Porous Ceramic Cups Research Articles

Response characteristics of an insertion tensiometer investigated via the vacuum saturation method

Tensiometers are devices that can be used to monitor suction variation in landslides and slopes. The soil suction that can be measured with a conventional tensiometer is limited to 85 ∼ 90 kPa due to water cavitation in the tensiometer. This low measurement range of suction may be insufficient to interpret and determine the hydraulic properties of unsaturated soil, especially in semihumid and semiarid climate regions. However, in most geotechnical engineering studies, conventional tensiometers are still utilized. Although several types of high-suction tensiometers have been developed in recent decades, high suction measurements are difficult in the field because the saturation procedures for these tensiometers are complex and time consuming. Hence, the development of a simple and rapid saturation method is necessary to support their application. The vacuum saturation technique is a simple and reliable technique for saturating the porous ceramic cup of a tensiometer. However, if a high-suction tensiometer is saturated via a vacuum syringe, the measurable maximum suction is usually<200 kPa, which limits the application of tensiometers in geotechnical engineering. In this paper, we proposed a simple saturation device and a saturation method (the vacuum cylinder saturation method, VCSM) to saturate high-suction tensiometers. Soil column experiments were conducted to investigate the advantages of the VCSM and the response characteristics of insertion tensiometers. The results indicated that high-suction tensiometers could easily and steadily measure a maximum suction of 350 kPa if saturated via the VCSM. The VCSM could effectively prevent or retard the occurrence of cavitation due to the high vacuum pressure and slow progress of water filling in the tensiometer shaft. In addition, the response curve of insertion tensiometers could be divided into three stages: installing disturbance stage, delayed response stage and equilibrium stage. The extent of the disturbance caused by insertion tensiometer installation is a key factor influencing the delayed response characteristics of the tensiometer response curve. This paper also provides greater insight into the saturation method of tensiometers and the application of insertion tensiometers.

ASSESSMENT OF SUBSTRATE SOLUTION EXTRACTION METHODS FOR DETERMINATION OF CHEMICAL ATTRIBUTES IN SOILLESS CULTURE OF BELL PEPPER AND MELON

ABSTRACT The aim of this study was to evaluate the efficiency of the porous ceramic cup extractors, associated with ion meters, for the determination of nutrients availability for bell pepper and melon crops in substrate. Substrate solution was acquired using aqueous extract 1:1.5 (v/v) and also the porous ceramic cup extractor. Electrical conductivity (EC), pH and macronutrient contents were determined for the substrate solution through analytical method. The concentrations of NO- and K+ in the solutions obtained with porous ceramic cup extractors, and the N and K contents in the diagnostic leaf for nutritional evaluation were also determined. The concentrations of NO3- and K+ using the porous ceramic cup extractors have strong correlation (r=0.96 and 0.92, respectively) with the ones obtained using the standard method, as well as a moderate correlation (r=0.65) and a strong one (r=0.71) with contents of N and K, respectively, in the melon diagnostic leaf; and a weak correlation (r=0.36 and 0.26, respectively) in the bell pepper diagnostic leaf. The use of porous ceramic cup extractors for obtaining the substrate solution and the determination of the N-NO- and K+ contents by means of specific ion meters are a fast method of evaluating nutrients availability in soilless cultures.

Watermelon fertigation with electrical conductivity and ph monitoring in the soil solution

In the olericulture, in general, is practiced intensive fertilization, which creates a risk of salinization and change of high pH, ​​which if not well monitored can cause production losses, excessive spending on fertilizers and environmental contamination. We developed this study with the aim of controlling fertigation on watermelon through the behavior of the electrical conductivity (EC) and pH in the soil solution obtained through porous ceramic cups extractors. The EC and pH values ​​were corrected by the current soil moisture for the moisture field capacity, due to different moisture values ​​at the time of extraction. The monitoring comprised 19 assessments during 80 days of cultivation. We can control the pH and EC of the soil and maintain them at optimal levels for the crop through real-time monitoring of the soil solution. The monitoring enabled the achievement of a balanced fertigation.

The herbicide glyphosate and its metabolite AMPA in the Lavaux vineyard area, western Switzerland: Proof of widespread export to surface waters. Part II: The role of infiltration and surface runoff

Two parcels of the Lavaux vineyard area, western Switzerland, were studied to assess to which extent the widely used herbicide, glyphosate, and its metabolite aminomethylphosphonic acid (AMPA) were retained in the soil or exported to surface waters. They were equipped at their bottom with porous ceramic cups and runoff collectors, which allowed retrieving water samples for the growing seasons 2010 and 2011. The role of slope, soil properties and rainfall regime in their export was examined and the surface runoff/throughflows ratio was determined with a mass balance. Our results revealed elevated glyphosate and AMPA concentrations at 60 and 80 cm depth at parcel bottoms, suggesting their infiltration in the upper parts of the parcels and the presence of preferential flows in the studied parcels. Indeed, the succession of rainy days induced the gradual saturation of the soil porosity, leading to rapid infiltration through macropores, as well as surface runoff formation. Furthermore, the presence of more impervious weathered marls at 100 cm depth induced throughflows, the importance of which in the lateral transport of the herbicide molecules was determined by the slope steepness. Mobility of glyphosate and AMPA into the unsaturated zone was thus likely driven by precipitation regime and soil characteristics, such as slope, porosity structure and layer permeability discrepancy. Important rainfall events (>10 mm/day) were clearly exporting molecules from the soil top layer, as indicated by important concentrations in runoff samples. The mass balance showed that total loss (10–20%) mainly occurred through surface runoff (96%) and, to a minor extent, by throughflows in soils (4%), with subsequent exfiltration to surface waters.

Comparison of lysimeters and porous ceramic cups for measuring nitrate leaching in different soil types

Environmental concerns over nitrate levels in surface and ground water have led to increased efforts to measure nitrate leaching from farmland. This study compared two methods of measuring leaching (lysimeters versus ceramic suction cups) using 12 soil monolith lysimeters (70 cm deep) containing four replicates of three contrasting New Zealand soils: Gorge silt loam, Mataura sandy loam (both stone-free soils) and Lismore stony silt loam. The ceramic suction cups were installed at 35 cm and 60 cm depths. Urea solution was surface applied at 250 kg N ha−1, followed by regular weekly irrigation. Nitrate leaching loss was calculated by combining the volume of drainage water collected from each lysimeter with the nitrate concentration in either the lysimeter drainage solution or the solution from the suction cups. Cup samples were taken twice per irrigation/drainage sequence: during irrigation and then immediately after irrigation ceased. No evidence of any difference in nitrate concentration and in cumulative leaching was observed between the first and second cup sampling times. However, there was a large variation in individual values measured by the suction cup samples. There were differences between the cumulative leaching loss measured in the lysimeter drainage and values estimated from the cups in the Gorge and Lismore soils. The cumulative leaching loss, measured from the top cups, bottom cups and lysimeter drainage, was 64, 68 and 54 kg N ha−1 respectively in the Gorge soil, 57, 68 and 62 kg N ha−1 in the Mataura soil and 61, 103 and 99 kg N ha−1 in the Lismore soil. It was concluded that suction cups were inappropriate for the determination of cumulative leaching in the structured Gorge soil and the Lismore topsoil, but ceramic cups could provide useful data on cumulative leaching in the Mataura sandy loam soil. It was hypothesised that preferential flow was likely to be the cause of the differences between the results obtained from suction cups and the lysimeter drainage, especially in the Lismore and possibly the Gorge soils, where the small sampler size was not able to capture a representative sample of the pore network responsible for the soil drainage.

Dinâmica de nutrientes na solução do solo em pomar fertirrigado de citros

O objetivo deste trabalho foi avaliar a dinâmica de nutrientes na solução do solo após a aplicação, via fertirrigação, de nitrogênio, fósforo e potássio a laranjeiras. O experimento foi realizado entre setembro de 2007 e outubro de 2009, em pomares de laranjeiras 'Valência' e 'Hamlin', enxertadas sobre citrumeleiro 'Swingle'. Foram avaliadas cinco doses de N, P2O5 e K2O (0, 25, 50, 100 e 200% da dose recomendada). A solução do solo foi extraída a 30 e 60 cm de profundidade, com o auxílio de extratores com cápsulas porosas. Foram realizadas 11 avaliações durante o período experimental, com as extrações iniciadas após 12 horas das fertirrigações. O aumento das doses reduziu o pH (pH~3,5, na maior dose), e aumentou a condutividade elétrica (CE~1,5 dS m-1, na maior dose) e os teores de NH4, NO3, P, K, Mn e Zn na solução do solo, nas duas profundidades amostradas. Nos meses com maior precipitação pluvial, houve perda potencial de nutrientes por lixiviação, pois maiores concentrações de NO3, K e B foram observadas à profundidade de 60 cm. A análise da solução do solo, obtida por extratores com cápsula de cerâmica porosa, pode ser considerada ferramenta auxiliar para monitorar e avaliar a disponibilidade de nutrientes às plantas.

The effectiveness of the nitrification inhibitor dicyandiamide (DCD) for mitigating nitrogen leaching losses from a winter grazed forage crop on a free draining soil in northern Southland.

Evidence suggests that the wintering of stock on forage crops is a significant contributor to N losses from livestock farming. Losses are likely to be exacerbated if crops are grown on shallow free-draining soils types and grazed by dairy cattle. A three-year trial (December 2008 - November 2011) was conducted in northern Southland on a soil classified as having severe vulnerability for nutrient leaching to groundwater. Porous ceramic cups were installed under a brassica crop which was grazed by dairy cows in June each year and the leachate collected regularly for N analysis. The treatments evaluated were with and without a single application of DCD applied at the time of crop grazing. Concentrations of nitrate-N in drainage water ranged from 40 mg/L in May 2011. Concentrations of dissolved organic N (DON) also increased from a low initial value (

Nutrient Solution and Nutrient Soil Solution Parameter Evolution in Tomato with Dynamic Fertigation under Saline Conditions

This trial was carried out to study the evolution of the nutrient parameters of the nutrient solution applied to tomato plants (Lycopersicum sculentum Mill. Forteza) cultivated in Mediterranean greenhouse conditions under different fertigation management models. The dynamic model is based on soil water content, which was measured by tensiometers, and on soil solutions obtained with suction cups (porous ceramic cup water samplers). The local traditional method consists of following technical recommendations, and the classical model requires the estimation of Crop Factor (Kc) and knowing the nutrient extraction. Nutrient solution and water applied are functions of the fertigation management criteria. The water used for fertigation was classified as C4-S3 according to the Riverside classification system. The cultivation period lasted from 15 August to 20 April. The nutrient parameters studied in nutrient and soil solution were pH, electrical conductivity (EC), nitrate (NO3 −), phosphate (H2PO4 −), potassium (K+), calcium (Ca2+), magnesium (Mg2+), sodium (Na+), and chloride (Cl−). The pH shows similar trends under the different treatments. Electrical conductivity is in the range of 2.8–4.5 dS m−1. Chloride, sodium, magnesium, and sulfate are exclusively modified by the salt concentration in the irrigation water, so it can be assumed that the three treatments vary equally. Nitrate, potassium, phosphate, and calcium are modified depending on each fertigation management method. Soil solution is modified by the nutrient solution applied. Dynamic management allows low nutrient concentration in the nutrient solution to be maintained and keeps soil nutrient concentration low, reducing fertilizer losses and therefore aquifer contamination.

Nitrate leaching from a maize × oats double-cropping forage system fertilized with organic residues under Mediterranean conditions

Further information about the environmental effects and best management options for agricultural use of organic residues in Mediterranean areas is required. A field experiment was carried out over two winter seasons in central Portugal, to evaluate NO3-N leaching losses originating from the soil application of cattle slurry (CS), sewage sludge (SS) and urban waste compost (UWC) to a double-cropping system producing oats and maize. A mineral fertilizer treatment (MIN) and a Control were included. The use of a nitrification inhibitor (DCD) with MIN (MIN+I) and CS (CS+I), an organic residue with high C/N ratio (pulp mill sludge – PMS) together with mineral fertilizer (PMS+M), and split application of residues (SS and UWC), were evaluated as measures to mitigate N leaching. Total fertilizer N applied in treatments were 80 and 170kgNha−1 to oats (Avena sativa L.) and maize (Zea mays L.), respectively. Water samples were collected at 0.70m deep, using porous ceramic cups. The highest annual NO3 losses were measured in MIN+I, PMS+M and MIN (185, 152 and 145kgNha−1, respectively) and with the split application of SS (145kgNha−1). In Control the maximum loss was 50kgNha−1. The use of DCD in spring fertilization is not recommended. The N lost by leaching and runoff following the application of organic residues was less than to 30% of N applied (IPCC factor). Compared to mineral N application, the use of organic residues in agriculture with an appropriate management can contribute to lower nitrate losses.

Calibração de extratores providos de cápsula porosa para monitoramento da salinidade e da concentração de íons

Os resultados satisfatórios obtidos no monitoramento da salinidade e concentração de íons na solução do solo, usando extratores de cápsulas porosas, motivaram a realização deste trabalho, o qual teve como objetivo a obtenção de curvas de calibração para estes extratores monitorarem a condutividade elétrica e a concentração de nitrato e de potássio na solução de dois tipos de solo (Latossolo Vermelho-Amarelo Argissólico franco arenoso, e o outro como Cambissolo Eutrófico), em Mossoró - RN. As concentrações de nitrato utilizadas foram as mesmas nos dois solos (0; 84; 168; 252; 336; 420 e 504 mg L-1); quanto ao potássio, foram utilizadas concentrações diferentes no solo arenoso (0; 117; 234; 351; 468; 585 e 702 mg L-1) e no argiloso (0; 117; 234; 351; 468; 585; 702; 1.170; 1.755; 2.340; 2.925 e 3.510 mg L-1). A condutividade elétrica da solução do solo e a concentração de nitrato e de potássio foram estimadas com precisão satisfatória a partir da solução coletada com extratores providos de cápsulas porosas, sendo necessária uma calibração prévia para cada tipo de solo.

The use of Porous Ceramic Cups for Sampling Soil Pore Water from the Unsaturated Zone

The use of Porous Ceramic Cups for Sampling Soil Pore Water from the Unsaturated Zone

The evaporation method: Extending the measurement range of soil hydraulic properties using the air‐entry pressure of the ceramic cup

AbstractKnowledge of hydraulic functions is required for various hydrological and plant‐physiological studies. The evaporation method is frequently used for the simultaneous determination of hydraulic functions of unsaturated soil samples, i.e., the water‐retention curve and hydraulic‐conductivity function. All methodic variants of the evaporation method suffer from the limitation that the hydraulic functions can only be determined to a mean tension of ≈ 60 kPa. This is caused by the limited measurement range of the tensiometers of typically 80 kPa on the dry end. We present a new, cost‐ and time‐saving approach which overcomes this restriction. Using the air‐entry pressure of the tensiometer's porous ceramic cup as additional defined tension value allows the quantification of hydraulic functions up to close to the wilting point. The procedure is described, uncertainties are discussed, and measured as well as simulated test results are presented for soil samples of various origins, different textures (sand, loam, silt, clay, and peat) and variable dry bulk density. The experimental setup followed the system HYPROP which is a commercial device with vertically aligned tensiometers that is optimized to perform evaporation measurements. During the experiment leaked water from the tensiometer interior wets the surrounding soil of the tensiometer cup and can lead to a tension retardation as shown by simulation results. This effect is negligible when the tensiometers are embedded vertically. For coarsely textured soils and horizontal tensiometer alignment, however, the retardation must be considered for data evaluation.

Nitrate and ammonium in soil solution in tobacco management systems

Tobacco farmers of southern Brazil use high levels of fertilizers, without considering soil and environmental attributes, posing great risk to water resources degradation. The objective of this study was to monitor nitrate and ammonium concentrations in the soil solution of an Entisol in and below the root zone of tobacco under conventional tillage (CT), minimum tillage (MT) and no-tillage (NT). The study was conducted in the small-watershed Arroio Lino, in Agudo, State of Rio Grande do Sul, Brazil. A base fertilization of 850 kg ha-1 of 10-18-24 and topdressing of 400 kg ha-1 of 14-0-14 NPK fertilizer were applied. The soil solution was sampled during the crop cycle with a tension lysimeter equipped with a porous ceramic cup. Ammonium and nitrate concentrations were analyzed by the distillation and titration method. Nitrate concentrations, ranging from 8 to 226 mg L-1, were highest after initial fertilization and decreased during the crop cycle. The average nitrate (N-NO3-) concentration in the root zone was 75 in NT, 95 in MT, and 49 mg L-1 in CT. Below the root zone, the average nitrate concentration was 58 under NT, 108 under MT and 36 mg L-1 under CT. The nitrate and ammonium concentrations did not differ significantly in the management systems. However, the nitrate concentrations measured represent a contamination risk to groundwater of the watershed. The ammonium concentration (N-NH4+) decreased over time in all management systems, possibly as a result of the nitrification process and root uptake of part of the ammonium by the growing plants.

Porous Ceramic Cups: Preparation and Installation of Samplers for Measuring Nitrate Leaching

Porous Ceramic Cups: Preparation and Installation of Samplers for Measuring Nitrate Leaching

Effects of nitrogen addition on dissolved N 2O and CO 2, dissolved organic matter, and inorganic nitrogen in soil solution under a temperate old-growth forest

Soil solutions at 15 cm and 60 cm depths under a Korean pine and broadleaf mixed forest (> 200 years old) at Changbai mountain, northeast China, were sampled using porous ceramic suction cups from July 2006 to October 2007, to study the effects of nitrogen (N) addition on the concentrations of dissolved nitrous oxide (N 2O) and carbon dioxide (CO 2), dissolved organic matter and inorganic N. The actual concentrations of dissolved N 2O and CO 2 in soil solutions could be obtained using a combination of continual three phase equilibrations and gas chromatography. The dissolved CO 2 concentrations in soil solutions at 15 cm and 60 cm depths varied from 4.3 to 15.5 and from 3.5 to 18.3 μg CO 2–C ml − 1 , respectively, and dissolved N 2O concentrations at both depths varied from 1.8 to 34.9 and from 2.5 to 99.3 ng N 2O–N ml − 1 , respectively. The addition of N sources such as (NH 4) 2SO 4, NH 4Cl and KNO 3 at a rate of 4.5 g N/m 2 each year tended to decrease concentrations of dissolved organic carbon (DOC) in soil solutions at 60 cm depth in 2007, which was contrary to the increase in dissolved CO 2 concentrations under N-fertilized forest plots. However, the N addition did not give an obvious effect on the concentrations of dissolved CO 2 and DOC in soil solutions at 15 cm depth. There was an increase in concentrations of NH 4 +–N, NO 3 −–N and dissolved organic nitrogen (DON) of soil solutions under N-fertilized forest plots. Rainfall after thawing in spring could promote the accumulation of dissolved N 2O in soil solutions at 15 cm and 60 cm depths, particularly at 60 cm depth under the (NH 4) 2SO 4 added plots, due to mineralization of DON and nitrification. All the tested properties of soil solutions at 15 cm and 60 cm depths were well correlated. Among these properties, the dissolved N 2O concentrations of soil solutions at both depths were better correlated with the DON concentrations at 60 cm depth, and the dissolved CO 2 concentrations at 15 cm depth with the DOC concentrations at both depths. Hence, both DOC and DON can contribute to the formation of dissolved CO 2 and N 2O in the soil solutions at varying depths under N-fertilized forest plots, respectively. Our observations strongly indicate that N inputs to temperate forest floors can affect the status of N and carbon processes in underlying forest soils.

Extração de K+ e Na+ por cápsulas de cerâmica porosa

To evaluate the efficiency of extraction of solutions containing known amounts of potassium and sodium, porous ceramic cups were used as samplers. Solutions with increasing, decreasing and random amounts of K + and Na + were tested and the concentration of both cations inside and outside the samplers were analyzed. Three types of porous ceramic cups were tested and the results indicated that they reacted differently in relation to the K + and Na + solutions. One of them presented high adsorption capacity for the cations, therefore, not being recommended for dynamic studies of these ions. There were no differences in the behavior of the K + and Na + cations. The extraction of the soil solution, using porous ceramic cup samplers, needs previous evaluation under controlled conditions to determine the exactness and precision of the results

다공 세라믹 컵을 이용한 디지털 토양수분 장력계 개발

This study was conducted to develop a 100 kPa soil tensiometer mainly consisted of a porous ceramic cup, water-holding tube, and a digital vacuum gauge, through theoretical design analysis and experimental performance evaluation. Major findings were as follows. 1. Theoretical analysis showed that air entry value of a porous media decreased as the maximum effective size of the pore increased, and the maximum diameter of the pores was <TEX>$2.9\;{\mu}m$</TEX> for measuring up a 100 kPa of soil-water tension. 2. Property analysis of tensiometer porous cups supplied in Korean domestic market indicated that main components were <TEX>$SiO_2$</TEX> and <TEX>$Al_2O_3$</TEX> with a porosity range of <TEX>$33.8{\sim}49.3%$</TEX>. 3. The porous cup selected through sample fabrication and air-permeability tests showed weight ratios of 87% and 11% for <TEX>$Al_2O_3$</TEX> and <TEX>$SiO_2$</TEX>. The analysis of SEM (scanning electron microscope) images showed that the sample was sintered at temperatures of about <TEX>$1150^{\circ}C$</TEX>, which consisted of pores with sizes of up to 25% of those for commercial porous cups. 4. The prototype soil tensiometer was fabricated using the developed porous cup and a digital vacuum gauge that could measure water tension with a pressure of 85 kPa in air tests. 5. In-soil tests of the prototype conducted during a period of 25-day drying showed that soil-water tension values measured with the prototype and commercial units were not significantly different, and soil-water characteristic curves could be established for different soils, confirming accuracy and stability of the prototype.

Residual effect and leaching of N and K in cropping systems with clover and ryegrass catch crops on a coarse sand

In low input farming systems without inorganic N-fertilizer input, cereal cropping is a challenge because of the need for an adequate N supply. The objective of this investigation was to explore the feasibility of using clover (red/white) catch crops instead of ryegrass in crop production on coarse sand. Two field experiments tested the effects of clover and ryegrass catch crops on N and K leaching and on grain yield of a succeeding spring barley. Treatments included animal manure regimes, main crops (spring barley = low soil N status or lupin = high soil N status) and levels of K fertilizer (no K or 80 kg K ha −1). The residual effect of the clover catch crop on grain yield of the succeeding spring barley was significantly higher than that of the ryegrass, especially under the low N conditions. When animal manure (70 kg total-N ha −1) was added to the spring barley succeeding a ryegrass catch crop, the difference in residual effect between clover and ryegrass catch crops disappeared. Thus, clover appeared to have the potential to substitute animal manure. Leaching of NO 3-N and K was estimated by means of porous ceramic suction cups installed at 1 m depth. Both the clover and ryegrass catch crops reduced the annual flow-weighted mean NO 3-N concentrations from 13–16 to 5–8 mg L −1, which is below the WHO maximum for drinking water. The annual NO 3-N leaching from a spring barley treatment without catch crops was approximately 100 kg ha −1. Clover and ryegrass catch crops reduced the losses significantly by approximately 40–80% depending on year and treatment, with ryegrass being more effective than clover. Catch crops reduced K leaching significantly but the relative effect was lower than for N. The clover catch crops appeared suitable for low-N cropping systems on coarse sand with respect to both production and environment.

Nitrate leaching from short‐rotation coppice

AbstractIn the UK, short‐rotation coppice (SRC) is expected to become a significant source of ‘bio‐energy’ over the next few years. Thus, it is important to establish how nitrate leaching losses compare with conventional arable cropping, especially if SRC is grown in Nitrate Vulnerable Zones. Nitrate leaching was measured using porous ceramic cups in each of the three phases in the lifespan of SRC, establishment, harvest and removal and was compared with conventional arable cropping. Nitrogen concentrations were increased in drainage water as soon as the crop cover was destroyed to plant the SRC (peak 70 mg L−1 nitrate‐N) and increased further (peak 134 mg L−1 nitrate‐N) on cultivation. Once the coppice crop was established, concentrations returned to a smaller level (average 18 mg L−1 nitrate‐N). Concentrations were not affected by the harvesting operation, and annual applications of nitrogen (40, 60 and 100 kg ha−1 N in the first, second and third years, respectively) had little effect. By contrast, concentrations in the arable rotation showed a regular pattern of increase in the autumn, and the average peak value over the 4 years was 54 mg L−1 nitrate‐N. When the SRC was ‘grubbed up’ and roots removed, the soil disturbance resulted in a flush of mineralization which, combined with a lack of crop cover, led to increased nitrate‐N in leachate (peak 67 mg L−1 nitrate‐N). In a normal life‐span of SRC (15–30 years), the relatively large nitrate losses on establishment and at final grubbing up would be offset by small losses during the productive harvest phase, especially when compared with results under the arable rotation.

Soil solution chemistry of a Brazilian Oxisol irrigated with treated sewage effluent

Irrigation is considered as a good alternative for sewage effluent use with the actual concerns for increasing use of water in agriculture, and the decreasing supply of good-quality waters, particularly in tropical countries. The irrigation management with sewage effluent must carefully be done, and impact of such practice on soil and environment-quality has to be well known. Short-term effects of effluent on soil are expected to be identified by soil solution chemistry changes. Therefore, the aim of the study was to evaluate the variation in soil solution chemistry during the irrigation of maize and sunflower crops with sewage effluent in a Brazilian Oxisol. For this, soil solution chemistry was monitored during 2 years by porous ceramic cups from the surface to 200 cm soil depth. The high content of bicarbonates and sodium in effluent induced soil solution sodification and alkalinization, with a total input of 2.44 tonnes of Na + and 4.40 tonnes of HCO 3 −. Partial leaching by dripping irrigation led to an increase in pH, sodium adsorption ratio (SAR) and electric conductivity (EC) within the upper soil meter. It was also identified a decrease in Na + along time that was attributed to both leaching and opening of soil exchange complex by Na +-induced tactoids expansion. The high Na + input had little influence on calcium concentration that remained constant but relatively low, as expected in tropical soil. Results about C and N chemistry showed mineralization of dissolved organic matter and rapid nitrification from ammoniac and organic nitrogen provided by effluent. The nitrate concentration decreased by plant uptake but also by leaching during the rainy season, pointing out a long-term risk of contamination of shallow groundwater environments.