Impact of fertigation versus controlled-release fertilizer formulations on nitrate concentrations in nursery drainage water

Abstract

Nitrate-nitrogen (N) losses in surface drainage and runoff water from ornamental plant production areas can be considerable. In N-limited watersheds, discharge of N from production areas can have negative impacts on nontarget aquatic systems. This study monitored nitrate-N concentrations in production area drainage water originating from a foliage plant production area. Concentrations in drainage water were monitored during the transition from 100% reliance on fertigation using urea and nitrate-based soluble formulations (SF) to a nitrate-based controlled-release formulation (CRF). During the SF use period, nitrate-N concentrations ranged from 0.5 to 322.0 mg L-1 with a median concentration of 31.2 mg L-1. Conversely, nitrate-N concentrations during the controlled-release fertilization program ranged from 0 to 147.9 mg L-1 with a median concentration of0.9 mg L-1. This project demonstrates that nitrate-N concentrations in drainage water during the CRF program were reduced by 94% to 97% at the 10th through 95th percentiles relative to the SF fertilization program. Nitrate-N concentrations in drainage water from foliage plant production areas can be reduced by using CRF fertilizer formulations relative to SF formulations/fertigation. Similar results should be expected for other similar containerized crops. Managers located within N-limited watersheds facing N water quality regulations should consider the use of CRF fertilizer formulations as a potential tool (in addition to appropriate application rates and irrigation management) for reducing production impacts on water quality.