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Published by the American Society of Agricultural and Biological Engineers, St. Joseph, Michigan

Citation:  Arrived after publication of proceedings. Paper presented at Total Maximum Daily Load (TMDL) Environmental Regulations: March 11-13, 2002 Conference, Fort Worth, Texas, USA  .(doi:10.13031/2013.10747)
Authors:   O. del Hierro, A.del Prado, A.Artetxe and M.Pinto

In intensive farming areas, continuing inputs of Nitrogen and Phosphorus from fertilizer and manure to the landscape often exceed its output in crop and animal products. This fact can result in an increased loss of N-P through runoff and leaching to ground water that may contribute to eutrophication of freshwater receiving bodies. In order to asses the nutrient flows from intensive farming systems, several plots (pasture and forestry) have been selected in a dairy farm placed on Iola Watershed, where runoff and leaching nutrient losses have been studied. At the same time, water samples from nearby rivers have been collected in order to relate nutrient concentrations from runoff, leaching and rivers. During the period from January to April of 2001, the total rainfall has been 514 mm and 200 ha of grassland have been fertilized with an average of 135 kg N ha-1 of manure and fertilizer. Under these conditions, preliminary results have shown a range from 1 to 13 mg NO3- L-1 and from 0.03 to 0.15 mg TDP L-1 in the rivers. However, there are hot spots exceeding European Community maximum admissible limits for drinking (50 mg NO3- L-1). The drainage water reflects a range from 15 mg NO3- L-1 to 120 mg NO3- L-1 and around 0.08 mg DP L-1 in flat fields. The runoff water ranged from 1.2 in forestry plots to 10.6 mg NO3- L-1 in pasture plots and from 0.15 mg TDP L-1 in forestry plots to 2.40 in pasture plots. The aim of the study was to evaluate the influence of an intensive dairy farm in the water quality of the nearby the farm rivers and to compare it with forestry rivers.

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