Showing papers on "Soil salinity published in 1980"

Spatial variability of soil sampling for salinity studies in Southwest Iran

Abstract: This study addresses the technology for soil sampling of large agricultural fields which are inherently variable in both space and time. Three several hundred ha fields in southwest Iran initially sampled on an arbitrarily selected grid of 80 m to ascertain soil salinity levels were analyzed using both geostatistical and classical statistical methods. The results from two fields showed that the variance structure of the salinity observations were spatially dependent, and hence, geostatistical techniques allowed best linear unbiased estimates of salinity values interpolated between spatially observed sampling locations to yield contour lines of isosalinity. In the third field, salinity observations were found to be spatially independent, and hence, were analyzed by classical methods to yield the number of soil samples necessary to observe the fiducial limits within which it is expected that the true mean salinity exists for given levels of probability.

Salt Affected Soils and Their Afforestation

Abstract: The paper describes the extent and distribution of the salt affected soils in different parts of India. From the management point of view these soils have been grouped into 2 categories (i) Saline soils, (ii) Alkali soils, and their distingushing characteristics have been explained. The work done on the relative tolerance of important forest species for soil salinity and alkali conditions in India as well as in other countries his been briefly summarised, which shows wide differences in the tolerance of the different species. A detailed account has been given or the planting techniques used for raising forest trees on the salt affected soils in India and other counries. It has been shown that the success of the plantations and the improvement in the soil depend to a great extent on the kind of planting techniques and soil working methods followed. Comprehensive details of the various trial. Undertaken on tree plantations in the salt affected soils in different parts of India and other countries have been discussed, which show scope of successful afforestation in certain situations. The systematic data collected through well planned experiments conducted at C.S.I.R.I., Karnal on a calcareous sodic soil canvincingly reveal that species like Prosopis Juliflora, Eucalyptus Hybrid . And Acacia Nilotica can be grown successfully by treating the soil of the planting pit with gypsum and F.Y.M. alongwith application of a small dose of nitrogenous and phosphatic fertilizer. This soil treatment has been found to yield as good results as in the case of replacement of the alkali soil with a normal soil. The various ameliorative effects caused by tree growth on the salt affected soils have been elucidated. The work done recently under pot culture condition. At CSSRI, Karnal with saline water irrigation has shown more adverse effect of salioe water irrigation on Albizzia letbbek than on Eucalyptus hybrid the addition of gypsum, S.Y.M. aad fertilizers appears to minimise the detrimental effects depending upon the composition of saline irrigation water. In view of the limited avaliable data in India a need for intensifying systematic research on critical evaluation of soil Working techniques and identification of suitable tree species for afforestation on the salt affected soils has been suggested.

A model for optimal irrigation scheduling with saline water.

Abstract: This chapter presents a model for optimal scheduling of irrigation with soil salinity parameters explicitly considered. Irrigation scheduling constitutes an essential component of proper irrigation management, particularly under conditions of scarcity of irrigation water and when excessive irrigation and runoff cause ‘external damages,’ as, for example, in the Colorado River Basin (Maletic, 1974; Young et al., 1974). Studies dealing with scheduling of irrigation (i.e., proper timing and quantities of water applied) have been published by Jensen and Heerman (1970), Kincaid and Heerman (1974), Dudley et al. (1971), Jensen (1972), Jensen (1977), Shalhevet et al. (1976), and others. However, most of the studies dealing with scheduling of irrigation have not taken parameters of salinity of the soil and of the irrigation water into account, the paper by Jensen (1977) being an exception.

Genetic Methods to Breed Salt Tolerance in Plants

Abstract: Increasing demands for plant products for food, chemicals and energy will require that many of the arid and semi-arid regions of the world be used for crop production. Soil salinity is a perennial problem in arid and semi-arid areas. Crops grown in these areas are quite often irrigated and irrigation frequently compounds difficulties with soil salinity. Also, in many irrigated areas, substantial amounts of brackish water are available to augment irrigation supplies. Soil salinity and the potential use of brackish water for irrigation in the arid and semi-arid regions of the world have created a great need for salt tolerant crops.

Crop response to saline soil conditions in the parkland area of Saskatchewan.

Abstract: The salinity tolerance of six annual crop species, wheat, oats, barley, rye, flax and rapeseed, were determined on saline soils that occur north of the Quill Lakes in the northeastern corner of the agricultural area of Saskatchewan. The relative merits of a salt-tolerant grass-legume mixture were also given consideration. The effects of salt stress on spring-sown cultivars became most apparent following exposure to hot, dry summer weather. In contrast, maximum salt tolerance for both winter wheat and winter rye was a function of winterkill. The winterhardiness of both winter annuals was reduced by saline conditions, but winter rye was more adversely affected than winter wheat. Large decreases in seed yield, plant dry weight and height occurred before the effects of increased soil conductivity were expressed for hectoliter weight, 1000-kernel weight, date of maturity, protein content and oil content. Among the spring and winter annual cultivars considered, Bonanza barley and Garry oats demonstrated the gre...

Salinity effects on hydraulic properties of soils.

Abstract: Laboratory determinations of saturated hydraulic conductivity and infiltration rate were conducted with four soils varying in texture from sand to clay and with five saline-sodic waters. The waters varied in total dissolved solids from 1250 to 15000 milligrams per liter and in SAR from 16 to 57 and were representative of saline groundwaters in New Mexico. Saturated hydraulic conductivities of the soils were not significantly affected by water quality if these waters were the sole source of irrigation water. Nevertheless, even small additions of high-quality water (“rains”) to soils previously equilibrated with the saline-sodic waters significantly decreased soil permeability. Dispersion and short- or longdistance transport of clay apparently clogged conducting pores when “rain” was introduced. Swelling was an important mechanism in reducing soil permeability only in the clay soil. The data suggest that, when saline-sodic water is the dominant irrigation source and is supplemented by “rains,” (1) all waters could be used on very sandy soils, (2) no saline-sodic waters should be used on fine-textured soils, and (3) slightly sodic, but not highly sodic, waters could be used on medium-textured soils.

Response of sugarcane to different types of salt stress

Abstract: Due to climatic conditions and prevailing water regime the yield and sucrose recovery in sugarcane are high in South Western India. However, excessive irrigation, poor drainage and luxuriant use of fertilizers have resulted in conversion of large fertile areas into saline lands. The salinity is due to the excess of Na+, Ca++, Mg++, SO4− and Cl− ions. Individual salts of NaCl, Na2SO4, MgCl2 and MgSO4 were employed in culture experiments to study salt stress effect on sugarcane variety Co 740. It was observed that sulphate salinity was more toxic to sugarcane than the chloride one. Sulphate salts caused more inhibition of growth, chlorophyll synthesis, PEPCase activity, decreased the uptake of K+ and Ca++ ions but stimulated nitrate reductase. The stress did not result in proline accumulation in the sugarcane cultivar Co 740. The degree of toxicity of different ions in decreasing order in sugarcane cultivar Co 740 is SO4−>Na+>Cl−>Mg++.

Alfalfa for Hydrologic Control of Saline Seeps

Abstract: Saline seeps affect extensive dry cropland areas in the northern Great Plains and methods need to be devised to control them. The effectiveness of alfalfa (Medicago sativa L.) in controlling saline seepage on northern Great Plains small grain dryland farms was studied from 1971 to 1977. Alfalfa, when grown on about 80% of the recharge area, reduced the deep percolation of soil water and provided hydrologic control for two seep areas within 1 year after its establishment in recharge areas. As the perched water table receded, the soil surface in the discharge (seepage) area dried allowing passage of farm implements, soil salinity decreased, and weeds, grasses, and crops grew better in the seepage area. In contrast, a buffer strip of alfalfa (occupying about 20% of recharge area) on the upslope side of a saline seep did not provide hydrologic control. Greenhouse data indicated that alfalfa yields will decrease rapidly if soil salinity increases to high levels above a saline water table. Reduced plant growth resulted when salts accumulated in the root zone as water moved upward by capillary action. When in situ root zone soil salinity reached an EC of 38 mmho/cm, alfalfa growth essentially ceased. We concluded that alfalfa can effectively control the hydrology of saline seep areas if it is grown on a major portion of the recharge area.

On the dependence of salt tolerance of beans (Phaseolus vulgaris L.) on soil water matric potentials

Abstract: Bean plants (Kora cv) were grown in potted soil artificially salinized by adding NaCl and CaCl2 to the irrigation water to obtain an electrical conductivity of the soil saturation extract (ECe) thirty days after emergence of 0.1, 0.3, 0.5 and 0.7 S/m at 25°C and a sodium adsorption ratio (SAR) of 4 (mmol/l)2. Thereafter, plants were irrigated when soil water matric potential (ΨM) was in the range of −20 to −30 kPa (wet treatment) and when ΨM was in the range of −40 to −60 kPa (dry treatment).

Changes in dry weight and mineral composition of some oil producing plants over a range of salinity stresses

Abstract: Using water culture technique, some experiments have been performed to investigate the effect of 60 days salinization treatments (0.0–100 meq 1−1 NaCl) on dry weight and on the content of some nutrient elements (Na, K, Ca, Mg, P, N) in castor bean, sunflower and flax plants. In general the content of sodium increased progressively with the rise of salinity level. The relatively low and moderate salinization levels (20 and 40 meq I−1 NaCl) resulted in a promotion rather than inhibition of the dry weight and in the content of most of the investigated elements in the different organs of the test plants. However with the rise of salinization level from 60 to 100 meq l−1, the dry weight and the content of these nutrient elements were mostly reduced.

Microhabitat relationships of six major shrubs in Navajo National Monument, Arizona.

Abstract: Six shrub species were studied to determine their microhabitat relationships as well as their effect on the immediate environment. Analysis of site characteristics and mineral composition of soils in open areas adjacent to shrubs and beneath shrubs allowed for comparison of the different habitats following shrub establishment. Soil pH differs beneath the various shrubs and all six species tended to create more alkaline soils beneath their canopy. All species showed increased soil salinity beneath their canopy. However, the concentration of total soluble salts in the soil surface beneath the shrubs varied with the species and was highest beneath fourwing saltbush. Significant increases in the concentration of magnesium and potassium ions beneath shrubs were observed. Nitrogen and phosphorus were also found in greater concentration beneath the shrub canopy. Soil depth differed beneath the shrub species, with sagebrush and fourwing saltbush growing on the deeper more highly developed types. There was a positive relationship between the presence of shrubs and the depth of the soil profile. It has long been known that shrubs influence the soil characteristics beneath their canopy (Fireman and Hayward 1952). Studies done in the last decade show that shrubs influence both the horizontal and vertical patterning of soil chemicals (Charley and West 1975). Sharma and Tongway (1973) studied the effects of two species of saltbush (Atriplex nummularia and Atriplex vesicaria) on soil salinity and related properties. They recognized an accumulation zone beneath the shrubs, a zone of compensation where leaching of minerals replaced those absorbed, and ‘a depletion zone from which mineral absorption exceeded the rate of replacement. Salt accumulation under shrubs, therefore, represents a redistribution of salts from peripheral regions of root activity (Charley and West 1975). Plants employ several “strategies” for the removal of mineral wastes. Leaching of minerals from leaves is accomplished when the solution of the leaf surface connects with that of the intercellular spaces of the mesophyll and ions are lost by diffusion. Salts are also excreted with the aid of salt glands, as is the case with many Atriplex species. Salts are also concentrated in the extracellular spaces of leaves during the process of transpiration, thus accumulating minerals in leaves. Leaf fall subsequently serves as a mechanism for the elimination of mineral wastes (Epstein 1972). Charley and West (1975) used the distributional patterns of carbon and nitrogen under and between shrubs as a measure of

Growth and chemical composition of dry beans as affected by soil salinity and N fertilization

Abstract: The effects of three levels of N (0, 50 and 100 ppm) and four salinity regimes (0.5, 1.5, 2.5 and 3.5 mmhos/cm) on the growth and mineral composition of dry beans (Phaseolus vulgaris L.) were investigated in a greenhouse experiment. Bean plants treated with N produced more dry weight and contained higher N than the untreated check. Growth and N uptake by bean plants generally decreased with increasing irrigation water salinity at all N levels. High salinity caused severe burning of the margins of older leaves and stunting of growth. At the low salinity levels (0.5 and 1.5 mmhos/cm), N additions had no effect on growth; however, the suppressing effects of higher salinity were alleviated somewhat with N fertilization.

Changes of Sodicity and Salinity In Soils Reconstructed on Strip-mined Land

Abstract: Soluble salt and sodium levels in soils spread over strip-mine spoils can and do change, and planning for reclamation should take this into account. At the site of several reclamation experiments in western North Dakota, upward migration of sodium increased the exchangeable sodium of topsoil spread over minespoil. Evidence is presented which indicates that chemical diffusion played an important role in this process.

Quality Of Irrigation Water And Effects Of Sulfuric Acid And Gypsum On Soil Properties And Sudangrass Yields

Abstract: The effects of irrigating a soil over a 3-year period with three waters of different qualities were evaluated in terms of chemical characteristics of the soil profile. The salinity content of the waters ranged from ECw of 3.2 X 103 to 0.55 X 103 millimhos per centimeter. The use of these waters resulted in different soil salinity contents, e.g., values of ECe X 103 for the surface 30 centimeters ranged from 3.50 to 2.13 for the high to low salt waters, respectively. Exchangeable sodium percentage (ESP) ranged from 18.4 to 24.0 in the surface 30 centimeters of soil, being highest with the lowest salinity water. The effects of relatively low rates of 93 percent H2SO4 (2.24 tonnes/hectare) and gypsum (3.84 tonnes/hectare) were evaluated in terms of plant yields and soil chemical properties over an additional 2-year period. Sudangrass (Sorghum sudanese) yields increased with decreasing salinity of the waters. Yields were increased significantly by H2SO4 and gypsum with all three waters the first year, but only with H2SO4 the second year. Significant negative correlations of ECe and ESP of the soil at depths of 0 to 30 and 30 to 60 centimeters with crop yields were found. Soil salinity and ESP were reduced significantly by both amendments one season after application. Sulfuric acid was generally superior to gypsum in terms of yield increases and soil improvement. This study demonstrated the usefulness of low rates of soil-applied amendments. Of particular interest is sulfuric acid, which gave significant results at a lower per-hectare rate than gypsum, and which is often available as a low-cost by-product.

Movement of Solutes and Soil Salinity

Abstract: Ye are the salt of the earth; but if the salt shall have lost its savour … it is henceforth good for nothing but to be cast out and trodden underfoot.

A proposal for reclamation by dilution of irrigation water

Abstract: A proposal is developed for reclamation of a soil which has become salinized from irrigation with saline water. The procedure permits continued irrigation after dilution of the saline irrigation water with higher quality water, which achieves partial reclamation without taking the land out of production, and without creating a large flux of drainage. Model calculations using a salt transport-chemical equilibrium model are performed for the case of a saline irrigation water derived from power plant cooling water residual (EC=4.2 mmho/cm), which is diluted by a high quality well water (EC=0.5 mmho/cm) to produce a water which is alternated with the saline water in cycles of two years. Soil salinity and drainage salt loads resulting under this system are compared with the simulated results of a more traditional method of salt leaching.