Irrigation and fertiliser strategies for minimising nitrogen leaching from turfgrass

Establishing and implementing management practices that limit N leaching from agricultural and horticultural land is a priority internationally. Movement of N through soil to surface and ground waters can degrade aquatic systems and compromise water used for drinking, industry and recreation. Reported annual rates of N leaching from turfgrass range from 0 to 160 kg N ha⁻¹ year⁻¹, representing up to 30% of applied N. Irrigation rate, fertiliser regime and turfgrass growth phase influence the amounts of N leached. Nitrogen losses tend to be low (<5% of applied fertiliser N) from established turfgrass that is not over-irrigated, and has received N fertiliser at 200–300 kg N ha⁻¹ year⁻¹. Efficient irrigation management is critical for efficient N use. Irrigation scheduling that does not cause water to move beyond the active rooting zone decreases the amount of N leached from established turfgrass, without being detrimental to, and in some instances enhancing, turfgrass growth and quality. Applying N fertilisers at rates and frequencies that match N requirements decreases N leaching from established turfgrass. Soil disturbance, such as during preparation of areas for planting turfgrass, can increase N leaching. Therefore, the main strategies for minimising N leaching from turfgrass are (i) optimise irrigation regimes, and (ii) ensure N is applied at rates and frequencies that match turfgrass demand. These strategies are particularly important during turfgrass establishment. Further work is required on turfgrass-soil N cycling and partitioning of N applied to turfgrass. Research needs to be conducted for a broad range of turfgrass species, turfgrass ages, soil types and climates.