Influence of soil type on nitrogen leaching of controlled release fertilizers

Misuse of nitrogen fertilizers has become an ever increasing problem in management of turfgrass lawns and fields. The environmental impacts of these practices are especially evident in sandy soils that are low in organic matter which can bind nitrogen, or in new turfgrass systems that have not developed mature root systems which are capable of nutrient uptake before leaching occurs. Controlled and slow release fertilizers are designed to release nitrogen over a longer period of time which should improve the efficiency of nitrogen use and reduce leaching. A lysimeter study was performed at the University of Georgia to determine if an experimental fertilizer (E 15-0-0) would reduce leaching compared to UMAXX (47-0-0) and an analog fertilizer (16-4-8). Soil retained nitrate-nitrogen (NO3-N) and ammonium-nitrogen (NH4-N) samples were collected from a USGA green’s mix, Florida soil, and Maryland soil. The experimental fertilizer leached more NO3-N than the other fertilizer types in all soils. The analog fertilizer leached more NH4-N during both trial years in the Florida and USGA soils. Developing an improved controlled release fertilizer would decrease the likelihood of leached nutrients. Further study should be performed in the field to more accurately simulate real world conditions that affect fertilizer application and fate to effectively evaluate nitrogen loss characteristics of these fertilizers.