Changes in vineyard floor management reduce the Na+ and Cl− concentrations in wine grapes grown with saline supplementary drip irrigation

In supplementary irrigated vineyards, saline drip irrigation caused excessive levels of sodium and/or chloride in the leaf lamina during ripening and in the fruit at harvest. Soils located along the vine line under the drippers were saline and sodic, whereas those in the mid-row were neither saline nor sodic. In a vineyard where soil from the mid-row had been mounded under the vine, we tested the effects that various changes to vineyard floor management had on soil salinity and sodicity, the concentrations of sodium and chloride in leaves and fruit, and yield. Both removal of the under-vine soil mound and its removal combined with harvesting and re-directing rain falling in the mid-row to under-vine soils reduced the salinity of under-vine soils by about 48%. Both rainfall harvesting and re-direction and application of soluble calcium reduced the soil exchangeable sodium percentage by 40% on average. Application of soluble calcium did not reduce soil salinity. Removal of soil mounded under the vine reduced the concentrations of sodium and chloride in juice on average by 34% in one of two seasons and rainfall harvesting and re-direction reduced the concentrations in both seasons by 33% on average. At some sampling times, changes to floor management decreased the concentrations of sodium and chloride in the vine without affecting soil salinity. It is proposed that changes to floor management can also increase the proportion of the vine water requirement that is met from rainfall and thereby reduce the concentrations of these ions in the vine. In a supplementary irrigated vineyard where soil is mounded under-vine, the sustainability of saline drip irrigation can be improved by removal of the mound. Where soil is not mounded under-vine, it can be improved by harvesting rain falling in the mid-row and re-directing it to the soil under vine.