Wight nursery eliminated fertilizer runoff by reducing fertilizer inputs and by improving the water drainage and collection systems. They looked closely at how much fertilizer they were putting on and found that they could grow quality plants at nutrient levels below published 'optimum' levels. They found that nitrate levels in their recycling ponds ranged from 15 to 30 PPM N, and adjusted soluble fertilizer injection up or down according to the N levels in the irrigation water. Superphosphate incorporation into growing media was eliminated entirely since recent research indicates this once-common amendment leaches from container media in 4 to 6 weeks. Collection pond capacities were increased to hold all irrigation runoff from the nursery as well as storm water from a one-half inch rainfall.
Nurseries have multiple options for managing runoff of water and nutrients.
Note that many BMPs center around irrigation practices since they have a great effect on the volume of runoff. Monitor nitrate and soluble salt levels in collection ponds and natural bodies of water up- and downstream from the nursery. Monitor growing medium fertility and avoid excessive fertility levels. Determine sufficient nutrient levels for your crops. Sufficiency levels may be lower than expected.