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Agricultural practices and nitrate pollution in ground water in the Central Valley of Chile

UNCW Author/Contributor (non-UNCW co-authors, if there are any, appear on document)
Robert C. Golembeski (Creator)
Institution
The University of North Carolina Wilmington (UNCW )
Web Site: http://library.uncw.edu/

Abstract: Nitrate contamination of groundwater is an issue of global concern. Anthropogenic fixation of nitrate has increased exponentially in the last century and the over-application of nitrogen fertilizer is currently the largest intrusion into the nitrogen cycle. Previous studies have determined that various regional conditions can contribute to the level of nitrate contamination in groundwater. In addition to chemical and physical conditions, fertilizer application rates and overirrigation can serve as compounding factors. This study attempted to analyze the previously mentioned conditions by monitoring nitrogen concentrations in ground water from sampling wells in the Central Valley of Chile over a 13-month period. Samples were collected monthly and nutrient concentrations were analyzed. In all wells, concentrations of nitrate and nitrite were determined to be well above the established MCL?s for each and a general trend was observed in the concentrations that correlates to seasonal changes in land-use practices. A field experiment was conducted to reduce fertilizer application rates and irrigation water volumes applied to test fields by deploying an experimental fertilizer/ irrigation system. Data from the sampling wells associated with the test fields shows a substantial decrease in nitrate and nitrite concentrations in the groundwater. Furthermore, when the experimental system was combined with improved water delivery methods (medium-volume furrow flooding and low-volume drip irrigation) a decrease in water volumes and fertilizer application rates of up to two? thirds was obtained without affecting crop yield rates. Results of this study suggest that the over-application of fertilizer and irrigation water reported in previous studies are in fact areas of concern and that a link exists between ground water recharge and irrigation volumes. It is further suggested that long-term application of the experimental system is necessary to prove its benefits to the agricultural, ecological, economical, and scientific communities. If the performance record for this device can be repeated under a variety of conditions its role in reducing global intrusions to the nitrogen cycle would be substantial.

Additional Information

Publication
Thesis
A Thesis Submitted to the University of North Carolina at Wilmington in Partial Fulfillment Of the Requirements for the Degree of Master of Science
Language: English
Date: 2009
Keywords
Groundwater--Pollution--Chile--Central Valley, Nitrates--Enivronmental aspects--Chile--Central Valley
Subjects
Groundwater -- Pollution -- Chile -- Central Valley
Nitrates -- Enivronmental aspects -- Chile -- Central Valley