Cm Of Soil Column Research Articles

CALICUM, Mg AND Na RELEASE KINETICS FROM SALINE- SODIC SOIL MIXED WITH SOME AMENDMENTS

This study was aimed to investigate the effect of phosphogypsum and humic acids on the leaching and releasing of salts from saline- sodic soil. A laboratory experiment was conducted in polyethylene columns (60.0 cm and 7.1 cm). The columns were filled with 30 cm soil (EC=73.78 dSm-1). The experiment included two factors, phosphogypsum added at levels 0, 5, 10 and 15 mtons ha-1 with symbols PG0,PG1, PG2 and PG3 respectively, and humic acids were added at levels 0, 50, 100 and 150 kg ha-1 with symbols HA0, HA1, HA2 and HA3, mixing them with the top 5 cm of soil column. The electrical conductivity and the concentrations of water soluble cations (Ca, Mg, and Na) in leachate were determined and sodium adsorption ratio (SAR) was calculated. Results showed that accumulative salts (TDS), sodium released from soil columns increased with increasing the level of addition, whether of phosphogypsum or humic acids. The highest value of salts and sodium released was 682.63 g L-1 and 7086.12 mmol L-1 respectively in the treatment PG3HA3, while the lowest value was 455.94 g L-1 and 3899.40 mmol L-1 respectively in the treatment PG0HA0. Calcium (mmol L-1) increased by increasing the level of phosphogypsum, decreased by increasing the level of humic acids, the highest value of accumulated calcium was 1599.0 mmol L-1 in PG3HA0 while the lowest value was 820.53 mmol L-1 in PG0HA3. The results showed that the best equation for describing release kinetics of sodium adsorption ratio in soil is the diffusion equation. Increasing level of phosphogypsum and humic acids increased the release constant velocity (K) of sodium adsorption ratio.

Sorption, persistence, and leaching of the allelochemical umbelliferone in soils treated with nanoengineered sorbents

Coumarins represent an important family of allelochemicals with fungicidal, bactericidal, insecticidal, nematicidal, and herbicidal properties. Like for other allelochemicals, the short persistence of coumarins in soils can reduce their biological activity and hamper their application as environmentally friendly agrochemicals. We evaluated the sorption of the coumarin umbelliferone by eight soils and six sorbent materials, and then selected two nanoengineered sorbents, hexadecyltrimethylammonium-modified Arizona montmorillonite (SA-HDTMA) and olive-mill waste biochar (BC), to assess the effect of their addition to two distinct soils on umbelliferone sorption, persistence, and leaching. Umbelliferone was sorbed to a greater extent by the acid soils (A1-A2, Kd > 4.0 L kg−1) than by the alkaline soils (B1-B6, Kd < 0.5 L kg−1). The addition of BC and SA-HDTMA at a rate of 4% to alkaline soil (B2) increased the umbelliferone sorption Kd value from 0.3 to 1.6–2.0 L kg−1, whereas their addition to acid soil (A1) increased the Kd value from 4.6 to 12.2–19.0 L kg−1. Incubation experiments showed that BC had more impact than SA-HDTMA on the persistence of umbelliferone in the soils, increasing its half-life from 0.3-2.5 to 1.2–14.4 days, depending on the soil. Furthermore, the addition of BC to the top 0–5 cm of soil columns reduced leaching of umbelliferone and led to accumulation of umbelliferone residues in the top 0–5 cm soil layer. The addition of nanoengineered materials, such as organoclays and biochars, could thus be a suitable strategy to increase the persistence and reduce the mobility of coumarins in the rhizosphere with the aim of prolonging their biological activity.

Study of Zeolite and Vermiculite to Reduce Lead and Cadmium in Wastewater of Alcohol Factory

Background: The wastewater of alcohol plants is called Vinasse. After conversion of molasses to alcohol and other derivatives, this compound must be removed as waste from the factory. If released without careful planning and proper management and supervision, this wastewater can cause serious and several social, economic, and environmental consequences. Therefore, it is very important to eliminate heavy elements before the waste goes deep into the soil or to underground water reservoirs. Objectives: The aim of this study is to use 2 natural absorbents zeolite and vermiculite to low-off or lower the movement of heavy metals lead and cadmium in the soil. Methods: To evaluate the potential of Vermiculite and Zeolites in refinement of metal pollutants cadmium and lead, 2 irrigation periods by Vinasse and 3 treatments were conducted. First, the soil of the region was irrigated by Vinasse up to the saturation level. Second, the soil of the region with 2 layers of Zeolites in the depths of 25 cm and 50 cm was irrigated by Vinasse up to the saturation level. Third, the soil of the region with 2 layers of Vermiculites (same depths as treatment two) was irrigated by Vinasse up to the saturation level. The experiment was performed within columns with diagonal of 90 mm and height of 1000 mm. Surface irrigation (flooding) with the volume of 2.3 l was conducted every 5 days. Sampling in the depths of 15 - 25 cm and 40 - 50 cm of soil columns and drained water from the bottom of the soil columns were collected 24 hours after each irrigation and samples were taken to a laboratory to perform chemical analysis. Results: The results showed that before the experiment, the amounts of lead and cadmium in soil were 2.6 mg/kg and 42.0 mg/kg, respectively. As for Vinasse, the amounts were 46.2 and 7.11 mg/kg, respectively. After irrigation by Vinasse in the depth of 15-25 in treatments 1, 2, and 3, the increases in the level of cadmium were 0.034, 0.042, and 0.04 mg/kg, respectively. In addition, the increases in the level of lead in the depth of 30-50 in treatments 1, 2, and 3 were 0.28, 0.036, and 0.034 mg/kg, respectively. Conclusions: The concentration of lead in drainage water in all three treatments decreased. Vermiculite was not effective in adsorbing lead compared to the treatment in which no adsorbent was used.

Fate of anilide and aniline herbicides in plant-materials-amended soils

The fate of herbicides trifluralin, pendimethalin, alachlor and metolachlor in paddy field soils amended with plant materials was investigated. The plant materials were purple sesbania, vegetable soybean and rice straw. The investigation was performed at two temperatures (25 and 40°C) and two soil water moistures (60 and 90% water-holding capacity). The results showed linear and Freudlich equations described the adsorption of amide compound to soil. Adsorption coefficient (K d ) fit to linear equation were in general greater in plant material-amended soils than in non-amended soil, especially in soil amending with rice straw. Increasing temperature and soil water moisture content shortened the half-lives of compounds in various treated soils. The movement of compounds in the soil columns showed the maximum distribution of aniline type compound, trifluralin and pendimethalin, appeared at the upper top of 0 to 5 and 0 to 10 cm of soil column, respectively, and of anilide type, alachlor and metolachlor, were distributed at 0 to 25 cm of the soil column. The mobility of chemicals in the different treated soils was simulated by the behavior assessment model (BAM). There was no significant difference among different plant material incubated soils on dissipation and mobility of compounds in soils.

The Fate of Cryptosporidium Parvum Oocysts in Reclaimed Water Irrigation-history and Non-history Soils Irrigated with Various Effluent Qualities

The present study aimed to look at the fate of protozoan parasite Cryptosporidium parvum oocysts applied through surface drip irrigation on reclaimed water irrigation-history and non-history sandy-loam (Hamra) soil columns. A new and simple isolation method for recovery of oocysts from soil samples was developed and used along this study. The new soil isolation method of oocysts is based on the "two phase separation method" formerly used to recover Clostridium perfringens spores from sedi- ments and soil samples with minor modifications. The range recovery achieved by this method was 64-95% (mean 61.2±17.4). The objectives of the second part of this study were to investigate several physical and chemical factors governing transport and survival of C. parvum oocysts in sandy-loam soil columns by breakthrough curves. Comparison of fresh water and reclaimed water irrigation revealed that reclaimed water irrigated-history soil was more hydrophobic allowingwater flowthrough channelswith poor oocysts retention and fast flow. Examination of the organic matter effect (originating from reclaimed water irriga- tion) on oocysts breakthrough revealed that their soil infiltration increased. Calculations of oocysts concen- tration at different columns depths showed that most of the oocysts were retained in the first 5 cm of soil column. In the present study, comparing the two soil types (history and non-history of effluents irrigation) beside the surface electrostatic charge, one of the main elements found to affect oocysts infiltration and transport in soil columns was soil hydrophobicity caused by soluble organic matter originating from reclaimed water irrigation. Therefore, prior to applica- tion in soil irrigation, reclaimed water should be treated to high quality (i.e. membrane technology as the best option) to prevent enhanced transport of various pathogens through those irrigated soils.

Leaching of oryzalin and diuron through undisturbed vineyard soil columns under outdoor conditions

Field studies monitoring herbicide pollution in the vineyards of Burgundy (France) have revealed that drinking water reservoirs are contaminated with several pre-emergence herbicides. An assessment of the leaching of two such herbicides, diuron and oryzalin, was therefore performed using lysimeters, under outdoor conditions, from May 2001 to May 2002. Four vineyard soils from Vosne-Romanée (Burgundy) were chosen along a topolithosequence: a rendosol and three calcosols. After 673 mm of rainfall, greater amounts of diuron than oryzalin were measured in percolates: respectively 0.10–0.84% and 0.02–0.43% of applied herbicide, depending on soils. Measurements for diuron metabolites detected greater amounts of DCPMU than DCPU in the percolates: respectively 0.05–0.13% and 0–0.04% of the applied diuron. At the end of the monitoring period, more residues of diuron than oryzalin were recovered in the soil profiles: respectively 4.6–9% and 1.4–4.4%. The oryzalin residues were found mainly in the upper 10 cm of soil columns, whereas diuron residues were present in the whole core. The mobility of both oryzalin and diuron seems fairly well-related to soil organic carbon content; the mobility of diuron is also related to soil texture (sand and coarse material contents). Under such experimental conditions, this study confirms that diuron leaching, and therefore potential groundwater contamination, is greater than that of oryzalin.

Carbon monoxide fluxes of different soil layers in upland Canadian boreal forests

Dark or low-light carbon monoxide fluxes at upland Canadian boreal forest sites were measured on-site with static chambers and with a laboratory incubation technique using cores from different depths at the same sites. Three different upland black spruce sites, burned in 1987, 1992 and 1995 and a control site, were chosen to determine the effects of fire, temperature, soil structure and soil covers on CO fluxes. Three different surfaces were observed at the sites — bare mineral soil with little living moss cover; burned feather mosses 5–30 cm deep; and unburned, living, green feather mosses. The static chamber measurements indicated similar deposition velocities for the burned and unburned feather moss sites [(1.54 ± 0.64) 10-2 cm s-1 ; (1.83 ± 0.63).10-2 cm s-1 ], but significantly lower rates for sites that had burned down to the mineral soil [(1.08 ± 0.53).10-2 cm s-1, excluding data with net CO emission]. This finding was confirmed by results from the incubation measurements and shows that fire intensities determine the long-term, post-fire effect on soil-atmosphere fluxes of CO. Temperature studies with the cores showed that CO consumption rates increased from (2 ± 1)% at – 15 °C to — 13 °C to (43 ± 20)% at 0 °C to 1.5 °C and (68 ± 15)% at 4 °C to 5 °C of the deposition velocity values obtained at 20 °C. This temperature dependence was consistent with results obtained from the static chamber measurements. The temperature range studied and the dark or low-light conditions were representative for the night-time of nearly the whole six snow-free months in the boreal ecosystem. In nearly all cases, deposition velocities determined for cores from the top 5 cm with the incubation technique were the same, within experimental errors, as those determined with the static chambers. Soil CO concentration profiles taken in situ, moreover, did not show any clear trend below 5 cm. Thus we conclude that the top 5 cm of soils are determining the dark soil-atmosphere CO fluxes at these sites. The top 5 cm of soil columns are most exposed to temperature (and probably moisture) variations and are most affected by fires as well.

Ecological pre-release risk assessment of two genetically engineered, bioluminescent Rhizobium meliloti strains in soil column model systems

In order to identify potential ecological risks associated with the environmental release of two Rhizobium meliloti strains, genetically engineered with the firefly-derived luciferase gene (luc), a pre-release greenhouse investigation was conducted. The upper 4 cm of soil columns (30 cm diameter; 65 cm depth), which were filled according to the horizons of an agricultural field (loamy sand), were inoculated with seeds of Medicago sativa (alfalfa) and R. meliloti cells at approximately 5×106 cells·g–1 soil. Four treatments were tested: inoculation with a non-engineered wild type strain (2011), strain L33 (luc +), strain L1(luc +, recA–) and non-inoculated controls. The fate of the engineered strains was followed by two methods: (1) selective cultivation and subsequent detection of bioluminescent colonies and (2) PCR detection of the luc gene in DNA, directly extracted from soil. Strain R. meliloti L33 declined to 9.0×104 cfu·g–1 soil within 24 weeks and to 2.8×103 cfu·g–1 soil within 85 weeks in the upper 25 cm of the soil columns. Decline rates for R. meliloti L1 were not significantly different. Vertical distribution analysis of the recombinant cells after 37 weeks revealed that in three of four columns tested, the majority of cells (>98%) remained above 10 cm soil depth and no recombinant cells occurred below 20 cm depth. However, in one column all horizons below 20 cm were colonized with 2.2×104 to 6.8×104 cfu g–1 soil. Ecological monitoring parameters included organic substance, total nitrogen, ammonium and nitrate, microbial biomass, culturable bacteria on four different growth media and the immediate utilization of 95 carbon sources (BiologGN) by soil-extracted microbial consortia. None of the parameters was specifically affected by the genetically engineered cells.

Intermittent evaporation from calcareous sandy soils as affected by sewage sludge

Saudi Arabia produces large quantities of aerobically digested sewage sludge, most of which is being dumped into landfills. Since most agricultural soils in Saudi Arabia are mainly calcareous sandy soils, and low in organic matter, the application of sewage sludge to these soils may be used as a source of organic matter for the improvement of some physical properties of these soils. In a laboratory study, the effect of added sewage sludge in upper depth 10 cm of soil columns at concentrations of 0, 50, 75, and 100 Mg ha‐1 on cumulative evaporation, percentage of water conserved, and soil moisture profile of slightly and moderately calcareous sandy soils (Typic Torripsamments) was investigated. Thirty‐four mm of irrigation water (tap water) was applied every 7 days. Soil columns were placed in a walk‐in controlled growth chamber with a constant temperature of 32°C. By the end of the third cycle at the 21st day, sewage sludge concentrations were significantly effective in reducing the cumulative evaporation, with the same trend as in the first and second cycles. Furthermore, evaporation was greater for high concentration (100 Mg ha‐1) of sewage sludge application than for the low concentration and control. The percentages of water conserved at 25, 50, 75, and 100 Mg ha‐1 were about 1.34, 1.53, 1.71, and 1.84 times those of the control for slightly calcareous sandy soil and were 1.24, 1.48, 1.63, and 1.81 times the control for moderately calcareous sandy soil. For both soils, results indicated that evaporation constants for different sewage sludge concentrations follow the same pattern. The results also showed that the high sewage sludge concentrations gave higher moisture content in soil columns. The results indicated that sewage sludge may be utilized in calcareous sandy soils as an organic amendment to reduce evaporation and increase percentage of water conserved.

Use of Undisturbed Soil Columns under Controlled Conditions To Study the Fate of [14C]Deethylatrazine

The fate of [14C]deethylatrazine [2-chloro-4-amino-6-(isopropylamino)-s-triazine] was studied under controlled conditions by using undisturbed soil columns in the laboratory. In a 13-week leaching study, the percentage of [14C]deethylatrazine recovered was greatest in the first leaching event (1.3% of the applied 14C), suggesting that preferential flow occurred. The total concentration of deethylatrazine leached from soil columns over the 13-week period was 4.9 μg/L (3.6% of the applied 14C). Unidentified polar degradates made up 3.8% of the applied radioactivity recovered in the leachate, and didealkylatrazine [2-chloro-4,6-(diamino)-s-triazine] and deethylhydroxyatrazine [2-hydroxy-4-amino-6-(isopropylamino)-s-triazine] occurred in trace quantities. Sixty-seven percent of the applied 14C remained in the top 10 cm of soil columns, with 48% as bound residues, 12% as unidentified polar degradates, 5.5% as deethylatrazine, 0.2% as didealkylatrazine, and less than 0.1% as deethylhydroxyatrazine. Keywords: Atrazine; deethylatrazine; didealkylatrazine; deethylhydroxyatrazine; mobility; leaching

Leachability and Efficacy of Starch-Encapsulated Atrazine

Controlled-release formulations have the potential to reduce atrazine leaching but may reduce herbicide bioavailability and weed control. This research was conducted to determine if starch-encapsulated atrazine produced by the extrusion process could be modified to provide an optimum rate of herbicide release for adequate weed control and reduced leaching potential in sandy soils. The dry flowable (DF) and six starch-encapsulated atrazine formulations of various mesh size (14 to 20 and 20 to 40), clay content (0 and 5%), and extruder processing speed (200 and 400 rpm) were evaluated. All starch encapsulations reduced the amount of atrazine leaching from the surface 5 cm of soil columns by an average of 68% compared with the dry flowable formulation. Compared with the larger starch granules (14 to 20 mesh) 8% more atrazine in the smaller granules leached from the surface 5 cm. Atrazine efficacy was measured using an oat bioassay conducted in the greenhouse. Smaller granules (20 to 40 mesh) provided equivalent efficacy to DF while large granules (14 to 20 mesh) did not. Extruder speed and clay content did not affect efficacy or leaching potential. This study indicates that finer starch granules should result in faster atrazine release and improved weed control while still reducing the leaching potential of atrazine.

Mobilization and fractionation of137Cs in calcareous soils

Mobility of137Cs was investigated in columns of calcareous loam and clay soils leached under river water, NH4OAc, KCl, CaCl2, and EDTA. Fractionation of Cs into ten sequential fractions was accomplished in the leached soils as well as in soil samples received carrier-free137Cs and incubated for 60 d. At the end of 90 d of leaching with river water and CaCl2, the bulk of Cs applied (>97%) was found to remain in the upper 1 cm of soil columns. On the other hand, the reduction in Cs concentration was approximately 30% with NH4OAc, 18% with KCl, and 10 to 25% with EDTA. The major soil constituents appeared to be responsible for retaining Cs were clay, silt, and Fe oxides. The leaching consistently increased the magnitude of fractions bound to clay minerals and in most cases decreased the fractions of water soluble, exchangeable, carbonate, and organic matter.

Nodulation Response of Soybeans (Glycine max L. Merr.) to Application Rate and Placement of Combined Nitrogen1

Uniform incorporation of ammonium nitrate (dispersed throughout a 30.5 cm soil column) impaired nodular development of soybeans (Glycine max L. Merr.) more than deep application (lower 10 cm of soil column) when ammonium nitrate was applied at a rate of 150 ppm N in growth chamber studies. Nodule fresh weight and haemoglobin content were decreased by nitrogen application, while nodule number was not as markedly affected, indicating an effect on nodule development rather than on root infection or nodule initiation. Greater nitrate content of roots and tops under dispersed nitrogen application, compared with deep application at the same rate, suggested that internal nitrate may be influencing nodulation. However, deep placement of 150 ppm combined nitrogen allowed greater root nitrate uptake than uniform incorporation of 50 ppm N, without concomitant inhibitory effects on nodulation. Nodulation response was not, therefore, strictly dependent upon internal nitrate content of the roots, indicating that application site may provide a means of partially alleviating the detrimental effect of combined nitrogen on nodulation.