What Is Loam Soil Made Of?

Understanding soil performance gives your plants a competitive advantage. According to the National Gardening Association, loam is "the ideal medium for growing most garden plants."

The Basics

Proportions of sand, silt and clay influence soil performance.

Soil is composed of three different sized particles: sand, silt and clay. Each of these particles has a different effect on the ability of the soil to absorb water and hold nutrients. Sand drains very quickly so does not hold water or nutrients well. Clay behaves in the opposite way. The soil texture is the type and quantity of each particle present.

Loams

A loam is a balance between soil particle influences.

The term "loam" means a combination of the three soil particles. A soil texture that is a simple loam has a balance in the properties of each soil particle, not the amounts. The Soil Science Society of America defines loam as, "soil material that contains 7 to 27 percent clay, 28 to 50 percent silt, and less than 52 percent sand." Thus, a simple loam has both an ample nutrient binding capacity and balanced water holding/draining properties. Loams are named for the dominant influence of soil characteristics exhibited. For example, a clay loam is a mixture but performs more like clay.

Application

Most soils have a mixed texture. If you have a sandy loam, adding organic matter increases water and nutrient retention. Incorporate sand and/or compost to increase drainage in manageable sized clay loam planting areas.

References

• National Gardening Association: A Soil Profile
• National Gardening Association: Improve Soil Fertility With Compost
• "The Nature and Properties of Soils: Twelfth Edition"; Nyle C. Brady and Ray R. Weil; 1999
• Soil Science Society of America: Glossary of Soil Science Terms: 'Loam'

Resources

• Natural Resources Conservation Service