DaKine 420 Tilthy Rich Calcium-Plus, 1,000 gTilthy Rich Calcium Plus combines a specially formulated blend of calcium plus zinc and manganese to benefit the soil ecosystem. This unique amendment is chelated with EDTA with a proprietary process that makes it highly soluble and readily available to both soil microbes and plants. As an easy to apply spray, Tilthy Rich activates once its leached into the soil by rain or irrigation. No more truckloads of costly, messy gypsum or insoluble pH raising