Nitrate nitrogen (NO3‐N), which is an essential source of nitrogen (N) for plant growth, is now also considered a potential pollutant by the Environmental Protection Agency (EPA). This is because excess applied amounts of NO3‐N can move into streams by run‐off and into ground water by leaching, thereby becoming an environmental hazard. Soils have varied retentive properties depending on their texture, organic matter content, and cation exchange capacity (CEC). The purpose of this study was to determine the effect of soil texture on NO3‐N retention to reduce NO3‐N contamination in the environment. A sand, 85:15 sand:peat Greensmix, a loamy sand, and sandy clay loam soils were placed in 2×3 inch metal cylinders and soaked in a 240 ppm solution of NO3‐N for seven days to saturate the soil with NO3 ions. The columns were leached with water to collect 10 soil percolate samples of 50 mL each until a total volume of 500 mL was collected. Nitrate‐N was measured in each 50‐mL aliquot by automated colorimetry. The results showed that soil texture affected the retention of N03‐N in the sand, which adsorbed the least amount of NO3‐N at 119 ppm, followed by the Greensmix at 125 ppm, loamy sand at 149 ppm, and sandy clay loam at 173 ppm. More NO3‐N was released in the first 50 mL of the sand percolate at 63% followed by the Greensmix, loamy sand, and sandy clay loam at 58,46, and 37% NO3‐N released, respectively. Soils with more silt, clay, and organic matter retained more NO3‐N than the straight sand. Therefore, a straight sand would be the poorest of soil types since NO3‐N retention was low.
[Show abstract][Hide abstract] ABSTRACT: Environmental issues associated with intensive use of nitrogenous fertilizers have generated an interest in alternative management systems. An experiment was conducted to mitigate nitrate leaching from sandy soil using different waste materials such as charcoal, manure, sawdust, wood ash, and control (no amendment). Urea was applied at the rate of 300 kg nitrogen (N) ha(-1). Nitrate was determined during six leaching events. During an incubation experiment, nitrate release was also determined in soil amended with charcoal at the rates of 0, 10, 20, and 40 t ha(-1). Urea was applied at the rates of 0, 100, 200, 400, and 1000 ppm N. Results indicated that urea application increased nitrate (NO3) concentration in leachate. Soil amendments substantially reduced NO3 in leachates irrespective of the type of material used. Waste amendments differed for NO3 leaching as follows: charcoal < wood ash < sawdust < manure. Leaching of NO3 enhanced up to the fourth leaching event and thereafter reduced significantly. Nitrate retention in soil varied among material in the order of manure > charcoal > wood ash > sawdust. Nitrate accumulation occurred in the lower layer (25-50 cm) of soil column after the leaching process. Application of charcoal retained greater NO3 level as compared to control soil during an incubation. Enhanced urea applications also enhanced NO3 release. This experiment suggests that waste material can be viably recycled to mitigate NO3 concentration in water.
Communications in Soil Science and Plant Analysis 03/2014; 45(5-5):680-687. DOI:10.1080/00103624.2013.867046 · 0.39 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: In Slovenia, groundwater is significant source of drinking water. It has been widely reported that contamination of groundwater from agricultural non-point source is one of the major pollution problems. The pollution of groundwater in areas of agricultural activity is a result of using of mineral nitrogenous fertilizers in large quantities. Applying excess nitrate fertilizers directly affects ground water quality, especial for NO 3 -N, which is highly mobile. Non-point loss of NO 3 -N from fields to water resources however is not caused by one single factor. Rather is caused by combination of factors including precipitation, crop uptake, irrigation, application of fertilizers and soil property. Although Slovenian areas of intensive agriculture have different soil characteristics, different rainfall regime and agricultural practice, their nitrate leaching regime appears to be similar and in majority related to the precipitation and fertilization.
[Show abstract][Hide abstract] ABSTRACT: Nutrient balances are useful indicators to assess the sustainability of farming systems. This study study investigates inflow and outflow of major nutrients in urban and periurban production systems in Kano, Nigeria. To this end, 16 households representing three different urban and peri-urban (UPA) farming systems were studied using the MONQI toolbox (formerly known as NUTMON) to calculate nutrient flows and economic performances. The farm nitrogen (N) balance was positive at 56.6, 67.4 and 56.4 kg farm−1 year−1 for commercial garden and crop-livestock (cGCL), commercial gardening and semi-commercial livestock (cGscL) and commercial livestock subsistence field cropping (cLsC) farm types, respectively. The same trend was observed for phosphorus (P) and potassium (K) in all farm types except an annual negative K balance of 16 kg farm−1 in cGCL. Across the different activities within the farms, land uses had positive N (359, 387 and 563 kg N ha−1 year−1) and P (74, 219 and 411 kg P ha−1 year−1) balances for all farm types, but again a negative K balance in cGCL with an average loss of 533 kg K ha−1 year−1. Partial nutrient balances in livestock production indicated a positive balance for all nutrients across the farms types but were slightly negative for P in cLsC. Commercial livestock keeping (cLsC) was economically more profitable than the other farm types with an average annual gross margin (GM) and net cash flow (NCF) of $9,033 and $935. Cropping activities within cGCL and cGscL had GMs of $1,059 and $194 and NCFs of $757 and $206, respectively, but livestock activities in both farm types incurred financial losses. Potassium inputs were limited under vegetable and crop production of cGCL, threatening long-term K nutrient availability in this system. Overall, the results indicated large annual surpluses of N and P in urban and peri-urban vegetable and crop production systems which pose a potential threat when lost to the environment. Appropriate policies should aim at promoting sustainable production through efficient nutrient management in the Kano UPA sector.
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