|Collins, Harold - Hal|
Submitted to: World Congress of Soil Science
Publication Type: Proceedings
Publication Acceptance Date: 10/1/2001
Publication Date: 8/1/2002
Citation: ALVA, A.K., COLLINS, H.P., PARAMASIVAM, S., SAJWAN, K.S. EVALUATION AND MITIGATION OF POLLUTANT TRANSPORT IN AGRICULTURAL SANDY SOILS. 17TH WORLD CONGRESS OF SOIL SCIENCE, Bangkok, Thailand, August 14-21, 2002, Vol. 1:116. 2002. Interpretive Summary:
Technical Abstract: Sandy soils in Pacific Northwest (PNW) and Southeastern agricultural regions in the United States often contain 95 to 98% sand in the soil profile with no confining soil horizons to a depth of up to 2.5 m. the saturated hydraulic conductivities of these soils range from 5.2 to 9.5 m/d In some areas, these soils may have shallow groundwater, thus providing favorable conditions for leaching of surface applied chemicals and soluble nutrients that could contaminate the surface waters as well as subsurface aquifers. In the Columbia Basin region of eastern Washington state, up to 30% of wells monitored contained NO3-N in excess of 10 mg/l, which is maximum contaminant level (MCL)for drinking water quality standards as per U.S. Environmental Protection agency. This area represents the premier potato production region of the U.S. with maximum production of high quality processed potatoes. Studies are in progress to improve nutrient and irrigation management that minimize nitrate transport below the root-zone. A Bromide tracer study, conducted in a Sandy Entisol in the citrus production region of Florida showed that the peak Br concentration in the soil surface disappeared 21 d after application, and Br was leached entirely from the top 2.4 m depth soil profile by 42 d after application. During this period cumulative water application, (i.e. rainfall plus irrigation) was 308 mm. In a study with a 25+ year old citrus trees, application rates of ammonium nitrate at either 28, 56, 84 or 112 Kg N/ha, nitrate concentrations in the surface 2.4 m depth soil profile returned to background concentrations (< 1 mg/Kg as NO3-N) by 35 to 42 d after application of N, across all N rate treat- ments. This shows rapid decrease in nitrate levels in the soil profile.