Concentrations and discharge amounts of NO3-N, PO4-P, 2,4-D herbicide, terbacil herbicide, and chlorobenzilate acaricide were determined in surface and subsurface drainage waters from a citrus grove located in an acid, sandy flatwood soil of southern Florida. The influence of fertilizer and pesticide upon water quality was examined for citrus growing in three soil management treatments: ST (shallow-tilled plowed to 15 cm); DT (deep-tilled and soil mixed within the top 105 cm); and DTL (deep-tilled to 105 cm and 56 Mt/ha of dolomitic limestone mixed with the soil). Average annual losses of NO3-N in both surface and subsurface drainage from ST, DT, and DTL plots were equivalent to 22.1, 3.1, and 5.4% of total N applied as fertilizer. Average annual losses of PO4-P in both surface and subsurface drainage from ST, ST, and DTL plots were equivalent to 16.9, 3.6, and 3.5% of total P applied as fertilizer. Deep tillage was thus observed to greatly decrease leaching loss of N and P nutrients. Loss of nutrients in surface runoff was very small for all three plots. Although the magnitudes were less, deep tillage also decreased leaching losses of terbacil and 2,4-D herbicide. Discharges of these herbicides in subsurface drainage were usually in the order: ST>DTL>DT. Discharge of 2,4-D was greater from drains with open outlets than from drains with submerged outlets. Discharge of terbacil did not differ for open or submerged drains. Chlorobenzilate pesticide was not detected in drainage water from any of the three soil treatments.

"Submitted in fulfillment of Grant No. R-800517 by the Institute of Food and Agricultural Sciences of the University of Florida." "August 1977." "Includes appendix." Includes bibliographical references (pages 125-129).