Effluent Application Research Articles

Fish farming effluent application in the development and growth of maize and bean plants

The irrational use of water resources in Brazil has been causing concern to all sectors of society, including agri­culture, which demands large amounts of water for its development. Thus, reuse of fish farming effluent is a viable alternative since it can be beneficial to plants. Therefore, the objective of this work was to evaluate the effect of fish farming effluent on the growth and development of maize and bean plants. Two water types (reservoir water and fish farming effluent) were evaluated using a completely randomized design with ten replications. At 50 days after sowing, the following were evaluated: plant height, root length, plant collar diameter, fresh matter of shoots, and dry matter of shoots and roots of maize and bean plants. Fish farming effluent application significantly influ­enced the development and growth of maize plants. For bean plants, the fish farming effluent did not influence their development and growth.

Association of septic tank and sand filter for wastewater treatment: full-scale feasibility for decentralized sanitation

Abstract Worldwide, 70% of the individuals who do not have access to sanitation facilities live in rural areas. A solution for these areas is the use of decentralized systems for wastewater treatment. However, most of the studies about this topic are performed in a laboratory or in pilot scale. This work investigated a full-scale decentralized system. The association of septic tank and sand filter was installed in a rural area in Brazil. Its feasibility, maintenance, and operational conditions were appraised. The septic tank was built with precast concrete rings (inner diameter: 1.90 m; total depth: 2.34 m; useful volume: 4.30 m3). The sand filter was also constructed with precast concrete rings (internal diameter: 1.90 m; surface area: 2.84 m2) and effluent application was intermittent. The hydraulic loading rate of the sand filter was 253 Lm−2day−1. The quality of the effluent met the legal aspects and the system proved to be effective for decentralized sanitation. The final effluent may be reused in agricultural activities; however, the frequency of maintenance of this system should be taken into account.

The effect of anaerobic baffled reactor effluent on nitrogen and phosphorus leaching from four soils in a laboratory column experiment

Leaching of nitrogen and phosphorus from soil columns during application of anaerobic baffled reactor effluent was evaluated. The soils used were from Inanda (Ia), Cartref (Cf), and Sepane (Se) forms, and a silica sand (SS). Each was packed into duplicate columns (103 mm internal diameter; 200 mm length), four each for up-flow and down-flow leaching. Effluent was delivered continuously for 6, 8 and 35 days at high (32 mm·h-1), medium (16 mm·h-1), and low (2 mm·h-1) rates, respectively. At each flow rate, 9 pore volumes were collected. Leachates were analysed for pH, electrical conductivity (EC), nitrate and phosphate. Leachate pH from all soils was lower than the original effluent (6.4). Leachate EC varied between 0.5 and 0.9 dS·m-1 compared to the effluent EC of 0.84 dS· m-1. At high flow rate, the amount of nitrogen leached was similar from all soils. At low and medium rates, more nitrogen was leached from the coarser-textured SS and Cf than the finer-textured Ia and Se, at both flow directions. Flow direction had a greater effect on nitrogen leaching from finer- than coarser-textured soils. Phosphorus concentrations were higher than the original effluent at medium and high flow rates indicating that the soils were a source of phosphorus. At low flow rate, phosphorus concentrations were much lower than the original effluent, indicating soil retention. Phosphorus leaching was greater from coarser- than finer-textured soils in the up-flow columns, but the opposite occurred in the down-flow columns.

Decolorization of BF Cibacete Blue (CB) and Red Solophenyle 3BL (RS) Using Aluminum Sulfate and Ferric Chloride

Coagulation process is largely applied for dye removal from textile wastewater treatment. This research aims to focus on implied mechanisms through coagulation of such wastewater. In this work, jar tests are performed to assess the coagulation process as a technique to treat synthetic solutions containing two textile dyes: BF cibacete blue (CB) and red solophenyle 3BL (RS). The effects of operational parameters such as coagulant type (FeCl3 and Al2 (SO4)3. 18H2O (alum)) and dose, initial pH, and dye concentration are studied. For a fixed 15 mg/L concentration of the two dyes, the FeCl3 optimal doses are found to 80 and 20 mg/L for RS and CB with removal rates of 65 and 89%, respectively. Regarding alum, discoloration is achieved at 44 and 77% for CB and RS with optimal doses of 80 and 40 mg/L, respectively. Similar efficiency trends are also obtained for a 50 mg/L concentration of the two dyes. The involved coagulation mechanisms are: charge neutralization followed by precipitation of the insoluble dye-coagulant complexes, and their adsorption into the Al or Fe hydroxides. It would be interesting to follow a real effluent application on the textile industry possibly containing the two dyes tested in this work.

Oxidative stress defence responses of wheat (Triticum aestivum L.) and chilli (Capsicum annum L.) cultivars grown under textile effluent fertilization

Oxidative stress is complex physiological phenomenon that accompanies virtually in all stresses including either the deficiency or the surplus of micronutrients in the soil. In response to reactive oxygen species (ROS) generation, plants use a range of mechanisms to minimize the toxicity and protect cell membranes from damage. There are known reports indicating that effluents from the textile industry can serve as a micronutrient supplier under otherwise limited conditions. However, the addition of these effluents may cause toxicity to plants due to the presence of some non-essential heavy metals and persistent compounds if supplied in excess. A mesocosm study was conducted with wheat (Triticum aestivum L) and chilli (Capsicum annum L) cultivars grown under textile effluent fertilization to evaluate the accumulation of malondialdehyde (MDA) and H2O2, and the enzymatic and non-enzymatic antioxidative defences developed against this stress. Our findings indicated that the accumulation of MDA and H2O2 were mainly stimulated in control plants (0% textile effluent) followed by 60% concentration of textile effluent fertilization. Plants counteract oxidative stress by increasing both enzymatic (Superoxide dismutase, SOD; catalase, CAT; peroxidase, POX; ascorbate peroxidase, APX; glutathione reductase, GR) and non-enzymatic (phenolic compounds, flavonoids and ascorbic acid) antioxidants significantly. The activities of major antioxidants were promoted by higher concentrations of textile effluents. In addition, low antioxidative defences against damage caused by oxidative stress to the controls were evident by yield loss and deteriorated product quality. Compared to the chilli cultivars, MDA and H2O2 were higher in wheat cultivars; at the same time activities of antioxidants were also higher in wheat cultivars. The results of this study showed that the application of textile effluents supplied plant nutrients which improved antioxidative defences by regulating the enzymatic and non-enzymatic antioxidative mechanisms while the nutrient deprived condition prevailed.

Impact of Treated Industrial Effluent on Physical and Chemical Properties of Three Subtropical Soils and Millet Nutrition

ABSTRACTThe use of treated industrial effluents to irrigate plants is an alternative, because of nutrients that can increase yield of the agricultural crops. This study was conducted to determine irrigation with treated effluent and gypsum application, which changes the chemical and physical characteristics of soils and the growth and nutrition of millet (Pennisetum glaucum). Thus, an experiment was conducted on PVC columns with three soil classes, Typic Hapludox, Typic Hapludult, and Arenic Hapludult. Nutrient and Na+ concentrations in the millet biomass reflected concentrations of elements in the effluent and soil. In the control, low N levels were found in the biomass, while higher leaf N concentrations were observed, due to irrigation with treated effluent. In the short term, irrigation with treated industrial effluent by controlled application could be an alternative and a complementary source of nutrients for plants, reducing the volume of nutrients and organic materials discharged into water bodies.

THE PRELIMINARY STUDY ON THE SUITABILITY OF AFRICAN CATFISH EFFLUENT AS IRRIGATION WATER SOURCE IN SOUTH WEST NIGERIA

The reuse of catfish pond effluent by irrigation can make a significant contribution to the integrated management of our water resources. The study was done to evaluate African catfish (Clarias gariepinus) quality pond effluent quality and its suitability for irrigation. Forty (40) samples were collected from five ponds. Physical and chemical parameters of catfish effluent samples from selected earthen ponds were determined in accordance with the American Public Health Association standards. Data were analysed using descriptive statistics. The results showed that there were variations in the chemical constituents of the effluent measured in the selected ponds. The mean values of physical and chemical parameters ranged as pH (6.2 – 8.1), total dissolved solids (140 -307 mg/l); suspended solids (32 – 78 mg/l), electrical conductivity of water (0.21 – 0.48 mmhos/cm), alkalinity (45 – 138 mg/l), total nitrogen (4.5 – 6.9 mg/l), total phosphorus (0.11 – 0.35 mg/l), sodium (11 -31 mg/l), calcium (24.1 – 69.0 mg/l), potassium (0.16 – 0.41 mg/l), magnesium (8.2 -12.0 mg/l), carbonate (8 -40 mg/l), bicarbonate (20 – 95 mg/l), chloride (10.4 – 25.8 mg/l), boron (0.2 – 0.4 mg/l) and biochemical oxygen demand (4.4 – 8.2 mg/l). All were within acceptable limits. The African catfish effluents in the studied earthen ponds are classified as C1 – S1 water. Hence there are none degree of restriction in the application of catfish effluent for irrigation.

Hydrochemical characteristics and the impact of anthropogenic activity on groundwater quality in suburban area of Urmia city, Iran

The aim of this research was to determine the main hydrochemical processes, quality change and groundwater pollution resulted from various human activities in the suburban area of Urmia city, located in the northwest of Iran. For this purposes, 62 groundwater samples were collected from urban, suburban and rural areas in September 2015. Furthermore, for determining the effect of anthropogenic activities on urban and suburban groundwater quality, a comparison was made between rural, suburban and urban groundwater. The results indicate that the main type of groundwater is Ca–HCO3, and the important processes controlling groundwater chemistry are mineral weathering, ion exchange and anthropogenic activity. The effect of anthropogenic activity such as increase in urbanization and change in land use caused the increase in the concentration of Ca, HCO3, Cl, Na, Mg, NO3 and pollution of groundwater in the suburban area. In suburban zone and especially in areas with low-depth groundwater, runoff infiltration, domestic effluent sewages and application of fertilizers caused an increase in nitrate in groundwater. In urban areas with impermeable surfaces, due to less infiltration, the amount of nitrate in groundwater is low, and groundwater is not contaminated. The results obtained from groundwater sustainability indicators (index of damages, index of pollution and groundwater quality index) show that the suburban area has low-hazard pollutant problem. Also, quality of 41% groundwater samples in the suburban zone and 13% in the rural zone is poor. In this paper, to determine the water quality for irrigation uses, sodium percent (Na%), sodium absorption ratio, residual sodium carbonate and permeability index were all calculated. The calculation of the irrigation water quality indices indicated that the quality of water for irrigation purposes can be classified as excellent to permissible categories.

Greenhouse Gas Emissions following Conversion of a Reclaimed Minesoil to Bioenergy Crop Production

AbstractThis study provides a comparative assessment of greenhouse gas (GHG) emissions when converting a reclaimed minesoil that was previously under meadow to miscanthus (Miscanthus × giganteus) and maize (Zea mays L.) land uses in Ohio, USA. Additionally, effluent from an anaerobic digester at rates of 0, 75, 150, and 225 kg N ha−1 rates was also assessed for C and nutrient fertilization. Results from the study show that land use conversion to maize had the highest net release of GHG equivalent of 6·6 Mg CO2equ ha−1 y−1, on average, across effluent application rates. Under miscanthus land use with no and high effluent application rates, net GHG equivalent on average was 4·3 Mg CO2equ ha−1 y−1, which was larger when compared with that under the meadow land use (1·6 Mg CO2equ ha−1 y−1). Miscanthus land use under medium rates of effluent application had similar net GHG equivalent (7·1 Mg CO2equ ha−1 y−1) to the maize land use. The application of effluent did increase CO2–C and N2O–N emissions; but increases in above‐ground–below‐ground biomass production (1·6 Mg C ha−1) in the meadow land use and C input from effluent retained in the soil in the miscanthus and maize land uses offset most of the effluent‐induced GHG equivalent emissions. Contribution of cumulative N2O–N to GHG equivalent emissions in general was 11% when no effluent was applied and 22% when effluent was applied across land uses. Findings from this study show that land use changes from antecedent meadow to maize and miscanthus during the first year of establishment would result in net increase of GHG emissions. Published 2017. This article is a U.S. Government work and is in the public domain in the USA

Impact of electroplating effluent on growth of Triticum aestivum and Hordeum vulgare

Abstract The present study was planned to determine the effects of electroplating industry effluent on germination and various growth parameters (shoot length, root length, numbers of nodes and internodes) of Triticum aestivum and Hordeum vulgare. Biochemical characteristics i.e. estimation of proline, protein and sugar content were also studied. Heavy metals form a major category of contaminants reported to be present in large quantities in wastewaters and are matter of concern due to their toxicity and non-biodegradable nature. Heavy metals released into the environment shows regular increasing trends which is a significant threat to the environment and public health. Results revealed that the application of effluent on the studied plants Triticum aestivum and Hordeum vulgare directly affects the growth parameters and the biochemical characteristics.

Assessing the environmental implications of applying dairy cow effluent during winter using low rate and low depth application methods

ABSTRACTDairy cow effluent collected over winter from a loose-housed barn was applied to a series of large infield plots (400 m2) using low rate and low depth (LRLD) application methods. Applications were confined to the winter period, at a time when soil moisture content was often at or very near to field capacity and was applied over two seasons. Cows were confined to the housing facility during winter only, and outside of this period they remained on pasture. Losses of nitrogen (N), phosphorus (P) and the faecal indicator bacterium Escherichia coli (E. coli) in surface runoff and subsurface drainage from the LRLD treatment were compared with losses from effluent applications that occurred during spring to autumn, at an application depth not exceeding the soil water deficit, i.e. a standard practice treatment (SP, typically 10–15 mm per application). The annual quantities of nutrients applied by the treatments and the grazing managements imposed were similar. Although winter losses of N were significantly greater for the LRLD treatment (15 vs. 8 kg N ha−1 for the SP treatment), on an annual basis fluxes were similar between treatments (approximately 20 kg N ha−1 year−1). Effluent management had no significant effect on the annual fluxes of P and E. coli although the latter varied considerably. Average contaminant fluxes over a 2-year period indicated that the LRLD management system did not lead to a significantly greater risk to water quality compared with standard practices.

Estimation of health risks caused by exposure to enteroviruses from agricultural application of wastewater effluents

Agricultural reuse of wastewater is a common practice worldwide, especially in arid and semiarid area due to the freshwater scarcity. Wastewater irrigation in the Middle East, one of the most water-stressed regions in the world, could be a key factor for socio-economic development, but the microbial contamination of untreated or partially treated wastewater is a serious public health concern. Potential transmission of enteric viral infections through wastewater reuse in agricultural activities represents a true health risk for exposed individuals. Accordingly, it is important to assess the health risks associated with wastewater reuse. A quantitative microbial risk assessment (QMRA) with Monte-Carlo simulation was used to estimate the annual risk of enterovirus (EV) infection and disease burden for farmers and consumers of wastewater-irrigated lettuce in Iran, a semiarid country in the Middle East region. Risk analysis was performed based on the measured concentrations of EV in effluent of two activated sludge wastewater treatment plants (WWTP). Wastewater effluent sampling was carried out over a nine-month period, and the presence of total and fecal coliforms and EV was determined. Fecal coliform bacteria were found at a high level exceeded the guideline limit for wastewater reuse in agriculture. EVs were detected in 40% of samples with the highest frequency in summer with a mean of 12 and 16 pfu/ml for WWTP-A and B, respectively. Statistical analysis showed no correlation between the concentration of fecal coliforms and EV. The estimated infection risk for EVs was 8.8 × 10−1 and 8.2 × 10−1 per person per year (pppy) for farmers of WWTP-A and -B, respectively which was about 2 log higher than the tolerable infection risk of 2 × 10−3 pppy. The estimated risk for lettuce consumers exhibited a lower level of infection and disease burden but higher than the guideline limits. The median disease burden for consumption of lettuce irrigated with activated sludge effluents was about 10−3 Disability Adjusted Life Years (DALY) pppy which exceeded the WHO guideline threshold of 10−4 DALY pppy. The results of study indicated that the activated sludge effluents require an additional reduction of EVs to achieve the acceptable level of risk for agricultural reuse of wastewater.

Competitive algal biosorption of Al3+, Fe3+, and Zn2+ and treatment application of some industrial effluents from Borg El-Arab region, Egypt

Three marine algal biomasses, namely Gelidium latifolium (Grev.) Bornet et Thuret, Ulva lactuca Linnaeus and Colpomenia sinuosa (Mertens et Roth) Derbes et Solier, were used in their raw dried forms to biosorb Al3+, Fe3+, and Zn2+ from aqueous solutions. The optimum biosorption conditions were initial element concentration, 1000 mg L−1; temperature, 40 °C; contact time, 1 h; pH, 4, 3, and 6 for Al3+, Fe3+, and Zn2+, respectively. The highest biosorption efficiency reached 63.78, 65.95, and 111.57 mg g−1 for Al3+, Fe3+, and Zn2+, respectively, using the brown algal biomass C. sinuosa. Examination of algal biomass surface using SEM showed several morphological changes in the cell wall surface due to biosorption such as rupturing, wrinkling, some cavity appearance, protuberance, and roughness as well as each algal type had a unique surface structure in its raw form. FTIR was used to characterize algal biomasses, and the contributing groups were variable according to heave metals and algal type as well. The thermodynamic studies revealed that the biosorption was nonspontaneous, endothermic, and chemical in nature. Freundlich isotherm model fitted slightly better than the Langmuir model in case of Zn2+ biosorption; meanwhile, Langmuir model fitted better in case of trivalent Al3+ and Fe3+. The algal biomasses were efficiently regenerated and reused for four cycles via 0.01 M Na2EDTA. Algal biomasses were applied under the optimum concluded conditions to treat 21 actual polluted industrial effluents from Borg El-Arab region, Egypt. The removal efficiency reached 80.81, 38.25, 91.79, 59.96, 95.33, 98.54, 27.39, 88.42, 36.59, and 96.98% for Al, Co, Cr, Cu, Fe, Mn, Mo, Ni, V, and Zn, respectively.

Effect of Ions on Clogging and Biofilm Formation in Drip Emitters Applying Secondary Sewage Effluent

AbstractOn‐site drip irrigation experiments that were continued for 54 days with a daily operation of 12 h with sewage effluent and groundwater application were conducted to investigate the effect of two typical ions (Fe2+ and Ca2+) on emitter clogging. At the end of the experiment, several representative emitters were sampled to investigate the clogging mechanism through measuring the dry weight of biofilm substances (DW) and analysing the mineral constituents of clogging solids and the extracellular polymeric substance (EPS) of attached biofilm. The plain emitters demonstrated significantly better anti‐clogging performance than the labyrinth emitters. For sewage application, the ions added increased the EPS and DW compared with sewage without ions added. Moreover, clogging in the labyrinth emitters increased with an increasing ion complex and concentration. Different irrigation water qualities produced similar mineral constituents of clogging solids: quartz, Ca + Mg carbonate, silicate, and iron oxide. However, the clogging risk and inducing mechanism varied with the types of ion added. Fe2+ promoted production of microorganisms and precipitation of solid particles, increasing the risk of biochemical clogging, while Ca2+ mainly caused chemical precipitation. A complex of Fe2+ and Ca2+ increased the risk of biochemical clogging under sewage application, while it caused chemical clogging for groundwater application. Therefore, the strategies for protecting emitter clogging should be developed through comprehensively considering water quality and emitter type used. Copyright © 2017 John Wiley & Sons, Ltd.

Changes in soil nutrients after 10 years of cattle manure and swine effluent application

Application of cattle manure and swine effluent to cropland builds nutrient pools, affects soil quality, and increases crop productivity. The objective of the present study was to evaluate the rate of change in soil nutrient concentration and soil chemical properties due to cattle manure and swine effluent application. The study was conducted from 1999 to 2008 near Tribune, KS, with 10 treatments (three levels each of cattle manure and swine effluent [P, N, and 2N], three levels of N fertilizer, and a control). Soil NO3-N, P, K, micronutrients, pH, and EC were measured annually. Swine P treatment resulted in significantly greater NO3-N concentration in most years compared with all other treatments, followed by the Cattle 2N and Swine 2N treatments. The cattle treatments, in the order Cattle 2N>Cattle N>Cattle P, built the total N, soil P, and total C level significantly over the years compared with all other treatments. Soil pH did not change over time for most treatments except for the Swine P and Swine 2N treatments. Soil K, Cl, Fe, Zn, and Cu concentration increased significantly in cattle and swine treatments in 2008 compared with their initial level in 1999, and compared with check and inorganic fertilizer treatments. A significant build up in soil nutrients due to cattle and swine nutrient application suggests that they are good sources of many essential nutrients, in places where nutrients are limiting, but can cause excessive accumulation and increased environmental risk. A quick build up from Cattle 2N and Swine P applications calls for lower rates and periodic soil tests to determine need for further applications.

Effect of application of dairy manure, effluent and inorganic fertilizer on nitrogen leaching in clayey fluvo-aquic soil: A lysimeter study

Dairy farm manure and effluent are applied to cropland in China to provide a source of plant nutrients, but there are concerns over its effect on nitrogen (N) leaching loss and groundwater quality. To investigate the effects of land application of dairy manure and effluent on potential N leaching loss, two lysimeter trials were set up in clayey fluvo-aquic soil in a winter wheat-summer maize rotation cropping system on the North China Plain. The solid dairy manure trial included control without N fertilization (CK), inorganic N fertilizer (SNPK), and fresh (RAW) and composted (COM) dairy manure. The liquid dairy effluent trial consisted of control without N fertilization (CF), inorganic N fertilizer (ENPK), and fresh (FDE) and stored (SDE) dairy effluent. The N application rate was 225kgNha−1 for inorganic N fertilizer, dairy manure, and effluent treatments in both seasons. Annual N leaching loss (ANLL) was highest in SNPK (53.02 and 16.21kgNha−1 in 2013/2014 and 2014/2015, respectively), which were 1.65- and 2.04-fold that of COM, and 1.59- and 1.26-fold that of RAW. In the effluent trial (2014/2015), ANLL for ENPK and SDE (16.22 and 16.86kgNha−1, respectively) were significantly higher than CF and FDE (6.3 and 13.21kgNha−1, respectively). NO3− contributed the most (34–92%) to total N leaching loss among all treatments, followed by dissolved organic N (14–57%). COM showed the lowest N leaching loss due to a reduction in NO3− loss. Yield-scaled N leaching in COM (0.35kgNMg−1 silage) was significantly (P<0.05) lower than that in the other fertilization treatments. Therefore, the use of composted dairy manure should be increased and that of inorganic fertilizer decreased to reduce N leaching loss while ensuring high crop yield in the North China Plain.

Optimizing Utilization of Palm Oil Mill Effluent and its Influences on Nutrient Availability and Soil Organic Matter on Ultisols

Optimizing the utilization of agroindustrial organic waste such as palm oil mill effluent (POME) can prevent environment pollution and soil nutrient cycling can be a valuable alternative to improve soil quality. The objective of this study was to evaluate the changes of soil organic fractions and nutrients after application of treated palm oil mill effluent. The treatments consisted of control and effluent application at rates of 5, 10, 15 and 20 ton ha -1 . The treatments were arranged in a completely randomized design with three replications. Application of effluent significantly increased total organic C, labile organic C, humic acid C, pH, total N, available P, and exchangeable K. A significant reduction of exchangeable Al also occurred with effluent application. The increases of total organic C and labile organic were found with the application of 20 t ha -1 of effluent, but the increase was not significant compared to the effluent application at rates of 10 and 15 t ha -1 . Sensitivity indexes of total organic C, labile organic C and humic acid C following effluent application were 24-66%, 103-197% and 95-114% respectively in which labile organic C showed the highest sensitivity index. Total organic C, labile organic C and humic acid were positively correlated with increasing rates of effluent application. Labile organic C revealed the strongest relationship (R 2 =0.91) with effluent application compared to total organic C (R 2 =0.88) and humic acid (R 2 =0.67). A significant increase of total N was only found by the effluent application at rate of 20 t ha -1 . Significant increases in available P and exchangeable K occurred at rate of 10, 15 and 20 t ha -1 . It can be concluded that the increase in soil organic carbon levels was related to the amount of organic (effluent) input added to the soil. In addition, the application of treated effluent can improve soil pH and nutrient availability.

Tetracycline resistance in semi-arid agricultural soils under long-term swine effluent application

ABSTRACTAnnually, millions pounds of antibiotics are released unmetabolized into environment along with animal wastes. Accumulation of antibiotics in soils could potentially induce the persistence of antibiotic resistant bacteria. Antibiotics such as tetracyclines and tetracycline-resistant bacteria have been previously detected in fields fertilized with animal manure. However, little is known about the accumulation of tetracyclines and the development of tetracycline resistance in semi-arid soils. Here we demonstrate that continuous land application with swine effluent, containing trace amounts of chlortetracycline, does not necessarily induce tetracycline resistance in soil bacteria. Based on the testing of more than 3,000 bacteria isolated from the amended soils, we found no significant increase in the occurrence and level of chlortetracycline resistant bacteria in soils after 15 years of continuous swine effluent fertilization. To account for a possible transfer of tetracycline-resistant bacteria originated from the swine effluent to soils, we analyzed two commonly found tetracycline resistant genes, tet(O) and tet(M), in the swine effluent and fertilized soils. Both genes were present in the swine effluent, however, they were not detectable in soils applied with swine effluent. Our data demonstrate that agronomic application of manure from antibiotic treated swine effluent does not necessarily result in the development of antibiotic bacterial resistance in soils. Apparently, concentrations of chlortetracycline present in manure are not significant enough to induce the development of antibiotic bacterial resistance.

Nitrogen source and application method impact on corn yield and nutrient uptake

ABSTRACTFarmers are looking for better management practices to utilize animal manure as an alternative to chemical fertilizers. A 2-year field experiment was conducted to study the effects of nitrogen (N) fertilizer source and application methods to Nicholson silt loam soil in central Kentucky, USA for no-till corn (Zea mays) production. The region has a temperate climate with a mean temperature of 14.5°C and rainfall of 1300 mm year−1. Treatments included a control, 179 kg N ha−1 urea ammonium nitrate (UAN) applied as preplant and sidedress, and swine effluent that was applied by three methods: broadcast, injection, and Aerway. Injection method produced the greatest corn grain yield (11.88 Mg ha−1) and biomass yield (18.9 Mg ha−1) in 2007. Results demonstrated that the effluent application methods and the timing of UAN application may not be agronomically important for corn production in this region. Hence, more studies are needed on different soils in this region.

Soil Quality after Six Years of Paper Mill Industrial Wastewater Application

The application of wastewater to irrigate soils may be an attractive option for paper mills, especially when the effluents can also provide nutrients to plants. Since there could be negative environmental effects, such activity must be preceded by a thorough evaluation of the consequences. The changes in soil quality of a Neossolo Fluvico Distrofico (Typic Udifluvent) were evaluated over a period of six years of irrigation with treated effluent from a wood pulp company. Although effluent application for six years did not affect soil resistance to penetration and soil hydraulic conductivity, it promoted a decrease in the mean size of aggregates and an increase in clay dispersion. Effluent application increased soil pH but did not change exchangeable Ca and Mg contents and organic carbon. After a full rotation of eucalyptus cultivation common in Brazil (six years), no negative effects in tree growth were found due to effluent irrigation. However, effluent addition caused higher values of Na adsorption ratio and intermediate electrical conductivity in the soil, which indicates a possible negative effect on soil quality if the application continues over a longer period. Therefore, a monitoring program should be carried out during subsequent crop rotations, and alternatives must be studied to obtain better effluent quality, such as adding Ca and Mg to the wastewater and using gypsum in the soil.