Nitrogen concentrations in soil solution and surface run-off on irrigated vineyards in Australia

Abstract

Background and Aims: Water and nutrients exported from vineyards through surface and subsurface pathways have the potential to adversely affect water quality downstream. This project aimed to improve the scientific understanding of the pathways and quantity of Nitrogen (N) leaking from Australian vineyards. Methods and Results: Seasonal water balance and N in soil solution was monitored in one Rutherglen Shiraz and six Riverina Chardonnay vineyards. Surface run-off was monitored in one vineyard in each wine region. Six vineyards were planted 2 years prior and one Riverina vineyard 10 years prior to study commencement. Two vineyards, one drip and one flood irrigated, were selected on each of the three main soil groups of the Riverina, the Rutherglen vineyard was drip irrigated. The annual risk of leaching extended up to 205 days, the average N (nitrate + nitrite) concentrations in soil solution (1 m) ranged from 0.64 to 82 mg N/L and surface run-off from 0.0 to 0.3 kg N/ha. Conclusions: The soil N concentration combined with the number of days in which drainage was likely, highlights the potential risk for N export by subsurface pathways, while surface run-off was insignificant. Higher soil N concentrations and fertiliser application increased the risk of N exported beyond the rootzone. Significance of the Study: N fertiliser inputs could be reduced without affecting vine performance, since several vineyards monitored were above the recommended petiole N concentrations at flowering. This would decrease production costs and reduce the risk of N leaching out of the soil profile to water tables or waterways.