Rice growth and yield response to salinity can be influenced by the duration and the timing of salt stress. The present study tested the effects of saline water irrigation from vegetative growth to maturity on rice growth and yield and ion concentrations in the straw and root and related them to changes in soil salinity and soil solute potential. The treatments consisted of five levels of saline water irrigation (electrical conductivity similar to 0.25 (control), 4, 6, 8, and 10 dS m(-1)) with two rice cultivars (BRRI dhan67 and BRRI dhan99) grown in pots in a rain shelter. Grain weight per pot, dry straw weight, and root weight were significantly reduced with increasing water salinity, but BRRI dhan99 was less affected. With prolonged saline water irrigation, salt concentration increased in the soil and lowered the soil solute potential. Increased saline water induced higher concentrations of Na+ in the straw (527-1200 mmol kg(-1) at 4-10 dS m(-1)) relative to the root. By contrast, higher Cl- concentrations accumulated in the root than in the straw. The decrease of K+ in the straw and root for increasing salinity was inconsistent, but the Na+/K+ ratio sharply increased in the straw with higher water salinity. The increased Na+/K+ explained most grain weight loss due to higher salinity (R-2 = 0.93) followed by Na+ (R-2 = 0.87) and Cl-1 (R-2 = 0.53). We conclude that the prolonged saline water irrigation has a cumulative effect on root zone salinity and solute potential that depresses grain yield in rice by increasing the Na+/K+ ratio in plants.

Background: Soil and water salinity are increasing problems worldwide, causing significantly reduced crop yields. Alfalfa (Medicago sativa L.) is often listed as salt-sensitive, but field testing of improved cultivars is limited. Forage systems and improved high-quality alfalfa varieties are needed to enable crop production under high salinity (HS) conditions. Methods: The objective of this study was to measure the yield and quality response of alfalfa to high saline conditions in the field and to document the relative saline tolerance of its varieties. HS irrigation water (electrical conductivity of water, or ECw 8.0-11.0dSm(-1)) was applied to 33 nondormant alfalfa cultivars and were compared with low salinity (LS) treatments (ECw 0.5-1.2dSm(-1)) over 4 years in a Mediterranean environment on a clay loam soil utilizing a split-plot design. Crops were harvested seven to eight times per year, and the forage quality was measured on selected harvests utilizing near-infrared spectroscopy. Results: The average yield loss due to HS treatment was 23.9% compared with LS treatment, but yields averaged 23.4Mgha(-1) under HS over the 3 full years of production. This level of production is considered to be economically viable in this region. Differences in salinity tolerance between lines were identified in the field; individual cultivars lost 5%-35% of their LS yield when grown under HS conditions. Forage quality was significantly improved under HS versus LS conditions, but improvements were negatively correlated with biomass yield (R-2>0.81), similar to responses observed in drought-stressed alfalfa. Conclusions: These yield results confirm greenhouse studies, indicating that alfalfa is highly salt tolerant once established in the field, with potential for further improvement with tolerant cultivars. Salinity tolerance should be chosen based on total biomass yield as well as on the salinity tolerance index (HS yield relative to LS yield). Agronomic practices to mitigate salinity and sodicity are critical, along with improved cultivars.

Environmental policies to address water quality impairments in the San Joaquin River of California have focused on the reduction of salinity and selenium-contaminated subsurface agricultural drainage loads from westside sources. On 31 December 2019, all of the agricultural drainage from a 44,000 ha subarea on the western side of the San Joaquin River basin was curtailed. This policy requires the on-site disposal of all of the agricultural drainage water in perpetuity, except during flooding events, when emergency drainage to the River is sanctioned. The reuse of this saline agricultural drainage water to irrigate forage crops, such as ‘Jose’ tall wheatgrass and alfalfa, in a 2428 ha reuse facility provides an economic return on this pollutant disposal option. Irrigation with brackish water requires careful management to prevent salt accumulation in the crop root zone, which can impact forage yields. The objective of this study was to optimize the sustainability of this reuse facility by maximizing the evaporation potential while achieving cost recovery. This was achieved by assessing the spatial and temporal distribution of the root zone salinity in selected fields of ‘Jose’ tall wheatgrass and alfalfa in the drainage reuse facility, some of which have been irrigated with brackish subsurface drainage water for over fifteen years. Electromagnetic soil surveys using an EM-38 instrument were used to measure the spatial variability of the salinity in the soil profile. The tall wheatgrass fields were irrigated with higher salinity water (1.2–9.3 dS m−1) compared to the fields of alfalfa (0.5–6.5 dS m−1). Correspondingly, the soil salinity in the tall wheatgrass fields was higher (12.5 dS m−1–19.3 dS m−1) compared to the alfalfa fields (8.97 dS m−1–14.4 dS m−1) for the years 2016 and 2017. Better leaching of salts was observed in the fields with a subsurface drainage system installed (13–1 and 13–2). The depth-averaged root zone salinity data sets are being used for the calibration of the transient hydro-salinity computer model CSUID-ID (a one-dimensional version of the Colorado State University Irrigation Drainage Model). This user-friendly decision support tool currently provides a useful framework for the data collection needed to make credible, field-scale salinity budgets. In time, it will provide guidance for appropriate leaching requirements and potential blending decisions for sustainable forage production. This paper shows the tie between environmental drainage policy and the role of local governance in the development of sustainable irrigation practices, and how well-directed collaborative field research can guide future resource management.

The gradual increase in the amount of land and water resources affected by salt in arid and semi-arid regions requires strategies to optimize the use of these marginal-quality resources. Recent field and greenhouse experiments have demonstrated the potential of growing certain 'pre-selected' varieties of alfalfa in highly saline conditions. A greenhouse study was conducted to determine the impact of irrigation with saline groundwater on alfalfa growth and production in saline-sodic soils. The sustainability of the system in terms of forage yield and quality was also evaluated. The study included three varieties of alfalfa (Medicago sativa, vars. SW8421S, PGI908S and WL656HQ) planted in pots filled with saline-sodic soil (Calcic Haplosalids) collected on the island of Lanzarote (Spain) and irrigated for 18 months with increasingly saline water. Although the yield of the alfalfa varieties was reduced by an average of 7, 20, 31 and 46% as the salinity of the irrigation water increased from 0.4 dS m(-1) to 2.5,5.0, 7.5 and 10.0 dS m(-1), respectively, their relative salt tolerance, based on the average electrical conductivity of the saturated soil extract (ECe), was much higher than those established in the literature. Based on their nutritional quality, all alfalfa varieties are categorized as 'supreme' quality, with metabolizable energy (ME) values in excess of 10 MJ kg(-1). Moreover, no detriment to quality was observed at the higher levels of irrigation water salinity. Mineral composition analysis revealed S, K and B levels near or above the established maximum tolerable levels (MTLs) suggesting that this forage could only be safely consumed by ruminants over the long term if combined with other forages with lower mineral content. (C) 2017 Elsevier B.V. All rights reserved.

Due to its potential toxicity to wildlife, selenium (Se) is a highly regulated trace element in the San Joaquin Valley (SJV) of California. Tall wheatgrass (TWG) is a Se-accumulating, salt tolerant forage suitable for cropping systems which re-use agricultural drainage waters. Utilization of TWG hay as an alternative Se supplement for dairy cattle could reduce the importation of 'new' Se into the SJV in the form of sodium selenite (SS) diet supplements. Our study used Se-enriched (4.65 mg/kg DM) TWG hay as a Se source for lactating dairy cows and measured Se accumulation in milk, blood, urine and feces to assess its bioavailability using several indices. Using a 3×3 Latin Square design, three pens of ~310 cows each were fed a similar total mixed ration over 4 week periods, except for Se which was higher in TWG and SS diets (0.53 and 0.65 mg/kg DM) vs. Control diet (0.35 mg/kg DM). Feeding Se-enriched TWG increased blood Se by 6.4% over Control; whereas SS increased it by 4.8%, suggesting higher Se bioavailability for TWG vs. SS. Marginal Se outputs in milk, feces and urine were judged to be better indicators of bioavailability as they estimate Se specifically from supplemental SS or TWG hay. In milk, TWG cows expressed 3.0% of supplemented Se vs. 0.6% for SS cows, supporting higher Se bioavailability for TWG. In contrast, more supplemental Se was retained and not expressed in feces by the SS cows (72.5%) vs. TWG cows (55.1%) which suggested higher Se bioavailability for SS. Based on published guidelines, Se intakes were 'adequate' for cows in all treatment groups, but milk and fat production increased with Se supplementation suggesting that Control cows were Se-deficient to some extent. Collectively, results suggest that the Se in TWG hay had comparable bioavailability to Se in the base diet.

Beef heifers which had grazed 'Jose' tall wheatgrass (TWG; Thinopyrum ponticum var. 'Jose'; 10 heifers) and creeping wildrye (CWR; Leymus triticoides var. 'Rio'; 10 heifers) with high levels of Se (>2 mg/kg DM) due to growth in saline soils, accumulated high Se levels in blood, liver and muscle (Juchem et al., 2012). We determined the decrease in Se levels in blood, liver and muscle from these heifers, particularly the decrease of Se in muscle, in order to determine the maximum feeding length of a low Se diet (LSeD) required sustaining Se-enriched beef. Immediately after grazing, all heifers were fed a LSeD containing <0.30 mg/kg DM for 209 d. Blood, liver and muscle samples, as well as body weight (BW), were collected at the beginning and end of the LSeD feeding period and at intermediate times. After grazing, CWR and TWG heifers had similar BW, but TWG heifers had higher levels of Se in whole blood (1.19 versus 0.81 mg/L), liver (2.67 versus 2.12 mg/kg wet weight (WW)), and muscle tissue (0.87 versus 0.63 mg/kg WW) than CWR heifers. The Se levels decreased with exposure time to the LSeD and, at 82 d of feeding the LSeD, Se levels were 77 (liver), 49 (blood) and 31% (muscle) lower. The BW gains for both groups were ~0.5 kg/d during the first 82 d of feeding, but increased thereafter. Levels of Cu in serum (0.28 versus 0.50 mg/L) and liver (1.14 versus 22.9 mg/kg WW) were lower at the end of grazing in TWG heifers, and suggested a potential Cu deficiency. Grazing forages with high Se levels can result in Se-enriched beef, but a LSeD feeding period of <82 d is required to maintain enrichment.

Halophytes have been considered as potential crops for the reuse of saline drainage water (DW) in the western portion of California's San Joaquin Valley. This management strategy can reduce drainage volumes through plant water consumption and concentrate salts and other contaminants prior to discharge of the final effluent into a solar evaporator. A field study was conducted in order to assess the performance of six halophytes species Salicornia bigelovii, Atriplex lentiformis, Distichlis spicata, Spartina gracilis, Allenrolfea occidentalis and Bassia hyssopifolia, under long-term irrigation (4-6 years) with saline (Na-sulfate dominated) agricultural DW. The suitability of the halophytes was evaluated in terms of biomass production, water consumption, mineral composition and nutritional quality as animal fodder. Results indicate that all species grew well under highly saline-sodic soil conditions (average ECe, = 28.6 dS m(-1); SAR = 39.4), with average standing biomass ranging between 3.8 and 17.4 tons dry matter (DM) ha(-1) depending on species. Under frequent irrigation in drainage lysimeters, daily evapotranspiration (ET) rates for the halophytes were 1.02-1.18 times higher than reference ET (ET0). For S. bigelovii daily ET rates were similar to that of a non-halophytic grass, Festuca arundinacea, irrigated with fresh water (7.5 mm day(-1) vs. 7.4 mm day(-1). Mineral composition and forage quality data indicate several drawbacks associated with the utilization of DW-irrigated halophytes as forages. All species had metabolizable energy (ME) values lower than 7 MJ kg(-1) DM, the minimum value considered to be acceptable quality for most classes of ruminant animals. Additionally, halophyte tissues contained high levels of salts (total ash content ranged between 6 and 52%), and accumulated Na+, Cl-, SO42-, NO3-, B and Se to levels close or above the maximum tolerable levels (MTL). Halophytes tested in this study can be classified as very low quality forage for which long-term grazing is not recommended. However, they could be used as a fodder supplement, if rations can be controlled. (C) 2013 Elsevier B.V. All rights reserved.

Two experiments were conducted to evaluate Se accumulation and health of non-pregnant, non-breeding beef cattle grazing on forages with a high Se content due to irrigation with saline drainage water. Heifers grazed experimental pastures of "Jose" tall wheatgrass (TWG; Thinopyrum ponticum var. "Jose") and creeping wildrye (CWR; Leymus triticoides var. "Rio") for 190 days in Experiment 1 (2007) and for 165 days in Experiment 2 (2008). In experiment 1, mean Se concentrations were similar in TWG and CWR herbage (4.0 versus 3.7 ± 0.26 mg/kg dry weight; p=0.34) as was crude protein (113 versus 114 ± 7.9 g/kg dry weight; p=0.94). Concentrations of Se in blood increased by 300% during the grazing period, and were similar for heifers grazing the TWG or CWR pastures (0.94 versus 0.87 ± 0.03 mg/kg; p=0.89). Heifers grazing on TWG gained more body weight than did heifers grazing on CWR (0.59 versus 0.27 ± 0.07 kg/days; p<0.01). In experiment 2, concentration of Se (4.0 versus 2.8 mg/kg ± 0.19 mg/kg dry weight; p<0.01) and crude protein (79 versus 90 ± 5.6 g/kg dry weight; p<0.01) differed, for TWG and CWR, respectively. Within 20 days, Se concentrations in blood had increased by 300% and by nearly 200% in heifers grazing on TWG or CWR. All data cited are least square means ± standard error of the mean. Data from our two grazing seasons are consistent in demonstrating the safety of grazing beef cattle for a period of up to 6 months on TWG and CWR forages having high levels of Se due to irrigation with saline drainage water. This suggests that forage production using saline drainage water is a viable alternative for saline soils with limited potential for producing high value, salt-sensitive, crops.

In the western San Joaquin Valley (SJV) of California, re-use of saline-sodic drainage water (DW) for the irrigation of salt tolerant forages and field crops is an important strategy for drainage water reduction and to extend irrigation water supplies. Drainage reuse designs require estimates of crop water use under saline conditions, so this study employed two methods to estimate the actual evapotranspiration (ETa) of saline-irrigated forages. Using sand-filled drainage lysimeters, ET was measured for ‘Jose’ tall wheatgrass (TWG; Thinopyrum ponticum var. ‘Jose’) creeping wildrye (CWR; Leymus triticoides, var. ‘Rio’) and Paspalum (Paspalum vaginatum, var. ‘SeaIsle’) irrigated with saline DW with an electrical conductivity (EC) averaging 13.2dSm−1. Annual ET in 2005 (20 January to 28 December) was 1470mm for TWG, 1376mm for CWR, and 1275mm for Paspalum. Comparing to standardized reference evapotranspiration (ETo), the annual (ETa/ETo)lys ratios in 2005 were 0.98 for TWG, 0.92 for CWR, and 0.85 for Paspalum. Forage ET was also estimated by a surface renewal (SR) method in large pastures of TWG and CWR irrigated with saline DW. For TWG, the seasonal (ETa/ETo)SR in 2005 was 0.94, slightly lower than the ratio of 0.98 determined by lysimetry. For CWR, the seasonal (ETa/ETo)SR was only 0.73 in 2005; however, in 2006 it was 1.03 which was closer to the ratio of 0.92 determined by lysimetry in 2005. Conditions were less uniform in the CWR pasture as compared to the TWG pasture which may have caused the greater variability in (ETa/ETo)SR for this forage. These findings, along with earlier work, demonstrate that tall wheatgrass, creeping wildrye and Paspalum are suitable candidates for DW re-use systems for the western SJV due to their high ET under saline irrigation and adequate dry matter production and forage quality.

Reuse of drainage water (DW) for irrigation reduces the volume of DW requiring treatment or disposal. We conducted a greenhouse study to evaluate the performance of the halophyte Salicornia bigelovii Torr. when irrigated with hyper-saline DW and seawater (SW) treatments, ranging from 1/3 strength to full strength (18-49 dS m(-1)), in a sand-culture system. Results indicate that Salicornia grows well over the entire range of iso-osmotic SW and DW salinity treatments. Moreover, when boron (B) was added to SW treatments to concentrations equivalent to that of corresponding 1/3- and 2/3-strength DW treatments (i.e., 9 and 17 mg L(-1)), growth was not affected, and tissue B concentrations were <150 mg kg(-1) dry wt. However, when plants were irrigated with synthetic DW where B was reduced to solution culture levels (0.5-1.0 mg L(-1)), plants generally performed worse than when irrigated with actual DW high in B at the same salinity level. Evapotranspiration (ET) rates exceeded that lost from an evaporation pan from 1.5 to 2.5 times. Using a method accounting for changes in the isotopic signature of water in the reservoir due to evaporation, we estimated that high ET rates were due primarily to high transpiration rates (>78% of ET). The salt content in the tissue was very high (ash content 43-52%), but ionic composition in the shoot tissue reflected that of the treatment water used to irrigate the plants. These data indicate that hyper-saline DW, characteristic of California's San Joaquin Valley, can be used to irrigate Salicornia and substantially reduce drainage volumes.

The use and disposal of biosolids, or wastewater treatment sludge, as a fertilizer and soil amendment is becoming increasingly widespread. We evaluated the multiyear use of biosolids in apricot ( Prunus armeniaca L.) production, grown on productive agricultural soils. Class A biosolids were initially applied annually at rates of 0, 1.9, 5.8, and 11.7 Mg. ha(-1) ( dry basis) to a 2-year- old apricot orchard on the USDAARS research site on the eastern side of the San Joaquin Valley, CA. These application rates provided estimated rates of 0 ( control), 57, 170, and 340 kg total N. ha(-1) yr(-1), respectively. Compared to the control treatment, the applications of biosolids significantly increased soil salinity ( electrical conductivity from 1: 1 soil - water extract) and total concentrations of nutrients [ e. g., calcium ( Ca), magnesium ( Mg), sulfur ( S), phosphorus ( P), zinc ( Zn), and copper ( Cu)] after 7 years but did not increase the concentrations of selected metals [ cadmium ( Cd), chromium ( Cr), cobalt ( Co), nickel ( Ni), and lead ( Pb)] between 0- and 60- cm soil depths. Mean concentrations of total nitrogen ( N) and carbon ( C) in soils ( 0- to 15- cm depth) ranged from a low of 1.3 g kg(-1) to a high of 5.2 g. kg(-1) and from 14.1 g. kg(-1) to 45.7 g. kg(-1) for the control and high biosolids treated soils, respectively.