Some characteristics of organic soils irrigated with municipal wastewater

Soil irrigation with wastewater (WW) gives the opportunity to solve the problems of its disposal, final purification or reuse. Many studies have examined mineral soils upon continued WW application. The aim of this paper was to examine the properties of organic soils 3 years after WW application was discontinued. Peat‐muck soil planted with Populus spp. or Salix spp., and mineral‐muck soil under grasses were irrigated for 4 years with municipal WW at a low (comparable with intensive NPK fertilization) and high WW rate (600 and 1200 mm yearly, respectively). Soils were analysed for organic matter (OM), pH, bulk density (BD), water holding capacity (WHC), P₂O₅, Fe₂O₃, Al₂O₃, MnO, Zn, Pb, Cu, Cr, magnetic susceptibility (MS) and dehydrogenase and catalase activities. The results were compared with control soils which have never received WW. The study showed that only P₂O₅, MnO and catalase activity (CA) were significantly affected by former WW application. On average, P₂O₅ increased by 30 per cent, whereas MnO decreased by 35 per cent with no differences between the two WW rates. CA decreased by 18 per cent at the high WW rate. Most of tested characteristics were determined by soil type. The peat‐muck soil showed higher OM, WHC, P₂O₅, MnO, Pb and CA than mineral‐muck soil and lower BD, MS, Fe₂O₃, Al₂O₃ and Cr. Soil depth influenced Fe₂O₃, MnO, Zn, MS and enzyme activities, while basic soil properties (OM, pH, BD, WHC and P₂O₅) were not changed by soil depth. Heavy metals (Zn, Cr, Cu and Pb) were below upper permissible limits. Copyright © 2010 John Wiley & Sons, Ltd.     

Xenobiotic organic compounds in runoff from fields irrigated with treated wastewater

Investigations of agricultural nonpoint source pollution typically focus on a relatively narrow range of targeted toxic and biostimulatory compounds (e.g., specific pesticides, nutrients). Regular application of numerous other organic compounds to agricultural fields in pesticide formulations, irrigation water, soil amendments, and fertilizers may result in their transport into surface waters via runoff. We examined whether potentially toxic dissolved and particle-associated "nontarget" organic compounds were present in surface runoff from agricultural fields irrigated with disinfected tertiary recycled water or wastewater effluent-dominated streamwater. Gas chromatographic-mass spectrometric analyses of filtered runoff samples revealed the presence of numerous nontarget compounds of potential toxicological significance including pesticide transformation products, pesticide adjuvant chemicals, plasticizers, flame retardants, pharmaceuticals, and personal care product ingredients. Although the toxicity of many of these compounds is poorly characterized, some may elicit subtle but profound toxicological effects. Agricultural runoff also represented a source of allochthonous natural organic matter to the stream system.     

Tephra-mulched soils irrigated with reclaimed urban wastewater in former dry-farming systems of Lanzarote (Spain)

On the island of Lanzarote, under extreme conditions of aridity and water scarcity, a certain amount of rainfed agriculture has been possible due to the use of tephra mulching, a system known locally as arenados, which is a very effective water and soil conservation system. The natural arenados are associated to already present tephra from recent volcanic eruptions. In artificial arenados a 5 to 20 cm layer of pyroclasts is placed over the soil. Over the last decade, the availability of urban reclaimed water (RW) has allowed irrigation networks to be established in artificial arenados with significant increases in crop yields. In this work, a preliminary evaluation of the sustainability of this new form of management was performed. Field plots irrigated with tertiary effluent for almost a decade were studied and compared with adjacent dry-farming fields, both cropped with sweet potatoes. In both cases, the soils had a covering of basaltic tephra mulch. The irrigation lines are placed on top of the mulch. Although this was not a controlled field experiment, since water and soil management was not exactly the same in the studied plots, some significant effects of RW irrigation on soil chemical properties were identified. Crop yields in the irrigated fields can be up to three times the yields obtained under rainfed conditions. The RW quality posed some restrictions for irrigation, particularly as regards salinity, sodicity and boron, although their buildup in soils appears to have been reduced by the mulch effect. In some field plots, crop critical threshold values of soil salinity and boron were reached with no harmful consequences. This developing soil degradation suggests that the sustainability of arenados systems under RW irrigation would appear to be under threat in the mid- to long-term based on current management practices. Further research is required on the salt and boron dynamics in this system, which is an example of conservation agriculture that also helps combat desertification.     

规模化猪场废水灌溉农田土壤Pb, Cd和As空间变异及影响因子分析

为了了解长期灌溉猪场废水对农田土壤Pb、Cd和As(简称重金属)的影响,采集了河北省京安猪场周边农田的清洁区和灌溉8年猪场废水的污灌区耕层(0～20 cm)共52个土壤样品,并测定了样品中重金属的全量和有效态含量,应用GIS结合地统计学方法对重金属进行了空间结构和分布特征分析,探讨规模化猪场周边农田土壤重金属积累的影响因子及其贡献.结果表明,重金属全量和有效态含量的变异函数均很好地符合球状模型,其中全铅、有效铅、全砷、全镉和有效砷受随机性因素和结构性因素共同影响,有效镉主要受结构性因素影响.根据背景调查、重金属与pH值和土壤养分的相关性分析以及重金属变异函数分析,土壤中Cd和As污染来源为猪场废水和化肥,Pb的污染来源为化肥.富集因子分析表明,污灌猪场废水对土壤Cd和As富集效应很小,施用化肥对Pb富集有较大贡献.灌溉猪场废水会降低土壤pH值而增加重金属有效态含量,因此,需注意施用猪场废水带来重金属污染风险.     

规模化猪场废水灌溉农田土壤Pb,Cd和As空间变异及影响因子分析

为了了解长期灌溉猪场废水对农田土壤Pb、Cd和As（简称重金属）的影响,采集了河北省京安猪场周边农田的清洁区和灌溉8年猪场废水的污灌区耕层（0～20 cm）共52个土壤样品,并测定了样品中重金属的全量和有效态含量,应用GIS结合地统计学方法对重金属进行了空间结构和分布特征分析,探讨规模化猪场周边农田土壤重金属积累的影响因子及其贡献。结果表明,重金属全量和有效态含量的变异函数均很好地符合球状模型,其中全铅、有效铅、全砷、全镉和有效砷受随机性因素和结构性因素共同影响,有效镉主要受结构性因素影响。根据背景调查、重金属与pH值和土壤养分的相关性分析以及重金属变异函数分析,土壤中Cd和As污染来源为猪场废水和化肥,Pb的污染来源为化肥。富集因子分析表明,污灌猪场废水对土壤Cd和As富集效应很小,施用化肥对Pb富集有较大贡献。灌溉猪场废水会降低土壤pH值而增加重金属有效态含量,因此,需注意施用猪场废水带来重金属污染风险。     

Ameliorative status of irrigated soils in Rostov oblast

The development of irrigation and the ameliorative status of irrigated lands in Rostov oblast are analyzed for a fifty-year-long period (1952–2001). Three stages of irrigation development are specified. The first stage (1952–1982) was characterized by poor operating conditions of irrigated lands. The second stage (1982–1990) was a period of the most intense irrigation and improvement of the ameliorative status of irrigated lands. The third period (1990–2001) was marked by a drop in the area of irrigated lands and exclusion of lands with unsatisfactory ameliorative status from irrigation. The natural and operating conditions of 18 irrigation systems allocated to areas with different lithological and geomorphic features and soils (chernozems, dark chestnut, meadow, alluvial, and other soils) are characterized. It is shown that soil irrigation often leads to the development of negative soil processes, such as salinization, alkalization, and waterlogging. They are related to the natural and operating conditions of irrigated systems. Secondary salinization and waterlogging are most active in irrigation systems used for rice growing independently of the natural conditions. Upon initially weak salinization of soils and rocks, secondary salinization and alkalization are slightly developed. In the secondary saline and solonetzic soils excluded from irrigation, residual solonetzic features are preserved for more than 15–20 years.     

Effective use of water in irrigated soils: Guidelines for soil salinity control

Abstract

Continued addition of irrigation water to the soil will add salts which may accumulate sufficiently to reduce plant growth and crop yields. Eventually, the accumulated salts may stop all growth, unless irrigation practices which move salts downward below the root zone are followed. Consequently, water is needed not only for growing plants but also for leaching salts out of the soil. The success of achieving these objectives primarily depends on the proper water management practices, which, in turn, depend on methods and timing of irrigation, quality and quantity of available water for irrigation, soil hydraulic properties, drainage systems, leaching requirement, and economics.     

Content and distribution pattern of dichlorodiphenyltrichloroethane (DDT) in soils of Moscow

The content and distribution pattern of dichlorodiphenyltrichloroethane (DDT) and its metabolites (DDE and DDD) in the surface layers of soils in Moscow are studied. The residual content of these substances in the soils varies within 2.22–1440 µg/kg (at a mean value of 158.9 ± 314.1 µg/kg and median 42.53 µg/kg). The correlation between the contents of DDT and its metabolites and DDD and organic matter is revealed. The highest contents of the pollutants are seen in the residential–transport and industrial zones of Moscow, while their lowest contents are revealed in the soils of the yards of preschool facilities and schools. With respect to the residual contents of the pesticide, most of the soils of Moscow can be considered uncontaminated (80.0%) and acceptably contaminated (7.5%).     

Human pharmaceuticals, hormones, and personal care product ingredients in runoff from agricultural fields irrigated with treated wastewater

Irrigation of crops with treated wastewater has the potential to introduce effluent-derived organic microcontaminants into surface waters through agricultural runoff. To determine whether compounds indicative of the presence of treated effluent in irrigation water could be identified in agricultural runoff, surface runoff samples collected from effluent-irrigated and rain-fed cultivated fields were analyzed for a broad spectrum of organic compounds. A variety of compounds was identified that appeared to be associated with irrigation with treated wastewater. These compounds included human pharmaceuticals (e.g., carbamazepine, gemfibrozil, carisoprodol), personal care product ingredients (e.g., insect repellent, polycyclic musks), and alkyl phosphate flame retardant chemicals. Most of these compounds appear not to have been previously reported in agricultural runoff. These compounds were present at concentrations below the few published aquatic toxicology data available; however, their potential to elicit more subtle effects in aquatic organisms cannot be excluded. None of these compounds were detected by broad-spectrum analysis in samples from the same fields during runoff-producing rain events.     

灌溉对哈萨克斯坦南部农业富镁土壤的影响

Irrational irrigation practices in the Arys Turkestan Canal command area in the southern part of Kazakhstan have led to the formation of soils with poor physical and chemical properties. To study whether irrigation and leaching practices and/or groundwater rise have contributed to the accumulation of Mg²⁺ on the cation exchange complex of these soils, historical changes in soil and groundwater quality were used as source data and the Visual MINTEQ model was applied to analyze the chemical composition of water and soils in the study area. The imposed irrigation regime and the leaching of light sierosem soils led to the dissolution and subsequent leaching of inherent gypsum and organic matter from the soil profile. Further, the domination of bicarbonate in the irrigation water promoted weathering of the carbonate minerals present as calcite. The higher concentrations of Mg²⁺ in comparison to Ca²⁺ in the irrigation water resulted in the replacement of Na⁺ by Mg²⁺ on the cation exchange complex. In the lower part of the command area, shallow groundwater has contributed to the accumulation of Na⁺ and to a large extent of Mg²⁺ on the cation exchange sites.     

Ferric iron transformation in soils with rotation of irrigated rice-upland crops and effect on soil tillage properties

We examined the relationship between the form of iron and the tillability (defined as the degree of ease of pulverizing a soil into small clods) of soils in upland fields that had been converted from paddy fields. The amount of iron (Fe.e) extractable with acetate buffer (pH 3.0) decreased from 0.959 g kg_-1 in a field that has been continuously used as a paddy field to 0.104 g kg-I in a field that had been converted into an upland field for a period of 5 y. There was no significant change in the free iron oxide content under upland conditions. These results indicate that ferric iron oxides are gradually crystallized to less reactive forms after the conversion of a paddy field into upland conditions. Both soil tillability (represented by the mean clod diameter after tillage) and the stability of the soil microstructure (represented by the sediment volume) also increased during the 3-y period after conversion and then remained constant for the last 2-y period of the study. On the basis of these results, two mechanisms for the improvement of soil tillability can be proposed as follows: crystallization of ferric iron oxides increased their resistance to microbiological reduction and due to this stabilization the iron oxides as a cementing reagent that contributed to the soil microstructure, which in turn affected the soil tillability. During the first year after drainage, however, there was no significant correlation between the soil tillability and amount of Fe_ac, presumably because the soil was not sufficiently dry in the first year after conversion, and the iron oxides did not affect appreciably the soil structure.     

Erosion resistance of irrigated soils in the republic of Azerbaijan

It was found that the average size of water-stable aggregates in irrigated soils varies in the range 0.23–2.0 mm, and the eroding flow velocity is 0.03–0.12 m/s. A five-point scale was used for assessing erosion resistance, predicting irrigation erosion, and developing erosion control measures on irrigated soils. According to this system, gray-brown soils and light sierozems were classified as the least erosion-resistant, sierozemic and meadow-sierozemic soils as low erosion-resistant, gray-cinnamonic soils as moderately erosion-resistant, mountain gray-cinnamonic soils as highly erosion-resistant, and steppe mountain cinnamonic soils as very highly erosion-resistant ones. The determination of the erosion resistance of soils is of great importance for assessing the erosion-resistance potential of irrigated areas and developing erosion control measures.     

Trace metal leaching in a spodosol irrigated with tomato packinghouse wastewater

Tomato packinghouse wastewater is often applied to land in Florida, but the sandy soils, low levels of organic matter, shallow groundwater and abundant rainfall present favourable conditions for leaching of wastewater‐borne trace metals. We investigated the leaching of copper (Cu), iron (Fe), manganese (Mn) and zinc (Zn) from a sandy siliceous, hyperthermic Oxyaquic Alorthods packed in two distinct soil horizons (Ap and A/E) in 12 polyvinyl chloride soil columns (30 cm internal diameter × 50 cm length). Thirty leaching events were conducted by daily applying tomato packinghouse wastewater at low (0.84 cm/day), medium (1.68 cm/day) and high (2.51 cm/day) rates for 30‐days period. Control treatment received de‐ionized water at the same application rate as the medium treatment (1.68 cm/day). Application of wastewater at three rates did not affect the mean concentrations of Cu in leachate (0.19–0.2 mg/L) because of retention of Cu in the soil profile. However, leachate Zn concentrations were twice as much (0.3–0.32 mg/L) following wastewater application than for the control (0.13 mg/L) treatment. Leaching losses of Cu and Zn were smaller with the medium wastewater treatment (similar to control treatment) than for the high wastewater treatment. Concentrations of Cu and Zn at the 50 cm soil depth were much less than the drinking water standards, suggesting a minimum risk of groundwater contamination under fields to which wastewater was applied. Our results imply that tomato packinghouse wastewater can be safely land‐applied at 1.68 cm/day to Florida’s Spodosols under vegetable production without concerns of significant trace metal leaching.     

The effect of pH on zinc transformation in autoclaved soils treated with pyrophosphate

Abstract

Zinc solubility in soils can be affected by both pH and pyrophosphate (PP), yet the reaction of PP is influenced by pH, thus there is a need to evaluate pH effect on Zn transformation in soils treated with PP. Samples of three autoclaved soils, a Dalhousie (DT) clay, a St. Bernard (ST) loam, and an Uplands (UT) sand were equilibrated first with PP (0.0 and 9.0 P mM), then with Zn (0.0, 0.5, 1.0 Zn mM) and followed by 0.03 M KC10₄ solutions at the initial pH of 4.5, 6.0, and 7.5 with constant ionic strength. The first equilibration was for PP sorption, the second for Zn sorption and PP desorption, and the third for Zn desorption and further PP desorption. And finally, Zn of selected samples were extracted with 0.5 M KNO₃ (exchangeable Zn, Zn_KNO3), 0.5 M NaOH (organic and Fe oxides associated Zn, Zn_NaOH) solutions, and concentrated HNO₃+H₂O₂ (residual Zn, ZnHNO₃).

Increases in pH reduced PP sorption in the UT and the ST soils while high or low pH values tended to reduced it in the DT soil, indicating a competition between PP and OH ions for sorption sites. Zinc sorption was linearly related to solution pH, the slopes varied from 0.10 to 1.06, lower values were associated with PP addition, with low Zn rate, with finer textured soils, with high contents of Fe and Al materials, and with high pH buffer capacity. The values of Zn desorption and Zn_KN03 were greater at low than high pH while the reverse was true for Zn_NaOH. The pH effects on Zn sorption‐desorption and fraction distributions were less significant in soil with than without PP. The overall effect of high pH and the presence of the sorbed PP was the increased Zn specific sorption, compared to the pH or PP effect alone.     

干旱区绿洲灌漠土对铜的吸附解吸特性研究

土壤对重金属的吸附解吸是影响土壤系统中重金属的移动性和归宿的主要过程.本文使用序批实验方法、单步提取方法、连续提取方法等研究了干旱区绿洲灌漠土Cu的吸附解吸特性.结果表明,灌漠土对Cu的吸附等温线可很好地用Freundlich等温方程拟合,灌漠土的Cu吸附可能受土壤理化综合因素影响,而不仅是某个土壤理化指标所控制;二次...     

Relationship between hydraulic and basic properties for irrigated soils in southeast Australia

This paper examines the potential of soil maps and spatial information on basic soil properties for predicting soil hydraulic properties in the Shepparton irrigation region (SE Australia). For this purpose, the relationship between locally measured soil hydraulic properties and basic soil properties, and soil categories was analyzed. Pedotransfer functions developed for Australian soil were tested. Furthermore, association of field‐scale final infiltration rates with basic soil properties was investigated. Water‐retention properties, and in particular subsoil water‐retention properties, were significantly correlated with readily available basic soil properties. Spearman's rank correlation coefficients were particularly high for clay content, bulk density, and the sum of exchangeable cations Ca²⁺, Mg²⁺, Na⁺, and K⁺. Water‐retention properties were adequately predicted using Australian pedotransfer functions. Water‐transmission properties such the saturated conductivity and the final infiltration rate were overall poorly correlated with basic physical and chemical properties. Generally, median water‐transmission properties did not significantly change with soil groups and “within‐paddock variability” accounted for over half of the “within‐soil‐type variability” for many soil types. We concluded that it is feasible to regionalize water‐retention properties for the Shepparton irrigation region using basic physical and chemical soil properties, whereas the information on basic soil properties and from soil maps was insufficient to reliably estimate water‐transmission properties. It is demonstrated why field‐scale estimates of final infiltration rates, obtained by fitting a model for surface irrigation to field measurements of advance, depletion, and recession, may be better correlated with basic soil properties.     

Salinization dynamics in irrigated soils of the Svetloyarsk irrigation system,Volgograd oblast

On the basis of soil surveys performed by the Volgograd hydrogeological reclamation expedition in 1998 and 2006, published data, and original materials obtained by the authors, the dynamics of soil salinization within the Svetloyarsk irrigation system in Volgograd oblast during the irrigation and post-irrigation periods have been traced. It is found that high irrigation rates under conditions of poor drainage and closed drainage basins upon both shallow (within the Caspian Lowland) and relatively deep (on the Ergeni Upland) occurrence of saline groundwater and the presence of natural salts in the soils and subsoils lead to the rise in the groundwater level above the critical level and the development of secondary salinization in the previously surfacesaline, deeply saline, and even nonsaline soils. During the post-irrigation period (15–18 years) under modern climatic conditions, the groundwater level has been descending to a depth of more than 3 m, and the degree of salinity in the upper meter of light chestnut and meadow-chestnut soils has decreased owing to the leaching of salts with atmospheric precipitation.     

层状土壤质地对地下滴灌水氮分布的影响

以均质砂土（S）、均质壤土（L）和上砂下壤层状土壤（SL）为对象,采用室内土箱试验,研究了土壤质地及其层状结构和地下滴灌灌水器流量对水分、硝态氮和铵态氮分布的影响。结果表明,SL层状土壤中,砂-壤界面增加了水分的横向扩散而限制了水分的垂向运动,致使界面下部形成水分和硝态氮积聚区。土壤硝态氮分布还受肥料溶液浓度和土壤初始硝态氮浓度影响,对试验采用的土壤初始硝态氮浓度较低而肥料溶液硝态氮浓度较高的情况而言,灌水器周围的硝态氮浓度与肥料溶液的硝态氮浓度相近,随着离开灌水器距离的增加,土壤硝态氮浓度减小。灌水器周围的土壤含水率和硝态氮浓度随灌水器流量的增大而增大。施肥灌溉使灌水器周围5～10 cm范围内的铵态氮浓度出现峰值,而土壤质地和灌水器流量对铵态氮浓度分布没有明显影响。因此地下滴灌水氮管理措施的制定应综合考虑土壤质地及其结构、初始土壤水氮状况、灌水器埋深及流量、灌水量、肥液浓度等因素。     

Carbon dioxide and gaseous nitrogen emissions from biochar‐amended soils under wastewater irrigated urban vegetable production of Burkina Faso and Ghana

To quantify carbon (C) and nitrogen (N) losses in soils of West African urban and peri‐urban agriculture (UPA) we measured fluxes of CO₂‐C, N₂O‐N, and NH₃‐N from irrigated fields in Ouagadougou, Burkina Faso, and Tamale, Ghana, under different fertilization and (waste‐)water regimes. Compared with the unamended control, application of fertilizers increased average cumulative CO₂‐C emissions during eight cropping cycles in Ouagadougou by 103% and during seven cropping cycles in Tamale by 42%. Calculated total emissions measured across all cropping cycles reached 14 t C ha^?1 in Ouagadougou, accounting for 73% of the C applied as organic fertilizer over a period of two years at this site, and 9 t C ha^?1 in Tamale. Compared with unamended control plots, fertilizer application increased N₂O‐N emissions in Ouagadougou during different cropping cycles, ranging from 37 to 360%, while average NH₃‐N losses increased by 670%. Fertilizer application had no significant effects on N₂O‐N losses in Tamale. While wastewater irrigation did not significantly enhance CO₂‐C emissions in Ouagadougou, average CO₂‐C emissions in Tamale were 71% (1.6 t C ha^?1) higher on wastewater plots compared with those of the control (0.9 t C ha^?1). However, no significant effects of wastewater on N₂O‐N and NH₃‐N emissions were observed at either location. Although biochar did not affect N₂O‐N and NH₃‐N losses, the addition of biochar could contribute to reducing CO₂‐C emissions from urban garden soils. When related to crop production, CO₂‐C emissions were higher on control than on fertilized plots, but this was not the case for absolute CO₂‐C emissions.     

Bioavailable potassium in river-bed sediments and release of interlayer potassium in irrigated arid soils

Abstract. Crop responses to applied potassium fertilizers are erratic in many arid and semi-arid soils. The potassium supplying potential of river-bed sediments and release of interlayer potassium from eleven alkaline soils were measured in two separate experiments. Sediments from the Chenab and Ravi Rivers in Pakistan were exhausted of potassium by successively growing wheat, maize, mungbean, and wheat in them for a total of 200 days, using Hoagland solution to supply optimum amounts of other nutrients. Cumulative plant dry matter yield was significantly greater on the Chenab sediments. The quantities of potassium supplied to plants from the sediments of the two rivers were also significantly different. Interlayer potassium was extracted for 1230 minutes from a Udic Haplustalf (Pindorian series) by twelve different solutions each with the same electrolyte content (100 cmol). The sodium adsorption ratios (SAR) of the solutions were adjusted to 5, 10, 25, and 50, each with Ca: Mg ratios of 25:75, 50: 50 or 75:25, using solutions of sodium, calcium and magnesium chloride. The potassium released from the soil was inversely related to solution SAR. Increasing proportions of magnesium relative to calcium in solution favoured the release of potassium, except in the SAR 50 solution. Significantly different quantities of potassium were extracted by various solutions. Maximum potassium (442 mg/kg) was extracted by SAR 5 solution with a Ca: Mg ratio of 25:75. Interlayer potassium subsequently removed by this solution from 11 alkaline soils ranged from 407 to 499 mg/kg. The potassium released from all but three of the soils was related to their clay content (r= 0.72; n= 8). The release of potassium from the soils followed the Elovich function. The intercept (X₁) and slope (X₂) estimated for the function was related to potassium released (y) by the equation: y=?1.13 + 2.74X₁?0.014X₂ (r= 0.998; n= 8) The results imply that river sediments treated with irrigation water containing magnesium and sodium ions can contribute substantial amounts of available potassium for plant growth.