WORKSHOP 'Application of Rapid Field Tests in Saline Environments and Agriculture (original) (raw)
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under saline conditions in the western San Joaquin Valley of California
2000
electrical conductivity of the saturation extract (dS m -1 ); ECiw, electrical conductance of the applied 21 irrigation water (dS m -1 )Abstract 26 27 2 Salinity and trace minerals threaten crop production in California's arid western 28 San Joaquin Valley (WSJV). We used data collected from a container trial at Davis and at 29 32.4 ha site in Kings County to parameterize and validate a dynamic simulation model 30 formulated to predict the growth and quality of a common Bermuda grass (Cynodon 31 dactylon (L.) Pers. pasture under variable saline conditions. The model simulates the 32 flow of water, salts and trace elements between soil and plant, and uses the amount and 33 quality of rainfall and irrigation water, soil, plant, and atmospheric variables to estimate 34 crop growth and quality. Stocking rates and potential average daily weight gains of 35 grazing animals are also predicted. Plant growth is described by the intrinsic growth rate 36 of the crop at different soil salinity and nitrogen levels. Soil salinity is estimated through 37 the balance of total dissolved solids (TDS) in the soil, plant uptake, irrigation, run-off 38 and drainage water, and the leaching fraction. Crop quality is predicted using ADF, 39 NDF, crude protein, ash, and trace minerals in the biomass throughout the growing 40 season, using leaf/stem ratios. Livestock production is simulated based on dry matter 41 availability, intake and energy balance. Our results indicate that although soil chemical 42 composition is highly affected by the amount and quality of the irrigation water, to some 43 extent it can be managed through irrigation time and frequency. Pasture yields of 12 Mg 44 DM ha -1 are possible in these soils. The forage quality allows grazing. Simulations show 45 that it is possible to keep 1 to 1.2 AU ha -1 unsupplemented during the growing season 46 with a gain of 1.0 kg of live weight per day in a well irrigated and fertilized pasture. 47 However, a balance must be achieved between the stocking rate, the desired ADG, the 48 accumulation of salts in the soil profile and the potential pollution of the ground water 49 due drainage and leaching. Using available weather data, crop-specific parameter values 50 and field scale measurements of soil salinity and nitrogen levels the model could be 51 adapted for use by farmers growing forages on saline soils elsewhere. 52 3
Success stories in saline agriculture in Pakistan: from research to production and development
… Title: Prospects of …
This paper describes some of the work on saline agriculture in Pakistan over the last 20 years, giving examples of successes in translating techniques from the laboratory to the farming community. Examples are given of projects demonstrating the use of halophytic species for fodder and fuel production, and improvements due to new agronomic techniques and plant breeding. Halophytes such as Atriplex species are highly productive and can provide maintenance diets but need supplementation for production, and increase water uptake. Trees such as Acacia and Prosopis species have a valuable role to play, both for revegetation and for biological drainage. The use of raised-bed technology, and on-farm seed priming, can improve production and efficiency of a range of crops in saline conditions.
Agricultural Water Management, 2005
An irrigation experiment with saline water at different concentrations was carried out over a 7-year period on the same clay-silty soil in the Volturno Valley at Vitulazio to evaluate long-term effects of irrigation with saline water on crops and soil. The spatial distribution of the experimental treatments remained the same throughout the 7-year period in order to assess the effects of salt accumulation. Three saline concentrations of irrigation water (0.25-0.5 and 1% of NaCl) and two irrigation levels (100% and 40% restitution of evapotranspiration) were applied. The electrolytic concentration (ECe) was measured every year in spring before the irrigation season. Autumn-spring rainfall caused leaching of salts from 0 to 0.4 m layer and an accumulation of salt in the deeper layers. Accumulation was directly correlated to the quantity of NaCl applied with irrigation. This allowed us to calculate, for the 0.4-1.1 m layer, the mean annual increase in ECe in (dS m À1 per t ha À1 year À1 of NaCl given). At the end of the experiment, it was observed that there was an increase in ECe at a depth of 3 m for the saltiest treatments. The percentage of exchangeable sodium (ESP), however, increased with the saline concentration of the irrigation water (quantity of NaCl) above all in the 0-0.4 m layer, and gradually decreased with depth. Irrigation with saline water led to an increase in ESP and a degradation of the soil physical properties that were estimated indirectly by measuring aggregate stability in water (IASW).
Modelling the effects of saline water use in agriculture
Irrigation and Drainage, 2006
Use of saline groundwaters is inevitable in rice-wheat, cotton-wheat, and millet-wheat crop rotations in the northern region of India due to limited canal water supplies. The UNSATCHEM model is calibrated and validated with field data on saline water use for the wheat and cotton crop. The calibrated and validated model has been employed to study different aspects of the salinisation process. The effect of irrigation water quality on the salinisation process is understood with the help of simulations in which irrigation waters of different SAR, SO 4 2À and Cl À concentrations are used. A linear relation is observed between the weighted average of irrigation water salinity and the root zone. The salinisation process under different conjunctive use practices is understood through simulations. The practices are compared on the basis of temporal changes in root zone salinity with reference to the sensitivity of the wheat crop to salinity for deciding the preference of one conjunctive use practice over another. The preference order, thus prepared, is verified with the published yield data of wheat from conjunctive use field studies. The effect of soil texture on salinisation is studied through simulations. The saturated water content influences the salinisation process more than the hydraulic conductivity. The long-term simulations as per water quality guidelines for a six-year period under wheat-cotton rotation are carried out to assess the sustainability of saline water use for crop production.
Short Term Effect of Saline Water Application on Some Chemical Properties of Soils
Saline soils, as they contain high concentration of soluble salt, are not very suitable for normal agricultural practices. Over the last three decades salt affected areas in Bangladesh have increased. The objective of this research was to investigate the effect of saline water application on some chemical properties of soils. A calcareous and a non-calcareous soil of silt loam texture were selected for the experiment. The salinity treatments were 0,6.5 and 13 dS/m in both soils. The treated soils were then incubated in laboratory condition for 7, 15,30,60, and 120 days. The water content of the incubated samples was maintained at field capacity. soil pH, EC, Cl, HCO3', available N, P, K, S, Ca, Mg, and Na were determined after each sampling. Saline water application did not increase the soil salinity, to harmful level' Different nutrients behave quite differently at different salinity levels. The relationship between pH EC, precipitation and dissolution of calcium carbonate ...
An improved methodology to evaluate crop salt tolerance from field trials
Agricultural Water Management, 2019
The salt tolerance of crops is commonly expressed in descriptive parameters such as threshold or 50%-yield soil salinity and shape parameters describing the yield curve. Estimation by visual or simplified ordinary least squares (OLS) regression methods has multiple issues: parameter bias due to uncertainty in soil salinity, lack of independent estimates of the reference yield, questionable robustness of the threshold parameter and missing information about uncertainty and correlation of the parameter estimates. Here, we present a comprehensive OLS method together with an analysis of its statistical properties to alleviate and overcome such issues, on the basis of a numerical experiment that mimics observed yield responses to saline groundwater across a range of salinities in the experimental test facility Salt Farm Texel. The results indicate under which experimental conditions bias is not a major problem. The method allows estimation of the zero-observed-effect yield from the data, which is relevant to agricultural practice. Estimates for zero-observed-effect yield and threshold ECe are negatively correlated, underlining the difficulty of obtaining reliable threshold values. The estimated confidence regions are reliable and robust against soil salinity uncertainty, but large observation error jeopardizes the confidence intervals, especially for the slope parameter. Data uncertainty alone can be responsible for substantial differences from experiment to experiment, providing a partial explanation for the wide variety in reported parameters in the literature, and stressing the need for longterm repetitions. Given the lack of robustness of the threshold parameter, we propose to adopt the 90%-yield EC (ECe 90) as tolerance parameter. Its confidence bounds can be obtained from a simple reformulation of the original models. We also present uncertainty ellipses as a suitable tool to unite multiple-year estimates. The method is offered as a solid and generic basis for reliable assessment of the cultivation potential of varieties and crops on salt-affected soils.
2016
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The consequences of saline irrigation treatments on soil physicochemical characteristics
Euro-Mediterranean Journal for Environmental Integration
When saline water is used to irrigate crops in arid environments, appropriate irrigation management should be applied to avoid negatively impacting soil characteristics. In this study, the effects of irrigating date palms with saline water (2.24 g l −1) on soil physicochemical characteristics such as the electrical conductivity (EC e), the pH of the saturated soil paste (pH e), the concentrations of soluble cations (Ca 2+ , Mg 2+ , Na +), the sodium adsorption ratio (SAR), the saturated soil hydraulic conductivity (K s), and the volumetric water content of the soil (θ v) were evaluated in a Tunisian Saharan cropland, the Dergine Oasis, during a 4-year period (2012-2015). The effects of three different irrigation treatments of date palms on soil properties were investigated: low treatment (90% of the net irrigation requirement (NIR) of date palms was applied); medium treatment (100% of NIR was applied), and high treatment (110% of NIR was applied). The results showed that the application of saline water for irrigation inevitably has a negative impact on the physicochemical properties of the soil. Irrigation with saline water was observed to have severe negative impacts on the soil characteristics, especially EC e , Na + , K s , and θ v. However, among the three irrigation treatments applied, statistical analysis (Duncan's multiple range test) indicated that the high treatment significantly (p < 0.05) minimized the degradation of soil characteristics by the saline water; this treatment decreased EC e , Na + , and SAR and increased the water content, θ v , of the studied soil.