What Makes Great Garden Soil?

While percentages of sand, silt, and clay and soil pH may be of use, the following soil descriptors help profile true soil health

Soil Texture

Soil texture refers to the porosity and structure of the soil. Soil texture affects the ability of soil to hold water and nutrients and provide pore space for air and plant roots. In general, high clay soils tend to have too little pore space, while sandy soils have too much. Clay soils are sticky and tend to stay in place, even on the bottom of shoes, while sandy soils are prone to blow and wash away.

Soil Nutrients

Nutrients needed by plants for growth, flowering, and good health include: nitrogen, phosphorus, potassium, calcium, magnesium, and sulfur. Nitrogen is used for growth, and phosphorus is important for flowering and fruiting.

There is a whole array of other nutrients necessary for plant growth including: iron, magnesium, and copper.

Modern agricultural practices have tended to focus on the above elements of soil, while ignoring other components. The result has been a dramatic loss of soil fertility and overall degradation of soils.

Organic Matter

Organic matter is created from dead plant residues. That is, plants on the surface die and decay. They can then release essential nutrients back into the soil. As well, organic matter provides a layer of protection for the soil, called humus, which helps hold moisture.

Soil is Alive

Soil is inhabited by a wide array of microorganisms, fungi, and other life forms which help support plant life. Over fertilizing soil destroys these tiny soil inhabitants rendering the soil lifeless. The process of soil building then stops.

Over fertilizing, particularly with chemical fertilizers, causes a bloom of certain microorganisms, which then consume all the organic matter in the soil. Having eaten themselves out of house and home, they then die and can no longer contribute to the cycling of nutrients necessary for healthy plant growth.

This is similar to bodies of water which become eutrophic (without oxygen) from fertilizer run off. The fertilizer run off causes an algae bloom, which sucks all the available oxygen from the water body, such as a lake or pond. This condition, if bad enough, can kill a water body.

The Key to Great Soil

The key to great garden soil is to treat it like the living ecosystem that it is.

• Add organic matter via compost is one of the best methods for improving soil texture, moisture holding capacity, and to increase available nutrients.
• Protect soil. Always cover with a thick layer of mulch, even in the winter. The mulch holds in moisture and protects soil from washing or blowing away. The mulch slowly decomposes, adding organic matter to the soil.
• Use only organic fertilizers. Organic fertilizers must decompose to work, just like natural soil processes.

When soil is understood to be a living entity and cared for, it will be productive for generations to come.