Characterization of Slightly and Moderately Saline and Sodic Soils in Irrigated Agricultural Land using Simulated Data of Advanced Land Imaging (EO‐1) Sensor

Around the world, especially in semi‐arid regions, millions of hectares of irrigated agricultural land are abandoned each year because of the adverse effects of irrigation, mainly secondary salinity and sodicity. Accurate information about the extent, magnitude, and spatial distribution of salinity and sodicity will help create sustainable development of agricultural resources. In Morocco, south of the Mediterranean region, the growth of the vegetation and potential yield are limited by the joint influence of high temperatures and water deficit. Consequently, the overuse of surface and groundwater, coupled with agricultural intensification, generates secondary soils salinity and sodicity. This research focuses on the potential and limits of the advance land imaging (EO‐1 ALI) sensor spectral bands for the discrimination of slight and moderate soil salinity and sodicity in the Tadla's irrigated agricultural perimeter, Morocco. To detect affected soils, empirical relationships (second‐order regression analysis) were calculated between the electrical conductivity (EC) and different spectral salinity indices. To achieve our goal, spectroradiometric measurements (350 to 2500 nm), field observation, and laboratory analysis (EC of a solution extracted from a water‐saturated soil), and soil reaction (pH) were used. The spectroradiometric data were acquired using the ASD (analytical spectral device) above 28 bare soil samples with various degrees of soil salinity and sodicity, as well as unaffected soils. All of the spectroradiometric data were resampled and convolved in the solar‐reflective spectral bands of EO‐1 ALI sensor. The results show that the SWIR region is a good indicator of and is more sensitive to different degrees of slight and moderate soil salinity and sodicity. In general, relatively high salinity soils show higher spectral signatures than do sodic soils and unaffected soils. Also, strongly sodic soils present higher spectral responses than moderately sodic soils. However, in spite of the improvement of EO‐1 ALI spectral bands by comparison to Landsat‐ETM+, this research shows the weakness of multispectral systems for the discrimination of slight and moderate soil salinity and sodicity. Although remote sensing offers good potential for mapping strongly saline soils (dry surface crust), slight and moderately saline and sodic soils are not easily identified, because the optical properties of the soil surfaces (color, brightness, roughness, etc.) could mask the salinity and sodicity effects. Consequently, their spatial distribution will probably be underestimated. According to the laboratory results, the proposed Soils Salinity and Sodicity Indices (SSSI) using EO‐1 ALI 9 and 10 spectral bands offers the most significant correlation (52.91%) with the ground reference (EC). They could help to predict different spatial distribution classes of slight and moderate saline and sodic soils using EO‐1 ALI imagery data.     

Satellite Thermography for Soil Salinity Assessment of Cropped Areas in Uzbekistan

A change of canopy temperature can indicate stress in vegetation. Use of canopy temperature to assess salt stress in specific plant species has been well studied in laboratory and greenhouse experiments, but its potential for use in landscape‐level studies using remote sensing techniques has not yet been explored. Our study investigated the application of satellite thermography to assess soil salinity of cropped areas at the landscape level. The study region was Syrdarya Province, a salt‐affected, irrigated semi‐arid province of Uzbekistan planted mainly to cotton and wheat. We used moderate‐resolution imaging spectroradiometer satellite images as an indicator for canopy temperature and the provincial soil salinity map as a ground truth dataset. Using analysis of variance, we examined relations among the soil salinity map and canopy temperature, normalized difference vegetation index, enhanced vegetation index, and digital elevation model. The results showed significant correlations between soil salinity and canopy temperature, but the strength of the relation varied over the year. The strongest relation was observed for cotton in September. The calculated F values were higher for canopy temperature than for the other indicators investigated. Our results suggest that satellite thermography is a valuable landscape‐level approach for detecting soil salinity in areas under agricultural crops. © 2016 The Authors. Land Degradation & Development Published by John Wiley & Sons Ltd.     

Model-Based Integrated Methods for Quantitative Estimation of Soil Salinity from Hyperspectral Remote Sensing Data:A Case Study of Seffected South African Soils

Soil salinization is a land degradation process that leads to reduced agricultural yields. This study investigated the method that can best predict electrical conductivity (EC) in dry soils using individual bands, a normalized difference salinity index (NDSI), partial least squares regression (PLSR), and bagging PLSR. Soil spectral reflectance of dried, ground, and sieved soil samples containing varying amounts of EC was measured using an ASD FieldSpec spectrometer in a darkroom. Predictive models were computed using a training dataset. An independent validation dataset was used to validate the models. The results showed that good predictions could be made based on bagging PLSR using first derivative reflectance (validation R2 = 0.85), PLSR using untransformed reflectance (validation R2 = 0.70), NDSI (validation R2 = 0.65), and the untransformed individual band at 2257 nm (validation R2 = 0.60) predictive models. These suggested the potential of mapping soil salinity using airborne and/or satellite hyperspectral data during dry seasons.     

SOIL PROPERTY CHANGES FOLLOWING IRRIGATION WITH COALBED NATURAL GAS WATER: ROLE OF WATER TREATMENTS,SOIL AMENDMENTS AND LAND SUITABILITY

Saline‐sodic water is a by‐product of coalbed natural gas (CBNG) production in the Powder River Basin of Wyoming, USA and is being beneficially used in places as irrigation water. This study evaluated effects of 2 years of natural precipitation on soil properties of a hay field after the cessation of managed irrigation with CBNG water. The hay field had been irrigated with only CBNG water [CBNG(NT)], CBNG water amended with gypsum [CBNG(G)] or gypsum plus sulfur via a sulfur burner [CBNG(GSB)] in combination with soil amendments—gypsum ( +G ), elemental sulfur ( +S ), and both ( +GS ). Results indicated that infiltration rates were the lowest on fields irrigated with CBNG(NT), followed by CBNG(G) and CBNG(NT) +G treatments (12·2, 13·2, and 13·5 cm h⁻¹, respectively). The CBNG(GSB) +GS treatment had the highest infiltration rates (33·5 cm h⁻¹). By the second year, salinity and sodicity of treated soils had decreased in the A‐horizon of most CBNG‐water irrigated plots, whereas in Bt₁‐ and Bt₂‐horizons salinity generally decreased but sodicity increased; S and GS soil amended plots had higher profile salinities compared with NT and G soil treatments. Although Na⁺ leaching was observed in all fields that received soil and/or water amendments, CBNG(GSB) +GS plots had the lowest sodicity in the A‐ and Bt₁‐horizons. Effective managed irrigation requires knowledge of site‐specific soil properties, plant suitability, water chemistry, and amendments that would be needed to treat the CBNG waters and soils. This study indicates the greatest success was realized when using both soil and water amendments. Copyright © 2011 John Wiley & Sons, Ltd.     

Salinity and sodicity induced changes in dispersible clay and saturated hydraulic conductivity in sulfatic soils

Abstract

Irrigation is becoming a more commonly used practice on glacially derived soils of the Northern Great Plains. Threshold salinity and sodicity water quality criteria for soil‐water compatibility in these sulfatic soils are not well defined. This study was conducted to relate soil salinity and sodicity to clay dispersion and saturated hydraulic conductivity (K_sat) in four representative soils. Soil salinity (EC treatment levels of 0.1 and 0.4 S m^‐1) and sodicity (SAR treatment levels of 3, 9, and 15) levels were established to produce a range of conditions similar to those that might be found under irrigation. The response of each soil to changes in salinity and sodicity was unique. In general, as sodicity increased clay dispersion also increase, but the magnitude of the increase varied among the soils. In two of the soils, clay dispersion across a range of sodicity levels was lower under the 0.4 S m^‐1 treatment than under the 0.1 S m^‐1 treatment and in the other two soils, clay dispersion across a range of sodicity levels was similar between the two salinity treatments. Changes in K_sat were greatest in the finer textured soil (decreasing an order of magnitude across the range of sodicity levels), but was unchanged in the coarse textured soils. Results suggest that these sulfatic soils are more susceptible to sodicity induced deterioration than chloridic soils. These results and earlier field observations suggest that sustainable irrigation may be limited to sites with a water source having a SAR <5 and an EC not exceeding 0.3 S m^‐1 for these sulfatic glacially derived soils.     

SEVERITY OF SALINITY ACCURATELY DETECTED AND CLASSIFIED ON A PADDOCK SCALE WITH HIGH RESOLUTION MULTISPECTRAL SATELLITE IMAGERY

We hypothesised that digital mapping of various forms of salt‐affected soils using high resolution satellite imagery, supported by field studies, would be an efficient method to classify and map salinity, sodicity or both at paddock level, particularly in areas where salt‐affected patches are small and the effort to map these by field‐based soil survey methods alone would be inordinately time consuming. To test this hypothesis, QuickBird satellite data (pan‐sharpened four band multispectral imagery) was used to map various forms of surface‐expressed salinity in an agricultural area of South Australia. Ground‐truthing was performed by collecting 160 soil samples over the study area of 159 km². Unsupervised classification of the imagery covering the study area allowed differentiation of severity levels of salt‐affected soils, but these levels did not match those based on measured electrical conductivity (EC) and sodium adsorption ratio (SAR) of the soil samples, primarily because the expression of salinity was strongly influenced by paddock‐level variations in crop type, growth and prior land management. Segmentation of the whole image into 450 paddocks and unsupervised classification using a paddock‐by‐paddock approach resulted in a more accurate discrimination of salinity and sodicity levels that was correlated with EC and SAR. Image‐based classes discriminating severity levels of salt‐affected soils were significantly related with EC but not with SAR. Of the spectral bands, bands 2 (green, 520–600 nm) and 4 (near‐infrared, 760–900 nm) explained the majority of the variation (99 per cent) in the spectral values. Thus, paddock‐by‐paddock classification of QuickBird imagery has the potential to accurately delineate salinity at farm level, which will allow more informed decisions about sustainable agricultural management of soils. Copyright © 2011 John Wiley & Sons, Ltd.     

Multispectral and Microwave Remote Sensing Models to Survey Soil Moisture and Salinity

Soil moisture stress and salinity are considered as a major form of land degradation in rain‐fed agricultural regions. The study has been carried out for four distinct periods such as 2001, 2005, 2010, and 2015 that was selected according to the climatic variations that occurred more than a decade. The multispectral remote sensing‐based empirical models were employed on Enhanced Thematic Mapper Plus and Operational Land Imager imageries to estimate the rate of soil moisture stress and salinity from 2001–2015. The rate of soil moisture stress has been magnified to 143%, and salinity was increased by 70% particularly from 2005–2010 when the drought period occurred. The reliability of identifying the saline‐affected soils from the multispectral remote sensing models was significantly affected (R ² = 0.39) because of the extensive distribution of Nerium oleander plants and water logging state in the study region. The modified microwave water cloud model revealed the three‐layer information such as N. oleander , soil, and vegetation such that an imaginary part of the dielectric constant derived from simplified Hallikainen empirical model has got good correlation (R ² = 0.73) with ground electrical conductivity measurements. Copyright © 2016 John Wiley & Sons, Ltd.     

Effect of soil salinity and sodicity on Matricaria chamomilla,L. Growth

Abstract

Growth response of Matricaria chamomilla, L. was investigated on a range of soil salinity and sodicity levels using fine and coarse‐textured soil types. Twenty treatments including 4 levels of salinity and 4 levels of sodicity on each soil type were examined in addition to control. On the coarse‐textured soils, chamomile responded best under relatively low saline and sodic conditions. Plant growth decreased with increase in salinity and sodicity. On the fine‐textured soils, plants endured saline conditions up to 13 ECe and grew better under sodic conditions. The best growth of plants was achieved on fine‐textured soils with sodicity level of 31.8 Esp.     

Sodicity Intensifies the Effect of Salinity on Grain Yield and Yield Components of Wheat

ABSTRACT

This study reports the relationship of the leaf ionic composition with the grain yield and yield components of wheat in response to salinity x sodicity and salinity alone. The study was conducted in soil culture in pots with three treatments including control (ECe 2.6 dS m^{? 1} and SAR 4.53), salinity (ECe 15 dS m^{? 1} and SAR 9.56), and salinity x sodicity (ECe 15 dS m^{? 1} and SAR 35). The soil was treated before being put in the pots and the pots were arranged in a completely randomized factorial arrangement with five replications. The seeds of three wheat genotypes were sown directly in the pots and the study was continued till the crop maturity. At booting stage, the leaf second to the flag leaf of each plant was collected and analyzed for sodium (Na⁺), potassium (K⁺), and chloride (Cl^?). At maturity, plants were harvested and data regarding grain yield and yield components were recorded. This study shows that salinity and sodicity in combination decreases the grain yield of wheat more than the salinity alone with a greater difference in the sensitive genotype. This study also shows that as for salinity, the maintenance of lower Na⁺ and higher K⁺ concentrations and higher K⁺: Na⁺ ratio in the leaves relates positively with the better development of different yield components and higher grain yield in saline sodic soil conditions. Although, the leaf Cl^? concentration was increased significantly by salinity as well as salinity x sodicity and would have affected the growth and yield, yet it does not seem to determine the genotypic tolerance or sensitivity to either salinity or salinity x sodicity.     

Salinity tolerance of earthworms and effects of salinity and vermi amendments on growth of Sorghum bicolor

Salinity is a major factor limiting irrigated agriculture in arid regions. Vermi amendments can be used for improving the fertility of salt-affected soils. Current study was aimed to find out the response of different earthworm species to soil salinity and to check the effects of salinity and different vermi amendments on growth of Sorghum bicolor under salt stress. Eight earthworm species were subjected to different salinity levels for 4 weeks. Various vermi amendments and salinity treatments were provided in a factorial combination to S. bicolor plants to see their effect on growth and biomass parameters. L. mauritii, E. incommodus and P. posthuma were found to be the most salt-tolerant species showing good survival and growth till soil EC_e value of 10.48 mS cm^?1. Results showed that salinity significantly decreased plant growth that was enhanced by the application of different vermi amendments. Maximum growth of S. bicolor was recorded when vermicompost and vermiwash were used together under both saline and non-saline conditions. The results showed that the application of vermi amendments improved nutritional balance of the soil, delayed salt-induced damage to the plants and supported their growth so can be helpful in increasing crop production on saline soils.     

Salinity risk assessment using fuzzy multiple criteria evaluation

For agricultural productivity, primary salinity constitutes a hazard. Understanding the risk of secondary salinization is also important and it is necessary to map all these hazards and the overall risk. One approach is digital soil mapping. We have developed hazard maps of root zone (0–2 m) and subsurface (6–12 m) salinity, as well as groundwater height, using empirical best linear unbiased prediction using proximal and remotely sensed ancillary data. To convert the hazards into salinity risk maps and account for some uncertainty, fuzzy membership functions (FMF) were used in conjunction with semantic import models that consider the vulnerability of agricultural crops. Therefore, we developed memberships (μ) to three salinity risk classes and created maps of each, including root zone (μ_RSR) and subsurface (μ_SSR) salinity, and depth to groundwater (μ_GTR). To estimate groundwater (μ_GSR) and overall salinity risk (μ_OSR), fuzzy multiple criteria evaluation was undertaken. To account for μ_GSR, the μ_SSR and μ_GTR were combined using a t‐norm operator, and μ_OSR was accounted for by combining μ_RSR and μ_GSR using a t‐conorm operator. The approach was applied to an area growing irrigated cotton. Cross‐validation shows predicted μ_OSR was good, with an agreement rate of 70.6%. The predicted μ_OSR was consistent with that of many areas affected by point‐source salinity. The method provides an effective way of mapping salinity hazard and risk. Incorporation of FMF provides a meaningful continuum of membership and allows the incorporation of uncertainty. Salinity risk can be calculated relative to any vegetation community and locations where management actions to moderate soil salinization can be identified.     

Integration of two simple models in a geographical information system to evaluate salinization risk in irrigated land of the Valencian Community, Spain

Abstract. Salt affected soil is one of the main problems decreasing the productivity of irrigated agriculture in the Mediterranean area. Simulation models in combination with geographical information systems (GISs) could be used to evaluate the risk of salinization at a regional scale. In this study, two logical models (Pla and Riverside) were combined in a GIS to evaluate the risk of soil salinity and sodicity in the irrigated agriculture of the Valencian Community, Spain. Simple models were chosen so that they could be used at a regional scale. Before running them in a GIS framework, a soil and irrigation water survey was conducted to validate the models with observed data. The Pla model fitted observed data better than Riverside guidelines, probably because parameters of water quality, soil and climate were considered by the Pla model. The resulting maps indicated that the soils most affected by salts are those located in the south of study area, owing to the arid climate, and those areas near the coast due to saline intrusion. Close to 42% of the irrigated area was predicted to be somewhat affected by salinization. The regional-scale soil salinity assessment presented here for the Valencian Community is the first to be made for this region and will be useful in targeting critical areas that may require special management.     

SALTIRSOIL: a simulation model for the mid to long‐term prediction of soil salinity in irrigated agriculture

The SALTIRSOIL model predicts soil salinity, sodicity and alkalinity in irrigated land using basic information on soil, climate, crop, irrigation management and water quality. It extends the concept of the WATSUIT model to include irrigation and crop management practices, advances in the calculation of evapotranspiration and new algorithms for the water stress coefficient and calculation of electrical conductivity. SALTIRSOIL calculates the soil water balance and soil solution concentration over the year. A second module, SALSOLCHEM, calculates the inorganic ion composition of the soil solution at equilibrium with soil calcite and gypsum at the soil’s CO₂ partial pressure. Results from comparing predicted and experimentally determined concentrations, observations and predictions of pH, alkalinity and calcium concentration in calcite‐saturated solutions agree to the second significant figure; in gypsum‐saturated solutions the standard difference between observations and predictions is <3% in absolute values. The algorithms in SALTIRSOIL have been verified and SALSOLCHEM validated for the reliable calculation of soil salinity, sodicity and alkalinity at water saturation in well‐drained irrigated lands. In simulations for horticultural crops in southeast Spain, soil solution concentration factors at water saturation, quotients of electrical conductivity (EC₂₅) at saturation to electrical conductivity in the irrigation water, and quotients of sodium adsorption ratio (SAR) are very similar to average measured values for the area.     

Salinity threshold value of Quinoa (Chenopodium Quinoa ‎Willd.) at ‎various growth stages and the appropriate ‎irrigation method by saline ‎water

Salinity is one of the major agricultural problems in arid and ?semi-arid regions. Considering the variation of plant’s ?sensitivity to salinity during growth, a greenhouse study with completely randomized design? was conducted to determine the relative salinity tolerance of Quinoa (Chenopodium quinoa Willd.) at different growth stages from seedling establishment to maturity (establishment, flowering and seed filling) by evaluating the Salinity Threshold Value (STV). Eight levels of EC_i (i.e., Non-saline, 2, 4, 8, 12, 15, 20, 25 dSm^?1) with four replications and five levels (i.e., Non-saline, 10, 15, 20, 25 dSm^?1) with three triplications were applied at first and two last growth stages, respectively. A ?comparison was performed on some growth and yield parameters of plants irrigated by considering STV (T) and ?plants irrigated permanently by mentioned salinity levels regardless of STV (P) to choose ?which method (P or T) is better at each salinity level. The STV was ?evaluated 8, 20 and 15 dSm^?1 at each growth stage, respectively. Seedling of Quinoa was more sensitive to salinity than the mature plant. Therefore, after establishment Quinoa has the ?feasibility of irrigation by high-saline waters. The (P) ?method was suitable only if the freshwater was available during all growth period of the plant; otherwise at higher salinities irrigation should be performed by considering STV (T method) to minimize the intensity of growth and yield reduction and to prevent yield loss at very high salinities. To achieve this, if high-saline water is available it’s possible to ?use plant propagation techniques or cultivating Quinoa simultaneously with seasonal rainfall.?     

黑河中游不同土地利用方式地面节肢动物对土壤盐渍化的响应

在甘肃河西走廊黑河中游荒漠绿洲过渡区,天然沙质草地被相继转变为农田和防风固沙人工林,但目前尚缺乏不同土地利用/管理方式下地面节肢动物群落对土壤盐渍化响应的系统研究。以天然沙质草地转变的人工梭梭灌木林、人工杨树林、人工樟子松林和农田为研究对象,以天然草地为对照,基于5种研究样地表层土壤盐分及其组成和地面节肢动物群落的观测数据,采用RDA(Redundancy analysis)排序分析等方法,研究了不同土地利用/管理方式下地面节肢动物个体数量和类群丰富度对土壤盐分环境变化的响应机制。主要结果为:(1)土地利用变化与管理措施相互作用驱动了地面节肢动物群落的演变过程,天然草地植被转变为人工林和农田20多年后,显著降低了地面节肢动物群落的数量而对类群丰富度无显著影响。(2)地面节肢动物群落的变化受土壤pH、Na+、Mg2+、Cl-离子的共同影响,其中土壤pH、Na+和Mg2+离子对动物群落变化的贡献率最大,是关键生态因子。(3)动物个体数量随土壤pH的增加而增加,随Mg2+、Cl-离子浓度的增加而下降。研究表明,土地利用变化引起的土壤盐分环境改变是驱动地面节肢动物群落演变的重要因素之一。     

Costing yield loss from acidity,sodicity and dryland salinity to Australian agriculture

Salinity, sodicity and acidity are three major soil constraints that limit crop and pasture yields in Australia. In this paper estimates are made of the potential benefits arising from their treatment by measuring and mapping their impact on agricultural profit. This is achieved by estimating the increase in profit for Australia's main commodities that would occur if the three soil constraints were costlessly ameliorated. These estimates reveal the upper achievable limit on investment returns. They are also indicative of each soil constraint's economic significance to Australian agriculture. It was found that costless removal of salinity would increase annual profits by A$187 million, sodicity by A$1034·6 million and acidity by A$1584·5 million. This equates to 2·9 per cent, 15·8 per cent and 24·2 per cent of total net economic return. It was also found that worsening salinity extent and severity over 2000–2020 has a present value of A$496–A$712 million. Although soil salinity is currently the focus of much public attention, this analysis suggests that from a production viewpoint the correction of sodic and acidic soils may create greater private economic benefit. Opportunities vary considerably among industries. In particular, there is considerable opportunity for the horticultural and viticultural sector to address acidity issues. Whether gross benefits translate into net benefits is a complex question requiring access to context and location‐specific information. Copyright © 2005 John Wiley & Sons, Ltd.     

盐碱地土壤酶活性研究进展和展望

盐碱地是农业生产重要的后备土地资源,同时土壤盐渍化是灌溉农业生产过程中首要考虑的问题之一。近年来,越来越多的研究开始关注盐碱地改良利用过程中包括土壤生物学性质在内的土壤整体环境质量的改善。其中,土壤酶是土壤生物活动的产物,其活性水平是土壤环境质量的良好生物学指标,可以用来评价土壤退化程度及管理措施的效果和可持续性。本文总结说明了盐渍化土壤酶活性状况及盐碱胁迫机理,并对盐碱地改良利用过程中土壤酶活性的研究现状进行了综述。最后从存在问题和关注热点出发,提出了下一步的研究重点。     

Reclamation and salt leaching efficiency for tile drained saline‐sodic soil using marginal quality water for irrigating rice and wheat crops

Due to increased population and urbanization, freshwater demand for domestic purposes has increased resulting in a smaller proportion for irrigation of crops. We carried out a 3‐year field experiment in the Indus Plains of Pakistan on salt‐affected soil (EC_e 15·67–23·96 dS m⁻¹, pH_s 8·35–8·93, SAR 70–120, infiltration rate 0·72–0·78 cm h⁻¹, ρ _b 1·70–1·80 Mg m⁻³) having tile drainage in place. The 3‐year cropping sequence consisted of rice (Oryza sativa L.) and wheat (Triticum aestivum L.) crops in rotation. These crops were irrigated with groundwater having electrical conductivity (EC) 2·7 dS m⁻¹, sodium adsorption ratio (SAR) 8·0 (mmol L⁻¹)^1/2 and residual sodium carbonate (RSC) 1·3 mmol_c L⁻¹. Treatments were: (1) irrigation with brackish water without amendment (control); (2) Sesbania (Sesbania aculeata) green manure each year before rice (SM); (3) applied gypsum at 100 per cent soil gypsum requirement (SGR) and (4) applied gypsum as in treatment 3 plus sesbania green manure each year (GSM). A decrease in soil salinity and sodicity and favourable infiltration rate and bulk density over pre‐experiment levels are recorded. GSM resulted in the largest decrease in soil salinity and sodicity. There was a positive relationship between crop yield and economic benefits and improvement in soil physical and chemical properties. On the basis of six crops, the greatest net benefit was obtained from GSM. Based on this long‐term study, combined use of gypsum at 100 per cent soil gypsum requirement along with sesbania each year is recommended for soil amelioration and crop production. Copyright © 2010 John Wiley & Sons, Ltd.     

A soil-diagnostic key to manage saline and waterlogged catchments in the Mt Lofty Ranges, South Australia

Abstract. Dryland salinity in the Mt Lofty Ranges, South Australia has developed as a result of native vegetation being replaced with pastures that use less water. Groundwaters have risen and mobilized ions (sodium, chloride, sulphate and iron) stored within deeply weathered micaceous sandstones and schists. Salinity resulting from sodium chloride is common in agricultural catchments around Australia, but saline sulphidic soils (with sulphate and iron) have only been studied in South Australia. Salinity is also associated with waterlogging and secondary sodicity. The amelioration of dryland salinity and waterlogging involves management of whole catchments, not just the area that is currently saline. It is imperative that all processes operating in saline catchments and their interactions are clearly understood.
Salinity, waterlogging, sodicity, sulphidization and water erosion were studied in four saline sub-catchments in the Mt Lofty Ranges. Grey (bleached) and yellow mottles (iron depletions) or black and red stains (iron concentrations) develop under certain conditions of water saturation, salinization, sulphidization, sodification and water erosion in surface and subsurface horizons. The amounts of these diagnostic features were used to develop a farm planning key for managing saline catchments in the Mt Lofty Ranges. Using soil diagnostic features, soil-water processes in saline catchments are easily identified by farmers and land managers. Management options (e.g. fencing, tree planting and drainage) are then targeted to specific soils and can be easily incorporated by agricultural advisers into farm management plans. We recommend that soil diagnostic features which help predict the onset of land degradation be used in the production of land capability maps for farm planning purposes.