Organic matter boosts soil composition

No matter how poor your soil seems to be, it can always be improved with additions of organic matter.

Simply put, organic matter is any material originating from living material, including peat moss, manure, crop residues, compost or cover crops. It is also sometimes called a soil amendment, which is any organic material that is applied to the surface and incorporated into the soil through tillage.

Mulching is the application of organic matter to the soil surface but not incorporated. With all soils, addition of organic matter improves soil moisture retention, with more of that moisture being available to plants. Addition of organic matter allows less water to be used to grow gardens and landscapes.

Organic matter also increases the number of beneficial microorganisms and prevents establishment of diseases in the soil.

How does an amendment help soils?

North Idaho soils range from very sandy to very clayey. Sandy soils do not hold moisture well and can leach nutrients. Water moves through sandy soils very quickly, so it is difficult to keep plants watered in the heat of summer. Organic matter is a source of nutrients for plants and will help soils retain moisture.

Clay soils hold lots of moisture, but air pockets are very small, resulting in stunted plants and potential harmful root diseases. Addition of organic matter will “open up” clay soils and incorporate more air into them so roots will grow more extensively into the soil. Organic matter breaks up clay clods and improves aeration.

Organic matter sources

Choices of organic matter are limited by availability.

Composted manure could be high in salts, herbicide residues or weed seeds if you don’t know the source very well

for sawdust, bark or other fine woody materials, be sure to add nitrogen to speed decomposition and avoid nitrogen deficiency follow recommendations regarding the amount to apply to your situation because use of too much organic matter can be detrimental. A good rule of thumb when incorporating compost as a soil amendment is 25% of the planned tillage depth, i.e., 2 inches of organic matter tilled to a depth of 8 inches.

Green manure and cover crops

Grow a cover crop in the summer or fall before planting. There are many to choose from, including buckwheat for a summer cover crop and winter rye and winter field peas for winter cover crops when the cover crop just begins flowering till it in as deeply as possible

Mulching

Mulching reduces soil moisture evaporation, suppresses weeds, moderates soil temperatures and helps prevent soil compaction

mulches decompose slowly adding organic matter over a longer period, providing an excellent way to continually add organic matter

use bark in perennial beds if possible, since it decomposes more slowly. Grass clippings (which are free of herbicides) are an excellent material for vegetable gardens.

Michael Bauer is the Horticulturist for Moose Valley Farms in Naples. He can be reached at 267-5108.