Phosphorous Losses Research Articles

Integrating ACPF and SWAT to Assess Potential Phosphorus Loading Reductions to Lake Erie: A Case Study.

Lake Erie is threatened by eutrophication and harmful algal blooms due to excess nutrient loading from agricultural sources. To reduce nutrient loading to Lake Erie, widespread adoption of agricultural conservation practices (ACPs) has been proposed. However, identifying appropriate and effective locations for ACP placement has been challenging. Another challenge is understanding how effective the ACPs are in reducing nutrient loading and achieving water quality goals. Therefore, identifying the most effective ACPs, as well as spatially optimal placement of ACPs to achieve the maximum environmental benefit, is of paramount importance. The main objective of this study was to integrate the Agricultural Conservation Planning Framework (ACPF) with the Soil and Water Assessment Tool (SWAT) to assess the potential effectiveness of ACPs developed by ACPF in reducing phosphorous losses from an agriculturally dominated small watershed within the Western Lake Erie Basin. ACPF was used to develop a series of ACP opportunity plans, which were then integrated into a calibrated SWAT model. SWAT simulation of ACPF developed ACP opportunity plans for grassed waterways (GWs), contour buffer strips (CBSs), water and sediment control basins (WASCOBs), nutrient removal wetlands (NRWs), and farm ponds (FPs) revealed various reductions in sediment, soluble reactive phosphorus (SRP), and total phosphorus (TP) at the watershed-scale. The simulation of individual ACP opportunity plans revealed that GW resulted in the greatest annual average SRP and TP reductions (19% and 30%, respectively), followed by CBS (16% and 22%), and WASCOB (13% and 16%); NRWs were the most effective at reducing sediment (56%) but increased SRP (27%). Combined GW, CBS, and WASCOB opportunity plans resulted in the greatest reduction of SRP (34%), while the combination of all ACP opportunity plans resulted in the greatest reduction of TP (49%) and sediment (78%).

Effects of climate change, crop planting structure, and agricultural management on runoff, sediment, nitrogen and phosphorus losses in the Hai-River Basin since the 1980s

Investigating the spatiotemporal changes in the eco-hydrological processes and environment, as well as their drivers, is essential to manage the trade-offs among water supply, agricultural production, and environment at a basin scale. In this study, we developed a framework based on the Soil and Water Assessment Tool (SWAT), together with the historical data, to evaluate the effects of changes in climate, crop planting structure, and agricultural managements on the eco-hydrological processes and environment in the Hai-River basin during 1985–2015. The results showed that an increase in temperature not only reduced runoff and sediment but also increased nitrogen and phosphorous losses in the river basin. By contrast, an increase in precipitation increased runoff directly and increased sediment and nitrogen and phosphorous losses indirectly. Runoff caused directly the difference between sediment and losses of nitrogen and phosphorous. Changes in crop planting area and fertilizer application rate affected positively the losses of nitrogen and phosphorous. Changes in irrigation area affected negatively runoff. Different crop species had different impacts on runoff and sediment. Increase in crop planting areas of maize and vegetable generally reduced runoff and sediment, while increase in crop planting areas of wheat and beans generally increased both runoff and sediment. The findings gain insights into the impacts and driving mechanisms of the changes in climate, land use, crop planting structure and agricultural management on runoff, sediment, and losses of nitrogen and phosphorus in the Hai-River basin. • Impact of crop planting structure and managements on runoff, sediment, N and P loss were assessed. • Long-term hydrological observation data, statistics data and SWAT model were used. • Increase in crop planting area could increase N and P loss. • Different increases in crop planting area have different effects on runoff and sediment. • Temperature increase reduced runoff and sediment, but increased N and P loss.

Effects of rainfall intensity and slope on sediment, nitrogen and phosphorous losses in soils with different use and soil hydrological properties

The aim of this research was to analyse the effect of rainfall intensity and slope on soil and nutrient losses by hydric erosion in soils with different hydrological characteristics. This research was carried out on soils collected from slopes with different land uses/covers (LU/LC) -forest, scrub, agricultural, afforested and barren land-, from a mountain area (Sierra de Santo Domingo in the South Pyrenean region), where intensive farming and land use changes including land abandonment and changes in soil cover have occurred.Soils were placed on erosion boxes (30 cm × 20 cm) and compacted to a bulk density similar to that measured in the field (slope values ranged between 10 and 20%). Soil properties such as organic matter content, soil texture and N and P contents were analysed (values used as concentration in the original soil). Soils were subjected to simulated rainfall with intensity values usually recorded in the area during storms. Runoff volumes were collected at 10 min intervals from the time that runoff was generated. The steady infiltration rate as well as the average runoff rates and soil losses were evaluated for each land use. In the runoff samples, sediment concentration and nutrients (N and P) were analysed using different aliquots. The comparative analysis of the results obtained under simulated rainfall in plots with soils from different land uses allowed determining the differences in contribution of each land use to soil and nutrient losses when they are subjected to similar rainfall intensities. The results showed that the maximum runoff rates were reached in agricultural soil and barren land after 40 min at low intensity and after about 20 min at high intensity. However, in soils under forest, scrub and afforestation, runoff rates were much lower for the same rainfall intensity and duration period. Soil sealing was the main factor reducing infiltration in the agricultural and in barren LU/LC soils, while in the other cases runoff was mainly produced after saturation. Soil losses were more than 10xtimes higher in barren land and in agricultural soils than in the other land uses. Nitrogen losses in agricultural soils were about 3 times higher than in forest, and scrub or in afforested LU/LC. Under high intensity rainfall, there was an enrichment ratio (ER) of nitrogen in the sediment in relation to the original soil, which was higher in scrub and agricultural lands (up to 1.33 and 1.32, respectively) than in the rest of land uses (1.1 on average). Phosphorous losses were mainly associated with soil particles and the land uses that gave rise to higher P losses was agricultural under any intensity, while P losses increased significantly in forest and afforested LU/LC at high intensity. The enrichment ratio (ER) was higher in agricultural soils (up to 1.82, increasing with intensity), forest and afforested LU/LC (1.33 and 1.16, respectively under high intensity) than in scrub (1.22) and barren lands (near 1). Information gained in this research can be of interest to manage mountain agroecosystems to limit N and P supply from headwaters to hydrological systems.

Sustainable Conservation Tillage Improves Soil Nutrients and Reduces Nitrogen and Phosphorous Losses in Maize Farmland in Southern China

Monitoring nitrogen (N) and phosphorous (P) losses on farmland is essential for the prevention of agricultural non-point source pollution (NPS). This study was conducted on typical dry farmland in southern China to determine the effect of conservation tillage and conventional tillage (CT) on soil physical and chemical properties, nutrient movement, as well as on N and P losses. Four conservation tillage techniques (i.e., no-tillage direct seeding (NTDS), no-tillage transplanting (NTTS), minimum tillage direct seeding (MTDS), and minimum tillage transplanting (MTTS)), as well as one CT technique, were carried out in a randomized complete block design with three replicates each. The results suggest that MTDS and NTDS improved soil physical and chemical properties by ensuring adequate retention of these properties at the 0–20 cm soil depth. Low levels of N and P losses in runoff and drainage water were recorded under NTTS and NTDS compared to CT. Our results, therefore, suggest that conservation tillage approaches, such as MTDS and NTDS, are the most suitable tillage techniques for improving soil nutrients and reducing agricultural N and P losses while providing an eco-friendly and sustainable agricultural practice.

Phosphate Removal from Nursery Runoff Water Using an Iron-Based Remediation System

Phosphorous (P) losses from containerized plant production nurseries can be significant due to the low nutrient retention capacities of the media components. As environmental regulators establish, refine, and enforce nutrient criteria, effective methods are needed to reduce amounts of P in runoff and drainage water. This study investigated the use of a small scale flow-through ferrous iron (Fe(II))-based remediation system for chemically precipitating P. This system consisted of four inter-connected tanks, with the first two maintained under anaerobic conditions and the last two maintained under aerobic conditions. FeSO4 was introduced into the first of the aerobic tanks at different rates to achieve Fe:P ratios of 0, 9.0, 16.3, and 21.2. Water samples were collected from the systems, and P removal was monitored by ion chromatography. Phosphorus removal efficiencies of 78, 95, and 99% were observed for each respective treatment, indicating great potential for this conceptual system at Fe:P dosing ratios ≥16.3 and phosphorus concentrations between 3 and 5 mg/L. This type of system may especially be useful for nurseries with space limitations.

Managing controlled drainage in irrigated farmers’ fields: A case study in the Moghan plain, Iran

Conventional free subsurface drainage practices in the Moghan Plan, in northwest Iran, result in low irrigation efficiency and excessive volumes of drainage water causing extensive environmental problems. Controlled drainage (CD) is promoted to boost crop yields and reduce subsurface drainage flows and leaching of nutrients. This study was conducted to test management options for CD in irrigated farmers’ fields in the Moghan plain. Three options were tested: subsurface drains at 2 m with free outflow (FD), controlled drainage at 70 cm below soil surface (CD70) and controlled drainage with a varying depth depending on the crop stage (CDch). Irrigation gifts were based on the daily measured soil water content and thus varied per drainage treatment. In winter, wheat and barley were grown followed by maize in summer. For each crop and treatment, three replicates were made. The highest crop yields (for all crops) were found with CDch, followed by CD70. For wheat, the yields were respectively 27% and 41% higher in the CD70 and CDch compared to FD. For barley these increase was respectively 23% (CD70) and 34% (CDch) and for maize (forage yields) 19% (CD70) and 25% (CDch). The same trends were observed in water use efficiencies (WUE): compared to FD, the WUE was 26% in CD70 and 40% higher in CDch; for barley these increases were respectively 19% (CD70) and 32% (CDch), and for maize (forage yields) 30% (CD70) and 44% (CDch). Controlled drainage not only reduced subsurface drainage rates, but also nitrate and phosphorous losses. The average drain discharges with CDch were respectively 33%, 45% and 44% lower than FD for wheat, barley and maize. Flow-weighted NO3 concentration in drainage discharge of CD70 and CDch were, respectively, 15% and 9% for wheat, 9% and 13% for barley, and 8% and 7% for maize lower than in FD. Soil salinity decreased in FD, but slightly increased in the CD treatments. Thus, although controlled drainage clearly has advantages above free drainage practices, to optimize CD management options, more research is needed on the long-term effects of controlled drainage on soil salinity.

Endogenous phosphorus losses in growing-finishing pigs and gestating sows1

An experiment was conducted to determine the effects of diet composition, feeding level (FL), and BW on endogenous phosphorous losses (EPL) using growing-finishing (GF) pigs and sows. After an adaptation period, 48 GF pigs (initial BW 90.5 kg) and 48 just-weaned sows (initial BW 195 kg), both individually housed, were allotted to 12 dietary treatments in a 2 × 3 × 2 factorial arrangement. Treatments were animal type (GF pigs or sows), diet composition (a semipurified starch (STA), inulin (INU), or lignocellulose (CEL) based low-P diet), and FL (2.0 or 3.0 kg/d). Digestibility of DM, OM, CP, crude fat, and carbohydrates (COH), and fecal P excretion (in g/d, mg/kg DMI, and g/(kg BW·d)) were determined using TiO as indigestible marker. Digestibility of OM and COH differed among diets ( < 0.001) and was greatest in both types of pigs fed the STA diet and lowest in those fed the CEL diet. While digestibility of OM and COH was similar in sows and GF pigs that were fed the STA diet and the CEL diet, on the INU diet, sows had, compared with GF pigs, a greater digestibility of OM (92.2 vs. 87.2%) and COH (92.5 vs. 88.4%), respectively. Both BW and FL increased fecal P excretion (g/d). When expressed in mg/kg DMI, P excretion was higher in sows than in GF pigs on the STA diet (498 versus 236 mg/kg DMI), the INU diet (526 vs. 316 mg/kg DMI), and the CEL diet (928 vs. 342 mg/kg DMI). When expressed in mg/(kg BW·d), however, P excretion was similar in GF pigs and sows that were fed the STA diet and in those that were fed the INU diet, whereas it was greater in sows than in GF pigs that were fed the CEL diet (11.6 vs. 7.3 mg/(kg BW·d)). The results of this study indicate that EPL (mg/kg DMI) in pigs substantially increase with increasing BW. Application of EPL (mg/kg DMI) determined in GF pigs may underestimate EPL and therefore P requirements in gestating sows. Moreover, EPL is diet dependent and increases with an increasing content of dietary nonstarch polysaccharides (NSP). The degree of this increase may differ between sows and GF pigs and seems to depend on properties of dietary fiber.

Basal endogenous phosphorus losses in pigs are affected by both body weight and feeding level1

Two similar experiments were conducted to determine the separate effects of feeding level (FL) and BW on basal endogenous phospho-rous losses (EPL) from the digestive tract and minimal urinary P content in growing-finishing (GF) pigs and sows. After an adaptation period, 16 GF pigs (initial BW 85 kg) and 16 gestating sows (initial BW 201 kg), both individually housed and divided in 2 groups of 8, received the same semipurified low-P diet at a feeding level (FL) of 2 or 3 kg/d during a 22-d period. Grab samples of feces and spot samples of urine were collected 2 times per day on d 6-8, 13-15, and 20-22 of feeding the low-P diet in GF pigs and on d 20-22 in sows. Phosphorus content was determined and excretion in the feces (in g/d, g/kg DMI, and g/(kg BW·d)) was calculated using titanium dioxide as indigestible marker. In GF pigs, the fecal P excretion (g/d) decreased over time from the first to the third collection period (P

A regional assessment of the cost and effectiveness of mitigation measures for reducing nutrient losses to water and greenhouse gas emissions to air from pastoral farms

Using a novel approach that links geospatial land resource information with individual farm-scale simulation, we conducted a regional assessment of nitrogen (N) and phosphorous (P) losses to water and greenhouse gas (GHG) emissions to air from the predominant mix of pastoral industries in Southland, New Zealand. An evaluation of the cost-effectiveness of several nutrient loss mitigation strategies applied at the farm-scale, set primarily for reducing N and P losses and grouped by capital cost and potential ease of adoption, followed an initial baseline assessment. Grouped nutrient loss mitigation strategies were applied on an additive basis on the assumption of full adoption, and were broadly identified as ‘improved nutrient management’ (M1), ‘improved animal productivity’ (M2), and ‘restricted grazing’ (M3). Estimated annual nitrate–N leaching losses occurring under representative baseline sheep and beef (cattle) farms, and representative baseline dairy farms for the region were 10 ± 2 and 32 ± 6 kg N/ha (mean ± standard deviation), respectively. Both sheep and beef and dairy farms were responsive to N leaching loss mitigation strategies in M1, at a low cost per kg N-loss mitigated. Only dairy farms were responsive to N leaching loss abatement from adopting M2, at no additional cost per kg N-loss mitigated. Dairy farms were also responsive to N leaching loss abatement from adopting M3, but this reduction came at a greater cost per kg N-loss mitigated. Only dairy farms were responsive to P-loss mitigation strategies, in particular by adopting M1. Only dairy farms were responsive to GHG abatement; greater abatement was achieved by the most intensified dairy farm system simulated. Overall, M1 provided for high levels of regional scale N- and P-loss abatement at a low cost per farm without affecting overall farm production, M2 provided additional N-loss abatement but only marginal P-loss abatement, whereas M3 provided the greatest N-loss abatement, but delivered no additional P abatement, and came at a large financial cost to farmers, sheep and beef farmers in particular. The modelling approach provides a farm-scale framework that can be extended to other regions to accommodate different farm production systems and performances, capturing the interactions between farm types, land use capabilities and production levels, as these influence nutrient losses and GHG emissions, and the effectiveness of mitigation strategies.

A BATCH STUDY OF PHOSPHATE ADSORPTION CHARACTERISTICS ON CLAY SOIL

The research has been carried out on Phosphate (p-Adsorption) on clay soil through batch adsorption techniques. Main objectives of this study are to study the physical properties of clay soils, detection of Phosphate removal by adsor bent as a function of contact time, adsorbent dosage and p H , to study sorption kinetics. The results of this study shows the optimum contact time, dosage and p for adsorption of Phosphate on clay soil reaching the equilibrium condition after 60 minutes with remov al efficiency of 86% and 1400 mg as optimum dosage. Higher adsorption of Phosphat e was observed at p H 9.0. The rate of adsorption of Phosphate obeys fir st order rate equation. The obtained results of the batch ex periments are best fit to Langmuir and Freundlich a dsorption isotherms. From the experimental analysis it is concluded that clay soi l shows good removal efficiency and can be used as good adsorbents. st century are waste disposal from various industries, municipal dumping in the urban areas and increased use of chemical fertilize rs, pesticides and irrigation water. The residues of fe rtilizers, pesticides and irrigation water created adverse imp act on soil and water bodies. The pollutants such as sewage and fertilizers contain nutrients as phosphates and nitrates. If th e nutrients are in excess level they over stimulate the growth of aquatic plants and algae. These excessive growths of algae and aquatic plants clogs the water ways, use up dissolved oxyge n as they decompose and block light to deeper water affecting the respiration ability of fish and other invertebrates that reside inside the water. Lakes, rivers and other water bod ies undergo Eutrophication an aging process in natural conditio n that slowly fills in the water body with sediment and or ganic matter. These sediments when enter water bodies fis h respiration becomes impaired, plant productivity an d water depth becomes reduced and aquatic organisms and their environment becomes suffocated. When the levels of oxygen drops below two-five parts per million many types o f fish and bottom dwelling animals cannot survive. When this occurs it leads to the disruptions in the food chain by killi ng aquatic organisms in large numbers. Oxygen demanding materials such as nitrogen and phosphorous are high in animal wastes and they often harbor pathogenic organisms. Hence s ome special attention must be given for budgeting of fe rtilizers; Phosphorous in high doses may be susceptible to dra in freely in the soil immediately followed by heavy rainfall causes some phosphorous losses through volatilization and leaching process. Thus once the ecosystem are contaminated by these elements they become a potential threat for many ye ars. Therefore it is of crucial importance to study the mutual influence of the different minerals in soil retenti on process whose migration ability of particular component in ground water is explained by the retardation factor(R).Far mers extensively follow the irrigation process due to av ailability of water from various sources, where phosphate polluti on is caused by the use of fertilizers and pesticides. Th us the main objective of this work is to study the leaching and retention of phosphate in the clay soil available in the area us ed for agricultural process, determining the maximum amount of phosphate adsorbed and to evaluate the potentials o f phosphate migrating through the soil during ground water percolation by using a set of batch experiments who se results are fitted to the equations given by Langmuir and F reundlich isotherms.

Catchment Phosphorous Losses: An Export Coefficient Modelling Approach with Scenario Analysis for Water Management

This paper presents the development of an export coefficient model to characterise the rates and sources of P export from land to water in four reservoir systems located in a semi-arid rural region in southern of Portugal. The model was developed to enable effective management of these important water resource systems under the EU Water Framework Directive. This is the first time such an approach has been fully adapted for the semi-arid systems typical of Mediterranean Europe. The sources of P loading delivered to each reservoir from its catchment were determined and scenario analysis was undertaken to predict the likely impact of catchment management strategies on the scale of rate of P loading delivered to each water body from its catchment. The results indicate the importance of farming and sewage treatment works/collective septic tanks discharges as the main contributors to the total diffuse and point source P loading delivered to the reservoirs, respectively. A reduction in the total P loading for all study areas would require control of farming practices and more efficient removal of P from human wastes prior to discharge to surface waters. The scenario analysis indicates a strategy based solely on reducing the agricultural P surplus may result in only a slow improvement in water quality, which would be unlikely to support the generation of good ecological status in reservoirs. The model application indicates that a reduction of P-inputs to the reservoirs should first focus on reducing P loading from sewage effluent discharges through the introduction of tertiary treatment (P-stripping) in all major residential areas. The fully calibrated export coefficient modelling approach transferred well to semi-arid regions, with the only significant limitation being the availability of suitable input data to drive the model. Further studies using this approach in semi-arid catchments are now needed to increase the knowledge of nutrient export behaviours in semi-arid regions.

Characteristics of soil erosion, nitrogen and phosphorous losses under three grassland use patterns in Hulun Lake watershed

Characteristics of soil erosion, nitrogen and phosphorous losses under three grassland use patterns in Hulun Lake watershed

An experimental study on using rare earth elements to trace phosphorous losses from nonpoint sources

Controlling phosphorous (P) inputs through management of its sources and transport is critical for limiting freshwater eutrophication. In this study, characteristics of exogenous rare earth elements (REEs) and P and their losses with surface runoff (both in the water and sediments) during simulated rainfall experiments (83 mm h −1) were investigated. The results revealed that on average most REEs (La, 94%; Nd, 93%; Sm, 96%) and P (96%) transported with sediments in the runoff. The total amounts of losses of REEs and P in the runoff were significantly correlated, suggesting the possibility of using REEs to trace the fate of agricultural nonpoint P losses.

Environmental and economic impacts of reducing total phosphorous runoff in an agricultural watershed

The economy of northwest Arkansas relies greatly upon livestock and poultry production. The supply of production by-products is increasingly coming under scrutiny as an important source of water pollution in the region. This study uses stochastic dominance techniques to evaluate, environmentally and economically, a range of ten best management practice scenarios to lessen water pollution in the Lincoln Lake watershed. The goal is to generate rankings that could be useful for supporting producers’ and watershed managers’ selection of management practices to reduce total phosphorous losses in runoff. Specifically, this study compares scenarios in terms of net return risk reduction for bermudagrass hay producers. The results showed that environmental and economic rankings differ from each other. Although all scenarios analyzed were effective in reducing total phosphorous losses when compared to a baseline, six of them also decreased net returns. This suggests that including some best management practices may lead to increased net return risk. However, some scenarios were identified that may increase net returns, reduce total phosphorous losses and do not differ considerably from producers’ current management practices. The previous results suggested that the joint environmental-economic impact was important when considering scenarios and that producers’ risk attitudes and best management practices’ economic impacts should be accounted for when selecting scenarios. Producers and watershed managers can weigh trade-offs between total phosphorous losses reduction and net returns variability when making water conservation decisions.

Field experiments on greenhouse gas emissions and nitrogen and phosphorus losses from rice paddy with efficient irrigation and drainage management

Greenhouse gas emissions, nitrogen and phosphorous losses through ammonia volatilization, leaching and surface drainage from rice paddy under efficient irrigation and drainage were analyzed based on field experimental data in order to reveal the eco-environmental impacts of efficient irrigation and drainage on rice paddy. The results showed that total methane emission from rice paddy under the controlled irrigation was reduced by more than 80% and total nitrous oxide emission increased by 15.9% compared with flooding irrigation. Seasonal comprehensive global warming potentials (GWP) of methane and nitrous oxide were 62.23 gCO2 m−2 for rice paddy under the controlled irrigation, reduced by 68.0% compared with flooding irrigation. Due to large reduction in seepage and surface drainages, nitrogen and phosphorous losses through leaching were reduced by 40.1% and 54.8%, nitrogen and phosphorous losses through surface drainage were reduced by 53.9% and 51.6% from rice paddy under efficient irrigation and drainage compared with traditional irrigation and drainage. Nitrogen loss through ammonia volatilization was reduced by 14.0%. Efficient irrigation and drainage management is helpful to mitigate greenhouse gases emission, nitrogen and phosphorus losses and their pollution on groundwater and surface water.

Dentine caries inhibition through CO2 laser (10.6 μm) irradiation and fluoride application, in vitro

ObjectiveThe purpose of the study was to investigate whether dentine irradiation with a pulsed CO2 laser (10.6μm) emitting pulses of 10ms is capable of reducing dentine calcium and phosphorus losses in an artificial caries model. DesignThe 90 dentine slabs obtained from bovine teeth were randomly divided into six groups (n=15): negative control group (GC); positive control group, treated with fluoride 1.23% (GF); and laser groups irradiated with 8J/cm2 (L8); irradiated as in L8+fluoride 1.23% (L8F); irradiated with 11J/cm2 (L11); irradiated as in L11+fluoride 1.23% (L11F). After laser irradiation the samples were submitted to a pH-cycling model for 9 days. The calcium and phosphorous contents in the de- and remineralization solutions were measured by means of inductively coupled plasma optical emission spectrometer – ICP-OES. Additionally intrapulpal temperature measurements were performed. The obtained data were analysed by means of ANOVA and Tukey's test (α=0.05). ResultsIn the demineralization solutions the groups L11F and GF presented significantly lower means of calcium and phosphorous losses than the control group; and in L11F means were significantly lower than in the fluoride group. Both irradiation parameters tested caused intrapulpal temperature increase below 2°C. ConclusionIt can be concluded that under the conditions of this study, CO2 laser irradiation (10.6μm) with 11J/cm2 (540mJ and 10Hz) of fluoride treated dentine surfaces decreases the loss of calcium and phosphorous in the demineralization process and does not cause excessive temperature increase inside the pulp chamber.

Effect of Bioengineering Measures on Runoff, Soil and Nutrient Losses under Cashew Plantations in Western Ghat Region

A field experiment was conducted on lateritic soil of Western Ghat region in Goa State to study the effect of bioengineering measures viz. Half Moon Terraces + Vetiveria zizanioides + Stylosanthes scabra, continuous contour trench + Vetiveria zizanioides + Stylosanthes scabra, graded trench + Vetiveria zizanioides + Stylosanthes scabra, staggered contour trench + Vetiveria zizanioides + Stylosanthes scabra and semi elliptical trench + Vetiveria zizanioides + Stylosanthes scabra on runoff, soil and nutrient loss and growth of cashew. The study revealed that the bioengineering measures influenced the runoff, soil and nutrient losses and growth parameters of cashew. The reduction of runoff varied from 3.2 to 7.6% of the annual rainfall under different conservation treatments. Minimum runoff(3.5%) and soil loss (3.7 t/ha/year) were recorded under the treatment viz. continuous contour trench + Vetiveria zizanioides + Stylosanthes scabra. Minimum Nitrogen (13.95 kg/ha) and phosphorous (16.53 kg/ha) losses were recorded ill the treatment of continuous contour trenches with Stylosanthes scabra and Vetiveria zizanioides. Growth performance ofcashew was better under the combination of vegetative barriers with continuous contour trenches, graded trenches and staggered contour trenches. Overall, continuous contour trenches with Stylosanthes scabra and Vetiveria zizanioides was found to be the best soil and water conservation treatment among all other bioengineering measures for cashew plantations in Western Ghat region.

Subsurface Drainage and Water Quality: The Illinois Experience

Drainage of excess water from agricultural lands is essential for crop growth. In the Midwestern U.S., Illinois, Indiana, Iowa, Ohio, Minnesota, Michigan, Missouri, and Wisconsin are some of the states that are highly drained with intensive subsurface drainage systems. Illinois alone has a total drained area of approximately 4 million ha. Many watersheds in east-central Illinois have less than 1% surface gradient and poorly drained soils, yet subsurface drains have made these lands some of the most productive farmlands in the world. Subsurface drainage enhances productivity and reduces sediment transport and phosphorous losses from fields; however, it increases NO3-N delivery to the receiving water bodies. Nitrate-N is mobile and can be lost from the soil profile by leaching and through subsurface drains (tile drains). Nitrate-N concentrations in drinking water reservoirs in many Midwestern states frequently exceed the EPA's maximum contaminant level (MCL) of 10 mg L-1. Several studies show NO3-N concentration data of more than 10 mg L-1 in discharges from subsurface drains. This article presents a history of subsurface drainage in Illinois, summarizes the results of decade-long field and watershed-scale research on subsurface drainage, and provides information on some innovative practices that are currently being evaluated to meet water quality challenges. It has been observed that infiltration is the predominant hydrologic process, and surface runoff rarely occurs from these watersheds. It has also been observed that base flow contributes significantly higher nutrient loadings into the streams than the subsurface drains from these watersheds.

Controlled drainage — effects on drain outflow and water quality

A field experimental project was set up in southern Sweden to assess the effects of controlled drainage on hydrology and environment. Controlled drainage makes it possible to vary the drainage intensity with the variation in drainage requirement during season by controlling the height of a riser in the drain outlet and thus to a certain degree control the amount of outflow of solutes via the drainage system. During periods with low drainage demand, the riser in the drain outlet can be raised and the groundwater level in field will rise up to the level of the riser before the discharge takes place. Three plots, each with an area of 0.2 ha (40 m×50 m) were installed on a loamy sand. One plot was drained by conventional subsurface drainage (CD) and two plots were drained by controlled drainage (CWT). The plots contained four lateral drain tubes, at 10 m spacing and placed at 1 m depth. Each plot was isolated by a double layer of plastic sheeting placed in the back-filled trenches to a depth of 1.6 m to prevent lateral leakage and subsurface interactions. Measurements of precipitation, drain outflow and soil and air temperatures were carried out hourly. Groundwater levels were measured and samples of drain outflow were collected twice a month for nitrogen and phosphorous analyses. Mineral nitrogen contents in soil were measured three times a year. Controlled drainage had a significant hydrological and environmental effect during the 2 years of measurement (1996–1998). Compared with CD, the total drain outflow from CWT was 79% less in Year 1 and 94% in Year 2. The total reduction in nitrate losses with CWT corresponded to the reduced outflow rates. Compared with CD, the total amounts of nitrate in drain outflow were 78% less in Year 1 and 94% in Year 2. The highest concentrations of nitrate were measured at the time of the largest outflow rates. The phosphorous losses were 58% less for CWT as compared to the CD values in Year 1 and 85% less in Year 2. The reduction in nitrogen content in the soil profile during the winter season was 60–70% less in CWT than in CD.

The Interaction Between Dietary Fructose and Magnesium Adversely Affects Macromineral Homeostasis in Men

Objective: Studies with rats have found that an interaction between fructose and magnesium affects macromineral metabolism; high dietary fructose significantly increased kidney calcification in both male and female rats, particularly when dietary magnesium was low. This study tests the hypothesis that an interaction between dietary fructose and magnesium adversely affects macromineral homeostasis in men.Methods: Eleven men aged 22 to 40 years were fed a mixed, Western diet for four 42-day dietary periods in which dietary magnesium was either approximately 170 or 370 mg/day and dietary fructose was either 4% or 20% of energy. A decaffeinated beverage containing high fructose corn syrup replaced cornstarch, bread and rice in the low fructose diet to give the high fructose diet.Results: High dietary fructose significantly (p<0.01) increased magnesium balance during both low and high dietary magnesium intakes. Ultrafilterable and ionized serum magnesium also apparently were related to magnesium and fructose intakes; they were higher when fructose was fed and when Mg intakes were high. High fructose depressed calcium balance: the effect tended to be more marked when dietary Mg was low. High dietary fructose also significantly (p<0.005) decreased phosphorous balance. Urinary phosphorous losses were significantly (p<0.001) higher when high dietary fructose was fed. High dietary fructose also increased the concentration of serum alkaline phosphatase (p<0.005).Conclusion: These findings indicate that dietary fructose adversely affects macromineral homeostasis in humans and suggest further studies to see if a high fructose diet coupled with low dietary magnesium and marginal calcium leads to bone loss.