Garden Soil 101
Posted: November 26, 2012
Each part has a role to play. The mineral portion of soil makes up about 50% of the soil and provides the structural component that anchors plants and provides essential nutrients. The air in the soil is more important than many gardeners realize. About 25% of the soil is air space. The plant roots must have air to breathe and grow. Many root diseases get started because the roots are starved for air. When the soil is compacted the air is forced out. The air space in the soil is reduced and roots have to exert more energy to grow and take up water and nutrients. Soil compaction results when we walk on or work soil when it is wet or use heavy equipment in the garden.
The water portion, which is about 25% of the soil, plays the critical role of the go between. The nutrients held by the soil solids become soluble and move into the water solution. Plants take up that water. The plant removes the nutrients, and then transpires the water into the atmosphere. This water cycle keeps plants from wilting. When the available soil moisture becomes limited the plant must exert more energy to extract it from the soil. That energy would have gone to growth and fruit production. Having sufficient soil moisture ensures the plant will reach its potential.
Organic is the final component. The organic component is composed of both living and non-living material. The living material is the organisms that break down dead organic materials. These organisms range in size from a visible earth worms to invisible fungi or bacteria. As they break down dead material, they benefit the soil by releasing nutrients and improving the soils drainage and water holding capacity. Have you ever stopped to think what our world would look like if we did not have these decomposing organisms? The non-living component of soil is the decaying plant and animal material. This dead material is a great source of nutrients for living plants and serves as a reservoir for moisture. Garden soils range from 2% to 5% organic matter. If the organic matter is increased by 2%, you will notice a nice increase in plant growth.
For more information contact your local extension office. In Lackawanna County call 570-963-6842 or email LackawannaMG@psu.edu
John Esslinger, Extension Educator
Penn State Extension