What soil problems might empty fields cause?

The left overs left behind in the soil as irrigated water for farming evaporates, which makes the soil water have a higher osmotic content for the plants. A higher concentration of solutes means there is a lower amount of water. Therefore, more water will run/diffuse out of the plants cells right into the soil rather than the amount of water that runs/diffuses into the plant cells. The plant cell will lose water and shrink, weakening the plant. This is very bad for crops and will be a major factor in up to billions of dollars worth of loss in crops because the plants either have a lower food output, and/or have a lower chance to survive because of lower water content. As the years go on, this will be another issue humanity has to face if it wants to survive.