is fundamental to the biophysical processes that sustain ecosystem function and food production, particularly in drylands where a tight coupling exists between ecosystem productivity, surface energy balance, biogeochemical cycles, and water resource availability. Currently, drylands support at least 2 billion people and comprise both natural and managed ecosystems. In this synthesis, we identify some current critical issues in the understanding of dryland systems and discuss how arid and semiarid environments are responding to the changes in climate and land use. The issues range from societal aspects such as rapid population growth, the resulting food and water security, and development issues, to natural aspects such as ecohydrological consequences of bush encroachment and the causes of desertification. To improve current understanding and inform upon the needed research efforts to address these critical issues, we identify some recent technical advances in terms of monitoring dryland water dynamics, water budget and vegetation water use, with a focus on the use of stable isotopes and remote sensing. These technological advances provide new tools that assist in addressing critical issues in dryland ecohydrology under climate change.
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Limitations to agricultural productivity imposed by the root-zone constraints in Australian dryland soils are severe and need redemption to improve the yields of grain crops and thereby meet world demand. Physical, chemical and biological constraints in soil horizons impose a stress on the plant and restrict plant growth and development. Hardsetting, crusting, compaction, salinity, sodicity, acidity, alkalinity, nutrient deficiencies and toxicities due to boron, carbonates and aluminium are the major factors that cause these constraints. Further, subsoils in agricultural regions in Australia have very low organic matter and biological activity. Dryland salinity is currently given wide attention in the public debate and government policies in Australia, but they only focus on salinity induced by shallow groundwater. However, the occurrence of transient salinity in root-zone layers in the regions where water tables are deep is an important issue with potential for larger economic loss than water table-induced seepage salinity. Root-zone constraints pose a challenge for salinity mitigation in recharge as well as discharge zones. In recharge zones, reduced water movement in sodic horizons results in salt accumulation in the root zone resulting in chemical and physical constraints that reduce transpiration that, in turn, upsets salt balance and plant growth. High salinity in soil and groundwater restricts the ability of plants to reduce water table in discharge zones. Thus plant-based strategies must address different kinds of limitations in soil profiles, both in recharge and discharge zones. In this paper we give an overview of plant response to root-zone constraints but with an emphasis on the processes of salt accumulation in the root-zone of soils. We also examine physical and chemical methods to overcome subsoil limitations, the ability of plants to adapt to and ameliorate these constraints, soil modification by management of agricultural and forestry ecosystems, the use of biological activity, and plant breeding for resistance to the soil constraints. We emphasise that soil scientists in cooperation with agronomists and plant breeders should design site-specific strategies to overcome multiple soil constraints, with vertical and lateral variations, and to develop plant-based solutions for dryland salinity.
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It is hypothesised that a quantitative assessment of the changes in soil quality provides a measure of sustainable management. This chapter defines soil quality and presents an approach to quantify both the inherent and dynamic dimensions of soil quality in terms of minimum data sets and pedotransfer functions in combination with procedures and models used in statistical quality control. It also explores the concept of designing inherently sustainable land management systems combined with process quality control procedures to ensure quality performance of the management system design. -from Authors
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Dryland river systems are becoming saltier, severely degrading the quality of water used for agriculture and limiting its domestic use. In this context, it is becoming important to understand how the sources and abundances of salts in these river systems will respond to increasingly arid climates. Using the Rio Grande in the Southwest U.S. as an example dryland river system, we show that changes in climate over the last century are closely linked to variations in salt chemistry and therefore salt sources. Starting ∼25 years ago there has been a shift toward more Cl-rich surface waters in the Rio Grande. This shift may reflect a tipping point in the relative influence of anthropogenic activities on the overall surface water budget. Climate change is accelerating this transition through the loss of rain and snow in the headwaters region, resulting in a loss of connectivity of surface flow in the upper and lower sections of the river. The implication of this relationship for dryland rivers is that salt chemistry and sources are likely to become more heterogeneous in the future, reflecting more localized natural (inflow of groundwater) and anthropogenic (waste and industrial effluents, irrigation returns) influences.
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Aggregates are formed by joining of structural units of different sizes in a hierarchical order. During wetting, the aggregates may either disintegrate completely (slaking) or remain intact with only loosening at the points of weakness (mellowing). This study investigated the effect of saline-sodic solutions with sodium adsorption ratio (SAR) of 5 and 20 and electrical conductivity (EC) of 0.1 to 4 dS m-1 after a number of wetting-drying cycles on soil mellowing. A Vertic Palexeralf with a coefficient of linear extensibility (COLE) value of 0.15 and a Typic Haploxeralf with COLE of 0.05 were studied. Using a Ca solution, the degree of aggregation in both soils was improved about two times in >50 and 20- to 50-μm aggregates compared with the original soils. The values for the Vertic Palexeralf were three times those of the Typic Haploxeralf. In contrast, sodic solutions led to the collapse of aggregates. Mellowing ratios of aggregates changed after 10 wetting-drying cycles and were ≈0.6 to 0.7 for SAR 5 and 0.8 to 1 for SAR 20 for the Vertic Palexeralf; for the Typic Haploxeralf they were 0.7 to 0.8 and 0.9 to 1.2 for SARs 5 and 20, respectively. Mellowing ratios between 0.9 and 1 were obtained for the Vertic Paleoxeralf minicores using solutions of SAR 20 and EC 0.1 dS m-1. The mellowing ratio was 0.2 when a solution of SAR 5 and EC 4 dS m-1 was used. In soils where aggregates collapsed without hierarchical breakdown, mellowing ratios were always higher, indicating structural degradation.
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We surveyed 15 commercial irrigated orchards of 'Western' pecan [Carya illinoinensis (Wangenh.) K. Koch] along a 120-km stretch of the middle Rio Grande basin in southern New Mexico. Our intent was to determine if high salinity and boron (B) broadly threaten pecan cultivation in this region. Ten of the fifteen sites were found to be on soils considered too saline for pecan trees (>2-3 dS m -1 in the soil saturation extract of the upper 0-60 cm of soil depth). Of these 10 sites, 4 had saturation extract Na concentration exceeding 20 mM, which is at or about the concentration corresponding to pecan seedling rootstock growth suppression. A laboratory study showed that cell membranes of excised, subapical seedling root segments from 'Riverside' pecan were damaged by about twice the salinity of the saturation extract at the highest salinity sites (9 dS m -1). At all sites, midsummer leaflet B concentration surpassed the published accepted range for pecan of about 50 to 100 mg B kg -1 dry weight, especially at the sites with higher soil salinity. Evaluation of two nearby sites (low salinity and B and high salinity and B orchards) showed that the higher salinity and B were associated with 25% lower yield efficiency, 3% lower percentage kernel, 13% lower mass per nut, and a 9 to 16% reduction in the tree's capacity to recycle N and P into perennial storage organs. The findings bring attention to the sustainability of current irrigation and soil management practices in much of this concentrated pecan producing region.
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Semi-arid and and rivers typically exhibit increasing salinity levels downstream, a trend often attributed to irrigated agriculture, primarily due to evapotranspiration. In contrast, the results of our investigations in one salinized river suggest that geological sources of salt added by groundwater discharge are more important than agricultural effects. We performed detailed synoptic sampling of the Upper Rio Grande-Rio Bravo, an arid-climate river with significant irrigated agriculture, and identified a series of salinity increases localized at the distal ends of sedimentary basins. Using Cl/Br, Ca/Sr, 87Sr/86Sr, and 36Cl/Cl ratios and δ234U values as environmental tracers, we show that these increases result from localized discharge of high-salinity groundwater of a sedimentary brine source. These groundwater fluxes, while very small (<1 m3s-1), are the dominant solute input and, combined with downstream evapotranspirative concentration, result in salinization. Furthermore, 36Cl/Cl ratios and δ234U values for these brines are close to secular equilibrium, indicating brine ages on the order of millions of years. The recognition of a substantial geologic salinity source for the Rio Grande implies that alternative salinity management solutions, such as interception of saline groundwater, might be more effective in reducing salinity than changes in agricultural practices.
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Slow internal drainage is a major problem in the reclamation of saline-sodic soils. This field experiment was conducted on a low-permeability, saline-sodic soil (a fine-loamy, mixed, thermic Typic Natrustalf) near Lahore, Pakistan, to compare field-saturated hydraulic conductivities (K rs) after various treatments. Treatments were: (i) deep-rooted perennial alfalfa (Medicago sativa L.), (ii) sesbania [Sesbania bispinosa (Jacq.) W.F. Wright]-wheat (Triticum aestivum L.)-sesbania rotation, (iii) incorporated wheat straw at 7.5 Mg ha -1, and (iv) a fallow control. These four treatments were each combined with and without 25 Mg ha -1 of gypsum, subsoiling to 0.45 m, and open-ditch drainage. The K rs of the soil under each treatment was measured in each 20-cm increment to 120 cm after 6 mo and 1 yr. Gypsum applications increased the K rs of the top 20-cm soil layers. Compared with uncropped plots, K rs of the 0- to 20-cm depth on cropped plots with gypsum increased about twofold after 6 mo and about fourfold after 1 yr. The crop rotation significantly increased the K rs of the 0- to 20-cm (with and without gypsum) when compared with wheat straw or fallow treatments. The K rs on plots with alfalfa plus gypsum were significantly greater to 80 cm than the K rs on fallow plots. Neither subsoiling nor open-ditch drains improved soil permeability. Gypsum plus sesbania-wheat-sesbania rotation most increased permeability of the surface layer; gypsum plus alfalfa was best to improve the permeability of the deeper layers.
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Additional index words. irrigation, drainage, stress physiology Summary. Irrigated production of pecans in the southwestern United States started with notoriously inefficient flood irrigation along river basins. Today, most surface-irrigated orchards are laser-leveled, and many orchards in upland areas are under sprinkler or drip irrigation. Technical and scientific knowledge for improving water management also has evolved from studying drought effects on tree perfor-mance to an improved understanding of water relations, salt effects, evapotranspi-ration processes, and the distribution of water and salts in irrigated fields. Yet, research was conducted at the Texas A&M Univ. at El Paso. Use of trade names does not imply endorsement of the products named nor criticism of similar ones not named. The cost of publishing this paper was defrayed in part by the payment of page charges. Under postal regulations, this paper therefore must be hereby marked advertisement solely to indicate this fact, many growers still experience difficulties with water management and may benefit from maintaining the soil water suction above saturation but below 30 to 40 cb until shuck opening. The soil salinity should be kept below 2.5 dS·m -1 , and irrigation water should be applied to essentially the entire root zone for optimum tree growth. Due to extreme soil variability existing in most irrigated fields of the southwestern region, these guidelines alone are not adequate. Soil profiles, root distributions, water quality, and irrigation methods may have to be examined to improve water management.
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The sources of SO4 along a ~ 550 km stretch of the Rio Grande in New Mexico and western Texas were investigated using stable S isotopes. During 2007 and 2008, the δ34S of dissolved SO4 in the Rio Grande surface water varied over a narrow range from − 1.6 to + 0.9‰, which was consistent with the δ34S of local fertilizers (− 2.1 to + 1.6‰) and was not consistent with Paleozoic evaporite sources of SO4 in regional bedrock (+ 7.6 to + 12.9‰). This is likely due the fact that SO4 is the major component of N–P–K fertilizers used in the Rio Grande Valley, constituting about half of the total fertilizers by mass. The SO4/Cl ratios of the groundwater system are relatively low (0.06 to 3) compared to the fertilizer source, suggesting that more Cl is added to the Rio Grande from geological sources as compared to SO4. In the Mesilla Basin in southern New Mexico, we identified zones of mixing between recharging irrigation water with groundwater within the depth range of ~ 50–200 m below the ground surface. For this aquifer, Principal Component Analysis (PCA) indicated that Na–K–Cl concentrations were largely attributable to geological sources and SO4–Mg–Ca concentrations to anthropogenic sources. Here, an additional anthropogenic source of SO4 (with a δ34S of − 2.7‰) was linked to anaerobic decomposition of manure on a horse farm. In this case SO4 concentrations (800 mg/L) increased by about three times compared to background SO4 concentrations in groundwater (< 300 mg/L). Because of the common application of H2SO4 in fertilizer manufacturing, anthropogenic SO4 fluxes to rivers and shallow aquifers from irrigation waters can be significant worldwide.Research highlights► Sulfate is a major component of N–P–K fertilizers used in the Rio Grande Valley. ► Sulfate loads in the Rio Grande are controlled by the application of fertilizers. ► Anthropogenic sulfate fluxes from irrigation waters may be significant worldwide.
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California's diverse environmental gradients serve as natural experiments for examining controls on soil mineral distribution in landscapes. In this paper we use example soilscapes from throughout California to examine how lithology, climate, topography, and duration of pedogenesis interact to produce distinctive weathering environments and characteristic suites of soil minerals. Seven soil-geomorphic sequences were assembled from the literature to illustrate major soil mineralogical trends: 1) granitic terrain of the Peninsular Ranges, 2) granitic terrain of the central Sierra Nevada, 3) andesitic terrain of the northern Sierra Nevada, 4) fluvial terraces on the east side of the Great Valley, 5) marine terraces of the central coast, 6) ultramafic terrain of the Klamath Mountains, and 7) an alluvial fan in the Mojave Desert. Results of this analysis show that kaolin is present in virtually all pedons, irrespective of climate, parent material, age, or topographic position. Kaolin does not form in ultramafic soils due to insufficient aluminum. Many secondary clay minerals reflect the state's strong climatic influence, with palygorskite, smectite, and vermiculite in the dry, hot environments; hydroxy-interlayered minerals, gibbsite, and short range-ordered minerals in the cool, moist environments. In arid and semi-arid regions, the distribution of calcite, gypsum, and soluble salts is strongly related to patterns of eolian dust deposition and water infiltration and leaching.
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Soil salinity caused by natural or human-induced processes is a major environmental hazard. The global extent of primary salt-affected soils is about 955 M ha, while secondary salinization affects some 77 M ha, with 58% of these in irrigated areas. Nearly 20% of all irrigated land is salt-affected, and this proportion tends to increase in spite of considerable efforts dedicated to land reclamation. This requires careful monitoring of the soil salinity status and variation to curb degradation trends, and secure sustainable land use and management. Multitemporal optical and microwave remote sensing can significantly contribute to detecting temporal changes of salt-related surface features. Airborne geophysics and ground-based electromagnetic induction meters, combined with ground data, have shown potential for mapping depth of salinity occurrence. This paper reviews various sensors (e.g. aerial photographs, satellite- and airborne multispectral sensors, microwave sensors, video imagery, airborne geophysics, hyperspectral sensors, and electromagnetic induction meters) and approaches used for remote identification and mapping of salt-affected areas. Constraints on the use of remote sensing data for mapping salt-affected areas are shown related to the spectral behaviour of salt types, spatial distribution of salts on the terrain surface, temporal changes on salinity, interference of vegetation, and spectral confusions with other terrain surfaces.As raw remote sensing data need substantial transformation for proper feature recognition and mapping, techniques such as spectral unmixing, maximum likelihood classification, fuzzy classification, band ratioing, principal components analysis, and correlation equations are discussed. Lastly, the paper presents modelling of temporal and spatial changes of salinity using combined approaches that incorporate different data fusion and data integration techniques.
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Pecan orchards require more irrigation water to maximize yield than any other crop grown in the Southwest US. This paper reports daily evapotranspiration (Et) measurements for 2001 and 2002 in a 5.1 ha, mature pecan orchard on the Rio Grande floodplain, 7 km south of Las Cruces, NM, USA. The 21-year-old stand had an average tree height of 12.8 m, diameter at breast height of 30 cm, and tree spacing of 9.7 m × 9.7 m. Additional pecan orchards surrounded the study orchard. When the tensiometer reached a suction of 65 kPa at the 45 cm depth, the orchard was flood-irrigated. Sparling meters were installed on the pumps and read before and after each irrigation. The total irrigation amount was 1940 mm in 2001 and 1870 mm in 2002. A walk-up tower was placed in the orchard’s center to support flux sensors at 16 m height. The instrument package included a net radiation (Rn), discs for soil heat flux (G), and two sets of one-propeller eddy covariance (OPEC) sensors. OPEC systems measure sensible heat flux (H) with a sensitive, vertically oriented propeller anemometer and a fine-wire thermocouple. Latent heat flux (LE) was obtained as a residual in the surface energy balance LE = Rn − G − H. The maximum daily evapotranspiration was 8 mm/day, and the yearly cumulative evapotranspiration averaged for 2 years was 1420 mm, resulting in a yearly average irrigation application efficiency of 79%. The crop coefficient (daily measured Et/reference Penman Et) ranged from 0.2 to 1.1. Increased evaporation due to irrigation was detected only for the April 9 irrigation in 2001. The seasonal water use was 4% lower in 2001 and 12% lower in 2002 than previously reported values.
Article
Soil salinity and sodicity have long been recognized as the major concerns for irrigated agriculture in the Trans-Pecos Basin, where fields are being flood irrigated with Rio Grande River water that has elevated salinity. Reclamation of these salt-affected lands is difficult due to fine-texture, high shrink-swell soils with low permeability. Conventional practice of subsoiling to improve soil permeability is expensive and has had limited success on the irrigated soils that have appreciable amounts of readily weatherable Ca minerals. If these native Ca sources can be effectively used to counter sodicity, it can improve soil permeability and reduce amelioration costs. This study evaluated the effects of 3 yr of polyacrylamide (PAM) application at 10 mg L concentration during the first irrigation of the season to evaluate soil permeability, in situ Ca mineral dissolution, and leaching of salts from the effective root zone in a pecan field of El Paso County, TX. Results indicated that PAM application improved water movement throughout the effective root zone that resulted in Na leaching. Polymer application significantly decreased CaCO (estimated based on inorganic C analysis) concentrations in the top 45 cm compared with baseline levels, indicating solubilization and redistribution of calcite. The PAM application also reduced soil electrical conductivity (EC) in the top 60 cm (4.64-2.76 dS m) and sodium adsorption ratio (SAR) from 13.1 to 5.7 mmol L in the top 75-cm depths. As evidence of improved soil conditions, pecan nut yields increased by 34% in PAM-treated fields over the control. Results suggested that PAM application helped in effective use of native Ca sources present in soils of the study site and reduced Na by improving soil permeability.
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The Rio Grande, which forms the United States-Mexico border for much of its course, receives diverse pollutants from both urban and agricultural areas, most notably in the sister cities of El Paso (TX, USA)-Ciudad Juárez (CHI, Mexico). This study aimed to describe regional trends in water quality in waters near the El Paso-Ciudad Juárez metroplex and to examine the potential for water quality improvement through the use of a created wetland. Very few differences in nutrient chemistry were found among drains, canals and the Rio Grande, with the exception of elevated chloride and lower phosphorus levels found in the drains. Overall, chloride concentrations increased with distance downstream, likely due to concentration of salts via evaporation from irrigated agriculture. A wastewater treatment plant (WWTP) contributed substantially to total phosphorus and nitrate levels, which, together with ammonia, tended to exceed state criteria for water quality downstream of the WWTP outflow. The created Rio Bosque wetlands reduced nitrate concentrations in the water, possibly via denitrification enhanced by algae; algae increased in biomass as water flowed through the wetlands. However, the diversion of water for irrigated agriculture, resulting in the absence of water, and thus aquatic plants, in the wetland in the summer has limited the ability of this wetland to improve regional water quality.
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The electrical permittivity and conductivity of the bulk soil are a function of the permittivity and conductivity of the pore water. For soil water contents higher than 0.10 both functions are equal, facilitating in situ conductivity measurements of the pore water. A novel method is described, based on simultaneous measurements of permittivity and conductivity of the bulk soil from which the conductivity of the pore water can be calculated. A prototype of a pore water conductivity sensor based on this method is presented. Validation results show that the method can be used for a broad range of soils and is valid for water contents between 0.10 and saturation and for the conductivity of the pore water up to 0.3 S m-1.
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Groundwater represents an important supply source for municipal and irrigation uses in Far West Texas. The City of El Paso receives about 50 percent of its municipal water supply from surface water and 50 percent from local groundwater. Groundwater pumping in El Paso is from the Hueco Bolson and the Mesilla Bolson. Historic groundwater pumping in the Texas portion of the Mesilla Bolson has not resulted in significant changes in groundwater levels or groundwater quality in existing wells. Historic pumping in the Hueco Bolson has resulted in lowered groundwater levels and brackish groundwater intrusion. The groundwater level declines have resulted in the intrusion of brackish groundwater into areas that historically pumped fresh groundwater. A 1979 assessment concluded that El Paso would deplete fresh groundwater in the Hueco Bolson by 2030 if groundwater pumping continued to increase. Partly as a result of the 1979 assessment, El Paso reduced its groundwater pumping from the Hueco Bolson by increasing surface water diversions from the Rio Grande, increasing conservation efforts, and increasing reclaimed water use. As a result, groundwater levels in many parts of the Hueco Bolson have stabilized. Brackish groundwater intrusion remains an issue, and is being addressed with a brackish groundwater desalination plant, currently under construction. The new wells and existing wells that will supply this desalination plant will also assist in the management of brackish groundwater intrusion by intercepting the brackish groundwater before it can flow towards existing fresh groundwater wells. The 2006 Far West Texas Regional Water Plan contemplates a groundwater transfer project to meet increasing demands in El Paso County beginning about 2030, mostly from the Dell City area in Hudspeth County, Texas. Groundwater management in the Dell City area is governed by a groundwater conservation district that has established limits on groundwater pumping based on existing and historic uses. Groundwater pumping for irrigation began in the Dell City area in 1948, and groundwater levels have been essentially stable for since the 1980s. Future planning for a groundwater transfer project will require a detailed understanding of the hydrogeology of the groundwater in the Dell City area.