The increasing use of recycled water for irrigation requires reliable indicators to assess potential impacts on soil physical properties. Traditional irrigation water quality assessments rely primarily on the Sodium Adsorption Ratio (SAR) to evaluate soil permeability hazards; however, SAR does not account for the potential dispersive effects of potassium or differences in the flocculating roles of calcium and magnesium. This study evaluated the influence of irrigation water cation composition on soil structural stability using a greenhouse experiment with strawberry plants irrigated with synthetic recycled waters of contrasting cation ratios. Soil permeability, infiltration rate, clay dispersion, and soil water content were monitored to assess structural responses. Irrigation with waters dominated by dispersive cations significantly reduced soil permeability and infiltration compared with calcium-dominated treatments. Clay dispersion was strongly associated with irrigation water cation composition and appeared to be the primary mechanism driving soil structural degradation. Among the evaluated indices, the Cation Ratio of Soil Structural Stability (CROSSf) showed stronger relationships with soil physical indicators than the traditional Sodium Adsorption Ratio (SAR). These results are consistent with previous laboratory column experiments and confirm that CROSS provides improved predictions of soil permeability hazards under cropping conditions. Incorporating indices such as CROSS into irrigation water quality assessment frameworks may improve the management of agricultural systems increasingly relying on recycled water.

The increasing utilization of non-conventional water sources, particularly in arid regions, necessitates strategies for effectively harnessing these resources. This study examines the impacts of using marginal quality waters, including recycled wastewater (RW) and brackish groundwater (BW), compared to those using desalinated brackish water (DW) as a control, on alfalfa cultivation in Fuerteventura, Canary Islands, over four years. Employing a 25 % leaching fraction in addition to organic amendments and gypsum application, the study evaluates the effects on alfalfa biomass production, mineral composition, and soil quality on two soil types (sandy-loam and clay-loam) affected by salinity. Initial and post-treatment analyses of the topsoil and soil profile revealed significant improvements in soil quality such as reductions in electrical conductivity (ECe), sodium absorption ratio and boron content, especially with RW irrigation. For instance, ECe decreased by 51 % and 26 % in the first 30 cm under irrigation with RW and BW, respectively, with regard to its initial soil conditions. Alfalfa yields under RW and BW reached 97 % and 79 % relative to those irrigated with DW in sandy-loam soil, and 92 % and 73 % in clay-loam soil, respectively. This demonstrates the capability of RW to sustain productivity levels close to those achieved with DW, highlighting its potential as a viable irrigation alternative in arid conditions. Nevertheless, irrigation with BW led to a significant reduction in alfalfa yields after the second year, which could become more pronounced over a longer period of use. Mineral analysis of alfalfa showed that irrigation water quality significantly affects the accumulation of nutrients such as iron and boron, which exceeded adequate levels for optimal livestock nutrition. The study's findings underline the importance of tailored water management strategies that optimize the use of marginal waters, ensuring sustainable agricultural practices in water-scarce environments while mitigating potential risks associated with soil salinization and nutrient imbalances.

Soil sodicity, salinity, clay dispersion, and clay soil cracking are significant issues for modern agriculture, especially in arid and semi-arid regions of the world. Sodium adsorption ratio (SAR) has traditionally been used to estimate potential changes in infiltration rates or hydraulic conductivity when sodium cations dominate irrigation water quality. Recent research indicates that the cation ratio of soil structural stability (CROSSf and CROSSopt) provides better predictive capabilities for soil structure and threshold electrolyte concentration than SAR, especially when water used for irrigation or aquifer recharge contains both potassium and sodium cations. In this study, soil columns filled with clay loam were used to assess the impact of recycled water reuse on soil structure stability and saturated hydraulic conductivity. Ten treatments were prepared using chloride solutions of sodium, potassium, calcium, and/or magnesium to create a broad range of synthetic recycled water qualities with varying SAR, CROSSf, and CROSSopt values. After a pre-saturation process, the columns were maintained to have a constant 1 cm head of treatment solutions with a salinity of 1.5 dS/m. The results showed that CROSSf had a stronger correlation with saturated hydraulic conductivity and soil aggregate stability in comparison to CROSSopt and SAR. The R2 for saturated hydraulic conductivity and soil structure were 0.90 and 0.94 for CROSSf, 0.41 and 0.60 for CROSSopt, and 0.75 and 0.78 for SAR, respectively. Notably, the treatments that received solutions with 0-SAR values but contained potassium had significantly more dispersible clay throughout the entire soil column than the treatment that received calcium chloride solution. It was concluded that the CROSSf model could offer enhanced accuracy and insight into predicting the impact of recycled water reuse for irrigation on soil infiltration rate and soil aggregate stability.

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The sodium adsorption ratio (SAR) and cation ratio of soil structural stability (CROSSf) are indices used to characterize sodicity and predict the soil water infiltration hazard. The CROSS differs from SAR in that it includes potassium as an additional dispersion agent and discounts the flocculating power of magnesium. In this study, strawberry growth and development were evaluated under a controlled greenhouse environment in pots filled with clay loam soil. The study objective was to evaluate the correlation between plant growth and development to SAR and CROSSf indices. Treated wastewater was simulated by preparing chloride solutions of different cation compositions (sodium, potassium, calcium and magnesium). In total, 11 treatments were prepared with an EC of 1.5 dS/m. The SAR treatments included values of 0, 4.9, 9.8, and infinity. The same treatments had CROSSf values ranging from 0 to 12.6 and infinity. The cationic composition in the plant and the sugar content of the fruit were also measured. Increased CROSSf had a better correlation with reductions in both average fresh- and dry-biomass with R2 of 0.6 and 0.5 compared with R2 of 0.3 and 0.2 for SAR, respectively. Additionally, CROSSf exhibited a stronger correlation with fruit production, displaying an R2 value of 0.56 in contrast to SAR's R2 value of 0.29. Moreover, the maximum Na, K, Mg, Ca, and Cl the strawberry plants can uptake were 21, 40, 7.7, 24, and 29 parts per thousand, respectively, while the maximum uptake from the slow-release fertilizer was 0 (because the fertilizer does not contain sodium), 14, 5.3, 9.1 and 0 parts per thousand, respectively, based on the plant content at the end of the experiment. We concluded that the CROSSf is an appropriate model for predicting plant sodicity impacts, especially when using recycled water for irrigation with different qualities.

This article presents findings from a field research study conducted in the San Joaquin Valley of California in 2016–2018 to appraise the effects of soil salinity and sodicity on evapotranspiration and energy balance components of micro-irrigated pistachio orchards. Actual evapotranspiration (ET a ) and tree physiologic parameters were measured during consecutive growing seasons in mature orchards grown on non-saline and saline/sodic soils. Salinity and sodicity decreased pistachio water use by about 30%, with ET a reductions varying along the growing season. Accurate information on the dynamics of ET a and energy balance components along the growing season can improve water management for nut orchards exposed to long-term saline-sodic conditions. Results show that the main driver of ET a was the net radiation (Rn), which supplied most of the energy to vaporize water, irrespective of the growth period and level of salinity/sodicity. Field observations revealed that Rn was lower for salt-affected trees due to smaller canopies, which intercepted less light than non-saline trees. Secondarily, the exchange of sensible heat (H) between the ambient air and tree canopies was affected by the interaction between salinity–sodicity and seasonality. Early in the season, salinity and sodicity affected ET a mainly through the reduced canopy growth, which decreased the available energy (Rn–G) for ET a and reduced the water uptake as a result of the lower soil water potential. Late in the season, an increase in H and a decrease in the contribution of the aerodynamic component (β coefficient) to the latent heat flux (LE) occurred, which determined a further reduction of ET a due to a physiological response. The decrease in the β coefficient during the late season was associated with a direct impact of ion accumulation on leaf functionality. Collecting data on the contribution of the aerodynamic component to LE offers a low-cost method to detect and quantify physiological stress, while providing useful information for managing irrigation in salt-affected orchards. The results presented in this article provide insights to improve irrigation management of salt-affected pistachio through integration of weather measurements, energy balance components, and plant-based parameters.

In California, a significant percentage of the pistachio acreage is in the San Joaquin Valley on saline and saline-sodic soils. However, irrigation management practices in commercial pistachio production are based on water-use information developed nearly two decades ago from experiments conducted in non-saline orchards sprinkler-irrigated with good quality water. No information is currently available that quantify the effect of salinity or combined salinity and sodicity on water use of micro-irrigated pistachio orchards, even though such information would help growers schedule irrigations and control soil salinity through leaching. To fill this gap, a field research study was conducted in 2016 and 2017 to measure the actual evapotranspiration (ETa) from commercial pistachio orchards grown on non-saline and saline-sodic soils in the southern portion of the San Joaquin Valley of California. The study aimed at investigating the functional relations between soil salinity/sodicity and tree performance, and understanding the mechanisms regulating water-use reduction under saline and saline-sodic conditions. Pistachio ETa was measured with the residual of energy balance method using a combination of surface renewal and eddy covariance equipment. Saline and saline-sodic conditions in the soil adversely affected tree performance with different intensity. The analysis of field data showed that ETa, light interception by the tree canopy, and nut yield were highly and linearly related (r2 > 0.9). Moving from non-saline to saline and saline-sodic conditions, the canopy light interception decreased from 75% (non-saline) to around 50% (saline) and 30% (saline-sodic), and ETa decreased by 32% to 46% relative to the non-saline orchard. In saline-sodic soils, the nut yield resulted around 50% lower than that of non-saline orchard. A statistical analysis performed on the correlations between soil physical-chemical parameters and selected tree performance indicators (ETa, light interception, and nut yield) revealed that the sodium adsorption ratio (SAR) adversely affected tree performance more than the soil electrical conductivity (ECe). Results suggest that secondary effects of sodicity (i.e., degradation of soil structure, possibly leading to poor soil aeration and root hypoxia) might have had a stronger impact on pistachio performance than did salinity in the long term. The information presented in this paper can help pistachio growers and farm managers better tailor irrigation water allocation and management to site-specific orchard conditions (e.g., canopy features and soil-water salinity/sodicity), and potentially lead to water and energy savings through improved irrigation management practices.

Author(s): Grattan, Stephen R | Abstract: Esta publicacion provee las pautas sobre la tolerancia a la sal que tiene una variedad de cultivos, basada en el uso del agua de cierta calidad a largo plazo y no incluye el agua de lluvia u otras fuentes de agua que pudieran ser usadas para filtrar las sales de la zona de raices. Tambien se aborda el tema de la tolerancia del boro.

Recent prolonged droughts in California have emphasized the urgent need to implement more efficient water management practices for high value tree crops. Accurate estimation of evapotranspiration (ET), a main component of consumptive water use, is critical for improving management of micro-irrigated pistachio orchards grown in the San Joaquin Valley of California. We estimated ET of three mature commercial pistachio orchards on non-saline and increasingly saline soils in 2015 and 2016, using the Mapping Evapotranspiration at high Resolution with Internalized Calibration (METRIC) method and Landsat 8 satellite observations. Based on a comparison with field observations at 8 sites, we modified the parameterizations of the momentum roughness length and net radiation for pistachio tree crops and reduced the uncertainty of daily ET estimates. When compared with field data, the recalibrated METRIC ET estimates had an R-2 of 0.59, a mean absolute error of 1.1 mm/day, and a RMSE of 1.4 mm/day during Landsat overpass dates (n = 72). The METRIC ET map captured the temporal dynamics and spatial heterogeneity both within and among the orchards. The mean annual crop season estimated ET (mid-March to mid-October in 2016) with remote sensing decreased by 32% from 1064 +/- 99 mm in the non-salt affected control orchard to 725 +/- 82 nun in the orchard with the highest level of soil-water salinity. The ET reduction was consistent with canopy volume differences among the study orchards, as shown by summer Normalized Difference Vegetation Index (NDVI) from Landsat observations, e.g., 0.72 +/- 0.06 in the control vs. 0.52 +/- 0.06 in the most saline orchard. The available energy was controlled mostly by canopy features and explained 64% of daily ET variation among all Landsat pixels and satellite overpass days. The normalized differenced water index (NDWI) could be considered as an important parameter to capture the partitioning of available energy for ET (R-2 = 0.38), suggesting that the lower soil osmotic potential in saline orchards further reduced crop ET.

The scarcity of high quality irrigation water is a global issue facing rice growers, forcing many to adopt water management systems that may result in increased salinity and yield reductions. While salt concentrations in field water have been shown to vary depending on water management, the distribution and build-up patterns of dissolved salts are unclear. This study was conducted to elucidate the within field spatial and temporal salinity dynamics in water-seeded rice cropping systems, and to assess current salinity thresholds for rice yield reduction. In this two-year study, water and soil salinity concentrations of eleven field sites were monitored weekly, with three sampling points being established in the top, middle and bottom basins of each field. There was a consistent spatio-temporal water salinity pattern among all fields: the maximum water salinity within a field occurred during week 2 to week 7 after planting, and was greatest farther from the irrigation inlet and where soil salinity was high. A model developed to predict water salinity within a field indicates that, averaged over an entire growing season, the position within a field contributed to 82% of the variation explained by the model, while preseason soil salinity contributed to 18%. Importantly, field water salinity was determined to be the most sensitive salinity metric for rice yield, as preseason soil salinity was a poor predictor of yield loss. The threshold field water salinity concentration was estimated at 0.88 dS m(-1), lower than the previous report of 1.9 dS m(-1). These results illustrate the ability to predict water salinity in a rice field with few parameters, while highlighting the importance of field water salinity as the main salinity metric for rice cropping systems. (c) 2017 Elsevier B.V. All rights reserved.

Salinity can be a greater problem in shallow soilless media than in field soils because of the small root zone volume that commonly occurs in such systems. Clonal integration (the capability of reciprocal resource trans location among interconnected plantlets through their shared stolon) can alleviate salinity injury in strawberry (Frctgaria x ananassa 'Albion'). Here we report the effect of clonal integration on leaf area, shoot and root dry biomass, net CO2 assimilation rate (A(N)), stomatal conductance (g(s)), intercellular CO2 (ci), transpiration (E), and instantaneous water use efficiency (WUE). Interconnected mother-daughter pairs of strawberry plants were grown in stirred solution culture under greenhouse conditions. Combinations with independent salinity levels on the mother and daughter side were imposed in a 4 x 3 complete randomized factorial design. Salinity levels of 1, 3, 6 and 9 dS m(-1) were established by adding calcium chloride (CaCl2) and sodium chloride (NaCl) as needed to a 1 dS/m nutrient solution. Interconnected daughter plants grew in 0.2 CaSO4, or the 1 dS m(-1) nutrient solution, or the same solution supplied to the mother plant. Values of all measured attributes decreased with salinity, with the exception of C-i, which increased at the highest salinity combination of mother and daughter plants. In contrasting salinity conditions, clonal integration ameliorated salt stress in mother plants through water transfer from daughter to mother plants. Interclonal resource translocation was mainly driven by the contrast in stress intensity between mother and daughter plants.

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Most soils cultivated for crop production fall within the pH range of pH 6-8, where nutrient availability to the plant is typically optimal. Profoundly acid soils (pH<5.5) and alkaline soils (pH >8), however, fall outside this optimal pH range and pose challenges for the plant such as low nutrient availability, ion toxicities and nutrient imbalances. The characteristics of acid and alkaline soils are described. Among the alkaline soils one needs to differentiate between calcareous (pH >7.5) and sodic (exchangeable sodium percentage, ESP >15) soils, as they present a different set of challenges. Most nutrients are not equally available to plants across the pH spectrum. Several mineral nutrients are severely affected in these non-optimal pH soils, particularly Ca, K, P and Fe. The reactions of plants to these nutrient elements under extreme soil pH conditions are discussed in detail, with emphasis on plant growth, morphological, physiological and membrane transport processes. Finally, a special case is presented of the recently discovered complex interactions between salinity, boron-toxicity and pH in plants.

Author(s): Grattan, Stephen R | Abstract: In many areas of California, salinity can have a detrimental impact on irrigated crops which can be exacerbated under drought conditions. While all soils and irrigation water contain dissolved salts, these salts vary in both concentration and composition depending on their location. Vegetable and row crops have varying degrees of tolerance to soil salinity, and soil salinity is influenced by the salinity of the irrigation water and management practices. This publication provides salt tolerance guidelines for a variety of crops, based on the long-term use of the given water quality and do not account for rainfall or other sources of water that could be used to leach salts from the root zone. Boron tolerance is also discussed.