Tips for improving your garden soil

A lot of research is being done these days on soil science – the study of the dirt under our feet. It’s becoming quite clear that the condition of the soil in our gardens has a tremendous effect on the vigor and health of the plants grown.

Organic matter makes up about 1 percent to 6 percent of soils’ components, but organic matter and the fungi and bacteria that feed on organic matter have the greatest influence in how well soil can hold water, how soil particles bind together, and how soil makes inorganic elements such as nitrogen, potassium, calcium and sulfur available to plants’ roots.

We can alter and improve the condition of our garden soil by adding organic matter. Compost, either homemade or store-bought, is a tremendous source of beneficial microorganisms, fungi and bacteria that improve the soil’s texture and condition. It’s the best type of soil conditioner. When compost has fully decomposed it becomes humus, the dark brown end product of decomposition. Seed-free straw and seed-free alfalfa hay, sawdust, autumn leaves (from disease and pest insect-free trees), lawn grass clippings, annual ryegrass, and weed-seed-free sterilized manures are other types of organic matter that can be added to garden soil.

Most types of organic matter must be tilled or turned into the soil – not an easy job. Some recent studies have shown that beneficial microorganisms from a top layer of organic matter used as mulch penetrate into the soil below. After several months as mulch, the amount of organic matter will have reduced significantly, making the job of tilling it in much easier.

Many cool-season lawn grasses (fescue, Kentucky bluegrass, annual rye) are completely dead now. (Bermuda grasses are like zombies; even extreme drought, extreme heat and several applications of herbicides won’t always kill off bermuda grasses). Consider covering what used to be your cool-season lawn area with a 3- to 4-inch layer of organic material this fall. Or fill the spaces between your roses in the planting beds with a layer of organic material. Fill your raised planting beds with organic matter as well. When used as mulch, the materials will also keep weeds down.

The easiest type of organic mulch/material to lay down evenly is the fallen leaves from your trees. A last mowing or scalping of dead cool-season grasses can be left on the soil surface to decompose. Straws and hay look a little shaggy when piled on the soil and they take longer to decompose than some other finer materials. The spiky pieces also tend to clump together when turned into the soil. We’re accustomed to over seeding our lawns with winter rye and then covering the seed with manures. Smelly manures attract the neighbors‘ cats and dogs, but they are great sources of beneficial fungi and bacteria. The very hardy seeds of last season’s winter rye often re-sprout the next fall; let’s hope that winter rains keep any re-sprouted ryegrass alive so that it can be tilled into the soil in spring.

Source: University of Wisconsin Cooperative Extension, 1998, (reprinted 2014). Authors; E.E. Schulte and K. A. Kelling

This story was originally published September 29, 2015 at 10:00 AM with the headline "Tips for improving your garden soil."