Groundwater Nitrate Pollution Research Articles

Groundwater nitrate pollution in an alluvium aquifer, Eskişehir urban area and its vicinity, Turkey

A large amount of the water requirement (municipal, industrial, etc.) of Eskisehir city, Turkey, is supplied from groundwater via wells in the urban area. The groundwater in the Eskisehir Plain alluvium has been polluted by municipal and industrial wastewater, and agricultural activities. The nitrate concentrations at nine sampling points on Porsuk River, the main water course in the plain, ranged from 1.5 to 63.3 mg/l during the period from July 1986 to August 1988. In the same period, the nitrate concentrations measured in water from 51 wells ranged between 2.2–257.0 mg/l. The nitrate content of the groundwater samples was 34.2% above 45 mg/l, the upper limit for nitrate in drinking water standards. High nitrate levels were observed in water from wells in the central and eastern parts of the urban area. The nitrate content of the well water is subject to seasonal fluctuation. In general, low nitrate concentrations were observed in wet seasons, and high ones in dry seasons.

Nitrate pollution of groundwater in northern China

Since the 1980s, nitrogen fertiliser consumption in China has increased substantially. High nitrogen application rates may increase the potential groundwater N-pollution. These effects were investigated in 14 cities and counties in northern China. The Merckoquant-nitrate-test strip was used to measure the nitrate concentration in water. Information on well depth, groundwater level, crop rotation, yield and fertiliser application was obtained. The results demonstrated that nitrate pollution of ground and drinking water has become a serious problem. At over half of the 69 locations investigated, which were distributed over an area of about 140 000 km 2, nitrate content in ground and drinking water exceeds 50 mg l −1, the allowable limit for drinking water. Critical situations were found in vegetable-producing areas, drinking water in the centres of small cities and towns and in farmers' yards, where nitrate contents in ground and drinking water were measured at 300 mg NO 3 l −1. In all locations with high nitrate content in the water, N-fertiliser was applied in large quantities, ranging from 500 to 1900 kg N ha −1 and the percentage of applied N taken up by crops was below 40%. An increase in the food requirements of an increasing population and the decrease in land resources in China will cause agriculture to intensify in the future. Fertiliser applications are expected to double or even triple within the next 30 years, making the problem of nitrogen fertiliser related pollution even more serious. Based on investigations and analysis, some suggestions for solving the problem, such as best management practices for nitrogen fertiliser and improving environmental awareness, are discussed.

Alternative Practices for Almond

Improving almond orchard management by integrating cultural practices, pest and disease controls, and vegetation management has been a goal of Univ. of California research and extension efforts for more than 25 years. Alternative cultural practices related to orchard floor management, fertilizer applications, and pest and disease control are currently important components of the almond production system. Nontillage, with or without a seeded cover crop, has improved potassium uptake and reduced pest problems. In-season fertilizer applications reduced the potential for nitrate pollution of groundwater. Minimizing dust, early harvest, and destruction of overwintering refugia are all cultural practices that reduce crop damage caused by pests. New methods of pest and disease monitoring using pheromone traps, egg traps, or a better understanding of disease life cycles have reduced unnecessary chemical applications. Degree-day phenology models have improved the timing of needed sprays. Expanded use of selective spray materials, such as narrow-range oils and Bacillus thuringiensis, reduce impacts on non-target species while natural predators and parasites are encouraged. Augmentative releases of beneficial insects are currently being evaluated as an additional alternative to in-season spraying. Cultivar and rootstock choices for new plantings present alternatives that can help avoid pests or diseases. Planting pattern affects productivity and is another factor to consider when evaluating alternative production practices for almond as new orchards are established.

Incorporation of spatial variability in modeling non-point source groundwater nitrate pollution

A methodology for incorporation of spatial variability in modeling non-point source groundwater nitrate contamination is presented. The methodology combines geostatistical simulation and unsaturated zone modeling for estimating the amount of nitrate loading to groundwater. Three dimensional soil nitrogen variability and 2-dimensional crop yield variability are used in quantifying potential benefits of spatially distributed nitrogen input. This technique, in combination with physical and chemical measurements, is utilized as a means of illustrating how the spatial statistical properties of nitrate leaching can be obtained for different scenarios of fixed and variable rate nitrogen applications.

Fertilizer-N use efficiency and nitrate pollution of groundwater in developing countries

Fertilizer-N use efficiency and nitrate pollution of groundwater in developing countries

Best Management Practices for Reducing Nitrate Contamination of the Groundwater on Dairy Farms

Groundwater studies conducted in north Florida indicate that improperly managed waste from dairy farms can create groundwater nitrate pollution. A study was conducted using suction lysimeters and the CREAMS computer model to evaluate recommended best management practices (BMPs) at several dairy farms in north Florida. The BMPs were determined from a nitrogen balance to reduce the amount of nitrate leaching from the dairies while maintaining economic vitality. A complete list of BMPs is given within the article.

Incorporation of spatial variability in modeling non-point source groundwater nitrate pollution

A methodology for incorporation of spatial variability in modeling non-point source groundwater nitrate contamination is presented. The methodology combines geostatistical simulation and unsaturated zone modeling for estimating the amount of nitrate loading to groundwater. Three dimensional soil nitrogen variability and 2-dimensional crop yield variability are used in quantifying potential benefits of spatially distributed nitrogen input. This technique, in combination with physical and chemical measurements, is utilized as a means of illustrating how the spatial statistical properties of nitrate leaching can be obtained for different scenarios of fixed and variable rate nitrogen applications.

Fertilizer-N use efficiency and nitrate pollution of groundwater in developing countries

Around 76% of the world's population lives in developing countries where more fertilizer-N is currently applied than in developed countries. Fertilizers are applied preferentially in regions where irrigation is available, and soil and climatic conditions are favorable for the growth of crop plants. Due to low N application rates during the last 3 or 4 decades, negative N balances in the soil are a characteristic feature of the crop production systems in developing countries. In the future, with increasing fertilizer-N application rates, the possibility of nitrate pollution of groundwater in developing countries will be strongly linked with fertilizer-N use efficiency. A limited number of investigations from developing countries suggest that, in irrigated soils of Asia or in humid tropics of Africa, the potential exists for nitrate pollution of groundwater, especially if fertilizer-N is inefficiently managed. In a large number of developing countries in West and Central Asia and North Africa, the small amount of fertilizer applied to soils (mostly Aridisols) that remain dry almost all the year, do not constitute a major threat for nitrate pollution of groundwater, except possibly when soils are irrigated. In Asia and the Pacific regions, where 70% of the fertilizers are used to grow wetland rice on soils with low percolation rates, leaching of nitrates is minimal. Climatic water balance and soil moisture conditions do not favor leaching of nitrates from the small amount of fertilizer-N applied to Oxisols and Ultisols in Latin America. In developing countries located in the humid tropics, attempts have not been made to correlate fertilizer-N use with nitrate level in groundwater; however, fertilizers are being increasingly used. Besides high rainfall, irrigation is becoming increasingly available to farmers in the humid tropics and substantial leaching of N may also increase.

An Economic Analysis of Groundwater Contamination from Agricultural Nitrate Emissions in Southern Ontario

This paper analyzes the costs and benefits of controlling groundwater pollution from agricultural use of nitrogen fertilizer in southwestern Ontario. The Village of Hensall, where nitrate concentrations have been observed above 10 mg/L in recent years, is selected as the study site.‘The CREAMS simulation model is used to estimate the effect of reducing nitrogen fertilizer on nitrate leaching and consequently on nitrate groundwater pollution. Estimates of the value of groundwater are obtained from the literature and are used to calculate the off‐farm cost of groundwater contamination. This procedure results in a wide range of values for the benefits of reducing nitrate pollution. Estimated annual benefits of improved ground‐water quality range from less than $1,000 to more than $30,000 for the village. The off‐farm benefits of nitrate groundwater pollution abatement outweigh the cost of using bottled water and also exceed the on‐farm cost of reducing nitrogen fertilizer application rates. Placing a tax on nitrogen fertilizer would reduce the level of nitrogen applications, but the farm cost of compliance to a nitrogen tax policy is substantially higher than the compliance cost under a regulatory policy that imposes a quantitative ceiling on nitrogen application rates over the part of the aquifer from which the village draws its water supply.

Nitrate pollution of ground waters from shallow basaltic aquifers, Deccan Trap Hydrologic Province, India

Analyses of groundwater samples collected from several locations in a small watershed of the Deccan Trap Hydrologic Province, indicated anomalously higher values of nitrate than the background. However, the NO3 concentrations in water from dug wells under pastureland where the subsurface material consisted of stony waste were minimum. The maximum values were reported for water from dug wells where the principal land use was agricultural. Lowering of NO3 values under shallow water-table conditions suggests denitrification. Higher concentrations of nitrate determined for samples collected from the wells with a deeper water-table indicate that denitrification process is inactive. The high values of nitrate coinciding with agricultural land use indicate fertilizers as the main source of nitrate pollution of ground-water. Decrease in Cl/NO3 ratio for agricultural land use confirms this inference.

Nitrate Pollution In Groundwater In Selected Districts Of Nepal

A survey was made of the nitrate concentrations in groundwater from one hundred wells in the Patan and Bhaktapur districts of the Bagmati zone and the Chitwan district of the Narayani zone, Nepal. The former districts are urban and the latter rural. Although the survey is small, it has demonstrated that there is a significant incidence of nitrate concentrations that exceed the World Health Organization's recommended limit for drinking water and that drinking-water supplies from many other wells are approaching this limit. A need exists for a larger study to determine how widespread the problem is. The primary cause is probably nitrification of nitrogen excreted by humans and to a lesser extent by animals inside settlements.

Potential nitrate pollution of groundwater in Germany: A supraregional differentiated model

Implemented on behalf of the Federal Ministry for Research and Technology (BMFT), a model is developed to trace the nutrient flow of nitrate in the soil and the groundwater on a supraregional scale. Research work is intended to indicate regionally differentiated hazardous potentials and thereby provide a basis for recommending comprehensive measures to protect groundwater in Germany. The adaption of the model to the hydrogeological and agricultural conditions of other states is possible in principle. This article focuses on the hydrogeological model parts. A high nitrate pollution of groundwater can be expected in all regions with intensive agricultural use of the topsoil. In particular, groundwater in solid rock areas is susceptible to nitrate pollution. There a rapid groundwater turnover and thus a short residence time for the groundwater in the aquifer is typical. Oxidizing aquifer conditions usually prevail in solid rock aquifers, preventing nitrate degradation. In many loose rock areas, in contrast, the groundwater has a low flow velocity and a long residence time in the aquifer. Because of a lack of free oxygen, a complete degradation of nitrate can occur, as long as iron sulfide compounds and/or organic carbon are available in the aquifer. A more detailed presentation of the whole research work is given in Wendland et al. (1993).

264 UPTAKE OF FOLIAR UREA BY PEACH LEAVES

Foliar urea sprays offer an alternative to soil applied fertilizers which could greatly reduce the potential for nitrate pollution of groundwater, The approach in the past has been to apply relatively small doses of urea in order to minimize leaf phytotoxicity. Our approach is to apply relatively large doses in the fall when leaf phytotoxicity is not a serious concern. Results on peach trees in the field indicated rapid uptake of foliar applied solutions of 4.3 to 8.8% urea (w/w) (2.0 to 4.0% N). About 80-90% of the urea was absorbed by the leaf within 24 hours. Leaf N levels suggest the majority of this urea was translocated from the leaf into the tree within 1 week despite damage to the leaf. There were no negative effects on flowering, fruit set and production in the following year as long as a very low biuret formulation of urea was used.

433 PB 180 ASSESSMENT OF NITROGEN DEMAND IN MATURE, ALTERNATE BEARING PISTACHIO TREES

Contributions of nitrogen (N) fertilizer applications to nitrate pollution of groundwater is an increasing public health concern. In an effort to improve N fertilizer efficiency, a study was initiated to determine periods of tree N demand in mature, alternate bearing pistachio trees. Seasonal patterns of nitrogen accumulation in the branches (i.e. fruit, current year wood, one year old wood, and leaves) and roots were monitored monthly. Branches from heavily fruiting trees contained almost six times more nitrogen than branches from light fruiting trees by September; a result of the large amount of N accumulated in the fruit. Nitrogen accumulated in the branches during the Spring growth flush and nut fill periods in both heavy and light fruiting trees. Root nitrate and total N concentrations, however, peaked during the Spring growth flush and subsequently decreased during nut fill. The relationship between tree N demand and the capacity for N uptake is discussed.

Minimizing nitrate leaching in agricultural production: How good can we get?

Abstract Numerous examples of high levels of nitrate pollution of groundwater are associated with agricultural practices. The problem tends to become especially severe as application rates of available N (either as manure or commercial fertilizer) exceed levels needed for economically optimum crop production. Over recommending and over applying N fertilizers is common, application rates more closely related to actual plant needs can greatly reduce nitrate pollution. Nitrate soil tests, including the older deep sampling in the drier regions and the new shallower Pre‐Sidedress Nitrate Soil Test in the humid region, offer the possibility of reducing the extent of over fertilizing with N. Tissue tests, including the end of season stalk nitrate test for com, also offer the promise of helping to increase the accuracy of N fertilizer recommendations. Other management tools available to reduce the extent of nitrate pollution include sidedress application for most N fertilizer (in the humid regions or under irriga...

Nitrate pollution of groundwater in the alsatian plain (France)—A multidisciplinary study of an agricultural area: The Central Ried of the ill river

The area studied is part of the “Ried Central” of the Ill river (Middle Alsatian plain in northeastern France). This area is located mainly in the present floodplain of the Ill. The closeness of the water table to the surface results in quasi general soil hydromorphism. The economic constraints of the last two decades led to deep changes in agricultural activities in the study area. These have essentially involved a marked extension of intensive cultivation of grain corn at the expense of grasslands. The study of the influence of this change on the parallel increase in the concentration of nitrate in groundwater is only feasible when a multidisciplinary approach is adopted. The analyses carried out in the field and in the laboratory show that nitrate reduction occurs in gleyed or peaty horizons of hydromorphic soils. The aptitude and efficiency of the permanent ambient vegetation (alluvial forests and grasslands) in retaining nitrate must be emphasized. The amount of nitrate eliminated from the aquifer by rivers fed by this aquifer is considerable. This evacuation of nitrate into the Ill is a fine example of waste and illustrates the absurdity of the economic situation responsible for excessive nitrogen fertilization of farmlands. In determining hazard zones, this study also proposes practical solutions to the problem of nitrate pollution: diminution of land area under cultivation, reintroduction of grasslands, and a more judicious use of nitrogen manure.

Opportunities and Challenges for the Inclusion of Soil-improving Crops in Vegetable Production Systems

The ability of certain crops to improve soil fertility or physical conditions has long been recognized. As early as the Chow dynasty (1134-247 B.C.) in China, there were reports of crops whose value for soil improvement was “greater than silkworm excrement” (Pieters, 1927). Romans around the time of Christ likewise waxed eloquently on the value of green manures, as in this line from Virgil: “Sow your wheat on land where grew the bean, the slender vetch or the fragile stalks of the bitter lupine.” The potential benefits of soil-improving crops (SIC-s) are many and varied. In addition to the continued use of legumes as a source of biologically fixed N, in more recent years, SICs have been commonly included in cropping systems to retard soil erosion and build up organic matter. In addition to these objectives, a 1988 survey of New England farmers using cover crops revealed that nearly half expected to derive some weed control from the SIC (Schonbeck, 1988). Fewer used SIC to conserve nutrients or make certain elements (such as P) more available, or to control insects and pests. Growers with soil compaction problems may grow a deeprooted SIC to break up dense soil layers (Foulds, 1989). No single SIC can impart all the above benefits to a particular cropping system. In addition, there are some potential negative effects of SICs, including: depletion of soil moisture, lowering of spring soil temperatures, disruption of field operations, allelopathy, and the creation of habitat for harmful organisms. Even nitrate pollution of groundwater is a potential problem with the improper management of legumes in cropping systems. The realized value of the SIC to a particular cropping system will, of course, depend on the selection of species, management of those species, and interaction with the rest of the cropping system, including crops, weather, weed

The On‐Farm Costs of Reducing Groundwater Pollution

AbstractAgricultural chemicals ate a source of groundwater pollution in some areas. Regulatory options to reduce such nonpoint pollution imply costs to producers. By integrating plant simulation, hydrologic, and economic models of farm‐level processes, this study evaluates on‐farna costs of strategies to reduce nitrate groundwater pollution. The empirical focus is on intensively managed, irrigated farms in the Columbia Basin of Oregon. Results suggest that changes in timing and application rates of nitrogen and water reduce nitrate pollution with little loss in profits. Once such practices are adopted, further reductions in nitrates can be achieved only at increasing costs to producers.

Managing nitrogen for sustainable corn systems: Problems and possibilities

AbstractExcessive nitrogen fertilizer use in corn production has resulted in widespread nitrate pollution of ground water and economic losses for farmers. In addition, reliance on nitrogen fertilizers produced with large amounts of fossil fuels may not be economically or environmentally sustainable in the future. Although leaching of significant amounts of nitrate to the ground water is inherent in growing corn, several techniques are available for more environmentally and agronomically sound management. The following management practices are discussed in this article: sidedress as the main method of N fertilizer application; the pre-sidedress (Magdoff) nitrate soil test; farm-based nitrogen sources (manures, green manures, and rotations with sod crops); cover crops for lowering profile nitrate during the most likely period for leaching; and the end of season stalk nitrate test.

Nitrate protection zones: Targeting and land use over an aquifer

This article describes an exercise aimed at combining the pedological, climatological and hydrogeological factors which affect nitrate pollution of groundwater for the chalk aquifer of East Kent (including the Isle of Thanet), UK. A spatial model is developed using overlays of the relevant factors deemed to affect nitrate concentration at abstraction points, generally boreholes in the chalk. The output from the model is related to the land use pattern in the mid-1980s. This article shows how a risk-assessed, incrementally implemented set-aside policy might operate to maximize for environmental benefits and would be useful in the implementation of a Nitrate Sensitive Areas policy.