Kent Cushman

Effects of Water and Nutrient Strategies on Water Quality and Crop Yield

South Florida accounts for a large fraction of the vegetables produced in Florida. For a given crop season, the typical south Floridian vegetable grower applies fertilizer with a single application and irrigates via seepage irrigation. Large portions of fertilizer may leach to the ground water due to fluctuating high water table levels, which at times reach the soil surface. To account for leaching losses of fertilizer N, growers apply additional amounts of fertilizer to maximize yield. Environmental regulations such as TMDL require the implementation of water and nutrient BMPs to reduce the nutrient loadings to receiving water bodies. However, the effects of several BMPs on crop yield and water quality have not been quantified. A study was undertaken in south Florida to examine the effects of water and nutrient management practices on yield and water quality. Two vegetable production systems were installed and monitored simultaneously for two crop seasons. The first system involved the typical grower’s management practice in southwest Florida. The second system was similar to the grower’s management practice but soil moisture content was used to manage the water table and University of Florida fertilizer recommendations were used. Results revealed a significant difference in the crop yield between the two systems during the second crop season. This was likely due to leaching of relatively large amount of fertilizer N from the bed caused by a higher than normal rainfall. Surface and ground water quality data for the 2-year period are currently being compiled.