Soil disturbance and salinisation on a vineyard affected by landscape recontouring in Marlborough, New Zealand

• Recontouring shifted morphology from well-differentiated in to poorly differentiated.
• Morphology change accompanied by less chemical differentiation in disturbed profile.
• No difference in organic C and N between the virgin and recontoured landscapes.
• Saline siltstone integration into soil has led to salt accumulation in the profile.
• Salt accumulation in infilled gullies has led to elevated pond water salinity.

This paper investigates the effects of landscape recontouring on soil morphology, topsoil organic matter, and soil and water salinisation on a vineyard site in the NE South Island, New Zealand.Soil pits in representative locations in the virgin and recontoured landscapes were opened for profile comparison, in addition to hand auger transects across infilled gullies and topsoil pit sampling. Disturbed soils exhibited a simplified profile form compared to undisturbed virgin soils, leading to reclassification. Soil mixing in disturbed profiles resulted in more even distribution of some total exchangeable bases compared to virgin profiles. No significant differences in topsoil organic C and N were found between recontoured and virgin landscapes, and the spatial variability was less in the recontoured landscape. Diffuse throughflow in infilled gullies was found to be causing accumulations of salts in an irrigation pond to levels likely to be negative for viticulture. Immediate negative effects for viticulture in the disturbed soil appear to be low, as ersatz soil profiles were reconstructed after recontouring had taken place and the topsoil was well preserved. As this process is widespread in the region, concern is primarily for salinisation potential of throughflow and receiving waters.