Soil Test Phosphorus (STP) Levels in Georgia's Agricultural and Non-Agricultural Soils Over a 19-Year Period.

The Agricultural and Environmental Services Laboratories (AESL) of the University of Georgia offer an extensive soil testing program to the public including the agricultural producers and homeowners. Soil samples submitted to the laboratory were generally tested for fertility status following the Mehlich I extraction method. After analysis, the clients are given data interpretation, and fertilizer recommendations if needed. The laboratory’s database covering the years 1991 to 2009 showed that most soil samples were from fields grown to cotton (336,013 samples) and peanuts (136,693 samples). Soils from homeowners were taken from vegetable gardens and lawns and reached a combined number of 149,751 samples. Since fertilization is a usual management in most crop production along with recent rise in the use of poultry litter, the general public has raised concerns on P build up in soil and its effect on nearby waterbodies. With extensive database and access to soils data, soil test P summaries were calculated and categorized according to year, soil regions, and crops grown. Data were further grouped based on percent of samples analyzed that tested low, medium, high and very high following the fertility categories adopted by the University of Georgia. Summaries indicated that about 60% of cotton soils tested medium to high levels of soil P, and 35 to 51% of soils coming from peanut farms tested high and very high levels of STP. About 58% of the homeowners’ vegetable garden soils tested very high in STP. In contrast, most home lawn soils tested low in STP. Details of the categories and implications on fertility management will be discussed.