Showing papers on "Soil salinity published in 1985"

Ecophysiological adaptations of coastal halophytes from foredunes and salt marshes

Abstract: Ecophysiological strategies of coastal halophytes from foredunes and salt marshes are discussed. A comparison is made of the factors that limit growth in salt marshes and sand dunes. In salt marshes, zonation and succession are primarily governed by variation in soil salinity, which strongly depends on inundation with seawater. Results are described of experiments which aim at separating salinity and inundation effects on growth, osmotic and mineral relations in a comparison of salt-marsh halophytes. The growth response of plants cannot simply be correlated (and causally explained) with the concentration of Na, Cl, and K in the tissues. Also, the compatible osmotic solutes proline and methylated quaternary ammonium compounds may accumulate both in species with a positive response to increased salinity and in species with a growth reduction under seawater inundation. More likely inadequate adaptation of the plants water potential with these components is partly the cause of retarded growth. Disfunctioning of the plant in this respect may be at three levels: (a) total water potential of the plant, (b) (loss) of turgor pressure potential; (c) regulation at the cellular level.

Principles and strategies in breeding for higher salt tolerance

Abstract: Salinity is an environmental component that usually reduces yield. Recent advances in the understanding of salt effects on plants have not revealed a reliable physiological or biochemical marker that can be used to rapidly screen for salt tolerance. The necessity of measuring salt tolerance based upon growth in saline relative to non-saline environments makes salt tolerance measurements and selection for tolerance difficult. Additionally, high variability in soil salinity and environmental interactions makes it questionable whether breeding should be conducted for tolerance or for high yield. Genetic techniques can be used to identify the components of variation attributable to genotype and environment, and the extent of genetic variation in saline and nonsaline environments can be used to estimate the potential for improving salt tolerance. Absolute salt tolerance can be improved best by increasing both absolute yield and relative salt tolerance.

The impact of grazing on plant communities, plant populations and soil conditions on salt marshes

Abstract: Grazing an abandoned salt marsh causes retrogressive succession, since mid salt-marsh communities change into lower salt-marsh communities. Grazing and mowing are compared in detail. Both management practices enhance species diversity in an abandoned salt marsh. This can be attributed to the removal of litter. The finding that lower salt-marsh species appear more with grazing than with mowing or abandoning is not related to a higher soil salinity as compared to mowing or abandoning, but probably to locally baring of the soil by grazing animals. Only species of pioneer or unstable environments seem to have a persistent seed bank, for other species seed dispersal seems to be a limiting factor for their establishment.

Crop tolerance to saline sprinkling water

Abstract: Crops sprinkled with saline irrigation water are subject to foliar salt absorption and injury as well as to injury from soil salinity. Yield reductions caused by soil salinity alone are well documented, and data are presented here for 71 agricultural crops. Factors affecting these data and their applicability to sprinkler-irrigated crops are discussed. Although foliar injury has been observed with many sprinkled crops, particularly tree crops, essentially no information is available to predict yield losses as a function of the salt concentration of the irrigation water. Salinity thresholds for sprinkling-induced foliar injury are estimated for some crops; however, climatic conditions greatly affect the onset and degree of injury. Management strategies that minimize sprinkling injury are mentioned.

Effect of salinity on mycorrhizal onion and tomato in soil with and without additional phosphate

Abstract: Vesicular-arbuscular mycorrhizal fungi (VAM) are known to increase plant growth in saline soils. Previous studies, however, have not distinguished whether this growth response is due to enhanced P uptake or a direct mechanism of increased plant salt tolerance by VAM. In a glasshouse experiment onions (Allium cepa L.) were grown in sterilized, low-P sandy loam soil amended with 0, 0.8, 1.6 mmol P kg−1 soil with and without mycorrhizal inoculum. Pots were irrigated with saline waters having conductivities of 1.0, 2.8, 4.3, and 5.9 dS m−1. Onion colonized withGlomus deserticola (Trappe, Bloss, and Menge) increased growth from 394% to 100% over non-inoculated control plants when soil P was low (≤ 0.2 mmol kg−1 NaHCO3-extractable P) at soil saturation extract salinities from 1.1 dS m−1 to 8.8 dS m−1. When 0.8 and 1.6 mM P was added no dry weight differences due to VAM were observed, however, K and P concentrations were higher in VAM plants in saline treatments.Glomus fasciculatum (Gerdeman and Trappe) andGlomus mosseae (Nicol. and Gerd.) isolates increased growth of VAM tomato 44% to 193% in non-sterilized, saline soil (10 dS m−1 saturation extract) despite having little effect on growth in less saline conditions when soil P was low. Higher tomato water potentials, along with improved K nutrition by VAM in onion, indicate mechanisms other than increased P nutrition may be important for VAM plants growing under saline stress. These effects appear to be secondary to the effects of VAM on P uptake.

Soil Nitrogen Transformations as Affected by Salinity

Abstract: The results presented in this paper reveal that salinity has a major influence on soil N transformations. Studies were conducted to test the effects of Na2SO4, NaCl, and CaCl2, applied at rates that produced electrical conductivities of saturation extracts (ECe) of 5, 10, 15, and 20 dS m−1, on ammon

Soil Salinity Under Irrigation: Processes and Management

Abstract: 1 Introduction.- 1.1 Impact of Salinity on the Development of Soil Science.- References to Chapter 1.- I Soil Salinity under Irrigation - Processes.- 2 Basic Chemistry of Salinity.- 2.1 Salt-Affected Soils: Thermodynamic Aspects of the Soil Solution.- 2.2 Colloid Properties of Clay Minerals in Saline and Sodic Solution.- References to Chapter 2.- 3 Chemical Reaction and Control of Soil Physical Properties.- 3.1 The Effect of Electrolyte Concentration on the Hydraulic Properties of Sodic Soils..- 3.2 Soil Structure in Saline and Sodic Soils.- 3.3 Potassium, Magnesium and Boron in Soils under Saline and Sodic Conditions.- References to Chapter 3.- 4 Movement and Accumulation of Salts in Soils.- 4.1 Salt and Water Movement in the Soil Profile.- 4.2 Field Scale Water and Solute Transport Through Unsaturated Soils.- References to Chapter 4.- 5 Diagnostic Criteria and Methodology.- 5.1 Principles and Methods of Monitoring Soil Salinity.- 5.2 Reassessment of Water Quality Criteria for Irrigation.- References to Chapter 5.- II Soil Salinity under Irrigation - Management.- 6 Irrigation Management and Field Salt Balance.- 6.1 Leaching for Salinity Control.- 6.2 Drainage Design for Salinity Control.- 6.3 Spatial Variability Considerations in Salinity Management.- References to Chapter 6.- 7 Reclamation of Sodic Soils.- 7.1 Amendments for Reclaiming Sodic Soils.- 7.2 Simulation Modeling for Reclamation of Sodic Soils.- References to Chapter 7.- 8 Management Aspect for Crop Production.- 8.1 Analysis of Crop Salt Tolerance Data.- 8.2 Prediction of Crop Yield and Water Consumption under Saline Conditions.- 8.3 Plant Response to Salinity: Experimental Methodology and Application to the Field.- 8.4 Management of Irrigation with Brackish Water.- 8.5 Plant Nutrition under Saline Conditions.- References to Chapter 8.

Salt tolerance of rice cultivars

Abstract: The dry matter production and the concentration of nutrients in rice (Oryza sativa L.) cultivars from soil adjusted to different levels of salinity were evaluated under a greenhouse conditions. Soil salinity levels were produced by applying 0.34 mol l−1 solution of NaCl which resulted in the following levels, control (0.29), 5, 10 and 15 dS m−1 conductivity of saturation extract. The effect of salinity on dry matter production varied from cultivar to cultivar.

Drip irrigation of cotton with saline-sodic water

Abstract: A two-year study was conducted in the Negev region of Israel, using the drip method, to determine the effect of four levels of water quality (EC =1.0, 3.2, 5.4 and 7.3 dS/m) in combination with three soil amendment treatments (gypsum spread on the soil surface along the drip laterals after planting, injection of H2SO4 into the water during each irrigation, and a control) on plant response, salt distribution in the soil profile, and soil sodification processes. Salinity did not reduce yields even at the highest level, in spite of sodium and chloride accumulation. The highest seed cotton yield (6.4 t/ha) was obtained with the local well water (EC =3.2 dS/m), indicating an optimal response to salinity. The addition of soil amendments during the irrigation season, although reducing exchangeable sodium accumulation near the emitter, endangers the next crop by increasing sodium accumulation under the plant row. It is therefore, recommended that the amendment be applied only before the winter.

Crop production and management under saline conditions

Abstract: This review evaluates management practices that may minimize yield reduction under saline conditions according to three strategies: (I) control of root-zone salinity; (II) reduced damage to the crop; (III) reduced damage to individual plants. Plant response to salinity is described by an unchanged yield up to a threshold soil salinity (a), then a linear reduction in relative yield (b), to a maximum soil salinity that corresponds to zero yield (Y0). Strategies I and II do not take into consideration any change in the parameters of the response curve, while strategy III is aimed at modifying them.

Assessment of Long-Term Salinity Changes in an Irrigated Stream-Aquifer System

Abstract: Changes in salinity in groundwater and surface water in the Arkansas River valley of southeastern Colorado are primarily related to irrigation practices. A solute transport model was applied to an 11-mile reach of the valley to compute salinity changes in response to spatially and temporally varying stresses. The model was calibrated in 1973 using detailed field measurements made during 1971 and 1972. In 1973 the calibrated model was used to predict that a gradual long-term increase in groundwater salinity of about 2–3% per year would occur if the observed irrigation practices continued. The study area was resampled during the winter of 1982 to help evaluate if any long-term changes in salinity are actually occurring. Nonparametric and parametric statistical tests were used to help assess the significance of observed changes in groundwater salinity. These tests indicate that a statistically significant increase in salinity occurred between the winters of 1971 and 1972 (the model calibration period). However, a comparison of the winter 1972 and winter 1982 data indicates that no significant net change in salinity has occurred during this 10-year period. An analysis of the few available historical data (1895, 1923, 1959–1961, and 1964) supports the hypothesis that groundwater salinity in this irrigated area has reached a long-term dynamic equilibrium in response to irrigation practices. The model predictions of long-term salinity increases were invalid probably because the calibration period occurred during a short-term annual trend of increasing salinity in the river (and hence in leaky irrigation canals and in applied irrigation water), which was not representative of the long-term trend.

Economic halophytes — a global review

Abstract: Not less than about 400 million ha and perhaps as much as 950 million ha of land in arid and semi-arid regions may be salt-affected from natural and anthropogenic causes (Massoud 1974, Ponnamperuma 1977). Definitive data on the annual worldwide loss of farmland due to salinization and related causes is lacking. However salinity is unquestionably the most important problem of irrigated agriculture (Dregne 1977), and one-fifth of the irrigated lands of the world, approximately 47 million ha, is salt-affected today (Maas & Hoffman 1977).

Salinity pollution from irrigated agriculture

Abstract: SALINITY pollution is not a recent phenomenon resulting from industrialization or the modernization of agriculture, but an age-old problem of irrigated agriculture thought to have caused the decline of certain ancient civilizations. Six thousand years ago, on the Tigris-Euphrates floodplain in Mesopotamia, Sumerian irrigation practices caused a salt build-up in water and soils that inhibited food production and no doubt contributed to the decline of Sumerian culture. In the American Southwest, the decline of Indian civilizations, centuries ago, is also attributed to salinization of land and water. Soil and water salinity occur in arid and semiarid regions wherever irrigated agriculture is practiced. Today, salinity seriously affects productivity on about 50 million acres (20 million hectares) of the worlds irrigated land ( 14 ). In the United States, an estimated 20 to 25 percent of all irrigated land [about 10 million acres (4 million hectares)] suffers from salt-caused yield reductions ( 2 ). Though less menacing than pollution from heavy metals or toxic organic compounds, salinity constitutes the most serious water quality problem in many arid and semiarid river basins. In the United States, irrigated agriculture in 1977 accounted for 82 percent of all water consumption, 47 percent of all diversions …

Performance of some forest tree species in saline soils under shallow and saline water-table conditions.

Abstract: Field studies were carried out to study the influence of seasonal variations in salinity and soil moisture profiles due to fluctuating water table on the performance of 16 tree species. Over a yearly cycle water table having an EC of 2–46 mmhos/cm fluctuated between 10–140 cm from the surface. Seasonal variation in salinity profiles indicated that subsurface planting (30 cm below surface) provides less hostile saline environment to the roots. Due to genetic differences, species of trees differed in their ability to withstand salinity and aeration stresses individually and simultaneously. In areas where salinity is not associated with high water table conditions, tree species likeAcacia auriculiformis, Terminalia arjuna andLeucaena leucocephala can be grown. Tree species likeCasuarina equisetifolia Tamarix articulata andProsopis juliflora can be planted where high salinity or high water table conditions exist separately or simultaneously. If planting occurs on ridges,Acacia auriculiformis, Acacia nilotica andTerminalia arjuna can also be grown in these conditions.

Distribution of VA mycorrhiza on halophytes on inland salt playas

Abstract: The value of mycorrhizal association for higher plants has been well established. However, the impact of high salinity on the mycorrhizal relationship has not been investigated to any great extent. Inland salt playas represent an opportunity to test the impact of salinity because it is possible to obtain a gradient by following a transect from the centre of the salt playa to the higher outer zones. In a salt playa near Goshen, Utah, the sodium concentration ranged from 27,150 ppm in the centre to 25 ppm in the outer zone. In the playas with sodium concentrations of 20,000 ppm, no mycorrhiza were detected on the halophytes and no spores of mycorrhizal fungi were found in the soil. One percent of the roots of salt grass in soils containing 8,450 ppm of sodium were mycorrhizal. In soils containing 622 ppm of 45 percent of the roots of a salt-tolerant grass (hybrid ofAgropyron repens × Agropyron spicatum) were mycorrhizal. Halophytes such asSalicornia pacifica var.utahensis which are among the most salt tolerant halophytes of the inland salt playas rarely had mycorrhizal roots. The mycorrhizal associations appear to be very limited in inland salt playas with sodium content.

Prediction of leaching fraction from soil properties, irrigation water and rainfall

Abstract: Fine textured soils (> 40% clay) form a major proportion of irrigated soils in northeastern Australia. More than half these soils are irrigated with groundwater, some of which has high salinity (electrical conductivity > 2.9 mS cm−1). A simple prediction of salt leaching was sought to aid in land management decisions.

Evapotranspiration of citrus as affected by soil water deficit and soil salinity

Abstract: The extent to which evapotranspiration (ET) of Valencia citrus trees is affected by differing soil water depletions (SWD) and soil salinity regimes was determined during five seasons during which soil salinity levels varied. Three weighing lysimeters, each with a 14 year old tree, were used to measure daily ET and to schedule irrigation to maintain SWD at maxima of 15, 75 and 150 mm respectively. Tensiometers and salinity sensors were used to indicate the in situ soil matric and soil solution osmotic potentials. Total soil water potential was calculated from tensiometer and salinity sensor readings weighted for root density with depth. The total of these for the summer months was found to be linearly related (Fig. 5) to the mean ET/Ep (Ep=A-pan evaporation). The slope and threshold of ET reductions with decreasing soil water potential for the low frequency irrigation treatment (150 mm SWD) show good agreement with the slope and threshold of yield decrease that is calculated from soil salinity in the lysimeter using previously reported salinity-yield relationships. The reduced water uptake due to increasing soil salinity has important implications for soil salinity control, since the lower uptake should in theory increase the leaching fraction. This implies a degree of self adjustment to the leaching fraction when irrigating with increasingly saline waters if water applications are scheduled as for non-saline conditions.

Breeding for salinity tolerance in rice

Abstract: Soil salinity was one of the major rice production constraints in South and Southeast Asia. The most relevant strategy was the genetic manipulation of plants to breed salt-tolerant varieties. Efforts to breed for salinity tolerance had been attempted but the progress was slow due to limited knowledge of the genetics of salt tolerance; inadequate screening and selection methods, and poor understanding of interaction of salinity and environments. Rice was moderately sensitive to salinity, threshold being EC3 dS/in beyond which yield starts decreasing. Salinity inflicted osmotic effects, ion toxicity and nutritional imbalance in rice. It affected almost all phases of growth of rice plant and decreased yield adversely. Considerable genetic variation in salt tolerance among rice varieties exists. It was thus possible to improve the genetic tolerance of rice varieties to salinity by adopting various breeding methods. In addition to conventional breeding, other innovative breeding techniques such as tissue culture, induced mutations and wide crosses needed to be explored. Inheritance studies on salinity induced panicle sterility had indicated that resistance to sterility was dominant character and presumably controlled by at least 3 pairs of genes. Uptake of Na in salt-tolerant sensitive varieties were also under genetic control. Recent studies conducted in Phytotron, greenhouse, and in field conditions indicated that seedling tolerance differs from flowering tolerance in rice varieties. Different morphological characters showed different response to salinity. Varieties also reacted differently for each character at different stages of development. Therefore, it was likely that different genes for salinity tolerance were involved at different physiological stages of development such as seedling growth, vegetative growth, and flowering

Root penetration and shoot elongation of tall wheatgrass and basin wildrye in relation to salinity

Abstract: Tall wheatgrass [Elytrigia pontica (Podp.) Holub Syn: Agropyron elongatum (Host) Beauv. ’Jose’] and basin wildrye [Leymus cinereus (Scribn. & Merr.) A. Love Syn: Elymus cinereus Scribn. and Merr. ’Magnar’] may have potential for increasing forage production once established on saline rangelands. The shoot and root elongation, osmotic adjustment, leaf water stress, and turgor at growth cessation of these grasses in response to drought and salinity were compared in a growth chamber experiment. Seedlings were grown in columns of soil initially saturated with solutions with an electrical conductivity of 1.0, 10, and 20 dS∙m−1 and allowed to grow until desiccated. The greater shoot elongation and root penetration of tall wheatgrass than basin wildrye at all soil salinities corresponds with the higher survival of tall wheatgrass than basin wildrye on a saline soil and on a nonsaline soil in central Nevada. As leaf water potential decreased, both species had similar or higher turgor maintenance in saline than no...

Changes in Soil Porosity and Surface Shrinkage in a Remolded, Saline Clay Soil Treated with Compost

Abstract: We studied modifications induced in soil porosity and in surface shrinkage in a saline clay soil treated with compost in laboratory trials, and we tested the effect of wetting and drying cycles. Porosity and pore size distribution were measured on thin sections prepared from soil samples by using electrooptical image-analysis (Quantimet 720). Shrinkage was measured on the surface of dried samples using the same apparatus. The application of wetting and drying cycles to the control samples first increased the proportion of pores ranging from 30 ±m to 1 mm in equivalent pore diameter to a maximum, and then these pores decreased steadily with further wetting and drying cycles. In treated samples the intra-aggregate porosity was higher than in control samples only after the first wetting and drying cycles; then it was always lower and at the end of the experiment decreased with respect to the beginning. Modifications of pore size distribution were also observed. The total surface shrinkage increased after wetting and drying cycles and in control samples was always higher than in treated samples but, at the end of the experiment, cracks were larger in treated samples. This unusual behavior of soil-compost interactions could be ascribed to the salinity of both soil and compost.

On the engineering properties of salina soil

Abstract: Summary Subsoil in desert regions is a product of temperature changes, wind and rainfall. Soil in a subtropical climate, such as that of Saudi Arabia, would be the best representative example for the study of soil condition in arid and extremely arid regions. A high temperature climate increases evaporation and reduces moisture in the soil, resulting in development of salt-bearing soil. Depending upon some geological, climatic considerations salt content in Saudi Arabia soil is invariably high. Understanding and anticipating the nature of changes in such considerations and the associated geotechnical problems in these regions is very important for practising engineers in the area. This is particularly important during the design and construction stage, in order to evaluate and solve unforeseen problems. The foundation problems which arise due to various concentrations of sodium or calcium chlorides in desert soils are pinpointed and discussed. The influence of the salt on the laboratory-observed properties of desert soil is investigated.

Emergence and establishment of basin wild-rye and tall wheatgrass in relation to moisture and salinity.

Abstract: Many saline, arid rangelands in the Great Basin once dominated by basin wildrye (Elymus cinereus Scribn. & Merr.) could again be highly productive following brush control and seeding of adapted species. The effects of spring precipitation and soil salinity on emergence and establishment of Jose tall wheatgrass [Agropyron elongafum (Host) Beauv. ‘Jose’l and Magnar, a selected cultivar of basin wildrye, were compared in central Nevada. Both species were seeded in circular plots on a nonsaline and a moderately saline soil (electrical conductivity of the saturation extract, ECe, of 7.0 ds *m-l) and irrigated to simulate a gradient in spring precipitation. Magnar basin wildrye required higher and more frequent irrigation and precipitation in April through June to produce an acceptable stand of seedlings (at least 2 seedlings per meter of row) on the moderately saline soil than on the nonsaline soil. Jose tall wheatgrass produced acceptable seedling stands without irrigation and excellent stands (6 seedlings per meter of row) with irrigation on both soils following a wet winter and during a dry spring. Although mature basin wildrye is well adapted to many saline, arid soils, it definitely will require supplemental irrigation to establish from seed. Tall wheatgrass is more salt tolerant and less sensitive to plant water stress at the seedling stage than basin wildrye, so it is more likely to establish on saline, arid soils without irrigation. However, mature tall wheatgrass may not persist in areas that receive less than 30 cm annual precipitation. Until more drought and salttolerant plant materials are available, saline, arid soils should not be seeded without supplemental irrigation. Valley bottoms and flood plains of the Great Basin historically were important grazing lands for the livestock of early ranchers (Lesperance et al. 1978). In the late 19th century, many of the cattle grazing sagebrush (Artemisia)/grasslands were wintered on the extensive basin wildrye (Elymus cinereus Scribn. & Merr.) stands dominating many of these lowlands (Hazelton et al. 1961, Lesperante et al. 1978, Young and Evans 1981). Because basin wildrye is sensitive to spring clipping and frequent herbage removal during the growing season (Krall et al. 1971; Perry and Chapman 1974, 1975, 1976), many stands were decimated by excessive grazing (Young et al. 1975). Recovering the forage production of these lowland ranges is desirable because the ranges are extensive and in close proximity to many ranch base properties. Many areas have the potential for high forage production due to the subsurface and overland drainage water they receive and the high water-holding capacity of the associated fine-textured soils. Extensive lowlands now dominated by greasewood [Surcobarus vermiculatus (Hook.) Torr.] and salt rabbitbrush [Chrysothamnus nauseosus ssp. consimilis (Greene) Hall and Clem] and lacking an understory of basin wildrye could be productive after chemical brush control (Cluff et al. 1983) and the establishment of forage species adapted to saline/alkaline and arid soils (Roundy et al. 1983). Seedling establishment on these soils may be limited by low Author is a range scientist, formerly with USDA/AR& Renewable Resources, University of Nevada, Renq, 920 Valley Road; presently at the School of Renewable Natural Resources, University of Arizona, Tucson. This study is a contribution from the USDA/ ARS and the Agricultural Experiment Station, University of Nevada, Reno. Manuscript accepted June 12, 1984. 126 water potential due to infrequent precipitation, low soil matric potentials and high soil salinity. Salts lower the osmotic potential of the soil solution and specific ions may be toxic to germinating seeds and seedlings. Precipitation in the Great Basin occurs mainly in fall, winter, and spring. As storms that provide effective precipitation become less frequent from March through June, soil water content decreases so that soil matric and osmotic potentials are decreased and soil water may be unavailable for seed germination or seedling growth (Roundy et al. 1984). Successful seeding establishment is dependent on frequency and amount of winter and spring precipitation and the ability of the seeded species to germinate and grow as soil matric and osmotic potentials decrease. Forage species most recommended for seeding saline, dry soils include Russian wildrye (Elymus junceus Fisch.), tall wheatgrass [Agropyron elongutum (Host) Beauv.], and basin wildrye (Plummer et al. 1955, 1968). Russian wildrye is difficult to establish because of poor seedling vigor (Hafenrichter et al. 1968, Vallentine 1961). Tall wheatgrass is well known for its salt and sodium tolerance (Carter and Peterson 1962, Dewey 1960, Moxley et al. 1978, Shannon 1978, Rauser and Crowle 1963) and has established well on wet saline soils, but may not persist on dry saline soils (Forsberg 1953, Ludwig and McGinnies 1978, McGinnies and Ludwig 1978, McPhie 1973). Rollins et al. (1968) and Eckert et al. (1973) reported difficulty in establishing tall wheatgrass and basin wildrye on a greasewood/rabbitbrush [Chrysothamnus nauseosus (Pall.) Britt.] site in central Nevada due to high salinity, sodicity, and high boron concentrations. Young and Evans (1981) suggested that many of the sites where basin wildrye occurred naturally are too dry for tall wheatgrass and too saline for crested wheatgrass [Agropyron desertorum (Fisch. ex Link) Schult]. Although basin wildrye has had a reputation for low seed germination and poor seedling vigor (Young and Evans 1981), a selected cultivar, Magnar, has been released which has high and viable seed production and high germination (Evans and Young 1983). The purpose of this study was to determine the establishment of Magnar basin wildrye and to compare it with that of Jose tall wheatgrass in relation to soil salinity and spring precipitation as simulated by irrigation in central Nevada. Simulation of spring precipitation by irrigation was intended to avoid the possibility of total seeding failure and to estimate the minimum precipitation necessary to establish these grass species on saline soils.

Growth, Nutrition, and Water Uptake of Tomato Plants with Divided Roots Growing in Differentially Salinized Soil1

Abstract: Des plants de tomate ont ete cultives en serre pour determiner les effets d'une distribution uniforme ou non de la salinite sur la croissance racinaire, sur la nutrition azotee et sur l'utilisation de l'eau

Drainage Required to Manage Salinity

Abstract: The amount of drainage required to prevent loss in crop productivity from excess soil salinity has been termed as the leaching requirement (Lr). Steady‐state models for predicting Lr are reviewed and compared with experimentally measured values. Values of Lr predicted from the exponential model, which computes the average soil salinity in the root zone based upon an exponential pattern of crop water uptake, correlated best with measured values. Acceptable estimates are also obtained with a simplified model that approximates an average soil salinity based on values for the top and bottom of the root zone. The highest correlation coefficient was 0.67, indicating that none of the models is completely satisfactory.

Relationship between root uptake-weighted mean soil water salinity and total leaf water potentials of alfalfa

Abstract: Alfalfa was grown in five laboratory soil columns and irrigated at a fixed average amount per day. One column received tapwater at 6-day intervals; the others saline water (h o=−12 m) at intervals of 4, 6, 8, and 12 days. The alfalfa was harvested at 24-day intervals. The resulting widely varying distributions of soil water content, pressure potential and osmotic potential were measured in detail. From these data variously weighted mean soil water potentials were calculated and correlated with measured total leaf water potentials. This indicated that in the moist, saline soil columns the alfalfa plants tended to maximize the root uptake-weighted mean total soil water potential and, since the pressure potentials were generally high compared with the osmotic potentials, also the uptake-weighted mean osmotic soil water potential (minimize the uptake-weighted mean salinity). For the drier nonsaline soil column the leaf water potentials were much lower than expected from the soil water retention function. This was attributed to dominant resistance for water flow through the soil and across the soil-root interface.

Saline groundwater management and optimal cropping pattern

Abstract: In areas having scarce canal water and poor quality groundwater, an opportunity exists to use the two sources conjunctively for irngation water supply. However, the use of saline water, either in isolation or by mixing with canal water, threatens soil salinization, unless steps are taken to protect the salt balance in the root zone. A deterministic linear programming model has been developed, incorporating both leaching requirements and the salinity response function of crops, to find the optimal cropping pattern and optimum use of saline groundwater. The model was applied to a canal command area.

Salinity and the persistence of parathion in flooded soils

Abstract: The persistence of parathion in five coastal saline soils of varying electrical conductivity and in one nonsaline soil sample was studied under flooded conditions. Parathion was decomposed faster in nonsaline soil than in saline soils and its stability increased with increasing electrical conductivity. The addition of salts to the nonsaline soil at 4, 8 and 16 dS −1 increased the persistence of parathion. Nitro-group reduction, and not hydrolysis, was the major route of parathion degradation in saline and nonsaline soils. The accumulation of aminoparathion was less pronounced in saline soils than in nonsaline soil concomitant with slow degradation of parathion in saline soils. The inhibition of nitro-group reduction in saline soils was related to low microbial activities as reflected in decreased dehydrogenase activity and slow iron reduction.