Water Management Is Key in Reducing Nutrient Runoff from Container Nurseries

Abstract

Environmentally compatible production practices are conscious efforts to design and retrofit nursery container growing areas to improve irrigation and nutrient efficiency, and reduce exposure of ground and surface water supplies to contaminated effluent. Irrigation of ornamental crops in containers can be very inefficient, using large quantities of water and fertilizer. Irrigation water and fertilizer use efficiencies are directly related to each other. Improving irrigation efficiency improves nutrient efficiency and reduces water volume and nutrients leaving production beds. Increasing efficiency can be accomplished in many ways. Grouping plant species and container sizes into blocks with similar water requirements improves efficiency. Redesigning overhead sprinkler systems to accomplish uniform distribution across growing beds or replacing worn nozzle orifices can significantly reduce application variability. Low volume/low pressure systems that distribute water directly into containers and apply less water in a specific amount of time compared to overhead sprinkler application, will conserve water. Applying irrigation in short cycles rather than long cycles improves wetting in substrates and conserves electrical energy, water and directly reduces nutrient leaching from containers. Creating microclimates in nurseries to optimize light or reduce container temperatures, disease pressure and crop stress can improve water and nutrient efficacy. Flow of water running off growing areas must be engineered to slow velocity, filter and contain effluent. Strategies should be site-specific. Capture, containment and recycling of irrigation water has been a common practice in many nurseries in the U.S., as a means to provide adequate water supplies. Vegetative filter strips adjacent to beds and containment basins have been installed at nurseries to reduce contaminants in runoff before water enters recycle irrigation supplies. In areas with sandy soils, some nurseries have developed closed systems where drainage channels and collection basins are lined to prevent nitrogen movement from runoff into shallow groundwater.