We’ve talked before about different types of soil and how it’s often necessary to add a soil amendment, like lime or sulfur, to get the soil in the right pH range for growing what you’d like to grow. But how much of these amendments should you use? And which ones for which situations?
A soil amendment is any substance you add to soil to improve its physical properties, like water retention, drainage or aeration. In order to get the most out of your amendments, they need to be thoroughly mixed with the soil. Burying amendments under a layer of soil will do nothing to change the properties of the soil on top, and sprinkling an amendment on top of soil will do little for the deeper areas where plants actually root. Soil amendments must be integrated with the soil, and yes, this means hard work.
As far as choosing an amendment, these are the basic properties of soil amendments commonly used in gardens:
- Lime–raises soil pH; improves nutrient availability
- Sulfur–lowers soil pH
- Gypsum–loosens and aerates soil; adds calcium
- Compost–improves soil texture; adds nutrients
- Peat moss–helps loosen heavy soil; improves moisture retention
- Manure–improves drainage, moisture retention; adds nitrogen
When it comes to knowing how much of any soil amendment you need, a soil pH test is the first step. From there, the size of your garden and the recommended application per quare foot comes into play. Watch the “Garden Math” video below for an explanation on how to calculate your soil amendment needs.