Spring weather has many people wanting to get out and start working in their garden. According to Ben Polley, an agronomy graduate student with University of Missouri Extension, most soil in southwest Missouri could be improved by the addition of organic matter.

“Most soils in the area have an organic matter content of one-half to three percent,” said Polley. “Ideally, the organic matter content should be closer to five percent.”

Soils that are red, gray, or yellow in color tend to have low levels of organic matter. As the level of organic matter increases, soils tend to become darker with black soils having four or more percent organic matter.

“Organic matter is important in developing good soil structure,” said Polley. “It serves as a bonding agent and helps create soil aggregates from soil particles.”

Good soil structure is important for a successful garden. This increases the amount of pore space in the soil, reduces erosion, and improves tilth of the soil. Additionally, the water holding capacity and ease with which roots can penetrate the soil are improved as soil structure improves.

In addition to improving the soil structure, organic matter can also help provide the nutrients plants need. As it decomposes, organic matter releases nitrogen that plants are then able to use. Organic matter is one of the main sources for many of the micronutrients that plants need.

“Organic matter levels can be increased by spreading one to three inches of peat, compost, or well-rotted manure on the soil and then working it in to the rooting zone. Adding organic matter to the surface does not provide the benefits that mixing it in top layer of soil does,” said Polley.

The additional organic matter will need to be added over time. It will need to be replaced as it decomposes. A soil test every few years helps keep track of organic matter and nutrient levels in the soil.