Reducing N runoff during irrigated cotton production

Nitrogen (N) fertiliser is applied both pre-plant and in-crop for high-yielding Australian irrigated cotton. Runoff during flood-furrow irrigation can be a major N loss pathway, particularly during the first two irrigations following pre-plant N application.

Over three seasons, we assessed the impacts of N fertiliser products, placement and application timing on N runoff from irrigated cotton grown on Vertisols. Greatest N runoff came from in-crop fertigation. N runoff was reduced by split N application, applying pre-plant urea with a nitrification inhibitor or polymer-coating and by optimising fertigation practice.