Last Thursday just before Fridays half inch down pour we took delivery of two truck loads of the wonderful food waste compost from San Francisco. This is the composted remains of what goes into your green compost bins. This is what I call recycling. We will put it to good use grow even more great vegetables, fruits and herbs. This also contains gypsum which is mined calcium sulfate. It provides the plants with the calcium and sulfur that they need to grow. The magic of gypsum is that in the soil it has the great benefit of flocculating the clay particles. This may sound painful but in effect if you imagine the clay particles in our soil as a stack of wet plates. Now imagine the gypsum acting like spacers between the plates where nutrients can now hold on. The stack is now bigger allowing more air in and soil develops a more crumbly structure. Magic.
Last Fall we tested our soil for all kinds of nutrients. Sulfur was down to medium levels. At high levels it can interfere with the availability of other nutrients. This gave me the green light to bring this wonderful mined mineral back into our compost mix.