Electrical Conductivity Of Saturated Extract Research Articles

Use of geophysical survey as a predictor of the edaphic properties variability in soils used for livestock production

The spatial variability in soils used for livestock production (i.e. Natraquoll and Natraqualf) at farm and paddock scale is usually very high. Understanding this spatial variation within a field is the first step for site-specific crop management. For this reason, we evaluated whether apparent electrical conductivity (ECa), a widely used proximal soil sensing technology, is a potential estimator of the edaphic variability in these types of soils. ECa and elevation data were collected in a paddock of 16 ha. Elevation was negatively associated with ECa. Geo-referenced soil samples were collected and analyzed for soil organic matter (OM) content, pH, the saturation extract electrical conductivity (ECext), available phosphorous (P), and anaerobically incubated Nitrogen (Nan). Relationships between soil properties and ECa were analyzed using regression analysis, principal components analysis (PCA), and stepwise regression. Principal components (PC) and the PC-stepwise were used to determine which soil properties have an important influence on ECa. In this experiment elevation was negatively associated with ECa. The data showed that pH, OM, and ECext exhibited a high correlation with ECa (R2=0.76; 0.70 and 0.65, respectively). Whereas P and Nan showed a lower correlation (R2=0.54 and 0.11 respectively). The model resulting from the PC-stepwise regression analysis explained slightly more than 69% of the total variation of the measured ECa, only retaining PC1. Therefore, ECext, pH and OM were considered key latent variables because they substantially influence the relationship between the PC1 and the ECa (loading factors>0.4). Results showed that ECa is associated with the spatial distribution of some important soil properties. Thus, ECa can be used as a support tool to implement site-specific management in soils for livestock use.

Earthworm activities increase the leaching of salt and water from salt-affected agricultural soil during the wet–dry process under simulated rainfall conditions

The objectives of this study were to (1) evaluate earthworm-induced leaching of water and salt from salt-affected agricultural soils with constant and fluctuating soil moisture conditions and (2) determine the effects of earthworms on the distribution of soil salt in casts, burrow walls, and surrounding soils responsible for salt leaching. Soils were kept in mesocosms at constant moisture (CM) or underwent one wet–dry process (WD). Each soil moisture treatment had three earthworm treatments, including (1) inoculation with high abundance of earthworms (five endogeic Aporrectodea trapezoides), (2) inoculation with moderate abundance of earthworms (three endogeic A. trapezoides), and (3) no earthworm treatment. The presence of earthworms significantly increased total leaching water volume compared to the same treatment without earthworms in both moisture treatments. In the treatment following the wet–dry process, more than 65 % of water leaching occurred during the rainfall event, whereas in the treatment following constant moisture, more than 60 % of water leaching occurred after the rainfall event. The presence of earthworms produced a higher salt amount in the leaching water than the same moisture treatment without earthworms, but only the low number of earthworms (three endogeic A. trapezoides) caused a significantly higher total amount of leached salt than the same moisture treatment without earthworms. The percentage of leached salt in leaching water during the rainfall event ranged from 75.31 to 79.93 % in the wet–dry treatment and from 41.28 to 50.65 % in the constant moisture treatment. The wet–dry process significantly increased the total amount of leached salt from salt-affected agricultural soil compared to the constant moisture treatment when earthworms were present, which may be due to the significantly higher electrical conductivity of saturation extract (ECe) of earthworm casts than those of burrow walls and surrounding soils in the 0- to 10-cm soil layer.

Implication of Gypsum Rates to Optimize Hydraulic Conductivity for Variable‐Texture Saline–Sodic Soils Reclamation

AbstractSodium (Na+) dominated soils reduce saturated hydraulic conductivity (Ks) by clay dispersion and plugging pores, while gypsum (CaSO4•2H2O) application counters these properties. However, variable retrieval of texturally different saline–sodic soils with gypsum at soil gypsum requirement (SGR) devised to define its quantity best suited to improve Ks, leach Na+ and salts. This study comprised loamy‐sand (LS), sandy loam (SL), and clay loam (CL) soils with electrical conductivity of saturation extract (ECe) of ~8 dS m−1, sodium adsorption ratio (SAR) of ~44 (mmol L−1)1/2 and exchangeable sodium of ~41%, receiving no gypsum (G0), gypsum at 25% (G25), 50% (G50) and 75% (G75) of SGR. Soils packed in lysimeters were leached with low‐carbonate water [EC at 0·39 dS m−1, SAR at 0·56 (mmol L−1)1/2 and residual sodium carbonate at 0·15 mmolc L−1]. It proved that a rise in gypsum rate amplified Ks of LS ≫ SL > CL. However, Ks of LS soil at G25 and others at G75 remained efficient for salts and Na+ removal. Retention of calcium with magnesium (Ca2+ + Mg2+) by LS and SL soils increased by G50 and decreased in G75, while in CL, it also increased with G75. The enhanced Na+ leaching efficiency in LS soil with G25 was envisaged by water stay for sufficient time to dissolve gypsum and exchange and leach out Na+. Overall, the superiority of gypsum for LS at G25, SL at G50 and CL at G75 predicted cost‐effective soil reclamation with a decrease in ECe and SAR below 0·97 dS m−1 and 5·92 (mmol L−1)1/2, respectively. Copyright © 2015 John Wiley & Sons, Ltd.

Effects of nano iron oxide powder and urban solid waste compost coated sulfur on chemical properties of a saline-sodic soil

The main limiting factors in saline -sodic soils are high amounts of salts, low soil organic matter (SOM) and low availability of macro and micro-nutrients. The effect of different amounts of nano iron oxide powder and urban solid waste compost coated sulfur (USWCS) on the chemical properties of a saline-sodic soil was investigated. The experiment was conducted using a randomized complete block design with factorial arrangement and three replications, in a farm near Qom city. Treatments used in this study included USWCS (0 and 15 ton/ha) and nano iron oxide powder (0 and 20 mg/kg); treatments were applied to treated plots of 4 m 2 and sunflower seeds were sown. The results show that 20 mg/kg of nano-iron oxide, significantly (P<0.05) increased electrical conductivity of saturation extract (ECe), availabil ity of nutrient elements (5.26, 30, 18.18% for phosphorous (P), iron (Fe), and copper (Cu), respectively) in soil, while nitrogen (N), pH and sodium adsorption ratio (SAR) in soil decreased significantly (P < 0.05). Fifteen (15) tons/ha of USWCS significantly increased soil ECe (6.1%), micro and macro-nutrients amounts (8.3, 21.1, 46.6, 45. 5, and 14.9% for N, P, Fe, Cu, and Manganese (Mn) respectively), but significantly (P < 005) decreased the soil pH and SAR, compared to the control. The combined effect of 20 mg/kg of nano iron oxide and 15 ton/ha of USWCS increased micro-nutrient availability, but decreased soil pH and SAR significantly. It was concluded that the combined application of USWCS and nano iron oxide increased the availability of nutrients in saline-sodic soil.

Growth and yield responses in wheat and barley to potassium supply under drought or moderately saline conditions in the south-west of Western Australia

This study assessed whether more potassium (K) was required for optimal growth and grain yield of cereal crops under drought and salinity than under non-stressed conditions. In 2011, three experiments on wheat (Triticum aestivum L.) with four K rates (0, 20, 40, 80 kg K/ha), four application times (0, 5, 10, 15 weeks after sowing, WAS) and two sources (KCl, K2SO4) were conducted in the central and southern grainbelts of Western Australia. The lack of plant response to K supply at the sites of Bolgart (36 mg K/kg at 0–30 cm) and Borden (25 mg K/kg at 0–30 cm), compared with significant gain in K uptake, dry matter and grain yield at Dowerin (29 mg K/kg at 0–30 cm), was not explained by differences in soil K levels. However, rain fell regularly through the growing season at Bolgart and Borden, whereas a dry spell occurred from stem elongation to grain development at Dowerin. The effectiveness of K application time followed the trend of 0, 5 &gt; 10 &gt; 15 WAS. In 2012, barley (Hordeum vulgare L.) was grown on a moderately saline (saturation extract electrical conductivity ~4 dS/m) and low K (20 mg K/kg) farm in the central grainbelt and treated with 0, 20, 40 and 120 kg K/ha. Applying K increased K uptake but decreased Na uptake, especially at 120 kg K/ha. Plant growth and grain yield increased with K supply, but the difference between the K rates was relatively small, indicating possible partial K substitution by Na. Higher than normal fertiliser K supply on low K soils would enhance the adaptation by cereals to water-limited environments, but K-fertiliser management on moderately saline soils may need to account for both K and Na uptake and use by the crops.

Concentration of injetion solution and its effects on soil and on yield of fertirrigated banana cv. Terra Maranhão

The Fertigation is the combined application of water and nutrients to a crop. It can be adapted to all types of agricultural crops. The objective of this study was to evaluate the effect of urea concentration in irrigation water on electrical conductivity of the soil solution and saturation extract along the first cycle of banana cv. Terra Maranhão. The experiment followed a completely randomized design with six treatments and ten replications. Treatments regarded for using three urea concentrations (1.0; 2.5 and 4.0 g L-1) in irrigation water applied by two micro irrigation systems (microsprinkler and drip). Results showed that there was a linear elevation of electrical conductivity of saturation extract and soil solution with the increase on concentration of urea in the injection solution. Urea should be used under concentrations up to 2.5 g L-1 in irrigation water without causing increase on electric conductivity of soil solution and saturation extract, considering 1.1 dS m-1 as the tolerated value for the crop. Nitrate in the soil solution increased significantly with the increase of urea concentration in the injection solution. The maximum concentration of nitrate in the soil occurred for 4,0 g L-1 concentration of the injection solution.

Soil salinization as a threat to the sustainability of deficit irrigation under present and expected climate change scenarios

Deficit irrigation (DI) strategies using moderately saline waters save water, but may enhance soil salinization. Based on data gathered during years 2007–2012 in three drip-irrigated grapevine, peach, and nectarine crops subjected to several irrigation and soil-mulching treatments, we assessed trends in root-zone soil salinity [saturation extract electrical conductivity (ECe)], related the changes in soil salinity (ΔECe) to field-wide leaching fraction (LF), evaluated management strategies for soil salinity control, and examined the sustainability of DI strategies under present and expected climate change (CC) scenarios in the Middle Ebro River Basin (ERB, Spain). ECe increased in 82 % of the irrigation seasons and decreased in 75 % of the non-irrigation seasons examined. Soil salinization trends were not apparent during the study years due to these annual salt accumulation–salt leaching cycles. ECe increases were higher in the more severe DI treatments and in the geotextile-mulched soil and lower in the full and less severe irrigation treatments and in the organic-mulched soil. As expected, ΔECe and LF were linearly and negatively correlated (P < 0.01), indicating that soil salinization increased with decreasing LF. These linear relationships provided a way to evaluate best management strategies (increased irrigation, rainfall harvesting, and soil mulching) for soil salinity control. These strategies decreased soil salinization, but did not guarantee the sustainability of severe DIs in the study area. The application of these relationships to the CC precipitation and crop evapotranspiration projections in the ERB shows that the examined DI strategies will be unsustainable due to soil salinization.

Estimativa de valores granulométricos do solo em locais não amostrados utilizando-se cokrigagem

Using the multivariate technique of kriging known as cokriging, it possible to estimate values of variables high cost of aquisition using variable of the low cost and fast acquisition, provided that both exhibit high spatial correlation. The objective of this study was to evaluate the use of electrical conductivity of 1:5 extract (ECe 1: 5) as a covariate in an analysis by cokriging to estimate the values of granulometric components of an Oxisol. In an area of 90 ha, soil samples were collected at 181 georeferenced points, at depth of 0 to 0.20 m. The samples were sent to the laboratory for characterization of soil particle size (coarse sand, fine sand, silt and clay) and measurement of ECe (1:5). Using the cokriging, we attempted to estimate the values of the variables soil texture using the ECe (1:5) as a covariate. Using the technique of cokriging, the best estimates of values for unsampled locations were obtained for the variables silt and clay, because they showed greater spatial correlation with the electrical conductivity of saturation extract (1:5).

Effectiveness of inorganic and organic mulching for soil salinity and sodicity control in a grapevine orchard drip-irrigated with moderately saline waters

Soil mulching is a sensible strategy to reduce evaporation, accelerate crop development, reduce erosion and assist in weed control, but its efficiency for soil salinity control is not as well documented. The benefits of inorganic (plastic) and organic (grapevine pruning residues) mulching for soil salinity and sodicity control were quantified in a grapevine orchard (cultivars ‘Autumn’ Royal and ‘Crimson’) drip-irrigated with moderately saline waters. Soil samples were taken at the beginning and end of the 2008 and 2009 irrigation seasons in six vines of each cultivar and mulching treatment. Soil saturation extract electrical conductivity (ECe), chloride (Cle) and sodium adsorption ratio (SARe) values increased in all treatments of both grapevines along the irrigation seasons, but the increases were much lower in the mulched than in the bare soils due to reduced evaporation losses and concomitant decreases in salt evapo-concentration. The absolute salinity and sodicity daily increases in ‘Autumn’ and ‘Crimson’ 2008 and in ‘Crimson’ 2009 were on the average 44% lower in the plastic and 76% lower in the organic mulched soils than in the bare soil. The greater efficiency of the organic than the plastic mulch in ‘Crimson’ 2009 was attributed to the leaching of salts by a precipitation of 104 mm that infiltrated the organic mulch but was intercepted by the plastic mulch. Although further work is needed to substantiate these results, the conclusion is that the plastic mulch and, particularly, the organic mulch were more efficient than the bare soil for soil salinity and sodicity control.

Phosphorus and Zinc Requirement of Rice under Saline Condition

A green house experiment was conducted for two consecutive years to study the phosphorus and zinc requirement of rice, irrigated with saline water. Three levels of water salinity viz. control (S0), 8.0 (S1) and 16.0 (S2) dSm−1 electrical conductivity (EC), three levels of phosphorus 40 (P1), 80 (P2) and 120 (P3) kg ha−1 and four levels of zinc sulphate (ZnSO4) viz. control (Zn0), 25 (Zn1), 50 (Zn2) and 75 (Zn3) kg ha−1 were tested in a factorial completely randomized design. Saline water having EC 16 dSm−1 decreased the plant height, number of tillers plant−1 and grain yield by 18.2, 24.0 and 52.3% during 1st year and 18.73, 22.13 and 51.63%, respectively during 2nd year of experimentation. Phosphorus application @ 80 kg ha−1 increased grain yield to extent of 19.12 and 29.02% during 1st and 2nd years over 40 kg ha−1 dose of phosphorus while ZnSO4 @ 50 kg ha−1 increased grain yield by 46.29 and 43.33% during 1st and 2nd year over control, respectively. On the basis of grain yield, positive interaction indicated that 95.10 kg ha−1 phosphorus and 60.68 kg ha−1 zinc sulphate were found to be optimum doses for getting higher yield of rice under salt stressed condition on sandy loam soils. The N, P, K, Ca, Na and Zn uptake by grain significantly increased up to 50 kg ha−1 ZnSO4 application. The electrical conductivity of saturated extract of soil after experimentation remarkably increased but pH was not affected with water salinity levels. Irrigation with saline water adversely affected the growth and yield of rice and nutrient uptake.

Regulated deficit irrigation, soil salinization and soil sodification in a table grape vineyard drip-irrigated with moderately saline waters

Irrigation with moderately saline waters may provoke soil salinization and sodification. The objectives of this three-year study were (1) to quantify these processes in two seedless table grapevines (Vitis vinifera cvs. Autumn Royal and Crimson) subject to a full irrigation and two regulated deficit irrigations (RDI, irrigated at 80% and 60% of net irrigation requirements from post-veraison till harvest) with 1.7dSm−1 electrical conductivity irrigation waters, and (2) to assess the impact of soil salinization on grapevine's response. Soil samples were taken three times along each irrigation season and soil solution samples were extracted weekly by suction cups. Soil saturation extract electrical conductivity (ECe) and sodium adsorption ratio (SARe) were high in Autumn Royal (4.4dSm−1 and 6.1 (mmoll−1)0.5) and very high in Crimson (7.0dSm−1 and 8.6 (mmoll−1)0.5) due to relatively low leaching fractions (LF) (0.20 in Autumn Royal and 0.13 in Crimson). Soil solution salinity and sodicity were generally higher in the more severe RDI than in the full irrigation treatment. Soil salinity and sodicity generally increased along the irrigation seasons and decreased along the non-irrigation seasons. Salt accumulation or leaching and LF were significantly correlated, so that LF estimates could anticipate the required irrigation depths for soil salinity control. Grapevine yield declined with increases in soil salinity. Leaf Na concentrations were very low (<0.1%), but leaf Cl concentrations were higher and the maximum value of 0.61% measured in the more severe Crimson RDI treatment was within the interval reported as toxic in grapevine. Despite the water saving benefits of drip irrigation in combination with deficit irrigation strategies, its implementation in low-precipitation semiarid areas must be cautiously assessed and monitored because soil salinization and sodification may threaten the sustainability and profitability of these grapevine orchards irrigated with moderately saline waters.

Crescimento inicial e consumo hídrico de nim submetido ao estresse salino e biofertilizante bovino

An experiment was carried out during the period of January to July/2010, in municipality of Areia, Paraiba State, Brazil, in order to evaluate effects of the irrigation with saline water, bovine biofertilizer and drainage of the soil on water consumption and growth of neem seedlings. The experimental design was in randomized blocks using factorial 5x2x2, referring to five levels of saline water (0.5; 1.5; 3.0; 4.5; 6.0 dS m-1) in soil without and with bovine biofertilizer and in pots without and with drainage. In plants the water consumption, growth in height, stem diameter, number of leaves, dry matter of roots, aerial part and total dry mass were evaluated and in soil the electrical conductivity of saturation extract – EC was determined. The bovine biofertilizer, after dilution in non saline water (0.49 dS m-1) e no chlorinated water in 1:1 ratio was applied once two days before sowing, equivalent to 10% of substrate volume. Irrigation was applied daily with each water type applying volume sufficient to maintain the soil with water content at level of field capacity. From results the increase in salinity of water inhibited the water consumption by plants independently of the soil with or without bovine biofertilizer. The salinity of water in soil with and without bovine biofertilizer also reduced the growth of neem plants but with more pronounced effect in the treatments without application of organic fertilizer to soil in liquid form.

Alterações dos atributos físicos e químicos de um Neossolo após aplicação de doses de manipueira

O resíduo gerado no processamento industrial da mandioca (manipueira) apresenta alta carga orgânica e elevada concentração de nutrientes. Tal resíduo, se descartado indiscriminadamente no solo, pode trazer sérios riscos ao ambiente. Assim, o objetivo deste estudo foi avaliar as alterações dos atributos físicos e químicos em um Neossolo Regolítico cultivado com alface e submetido às diferentes doses de manipueira. O experimento foi conduzido em casa de vegetação e se utilizou um delineamento inteiramente casualizado, com seis tratamentos compostos das seguintes doses: 0, 5, 15, 25, 45, 65 m³ ha-1 com cinco repetições. Para caracterização dos atributos do solo foram determinados parâmetros físicos (grau de floculação, argila dispersa em água) e químicos (condutividade elétrica do extrato de saturação do solo, pH, teor de P e teores de cátions trocáveis K+, Ca2+, Mg2+ e Na+) do solo. A aplicação de manipueira ao solo propiciou um aumento significativo do grau de floculação, do pH, da condutividade elétrica do extrato de saturação, dos teores de cátions trocáveis e do teor de P, além de uma diminuição significativa da argila dispersa em água, constatando-se também tendência à salinização, em virtude do uso da manipueira.

Changes in soil salinity in the habitats of five halophytes after 20years

Abstract Long-term soil salinity data are required to properly manage saline habitats. This study presents easy procedures for comparing soil salinity profiles, which were used to assess four saline wetlands in NE Spain. Soil salinity measurements at sites where different halophytes were dominant were recorded throughout the year in 1979–1980 and 1999–2000, with additional measurements in 1985. Electrical conductivity of saturation extracts (ECe) and the concentrations of major ions were measured in four hundred soil samples. To confirm the consistency of the quality of the lab measurements, we used saturation percentage (SP) statistics and the relationships between ECe and both the cationic and the anionic concentrations in the extracts (R 2 > 97%), and the relationship with the EC of the extracts at a soil-to-water ratio of 1:5 by weight (EC 1:5). The ECe of the soil samples ranged from 4 to 114 dS m − 1 , and the averages in the four wetlands (AN, PC, AL, and AG) were 38.6, 10.1, 22.3, and 68.5 dS m − 1 , respectively. The median of the sodium adsorption ratio [SAR, (meq L − 1 ) 0.5 ] in the samples was 69, 126, 64, and 28, respectively. At AN, the maximum average ECe in the upper 100 cm of the soil was 35.0 dS m − 1 for Artemisia herba-alba and 75.2 dS m − 1 for Suaeda vera ; at PC, the maximum value was 19.3 dS m − 1 for Puccinellia festuciformis ; and, at AL, it was 30.3 dS m − 1 for Salicornia ramosissima and 44.6 dS m − 1 for S. vera . At AG, the maximum average ECe was 69.2 for S. vera , and 85.2 dS m − 1 for Arthrocnemum macrostachyum . The ECe and SAR remained stable between the two sampling periods in three of the wetlands but, in AL, which was converted into a paddy, ECe was reduced from ~ 40 dS m − 1 to ~ 2 dS m − 1 and SAR was reduced from > 77 to ~ 2. The presence of saline non-sodic and saline–sodic soils at nearby wetlands reflects the pedodiversity of the area.

Soil Salinity Changes in the Jordan Valley Potentially Threaten Sustainable Irrigated Agriculture

The integrated effect of irrigation and agricultural practices on soil salinity in the Jordan Valley (JV), where over 60% of Jordan's agricultural produce is grown, was investigated in this study during 2009–2010. Due to the differences in agricultural operations, cropping patterns, irrigation management, and weather conditions, 206 top- and sub-soil samples were taken every 1 to 3 km from representative farms along a north-south (N-S) transect with 1 to 2 km lateral extents. Soil electrical conductivity of saturated extract (ECse), Ca, Mg, K, Na, Cl, and Na adsorption ratio (SAR) were determined in saturated paste extracts. Results indicated that about 63% of soils in the JV are indeed saline, out of which almost 46% are moderately to strongly saline. Along the N-S transect of the JV, ECse increased from 4.5 to 14.1 dS m−1 in top-soil samples. Similar increase was observed for the sub-soil samples. The major chemical components of soil salinity; i.e., Ca, Mg, and Cl, also showed a similar increase along the N-S transect of the valley. Moreover, compared to previous field sampling, results showed that changes in soil salinity in the JV were dramatic. In addition, it was found that Cl imposed an existing and potential threat to sensitive crops in 60% of the soils in the JV, where Cl concentrations were greater than 710 mg L−1. Under the prevalent arid Mediterranean conditions, improving the management of irrigation water, crops, and nutrient inputs and increasing water and fertilizer use efficiencies should be indispensable to conserve and sustain the already fragile agricultural soils in the JV.

Land Application of Treated Industrial Wastewater on a Chihuahuan Desert Shrubland: Implications for Water Quality and Mineral Deposition

Land application of wastewater conserves fresh water and recycles nutrients, but little is known of its impacts on arid and semiarid landscapes. Lagoon treated saline−sodic industrial effluent was applied from 2002–2005 to a 0.4-ha Chihuahuan Desert shrubland to assess the deposition and recovery of effluent components and changes in soil quality vis-à-vis a non-irrigated area. Effluent irrigation supplied 26% of the average annual nonstressed evapotranspiration (ET) of the native shrubs [Larrea tridentata (DC.) Coville and Prosopis glandulosa Torr. var. glandulosa], and increased both soil stress factors (sodicity, salinity, and pH) and soil fertility (N, P, and K). After 3 yr, the soil saturation extract electrical conductivity (ECe) reached as high as 6.1 dS m−1 and Cl− 76 molc m−3 at 105 cm depth under irrigated L. tridentata. After 4 yr, saturation extract sodium adsorption ratio (SARe) reached 25–35 at 7.5 cm under the irrigated shrubs and intershrub spaces. There were 27 Mg ha−1 of cumulative ionic deposits to the site comprised mostly of Na+, Cl−, and CaCO3 equivalent alkalinity, with soil analysis recovering most of the deposits (>57%) except for K+ and Na+ (8% to 13%). Subsurface leaching of and P was detected within the upper 1 m soil depth after 4 yr, and a high downward mobility of Cl− revealed the potential for deeper leaching at higher N loading rates. While long-term effects on the natural vegetation are unknown, results contribute to a limited scientific database for sustainable wastewater land application in semiarid regions.

Application of the swap model to predict impact of climate change on soil water balance in a Sicilian vineyard

In Sicily, the increasing scarcity of quality water is leading to irrigation with saline water in soils having a considerable susceptibility to salinization and degradation. In this paper, water flow and solute transport in a Sicilian irrigated soil was simulated by using the SWAP model, and the simulated results compared to measured values of soil moisture and salinity. The investigation was carried out in a vineyard located in Sicily (Mazara del Vallo, Trapani Province) within the framework of the Project: Evolution of cropping systems as affected by climate change (CLIMESCO). The soil hydraulic parameters were obtained by inverse method based on multi-step outflow experiments. The results obtained using field measurements from two soil profiles showed that SWAP provided reliable predictions of water content, θ, and of electrical conductivity of saturated extract, ECsat. The effect of climate change on soil water balance was predicted by application of SWAP under the soil-crop and irrigation management conditions currently practiced in the vineyard. Simulations were carried out with climatic data generated by the statistical downscaling process based on the global CGM HADCM3 for two IPCC scenarios (A2 and B1) and for the 2070-2100 time interval. The two mentioned IPCC scenarios (A2 and B1) were then compared to a third reference scenario (BASELINE) obtained by using the climatic data recorded from 1951 to 2004. The results indicated that the only significant effect of climate change was to shorten and to advance the crop cycle length, which decreased of 16 and 27 days respectively in B1 and A2 compared to values obtained for the BASELINE scenario. Further application of SWAP carried out simulating an advance in the irrigation starting time according to the advance in the crop cycle indicated that this could be considered a kind of adaptation strategy to be applied in the future in the vineyard to counterbalance the impact of climate change. This means that in the future farmers might be likely to anticipate the irrigation season in order to avoid any significant reduction in the crop productivity.

Incorporação de gesso para correção da salinidade e sodicidade de solos salino-sódicos

Com o objetivo de avaliar o efeito da aplicação do gesso nas características químicas de solos salino-sódicos coletados no Perímetro Irrigado do Moxotó, localizado no município de Ibimirim, PE, um experimento foi realizado em colunas de solo instaladas no Laboratório de Mecânica do Solo e Aproveitamento de Resíduo da Universidade Federal Rural de Pernambuco. Os tratamentos foram dispostos em um delineamento inteiramente casualizado com esquema fatorial de dois solos (S1 e S2) e sete níveis da necessidade de gesso (50, 75, 100, 125, 150, 175 e 200%) determinado pelo Método de Laboratório Schoonover-M1. O gesso foi incorporado aos solos, em três repetições, totalizando 42 unidades experimentais. As variáveis avaliadas foram: i) condutividade elétrica (CE), ii) cátions solúveis e iii) relação de adsorção de sódio (RAS) no extrato de saturação do solo. O nível de 100% da necessidade de gesso causou diminuição da sodicidade para valores de RAS &lt; 13 (mmol L-1)½, apresentando-se como método eficiente na redução dos teores de sódio em áreas afetadas por sais. A lâmina de lixiviação equivalente a três vezes o volume de poros (3VP) reduziu a condutividade elétrica (CE) no extrato de saturação para valores &lt; 4 dS m-1, razão por que foi indicada para a correção da salinidade dos solos em estudo.

Identificação de genótipos de feijão-caupi tolerantes a salinidade avaliado por meio de método multivariado

Objetivou-se com este trabalho identificar genótipos tolerantes ao estresse provocado pela solução de NaCl e pela mistura de NaCl, CaCl2 e MgCl2 na água de irrigação, nos estádios iniciais de desenvolvimento. Os níveis de condutividade elétrica do extrato de saturação foram: 0, 2,5; 5,0 e 7,5dS m-1. A tolerância do feijão-caupi foi avaliada através da redução relativa de matéria seca da parte aérea de cada genótipo. O genótipo CE-182 mostrou-se mais tolerante nos níveis 2,5; 5,0 e 7,5dS m-1 na água salinizada com solução de NaCl. Na solução de mistura dos sais, os genótipos CE-9 e CE-551 foram os mais tolerantes. De acordo com os resultados obtidos pelo agrupamento, utilizando-se o método hierárquico UPGMA, verifica-se que as combinações mais promissoras para cruzamentos e obtenção de progênies superiores no desenvolvimento de cultivares tolerantes à salinidade foram entre os genótipos CE-182 e CE-250 e entre CE-551 e CE-09.

IONIC DISPLACEMENT AND RECLAMATION OF SALINE‐SODIC SOILS USING CHEMICAL AMENDMENTS AND CROP ROTATION

ABSTRACTBiological, chemical and bio‐chemical strategies have been tested in the past for reclamation of saline‐sodic and sodic soils. The efficiency of two crop rotations (rice‐wheat and Sesbania‐wheat) alone or in combination with either gypsum (CaSO4.2H2O) or sulfuric acid (H2SO4) was tested for ionic displacement from four saline‐sodic soils. Pure gypsum was applied at 50 per cent of soil gypsum requirement at the time of planting rice and Sesbania, whereas 95 per cent pure sulfuric acid was added at 50 per cent soil gypsum requirement as one‐third applications by mixing with the first three irrigations. The rice crop biomass decreased at a soil saturation extract electrical conductivity (ECe) of 8 dS m−1, whereas wheat and Sesbania were influenced at a sodium adsorption ratio (SAR) of ≥40. Gypsum treatment helped the crops flourish well at these ECe and SAR levels. The infiltrated volume of water dropped with decrease in ECe : SAR ratio of soils and increase in crop biomass production. Crops rotation treatments alone helped leach sodium (Na+) and other ions successfully at SAR ≤ 21 but were less effective at SAR ≥ 40 at which point plants growth was also curtailed. Gypsum and H2SO4 treatments significantly aided leaching of Na+ and other ions with water at SAR ≥ 40 under both the crop rotations. Hence, crops effectively reclaimed soil at low sodicity level, whereas at high SAR, chemical amendments are obligatory in order to reclaim soils. This study also suggests that the required dose of H2SO4 should be applied with pre‐planting irrigation for better yield of the first crop. Copyright © 2011 John Wiley &amp; Sons, Ltd.