A SWB works on some simple principles. Imagine your soil is a glass of water. The bigger the glass the more water can be stored – this is same as your soil type. A loamy soil can store a lot more water than a light stony soil. When the glass is full, that equals field capacity. If you put more water in a full glass it just spills out. The same with a soil at field capacity – if more water is poured on, either from rain, effluent or irrigation, the excess has to go somewhere because the soil can’t hold it. The only places it can go are run-off or drainage.
So to drop the level of your glass of water you drink some – imagine this is through a straw. This is what happens with soil too. As the grass or crops grow, they draw water from the soil and transpire it out their leaves. This is the only way water leaves the soil once it is at field capacity. And as you get down the glass, it becomes harder to suck up the water. The same for grass – it is harder to get the second half of the water in the soil so the grass is under stress. Also, when it is cold and damp the grass doesn’t grow as much, so it doesn’t use as much water.
So a soil water balance is like keeping track of how full your glass is. Ideally you want it to be over half full, but not right to the top. Regen keeps a soil water balance running for your farm every day. Way easier than a Cirque du Soleil balancing act.