The best soils of Bordeaux are clay with good structure. These soils have excellent water and nutrient holding capacity and because of good structure they also have excellent internal drainage which allows good absorption of the water and nutrients. The presence of sodium in a soil or water can kill soil structure and serious problems from water saturation from poor drainage results. The most important part of vineyard site evaluation is the determination of soil and irrigation water sodium. When the soil structure is destroyed, heavy applications of calcium sulfate, gypsum, will be needed with heavy leaching of clean sodium free water.
Compaction is a poor soil structure problem.
It is the result of repeated heavy equipment passage down the vineyard rows. Heavy tractors and sprayers filled with water compact the soil, especially when the soil is moist. Repeated compaction will create hard soil which is very difficult to manage. The use of lighter equipment and less frequent tractor passage in the vineyard will reduce soil compaction. Slow internal soil drainage is a very serious problem in Texas.