Soluble fertilizers are used in irrigation water in the greenhouse industry, and for this reason, we pay very close attention to the "leaching fraction" when we fertigate with nutrient solutions.
Soluble fertilization applications are also routinely used in field situations where drip irrigation is used. This practice is very cost-effective, and given that precise applications of nutrients are applied at low concentrations, this practice typically has an extremely low potential for nutrient runoff.
Most large-scale container-nurseries now use slow-release forms (SRF) of fertilizers such as osmocote, nutricote or polyon. These SRF's are incorporated in the substrate prior to planting, or top-dressed on the surface of the substrate. These precise fertilizer applications, plus the slow-release technology in the casing around the fertilizer prill has been shown to greatly reduce the nutrient runoff potential from these operations.
Poor management however, can negate the good effects of all these practices, and over-irrigation is the primary factor in nutrient leaching and runoff. Until now, we have not had the tools to precisely estimate the water content of soils and substrates. It is this knowledge that will allow us to further reduce nutrient losses from these production systems. |
