Physico—Chemical Properties and Laboratory Hyperspectral Reflectance of Coastal Saline Soil in Shangyu City of Zhejiang Province, China.1

45 and 50 composite soil samples were collected, respectively, from two agricultural fields, that were enclosed and reclaimed from coastal tidal-fiat areas in 1996 and 1984 respectively, in Shemgyu of Zhejiang Province, China, to investigate the physico-chemical properties and the hyperspectral characteristics of the saline soils and to make an assessment on their relationships. The reflectance spectra of saline soils were measured using a spectroradiometer in laboratory. The mean spectral curves of the saline soils from the two sites different in reclamation year showed that the saline soil taken from the recently reclaimed land with higher salinity demonstrated a lower reflectance intensity in the spectral region from about 550 nm to 2300 nm. In addition, nine absorption bands, i.e., 488 nm, 530 nm, 670 nm, 880 nm, 940 nm, 1400 nm,1900 nm, 2 200 nm and 2 300 nm, were chosen as the spectral bands to investigate the relationships between soil physico-chemical properties by means of Pearson correlation analysis. Finally, the first two principal components were calculated from nine absorption bands and used to discriminate the saline soil samples taken from two sampled fields. The results indicate that it is feasible to detect physico-chemical properties of saline soils from fields reclaimed for varying time periods on the basis of the hyperspectral data.     

中国渤海海岸盐碱土及非盐碱土中土壤生物多样性

A plethora of information is available on the effects of salinity on plant growth and soil physico-chemical properties,but the effects on soil organisms are often neglected.Thus,a systematic investigation of how soil biodiversity,including bacteria,nematodes,mites,and earthworms,changes along saline gradients was conducted along the Bohai Sea coast at Laizhou City,Shandong Province,China,with 30 soil samples randomly selected and classified by salinity into two categories:saline and non-saline.Testing revealed a significantly higher abundance of the surveyed organisms in non-saline soils.The redundancy analysis showed that a negative correlation was observed between electrical conductivity and soil organism abundance in saline soil,but not in non-saline soil.Soil organic matter,available nitrogen,and total nitrogen all positively affected organism abundance in both saline and non-saline soils.The richness and Shannon diversity of nematodes were significantly higher in non-saline soils,but were not significantly different between soil types for other organisms.None of the environmental factors surveyed was obviously related to soil organism diversity.Consequently,our results suggested that soil electrical conductivity only negatively affected soil organisms in saline soil,while soil fertility positively affected soil organisms in both saline and non-saline soils.     

在盐水浇灌条件下堆肥对土壤性质、小麦生长以及作物营养的影响

A greenhouse experiment was conducted to test and compare the suitability of saline compost and saline irrigation water for nutrient status amendment of a slightly productive sandy clay loam soil,to study the macronutrient utilization and dry matter production of wheat(Triticum aestivum c.v.Gemmiza 7) grown in a modified soil environment and to determine the effects of compost and saline irrigation water on soil productivity.The sandy clay loam soil was treated with compost of five rates(0,24,36,48,and 60 m 3 ha-1,equivalent to 0,3,4.5,and 6 g kg-1 soil,respectively) and irrigation water of four salinity levels(0.50(tap water),4.9,6.3,and 8.7 dS m-1).The results indicated that at harvest,the electrical conductivity(EC) of the soil was significantly(P < 0.05) changed by the compost application as compared to the control.In general,the soil salinity significantly increased with increasing application rates of compost.Soluble salts,K,Cl,HCO 3,Na,Ca,and Mg,were significantly increased by the compost treatment.Soil sodium adsorption ratio(SAR) was significantly affected by the salinity levels of the irrigation water,and showed a slight response to the compost application.The soil organic carbon content was also significantly(P < 0.05) affected by application of compost,with a maximum value of 31.03 g kg-1 recorded at the compost rate of 60 m 3 ha-1 and the irrigation water salinity level of 8.7 dS m-1 and a minimum value of 12.05 g kg 1 observed in the control.The compost application produced remarkable increases in wheat shoot dry matter production.The maximum dry matter production(75.11 g pot-1) occurred with 60 m 3 ha-1 compost and normal irrigation water,with a minimum of 19.83 g pot-1 with no addition of compost and irrigation water at a salinity level of 8.70 dS m-1.Significant increases in wheat shoot contents of K,N,P,Na,and Cl were observed with addition of compost.The relatively high shoot N values may be attributed to increases in N availability in the tested soil caused by the compost application.Similarly,significant increases in the shoot contents of Na and Cl may be ascribed to the increase in soil soluble K and Cl.The increases in shoot P,N,and K contributed to the growth stimulation since P supplied by the compost was probably responsible in saline and alkaline soils where P solubility was very low.     

Dynamics of Soil Moisture and Salt Content After Infiltration of Saline Ice Meltwater in Saline-Sodic Soil Columns

Saline ice meltwater can be used for irrigation and leaching of salts in salt-affected soil regions.A laboratory experiment was conducted using soil columns to investigate the redistribution of soil moisture, salt and sodium adsorption ratio(SAR) in saline-sodic soil under the infiltration of saline ice meltwater.Soils were treated using saline water of three irrigation volumes(1 600, 2 400 and 3 200 mL) at four salinity levels.These four salinity levels included salt free(0 g L~(-1)), low salinity level(1.4 g L~(-1)), moderate salinity level(2.7 g L~(-1)) and high salinity level(4.1 g L~(-1)).The prepared saline water was frozen into ice, and then the ice was put on the surface of soil columns.After 96 h, the infiltration rate and soil moisture content of saline ice treatments were greater than those of salt-free ice treatments, increasing with the increase of ice salinity.Infiltration of saline ice meltwater increased soil moisture content in the upper layers for all treatments.Both salt contents and SAR values in the upper soil layers decreased in all saline ice treatments and were lower than those in salt-free ice treatment.However, this trend was reversed in the deeper(below 20 cm) soil layers.The highest desalting rate and lowest SAR were observed in high-salinity treatment under three irrigation volumes in the 0–15 cm soil layer,especially under irrigation volume of 2 400 mL.These results indicate that saline ice(0–20 cm) meltwater irrigation is beneficial to saline-sodic soil reclamation, and the best improvement effect would be achieved when using high-salinity ice under optimal irrigation volume.     

中国浙江省上虞市滨海盐土的物理化学性质及其实验超级光谱反射

45 and 50 composite soil samples were collected, respectively, from two agricultural fields, that were enclosed and reclaimed from coastal tidal-flat areas in 1996 and 1984 respectively, in Shangyu of Zhejiang Province, China, to investigate the physico-chemical properties and the hyperspectral characteristics of the saline soils and to make an assessment on their relationships. The reflectance spectra of saline soils were measured using a spectroradiometer in laboratory. The mean spectral curves of the saline soils from the two sites different in reclamation year showed that the saline soil taken from the recently reclaimed land with higher salinity demonstrated a lower reflectance intensity in the spectral region from about 550 nm to 2300 nm. In addition, nine absorption bands, i.e., 488 nm, 530 nm, 670 nm, 880 nm, 940 nm, 1400 nm, 1900 nm, 2 200 nm and 2 300 nm, were chosen as the spectral bands to investigate the relationships between soil physico-chemical properties by means of Pearson correlation analysis. Finally, the first two principal components were calculated from nine absorption bands and used to discriminate the saline soil samples taken from two sampled fields. The results indicate that it is feasible to detect physico-chemical properties of saline soils from fields reclaimed for varying time periods on the basis of the hyperspectral data.     

温室集约化生产系统对土壤质量的影响

Composite top- and subsoil samples were collected from the greenhouses in the Al-Balawneh area,Jordan,where intensive greenhouse production system（IGPS） has been practiced since 1998,to study the impact of IGPS on soil quality as measured by the chemical and biological properties to develop a sustainable production system.The study showed that IGPS led to higher electrical conductivity in top- and subsoils compared to an uncultivated soil（control）.Quality and amount of irrigation water,lack of efficient drainage,and quantity and types of applied fertilizers were major factors resulting in salt buildup.IGPS resulted in lower total N（TN） and NO₃-N in the soil compared to the control.The lower TN was due to crop uptake,microbial immobilization,volatilization,and irregular application of composted animal manure or poultry manure.In contrast,higher residual Olsen-P content was detected in both soil layers of greenhouses than in the control.Residual P was classified as very high in the topsoil layers and sufficient to high in the subsoil layers.Residual available K in the soils of greenhouses was relatively lower than that in the control and it was,however,classified as high to very high.A large increase of Cl and a considerable decrease in the bacterial count were observed in both soil layers of IGPS compared to the control treatment.Economically sustainable soil management practices need to be adopted by farmers to achieve a sustainable and profitable production.This can be accomplished through education,targeted towards the farming community in the central Jordan Valley.     

集约化管理的温室土壤养分现状研究

Nine districts covering the main greenhouse vegetable areas in Tianjin Municipality of the North China Plain were selected for the soil investigation in 2010 to survey the current soil nutrient status (soil available N, P and K), acidification and salinization due to excessive input of fertilizers in greenhouses in Tianjin. The study showed that, in particular, soil available P content increased with the age of greenhouses. In contrast, our results did not reveal higher K accumulation and lowered pH in the greenhouse soils compared with cultivation in open fields. Over-fertilization, causing high NO 3 accumulation, most likely resulted in salinity problems in the greenhouses. Ninety percent of the investigated greenhouse soils had electrical conductivity values of saturated paste extracts of 2-10 d S m-1 , which might affect the yields of vegetable crops like green bean, pepper, cabbage, carrot, eggplant, lettuce, spinach, celery, cucumber and tomato. The findings of our survey of the current fertility and salinity problems in greenhouse soils suggest that there is an urgent need to improve the farmers’ practices and strategies in fertilization management in greenhouses of China. Because education and the agricultural technical extension services may play a more important role in avoiding overuse of fertilizers, we suggest that current nutrient management practices should be improved in the near future through training of local farmers in farmers’ schools and through strengthening the agricultural extension services with practical techniques.     

黄河下游冲积平原土壤盐分的时空变异研究——个例研究

Soil salinity and hydrologic datasets were assembled to analyze the spatio-temporal variability of salinization in Fengqiu County, Henan Province, China, in the alluvial plain of the lower reaches of the Yellow River. The saline soil and groundwater depth data of the county in 1981 were obtained to serve as a historical reference. Electrical conductivity (EC) of 293 surface soil samples taken from 2 km × 2 km grids in 2007 and 40 soil profiles acquired in 2008 was analyzed and used for comparative mapping. Ordinary kriging was applied to predict EC at unobserved locations to derive the horizontal and vertical distribution patterns and variation of soil salinity. Groundwater table data from 22 observation wells in 2008 were collected and used as input for regression kriging to predict the maximum groundwater depth of the county in 2008. Changes in the groundwater level of Fengqiu County in 27 years from 1981 to 2008 was calculated. Two quantitative criteria, the mean error or bias (ME) and the mean squared error (MSE), were computed to assess the estimation accuracy of the kriging predictions. The results demonstrated that the soil salinity in the upper soil layers decreased dramatically and the taxonomically defined saline soils were present only in a few micro-landscapes after 27 years. Presently, the soils with relatively elevated salt content were mainly distributed in depressions along the Yellow River bed. The reduction in surface soil salinity corresponded to the locations with deepened maximum groundwater depth. It could be concluded that groundwater table recession allowed water to move deeper into the soil profile, transporting salts with it, and thus played an important role in reducing soil salinity in this region. Accumulation of salts in the soil profiles at various depths below the surface indicated that secondary soil salinization would occur when the groundwater was not controlled at a safe depth.     

利用作物水盐生产函数和土壤水盐动态模型制定咸水灌溉制度

Using a crop-water-salinity production function and a soil-water-salinity dynamic model, optimal irrigation scheduling was developed to maximize net return per irrigated area. Plot and field experiments were used to obtain the crop water sensitivity index, the salinity sensitivity index, and other parameters. Using data collected during 35 years to calculate the 10-day mean precipitation and evaporation, the variation in soil salinity concentrations and in the yields of winter wheat and cotton were simulated for 49 irrigation scheduling that were combined from 7 irrigation schemes over 3 irrigation dates and 7 salinity concentrations of saline irrigation water （fresh water and 6 levels of saline water）. Comparison of predicted results with irrigation data obtained from a large area of the field showed that the model was valid and reliable. Based on the analysis of the investment cost of the irrigation that employed deep tube wells or shallow tube wells, a saline water irrigation schedule and a corresponding strategy for groundwater development and utilization were proposed. For wheat or cotton, if the salinity concentration was higher than 7.0 g L^-1 in groundwater, irrigation was needed with only fresh water; if about 5.0 g L^-1, irrigation was required twice with fresh water and once with saline water; and if not higher than 3.0 g L^-1, irrigation could be solely with saline water.     

上海市土壤中持久性毒害污染物和盐分含量特征研究

Some farmland soils in Shanghai had high salinity levels, suggesting secondary salinization of the soils. The soil problems in Shanghai were studied, including the salinity and nitrate nitrogen (NO₃^--N) concentrations, heavy metal pollution characteristics, and organochlorine pesticide (OCP) residual levels and polycyclic aromatic hydrocarbon (PAH) contents. Accumulation of NO₃^--N in vegetable soils was the most significant among different functional soils. Heavy metal pollution was significant in the samples collected from the sewage-irrigated land and roadside. The identification of the metal sources through multivariate statistical analysis indicated that Pb, Zn, Cu and Cr in urban soils were from the traffic pollutants; excessive application of fertilizer and irrigation were the main reasons for the metal pollution in agricultural soils; Ni in the observed soils was controlled by parent soils. OCPs could still be detected in farmland soils but degraded greatly in last 20 years after prohibition of their usage. PAHs with 2-3 rings were the main components in industrial soils. The concentrated PAHs in the investigated soils were likely from petroleum and coal combustion.     

Spatial evaluation of soil salinity using the WET sensor in the irrigated area of the Segura river lowland

The electrical conductivity of the water within the soil pores (EC_p) measured with the WET sensor, appears to be a reliable estimate of soil salinity. A methodology combining the use of the WET sensor along with geostatistics was developed to delimit and evaluate soil salinity within an irrigated area under arid to semiarid Mediterranean climate in SE Spain. A systematic random sampling of 104 points was carried out. The association between EC_p and the saturation‐extract electrical conductivity (EC_se) was assessed by means of correlation analysis. The semivariograms for EC_p were obtained at three different soil depths. Interpolation techniques, such as ordinary kriging and cokriging, were applied to obtain EC_p levels in the unknown places. For each one of the soil depths, a model able to predict EC_se from EC_p was developed by means of ordinary least squares regression analysis. A good correlation (r = 0.818, p < 0.001) between EC_p and EC_se was found. Spherical spatial distribution was the best model to fit to experimental semivariograms of EC_p at 10, 30, and 50 cm soil depths. Nevertheless, cokriging using the EC_p of an adjacent soil depth as an auxiliary variable provided the best results, compared to ordinary kriging. An analytical propagation‐error methodology was found to be useful to ascertain the contribution of the spatial interpolation and ordinary least squares analysis to the uncertainty of the EC_se mapping. This methodology allowed us to identify 98% of the study area as affected by salinity problems within a rooting depth of 50 cm, with the threshold of EC_se value at 2 dS m^–1. However, considering the crops actually grown and 10% potential reduction yield, the soil‐salinity‐affected area decreased to 83%. The use of sensors to measure soil salinity in combination with geostatistics is a cost‐effective way to draw maps of soil salinity at regional scale. This methodology is applicable to other agricultural irrigated areas under risk of salinization.     

Influence of Laboratory Methods on Calcareous Saline Soils for EC Measurement and Leaching

Abstract

Electrical conductivity (EC) methods were tested using combinations of surrogate irrigation (SI) waters, soil salinity levels, and soils ground or retaining aggregates. The EC varied in low-salinity soils saturated with SI; the sum of the baseline EC_e and SI EC were not equal to the measured EC. The baseline EC_e and the SI EC sum in the high‐salinity ground soils were not equal to the any measured ECs. Salt‐removal potential from gypsiferous soils was examined using multiple extractions from the same soil sample. Calcium concentrations remained consistent over 14 extractions, whereas Na concentrations decreased. The EC_e decreased from more than 8 dS m^?1 in the initial extraction, to approximately 4 dS m^?1 by the 9th to 14th extraction. Multiple extraction data suggest that improved leaching will not lower soil ECs to less than approximately 4 dS m^?1 because of gypsum and calcite reservoirs in the tested soils.     

Potential of Carbon Dioxide Biosequestration of Saline–Sodic Soils during Amelioration under Rice–Wheat Land Use

Potential for carbon dioxide (CO₂) biosequestration was determined during the reclamation of highly saline–sodic soils (Aridisols) after rice (2003) and wheat (2003–2004) crops at two sites in District Faisalabad, Pakistan. Two treatments were assessed: T₁, tube-well brackish water only; and T₂, soil-applied gypsum at 25% soil gypsum requirement?+?tube-well brackish water. The irrigation water used at both sites had different levels of salinity (EC 3.9–4.5 dS m^?1), sodicity (SAR 21.7–28.8), and residual sodium carbonate (14.9 mmol_c L^?1). Composite soil samples were collected from soil depths of 0–15 and 15–30 cm at presowing and postharvest stages and analyzed for pH, EC_e, and sodium adsorption ratio (SAR). After rice harvest, there was no significant effect of gypsum application on EC_e, pH, and SAR at both sites, except pH at 0–15 cm depth decreased significantly with gypsum at site 1. After wheat harvest, EC_e, pH, and SAR decreased significantly with gypsum at site 1, whereas the effect of gypsum on these parameters was not significant at site 2. Compared to initial soil, EC_e and SAR in soil decreased considerably after rice or wheat cultivation, particularly at site 1, whereas pH increased slightly due to cultivation of these crops. For rice, the total CO₂ sequestration was significantly increased with gypsum application at both sites and ranged from 1499 to 2801 kg ha^?1. The total sequestration of CO₂ was also significantly increased with gypsum application in wheat at both sites and ranged from 2230 to 3646 kg ha^?1. The amounts of CO₂ sequestered by crops due to gypsum application were related to seed and straw yield responses of rice and wheat to gypsum, which were greater at site 1 than site 2. Also, the yield response to applied gypsum was greater for rice than wheat at site 1, whereas the opposite was true at site 2. Overall, the combined application of gypsum with brackish water reduced soil EC_e and SAR compared to brackish water alone, particularly at site 1. Our findings also suggest that the reclamation strategies should be site specific, depending on soil type and quality of brackish water used for irrigation of crops. In conclusion, the use of gypsum is recommended on brackish water–irrigated salt-prone soils to improve their quality, and for enhancing C biosequestration and crop production for efficient resource management.     

Soil texture affects the conversion factor of electrical conductivity from 1:5 soil-water to saturated paste extracts

Electrical conductivity(EC) of soil-water extracts is commonly used to assess soil salinity. However, its conversion to the EC of saturated soil paste extracts(ECe), the standard measure of soil salinity, is currently required for practical applications. Although many regression models can be used to obtain ECe from the EC of soil-water extracts, the application of a site-specific model to different sites is not straightforward due to confounding soil factors such as soil texture. This study was...     

SOIL SALINITY AND SODICITY APPRAISAL BY ELECTROMAGNETIC INDUCTION IN SOILS IRRIGATED TO GROW COTTON

In the Far West Texas region in the USA, long‐term irrigation of fine‐textured valley soils with saline Rio Grande River water has led to soil salinity and sodicity problems. Soil salinity [measured by saturated paste electrical conductivity (EC_e)] and sodicity [measured by sodium adsorption ratio (SAR)] in the irrigated areas have resulted in poor growing conditions, reduced crop yields, and declining farm profitability. Understanding the spatial distribution of EC_e and SAR within the affected areas is necessary for developing management practices. Conventional methods of assessing EC_e and SAR distribution at a high spatial resolution are expensive and time consuming. This study evaluated the accuracy of electromagnetic induction (EMI), which measures apparent electrical conductivity (EC_a), to delineate EC_e and SAR distribution in two cotton fields located in the Hudspeth and El Paso Counties of Texas, USA. Calibration equations for converting EC_a into EC_e and SAR were derived using the multiple linear regression (MLR) model included in the EC_e Sampling Assessment and Prediction program package developed by the US Salinity Laboratory. Correlations between EC_a and soil variables (clay content, EC_e, SAR) were highly significant (p ≤ 0·05). This was further confirmed by significant (p ≤ 0·05) MLRs used for estimating EC_e and SAR. The EC_e and SAR determined by EC_a closely matched the measured EC_e and SAR values of the study site soils, which ranged from 0·47 to 9·87 dS m⁻¹ and 2·27 to 27·4 mmol^1/2 L^−1/2, respectively. High R² values between estimated and measured soil EC_e and SAR values validated the MLR model results. Results of this study indicated that the EMI method can be used for rapid and accurate delineation of salinity and sodicity distribution within the affected area. Copyright © 2012 John Wiley & Sons, Ltd.     

Accumulation of Ions in Shoot and Seed of Quinoa (Chenopodium ‎quinoa Willd.) Under Salinity Stress

Quinoa (Chenopodium quinoa Willd.) is a high-nutrient halophyte suitable for ?cultivating in semi-arid climates and saline soils. The current study investigated the ?effect of various water salinities (EC_i) (i.e., 0.3, 10, 15, 20, and 25 dS m^?1) and different ?irrigation methods (IMs) on accumulation of calcium (Ca), magnesium (Mg), ?sodium (Na), and chloride (Cl) ions in shoot (stem+leaves) of quinoa at the end of vegetation (onset of flowering) and seed at the end of seed-filling. Therefore, 30 pots (five EC_i and two IM in three replications) were prepared with similar conditions. Considering that the salinity threshold value (STV) of quinoa varies during growth and is 8, 20 and 15 dSm^?1 at each of ?establishment, flowering, and seed-filling growth stages, the two IMs consisted of considering STV at each growth stage (T) and permanent irrigation by ?constant levels of EC_i(P). Results indicated that by increasing the EC_i from 0.3 to 25 dSm^?1 the amount of Na, Cl, and Mg in shoot increased 82.2%, 75.8%, and 8.7%, respectively, while Ca decreased 37.2%. In seeds, Na and Cl increased 43.3% and 50%, respectively, while Mg increased 8% and Ca did not change significantly. An increase in EC_i ?significantly changed ion accumulation content, especially at EC_i higher than STV, ?because it is the onset of damage due to salinity stress and particularly in? ??shoot compared to seed due to the halophytic properties of quinoa. The T ?method of irrigation was preferred due to less accumulation of Na and Cl in ?shoot and seed, and therefore less damage and loss, especially at higher ?salinities.?     

Increasing the Knowledge on the Management of Cu‐Contaminated Agricultural Soils by Cropping Tomato (Solanum Lycopersicum L.)

This paper increases the knowledge on the potential use of Cu‐contaminated agricultural soils with tomato (Solanum lycopersicum L.). The effect of Cu and its interaction with soil properties on plant biomass production and on the accumulation of this metal in plant tissues were evaluated by conducting biomass assays in four representative Mediterranean agricultural soils contaminated by Cu. Copper toxicity on plant biomass production, evaluated through the effective concentrations of Cu added to soil that reduce the biomass production by 50% (EC₅₀) and by 10% (EC₁₀), was higher in soils having less soil organic matter and clay content and even in soils with favourable properties but having salinity. For the cases in which tomato was collected, Cu concentrations in them were similar for all soils and doses and never exceed the maximum Cu concentration allowed by the Codex Alimentarius Commission Regulation (10 mg_Cu kg⁻¹ in fresh weight basis). According to our results, tomato could be cropped in Cu‐contaminated Mediterranean agricultural soils when concentrations of Cu determined in them rely between their respective EC₅₀ and EC₁₀, because production and quality of fruits, the latter understood as the Cu concentration in them, would not be compromised. For the soils assayed, these values would range between 32·9 and 1696·5 mg kg⁻¹, depending on soil properties. Because the baseline value considered is similar to those established in other parts of the European Mediterranean region, these results can be used as guidance for this region to establish adequate phytoremediation strategies and prevent land degradation processes. Copyright © 2014 John Wiley & Sons, Ltd.     

Changes of arbuscular mycorrhizal traits and community structure with respect to soil salinity in a coastal reclamation land

A comprehensive knowledge on the relationship between soil salinity and arbuscular mycorrhizal fungi (AMF) is vital for a deeper understanding of ecosystem functioning under salt stress conditions. The objective of this study was to determine the effects of soil salinity on AMF root colonization, spore count, glomalin related soil protein (GRSP) and community structure in Saemangeum reclaimed land, South Korea. Soil samples were collected and grouped into five distinct salt classes based on the electrical conductivity of soil saturation extracts (EC_se). Mycorrhizal root colonization, spore count and GRSP were measured under different salinity levels. AMF community structure was studied through three complementary methods; spore morphology, terminal restriction fragment length polymorphism (T-RFLP) and denaturing gradient gel electrophoresis (DGGE). Results revealed that root colonization (P < 0.01), spore count (P < 0.01) and GRSP (P < 0.01) were affected negatively by soil salinity. Spore morphology and T-RFLP data showed predominance of AMF genus Glomus in Saemangeum reclaimed land. T-RFLP and DGGE analysis revealed significant changes in diversity indices between non (EC_se < 2 dS/m) and extremely (EC_se > 16 dS/m) saline soil and confirmed dominance of Glomus caledonium only in soils with EC_se < 8 dS/m. However, ribotypes of Glomus mosseae and Glomus proliferum were ubiquitous in all salt classes. Combining spore morphology, T-RFLP and DGGE analysis, we could show a pronounced effect in AMF community across salt classes. The result of this study improve our understanding on AMF activity and dominant species present in different salt classes and will substantially expand our knowledge on AMF diversity in reclaimed lands.     

Utilizing a DUALEM‐421 and inversion modelling to map baseline soil salinity along toposequences in the Hunter Valley Wine district

In the oldest commercial wine district of Australia, the Hunter Valley, there is the threat of soil salinization because marine sediments underlie the area. To understand the risk requires information about the spatial distribution of soil properties. Electromagnetic (EM) induction instruments have been used to identify and map the spatial variation of average soil salinity to a certain depth. However, soils vary with depth dependent on soil forming factors. We collected data from a single‐frequency and multiple‐coil DUALEM‐421 along a toposequence. We inverted this data using EM4Soil software and evaluated the resultant 2‐dimensional model of true electrical conductivity (σ – mS/m) with depth against electrical conductivity of saturated soil pastes (EC_p – dS/m). Using a fitted linear regression (LR) model calibration approach and by varying the forward model (cumulative function‐CF and full solution‐FS), inversion algorithm (S1 and S2), damping factor (λ) and number of arrays, we determined a suitable electromagnetic conductivity image (EMCI), which was optimal (R² = 0.82) when using the full solution, S2, λ = 3.6 and all six coil arrays. We conducted an uncertainty analysis of the LR model used to estimate the electrical conductivity of the saturated soil‐paste extract (EC_e – dS/m). Our interpretation based on estimates of EC_e suggests the approach can identify differences in salinity, how these vary with parent material and how topography influences salt distribution. The results provide information leading to insights into how soil forming factors and agricultural practices influence salinity down a toposequence and how this can guide soil management practices.     

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.