Effects Of Sodicity Research Articles

Competence of Cow Manure as a Sustainable Feedstock for Bioenergy and Biofertilizer Production

Livestock development sector remained conspicuous in many developed and developing countries. Nevertheless, animal manure management became an increasing concern relative to environmental and economic constraints. The daily cow manure varies between 60-85 kg per 1000 kg of body biomass. Thus, 33 to 70 % of biomass could be recovered in the form of cow dung for value added products such as bioenergy and biofertilizer. Halhale dairy farm of Eritrea has a potential to produce approximately 25 tonnes of fresh cow manure per day. Proximate analysis of Halhale dairy manure (HDM) revealed that it contains a mean value of 14.35% of total solids, which inherently composed of 64.8% of Volatile solids and 23.3% of ash content. Detailed elemental analysis using X-ray fluorescent showed that it has 43.1% of C, 0.31% of S, 0.21% of P and 1.18% of K. Hydrogen and nitrogen contents of 4.57% and 1.58% were evaluated for HDM. Thermophysical parameters such as PH, SG and lower heating value(LHV) estimated as 7.025, 1.68 and 19.97 MJ kg-1 respectively. Significant LHV values indicate the aptness of HDM for fuel substitute. In addition, estimated C/N values of 25.68-27.3, ensure their best suitability for the biogas generation. Rich organic matter and high moisture content in HDM support large number of earthworms in vermicomposting. HDM have showed excellent N:P2O5 of 3.84 to favor the growth of any crop. Higher Si content of 4.32% along with desired micronutrients of 0.043% of Zn, <0.02% of Cu and 241 ppm of Mn, were measured for HDM samples. The effect of sodicity on soil measured in terms of sodium absorption rate (SAR), and a mean value of 0.84 was estimated for HDM.

An Appraisal of Fertility Status of Problem Soils of Tiruchirappalli District in Cauvery Delta Zone, Tamil Nadu, India

Soil fertility is an important factor for plant growth and has a global impact on both developed and developing countries. The present investigation was carried out on soil fertility status of farm in ADAC&RI, Trichy which comes under the Cauvery Delta Zone of Tamil Nadu. The pH value indicates that ADAC&RI farm soils are very strongly alkaline in nature. The rating of electrical conductivity was normal with values ranging from 0.16 – 0.72 dS m-1. The farm soil was low in available nitrogen, medium to high in available phosphorus and potassium. The average organic carbon content was low in the farm soil with values of 4.09 and 4.33 g kg-1 in A and D block, respectively. The available sulphur content of the farm was recorded as sufficient. This study clearly shows that, most of the soil nutrients in the ADAC&RI, farm was found to be low and need proper management practices to improve the soil quality for better crop production. The present investigation reveals the effect of sodicity on the status of available nutrients in soil.

Ameliorative Role of Silicon on Osmoprotectants, Antioxidant Enzymes and Growth of Maize Grown Under Alkaline Stress

PurposeMaize is a cereal crop which plays an important role in ensuring food security and social and economic stability. It is grown in different environments. Global agriculture is currently encountered with large scale alkalinity stress. Supplementing silicon, is an alternative way for overcoming the negative effects of sodicity on the plant growth and yield and is cheaper than other methods to reduce sodicity. Hence, a pot experiment was contemplated to examine the role of silicon in alleviating alkaline stress encountered by maize crop.MethodsAmeliorative role of silicon in alkaline stress soil was studied with four levels of alkaline stress (0, 25, 50, 75 mM) created through addition of sodium carbonate and three levels of silicon (0, 100 and 150 kg ha−1) applied to root using sodium meta silicate imposed on CO 8 maize as test crop. The experiment was conducted in factorial CRD with three replications.ResultsMaize crop experienced negative effect when grown in alkaline stressed soil. The growth (5 to 16 %), dry weight (28 to 59 %) and relative water content (5 to 23 %) reduced at various level of alkaline concentration. However, electrolyte leakage (6 to 49 %), proline (26 to 62 %), phenol (8 to 44 %), protein (6 to 19 %), anti-oxidant systems viz., peroxidase (30 to 52 %), SOD (4 to 16 %) and catalase activities (32 to 127 %) scaled up with levels of alkaline stress. Supplementing silicon in this soil ensured maize crop get a congenial environment to grow well and it was revealed by improved growth (5 to 10 %) and dry weight (17 to 30 %) of maize, relative water content (6 to 12 %) and antioxidant enzymes (25 to 52 %), water soluble protein (7 to10 %), phenol (10 to 18 %), while reduced electrolyte leakage (15 to 25 %) and proline (17 to 29 %).ConclusionsThe study divulged the primary role played by silicon in overhauling the hostile alkaline environment by promoting better growth and dry weight of maize through its regulatory action on osmoprotectants and anti-oxidant enzymes and maximum effect was evident with 150 kg Si/ha.

Reusing urine and coffee processing wastewater as a nutrient source: Effect on soil characteristics at optimum cabbage yield

Treatment and application of wastewater as a plant nutrient source is one of the waste management approaches currently used. This study attempted to investigate the effect of the application of human urine and coffee processing wastewater (UCPWW) on selected soil characteristics and compared it with rainwater and synthetic fertilizer in a completely randomized design. One-way analysis of variance (ANOVA) for difference and principal component analysis for correlation was employed. It was found that the soil organic carbon (SOC) and available phosphorus after production in a 1:2 ratio of UCPWW was significantly varied from the values before production and the soil treated with synthetic fertilizer (F=24.01, p=0.001; F=49.03, p=0.001, respectively). No significant difference was observed on micro-nutrients and the cation exchange capacity, but on some of the exchangeable cations: Na+(F=15.27, p=0.001) and Mg2+ (F=12.99, p=0.001) of 1:2 ratio application. The soil salinity was significantly increased and varied from other treatments: Na+ (F=11.88, p=0.04), Cl−(F=17.24, p=0.001), and total salinity (EC) (F=11.88, p=0.003), and significantly correlated with SOC and nutrients. The exchangeable sodium percentage (ESP), saturated electrical conductivity (ECe), and pH values for single round cultivation indicated no effects of sodicity, saline-sodicity, and salinity. However, the effect for repeated applications and cultivations, and mechanism of minimizing the salinity by the substrate should be studied before large-scale application.

Quantitative Dissection of Salt Tolerance for Sustainable Wheat Production in Sodic Agro-Ecosystems through Farmers’ Participatory Approach: An Indian Experience

To explore the comparative effects of field sodicity (soil pH) and irrigation water residual alkalinity (RSCiw) on physiological and biochemical attributes of salt tolerance, and crop performance of two wheat varieties (KRL 210, HD 2967), a total of 308 on-farm trials were carried out in sodicity affected Ghaghar Basin of Haryana, India. Salt tolerant variety KRL 210 maintained relatively higher leaf relative water content (RWC; 1.9%), photosynthetic rate (Pn; 5.1%), stomatal conductance (gS; 6.6%), and transpiration (E; 4.1%) with lower membrane injury (MII; −8.5%), and better control on accumulation of free proline (P; −18.4%), Na+/K+ in shoot (NaK_S; −23.1%) and root (NaK_R; −18.7%) portion compared to traditional HD 2967. Altered physiological response suppressed important yield-related traits revealing repressive effects of sodicity stress on wheat yields; albeit to a lesser extent in KRL 210 with each gradual increase in soil pH (0.77–1.10 t ha−1) and RSCiw (0.29–0.33 t ha−1). HD 2967 significantly outyielded KRL 210 only at soil pH ≤ 8.2 and RSCiw ≤ 2.5 me L−1. By comparisons, substantial improvements in salt tolerance potential of KRL 210 with increasing sodicity stress compensated in attaining significantly higher yields as and when soil pH becomes >8.7 and RSCiw > 4 me L−1. Designing such variety-oriented threshold limits of sodicity tolerance in wheat will help address the challenge to enhance crop resilience, closing the yield gaps and improve rural livelihood under the existing or predicted levels of salt stress.

Effect of Sodicity on Soil–Water Retention and Hydraulic Properties

AbstractThe present study analyses the effect of sodicity on unsaturated soil hydraulic properties. Permeameter and pressure plate experiments were conducted on six texturally different soils at va...

Adverse Impact of Sodicity on Soil Functions can be Alleviated through Addition of Rice Straw Biochar

ABSTRACTBeneficial effects of biochar on physicochemical properties in non-saline and non-sodic soils have been widely acknowledged. However, information is inadequate regarding potential of using rice straw derived biochar as an organic material to reduce sodicity stress. Soil samples varying in sodicity (SAR – Sodium Adsorption Ratio) levels [SAR2.5 (control), SAR20 and SAR30], collected from long-term field experiment were incubated for 8 weeks with different rates of rice straw biochar (B0: control, B1: 1%, B2: 2%, B4: 4% w/w). Carbon mineralization was adversely affected by sodicity, far greater in SAR20 than SAR30 soil. Irrespective of the SAR levels, addition of rice straw biochar enhanced cumulative respiration (CR) and microbial biomass carbon (MBC), more so at higher rate of application. Both pH and SAR significantly decreased in the biochar amended sodic soils, whereas opposite trend was noticed in the amended control. Furthermore, at all SAR levels, NO3–N concentrations were greater at differential biochar rates on day 14 and 56 of sampling; however, the results were contrary as far as NH4+-N was concerned. It may be concluded that rice straw biochar can be used as an organic amendment for reducing adverse effects of sodicity on soil functions governed by their rate of addition.

Actual Evapotranspiration and Tree Performance of Mature Micro-Irrigated Pistachio Orchards Grown on Saline-Sodic Soils in the San Joaquin Valley of California

In California, a significant percentage of the pistachio acreage is in the San Joaquin Valley on saline and saline-sodic soils. However, irrigation management practices in commercial pistachio production are based on water-use information developed nearly two decades ago from experiments conducted in non-saline orchards sprinkler-irrigated with good quality water. No information is currently available that quantify the effect of salinity or combined salinity and sodicity on water use of micro-irrigated pistachio orchards, even though such information would help growers schedule irrigations and control soil salinity through leaching. To fill this gap, a field research study was conducted in 2016 and 2017 to measure the actual evapotranspiration (ETa) from commercial pistachio orchards grown on non-saline and saline-sodic soils in the southern portion of the San Joaquin Valley of California. The study aimed at investigating the functional relations between soil salinity/sodicity and tree performance, and understanding the mechanisms regulating water-use reduction under saline and saline-sodic conditions. Pistachio ETa was measured with the residual of energy balance method using a combination of surface renewal and eddy covariance equipment. Saline and saline-sodic conditions in the soil adversely affected tree performance with different intensity. The analysis of field data showed that ETa, light interception by the tree canopy, and nut yield were highly and linearly related (r2 > 0.9). Moving from non-saline to saline and saline-sodic conditions, the canopy light interception decreased from 75% (non-saline) to around 50% (saline) and 30% (saline-sodic), and ETa decreased by 32% to 46% relative to the non-saline orchard. In saline-sodic soils, the nut yield resulted around 50% lower than that of non-saline orchard. A statistical analysis performed on the correlations between soil physical-chemical parameters and selected tree performance indicators (ETa, light interception, and nut yield) revealed that the sodium adsorption ratio (SAR) adversely affected tree performance more than the soil electrical conductivity (ECe). Results suggest that secondary effects of sodicity (i.e., degradation of soil structure, possibly leading to poor soil aeration and root hypoxia) might have had a stronger impact on pistachio performance than did salinity in the long term. The information presented in this paper can help pistachio growers and farm managers better tailor irrigation water allocation and management to site-specific orchard conditions (e.g., canopy features and soil-water salinity/sodicity), and potentially lead to water and energy savings through improved irrigation management practices.

Impact of sodium and iron levels on yield, nutrient content and uptake by cowpea (Vigna unguiculata L.)

A pot experiment was conducted to see the effect of sodicity and iron levels on cowpea. Four levels of sodium adsorption ratio (SAR) 10, 15, 20, 25 and iron (Fe) control, 5, 10, 15 and 20 kg Fe ha-1) were tested in completely randomized design with three replications. The results indicated that application of soil sodicity having SAR 15 recorded the maximum yield, phosphorus and potassium content and uptake and nitrogen uptake of cowpea over rest of the treatments. Application of Fe 20 kg ha-1 recorded the maximum and significantly higher yield, nitrogen, phosphorus and potassium content and uptake of cowpea over rest of the treatments. Among the treatment combinations combined application of SAR 15 with Fe @ +20 FeSo4.7H2O) proved superior in all these parameters over other treatments.

Mycorrhizal colonisation of cotton in soils differing in sodicity

Despite the reported importance of mycorrhizal symbioses for early growth and nutrient acquisition of cotton, little is known about how sodicity affects this relationship. Changes in mycorrhizal colonisation and nutrient uptake of cotton in a range of naturally non-sodic (exchangeable sodium percentages (ESP)<6) and low-sodic soils (ESP 6–10), from cotton production areas in southern Queensland and northern New South Wales, with different ESP (ranged between 1.4 and 9.8) was investigated in a glasshouse experiment. The experiment was a complete factorial design with 11 recently-collected soils and two mycorrhizae treatments (either inoculated with fresh “live” mycorrhizal inoculum or without inoculum). Linear mixed model analysis showed minimal effects of sodicity, when ESP was less than 10, on mycorrhizal colonisation, associated plant growth and nutrient uptake. Principle component and regression analysis showed that other sources of variation including soil pH and soil P content, rather than sodicity, might drive cotton colonisation in Vertosols with low to moderate ESP. The colonisation percentage was positively linearly correlated with P, Mg, and Zn uptake of cotton plants. Further investigation into mycorrhizal spore density and species diversity under sodic soil conditions is warranted.

Sodicity effects on hydrological processes of sodic soil slopes under simulated rainfall

AbstractSoil salinization can occur in many regions of the world. Soil sodicity affects rainfall‐runoff relationships and related erosion processes considerably. We investigated sodicity effects on infiltration, runoff and erosion processes on sodic soil slopes for two soils from China under simulated rainfall. Five sodicity levels were established in a silt loam and a silty clay with clay contents of 8.5% and 46.0%, respectively. The soils, packed in 50 cm × 30 cm × 15 cm flumes at two slope gradients (22° and 35°), were exposed to 60 min of simulated rainfall (deionized water) at a constant intensity of 125 mm h−1. Results showed that, for both soils, increasing soil sodicity had some significant effects on hydrological processes, reducing the infiltration coefficient (pr = −0.69, P &lt; 0.01) and the quasi‐steady final infiltration rate (pr = −0.80, P &lt; 0.01), and increasing the mean sediment loss (pr = 0.39, P &lt; 0.05); however, it did not significantly affect the cumulative rainfall to ponding (P &gt; 0.05). Moreover, increasing sodicity significantly increased the Reynolds number and the stream power (pr = 0.78 and 0.66, P &lt; 0.01, respectively) of the runoff, decreased Manning roughness and Darcy–Weisbach coefficient (pr = −0.52 and −0.52, P &lt; 0.05, respectively), but did not significantly affect the mean flow velocity, mean flow depth, Froude number and hydraulic shear stress. Stream power was shown to be the most sensitive hydraulic variable affecting sediment loss for both soils. Furthermore, as sodicity increased, the values of critical stream power decreased for both the silt loam (R2 = 0.29, P &lt; 0.05) and the silty clay (R2 = 0.49, P &lt; 0.05). The findings of this study were applied to a real situation and identified some negative effects that can occur with increasing sodicity levels. This emphasized the importance of addressing the influences of soil sodicity in particularly high risk situations and when predicting soil and water losses.

Combined Effect of Sodicity and Organic Matter on Soil Properties under Long‐Term Irrigation with Treated Wastewater

Core Ideas We observed increasing sodicity hazard and a decreasing saturated soil hydraulic conductivity from treated wastewater irrigation. All of the data on sodicity hazard could be incorporated into a single Gapon constant for calcium‐sodium exchange that depends on the ratio of soil DOC concentration to calcite content. All the data on Ks could be incorporated in a single power‐law relationship involving the ratio of ESP to soil DOC concentration. The increasing reuse of treated wastewater (WW) for irrigation brings with it a need to reconsider irrigation water quality criteria because of the expected lower quality of WW. In particular, the impacts of higher sodium and dissolved organic carbon (DOC) concentrations on soil permeability must be evaluated in practical field settings over long periods of WW reuse. Here we report the long‐term impact of WW reuse for irrigation on soils at three different semiarid‐zone field sites under row crop or orchard agriculture. The soils contain about 60% clay, dominated by smectite, and present an order of magnitude variation in calcite content (1–11%). In two of the sites, parcels irrigated with freshwater (FW) are available for comparison. Our results show an increasing sodicity hazard and a decreasing saturated soil hydraulic conductivity (Ks) from WW irrigation, although the depth profiles of soil chemical and physical properties were highly site‐specific. Despite this spatial variability, all of the data on sodicity hazard, represented by the relationship between exchangeable sodium percentage (ESP) and the soil sodium adsorption ratio (SAR), could be incorporated into a single Gapon constant for calcium–sodium exchange whose values depended uniformly on the ratio of soil DOC concentration to calcite content. Moreover, all of the data on Ks, for both FW and WW irrigation, could be incorporated into a single power‐law relationship involving the ratio of ESP to soil DOC. These two relationships unify complex interactions between sodicity and organic matter (OM) that influence soil permeability to yield simple correlations with predictive power. The main detrimental effect of WW application was related to sodicity hazard. Therefore, effort should be invested in reducing the SAR of WW for irrigation. This could be achieved, for example, by mixing WW with FW, including desalinized water, when and if available.

Clay Dispersion Induced by Changes in Some Soil Properties in Undulating Salt-Affected Landscapes of Southern Karnataka, India

Effect of sodicity on clay dispersion in salt-affected black soils of the Kabini canal command area in Chamrajnagar district, southern Karnataka was studied. Forty-eight soil samples were collected from nine soil profiles and analysed for physical and chemical properties. The clay dispersion ranged from 0.57% to 62.1%. High positive and negative correlations with exchangeable sodium and exchangeable calcium respectively, with clay dispersion were recorded, which can be predicted better with exchangeable sodium and available soil water. Based on clay dispersion value, 2%, 27% and 71% soils are dispersive, intermediate dispersive and non-dispersive respectively. Based on exchangeable sodium percentage, 50, 21 and 29 soils are dispersive, intermediate dispersive and nondispersive respectively. Application of gypsum and organics reduces the clay dispersion in surface soil. Sub-surface drainage will be more effective. Construction of soil and water conservation structures with pile foundation; providing cement lining for soil stabilization in normal construction; providing drainage lines for the structures; construction after refilling with non-dispersive soil will save the structures in salt-affected soils.

Effect of sodicity on growth of polyembryonic mango rootstocks

Effect of sodicity on growth of polyembryonic mango rootstocks

Determining effects of sodicity and salinity on switchgrass and prairie cordgrass germination and plant growth

Marginal and degraded lands are expected to be important resources in the production of biofuel feedstocks in order to avoid real or perceived competition with food, feed and fiber production. Globally, there are millions of hectares of salt-affected land available for lignocellulosic feedstock production. Greenhouse experiments determined the effects of irrigating with water having different levels of salinity and sodicity on seedling emergence, plant growth, and cation balance in plant tissues in several populations of switchgrass (Panicum virgatum L.) and prairie cordgrass (Spartina pectinata Link). The effect of salt stress on seedling emergence was more pronounced in switchgrass than prairie cordgrass with 31 and 15% reduction, respectively, compared with pure water. In a two-season greenhouse pot experiment, aboveground dry biomass production in control treatments was 8 and 21% higher in prairie cordgrass pc17-102 and pc17-109, respectively, than in EG 1102 switchgrass. Switchgrass EG 1102 produced greater biomass than prairie cordgrass populations when irrigated with moderately saline (5dSm−1) water, although differences were not detected with highly saline water (10dSm−1). Switchgrass EG 2101 emergence, plant growth and cation balance were severely affected by increasing levels of salinity. Overall, several prairie cordgrass populations and lowland switchgrass cultivars were found to have good emergence and high biomass production under moderate to high salt stress and may be good candidates for lignocellulosic feedstocks on salt-affected land.

Effects of sodicity induced changes in soil physical properties on paddy root growth

A study was conducted to investigate the influence of sodicity induced changes in soil physical properties on paddy root growth in the normal agriculture, semi-reclaimed and sodic soils. The root growth (length, length density, biomass and distribution pattern) were unfavourably affected by the soil physical properties (bulk density, soil aggregate stability, available water content, hydraulic conductivity and soil water retention potential) in the case of sodic soil. The microbial biomass carbon, bacterial, fungal population and dehydrogenase activity showed the lower values in the case of sodosol compared to the normal soil. These soil biological properties tend to sustain paddy root growth in normal and semi-reclaimed soils. Principal component analysis revealed that soil physical properties accounted for 98.2% of total variance in root growth. The study revealed that salt stress induces changes in soil physical properties limiting paddy root growth in the salt affected soils. It is important to reclaim sodosols to alleviate salt induced physical stress for optimum paddy root growth.

The effect of sodicity on cotton: Does soil chemistry or soil physical condition have the greater role?

Soil sodicity is widespread in the cracking clays used for irrigated cotton (Gossypium hirsutum L.) production in Australia and worldwide and sometimes produces nutrient imbalances and poor plant growth. It is not known whether these problems are due primarily to soil physical or to soil chemical constraints. We investigated this question by growing cotton to maturity in a glasshouse in large samples of a Grey Vertosol in which the exchangeable sodium percentage (ESP) was adjusted to 2, 13, 19, or 24. A soil-stabilising agent, anionic polyacrylamide (PAM), was added to half the pots and stabilised soil aggregation at all ESPs. Comparison of the effect of ESP on cotton in the pots with and without PAM showed that, up to ESP of 19, the soil physical effects of sodicity were mainly responsible for poor cotton performance and its ability to accumulate potassium. At ESP &gt;19, PAM amendment did not significantly improve lint yield, indicating that soil chemical constraints, high plant sodium concentrations (&gt;0.2%), and marginal plant manganese concentrations limited plant performance. Further research into commercial methods of amelioration of poor physical condition is warranted rather than application of more fertiliser.

Impact of waterlogging on the nutrition of cotton (Gossypium hirsutum L.) produced in sodic soils

Sodicity in Vertosols used for agricultural production can adversely affect the growth and nutrition of cotton (Gossypium hirsutum L.) plants. Cotton produced in sodic soils has reduced dry matter and lint yield and can develop toxic plant tissue concentrations of sodium (Na) but limited tissue concentrations of phosphorus (P,) potassium (K), and micronutrients. Crops produced on sodic soils frequently suffer from aeration stress after an irrigation or rainfall event, and it was hypothesised that the adverse physical and/or chemical conditions of sodic soils may exacerbate the effects of waterlogging. We measured the impacts of sodicity on the growth, nutrition, and root recovery time of cotton during and after waterlogging in two experiments. In the first, cotton plants were subjected to a 7-day period of inundation in Grey Vertosols with a range of exchangeable sodium percentage (ESP) values from 2 to 25%; 32P was placed in the pots and its accumulation in the plant was used to indicate root activity and recovery after the waterlogging event. In a second experiment, agar was dissolved in nutrient solutions with a range of Na concentrations (9, 30, and 52 mm) matching soil solution Na concentrations in sodic soils, in order to simulate a waterlogging event. Following the waterlogging event, the solutions were labelled with 32P, in order to determine the effect of sodic soil solution chemistry on the rate of recovery of cotton root function after the event. Plant nutrient analysis was used to determine the effects of sodicity and waterlogging on cotton nutrition. In both experiments, waterlogging reduced root activity and reduced the uptake and transport of labelled P by the cotton plants, decreased plant P and K concentrations, and increased the plant Na concentrations. Sodicity exacerbated the effects of waterlogging on root function and cotton nutrition in the soil experiment but not in the nutrient solution experiment, suggesting that any contribution of waterlogging to the patterns of nutrient accumulation in cotton crops produced in sodic fields occurs due to soil physical factors rather than soil solution chemistry.

Sorption of dissolved organic matter in salt-affected soils: Effect of salinity, sodicity and texture

Loss of dissolved organic matter (DOM) from soils can have negative effects on soil fertility and water quality. It is known that sodicity increases DOM solubility, but the interactive effect of sodicity and salinity on DOM sorption and how this is affected by soil texture is not clear. We investigated the effect of salinity and sodicity on DOM sorption in soils with different clay contents. Four salt solutions with different EC and SAR were prepared using combinations of 1M NaCl and 1M CaCl2 stock solutions. The soils differing in texture (4, 13, 24 and 40% clay, termed S-4, S-13, S-24 and S-40) were repeatedly leached with these solutions until the desired combination of EC and SAR (EC1:5 1 and 5dSm−1 in combination with SAR <3 or >20) was reached. The sorption of DOC (derived from mature wheat straw) was more strongly affected by SAR than by EC. High SAR (>20) at EC1 significantly decreased sorption in all soils. However, at EC5, high SAR did not significantly reduce DOC sorption most likely because of the high electrolyte concentration of the soil solution. DOC sorption was greatest in S-24 (which had the highest CEC) at all concentrations of DOC added whereas DOC sorption did not differ greatly between S-40 and S-4 or S-13 (which had higher concentrations of Fe/Al than S-40). DOC sorption in salt-affected soil is more strongly controlled by CEC and Fe/Al concentration than by clay concentration per se except in sodic soils where DOC sorption is low due to the high sodium saturation of the exchange complex.

Soil salinity and sodicity effects of wastewater irrigation in South East Australia

Abstract Although ‘sewage farming’ or wastewater irrigation started in Australia in the latter parts of the 19th century, it was in the late 1960s that a considerable interest was revived in arid and semi-arid parts of the world due to scarcity of alternative water sources and the urgency to increase local food production. The practice has manifold benefits in the form of water conservation, nutrient recycling, surface and ground water pollution prevention. But for arid and semi-arid regions like many parts of Australia, while wastewater irrigation can be an attractive solution to irrigation water problems, it might not be the ideal solution for the common soil types encountered in these regions. Due to characteristic low rainfall, high evaporation and low leaching, these soils tend to have higher salt accumulations. This paper examines the soil salinity and sodicity effects of wastewater irrigation in soil types typical to South Eastern Australia and takes the soils of Western Treatment Plant (WTP) as a case study to highlight these issues.