Although Best Management Practices (BMPs) have been developed to reduce the loss of nutrients, like P, to the environment, limited information exists on the main factors that control P loss to Florida groundwater. For example, while it is generally accepted that both irrigation and fertilizer P impact groundwater P, growers often ask if controlling one is more advantageous than the other in their efforts to reduce P leaching. There exists no easy tool to link fertilizer P input and other factors to groundwater P concentration. This 5-page fact sheet uses long-term data (six growing seasons) from a farm in Immokalee, Florida, to explain the effects of soil and agronomic factors, along with seasonal rainfall, on groundwater P. From these factors are derived simple equations to predict groundwater P concentrations. Written by Sanjay Shukla, Gregory S. Hendricks, Thomas A. Obreza, and Willie Harris, and published by the UF Department of Agricultural and Biological Engineering, August 2014.
A BMP study was conducted at the research farm of the UF/IFAS Southwest Florida Research and Education Center in Immokalee, FL. The study evaluated two production systems made up of two levels of water and fertilizer inputs for tomato and watermelon production with seepage irrigation. The average water and P fertilizer rates used by growers in south Florida were contrasted with the recommended BMP rates. Applying BMP-recommended water and phosphorus (P) inputs for seepage-irrigated tomato and watermelon in Florida can reduce water use and P leaching to groundwater without adversely impacting fruit yield. However, given the adverse impacts on watermelon yield due to lower than sufficient levels of K, further research is needed to evaluate the fertilizer recommendations for watermelon, especially K2O rates, to ensure economic viability of farms. Our results showed that adoption of BMP-recommended P rates as a BMP did not reduce crop yield and improved water quality. This 4-page fact sheet was written by Sanjay Shukla, Gregory S. Hendricks, Thomas A. Obreza, and Willie G. Harris, and published by the UF Department of Agricultural and Biological Engineering, June 2014.
Non-uniform tree growth and fruit yield are very common throughout many Florida citrus groves, but variable groves are typically managed as if they were uniform. This 4-page fact sheet provides information about the relationship between soil variability and citrus production, proposes recommendations for soil sampling that account for spatial variability, and suggests site-specific management practices for variable Florida citrus groves. Written by Kirandeep K. Mann, Arnold W. Schumann, Thomas A. Obreza, Willie G. Harris, and Jerry B. Sartain, and published by the UF Department of Soil and Water Science, January 2011.
Under what conditions can plants be used to remove phosphorus from common Florida soils? This 5-page fact sheet shows how calculations for the phosphorus saturation ratio and soil phosphorus storage capacity at various soil depths can be used to determine whether to use phytoremediation as a strategy to remove phosphorus from the soil. Written by D. Chakraborty, V.D. Nair, W.G. Harris, and R.D. Rhue, and published by the UF Department of Soil and Water Science, October 2011.
This 7-page fact sheet uses a new procedure to evaluate the soil from active and abandoned dairies in the Lake Okeechobee watershed to determine their potential to negatively impact water quality through phosphorus release. Written by V.D. Nair, M. Chrysostome, and W.G. Harris, and published by the UF Department of Soil and Water Science, October 2011.
One of the factors that determines whether a source of phosphorus will have a negative impact on water quality is solubility. This 3-page fact sheet discusses the significantly different solubility of commonly found phosphorus sources in Florida. Written by V.D. Nair and W.G. Harris, and published by the UF Department of Soil and Water Science, October 2011. (UF/IFAS photo by Milt Putnam)
SL336, a 4-page illustrated fact sheet by Vimala D. Nair, Willie G. Harris, Debolina Chakraborty, and Myrlène Chrysostome, presents an approach to assessing sandy soil phosphorus (P) assimilation capacity prior to reaching a threshold of environmental concern. Includes references. Published by the UF Department of Soil and Water Science, November 2010.
SL333, a 3-page illustrated fact sheet by Vimala D. Nair, Willie G. Harris, and Debolina Chakraborty, describes a practical means of determining when a soil has reached a level of P loading that constitutes an environmental risk. Includes references. Published by the UF Department of Soil and Water Sciences, October 2010.