MASTER GARDENERS: Microbes: The tiny and mighty
It is hard to imagine, but there are millions of living and competing organisms in even tiny amounts of our soil. These organisms are responsible in varying degrees in providing us with soils that are healthy enough to grow our fruits, vegetables, flowers, trees and grasses.
Last summer at the Regional Master Gardener Conference, Anne Sawyer gave a seminar on the tiny, but mighty, microbes in our soil. There is an astounding variety of friendly bacteria, fungi, nematodes and other very small life forms that are working so hard to live and to generally be beneficial to both our soils and what we are trying to grow in our soils. There are, of course, a few of the unfriendly varieties of tiny organisms in the soil, but these are generally a small minority. There are also some small organisms in our soil that war with many of the soil life forms. These warriors do help, to some extent, in keeping the unfriendly in check.
There are things that gardeners can do to help these tiny beneficial soil life forms help our plants.
Improving the habitat (homes) of these beneficial soil organisms can in part be accomplished by feeding them well-composted organics such as disease-free and harsh chemical-free plant materials, manure, fish and grass. Once you have fed them healthy compost, provide these microorganisms with air and water and do not compact the soil.
Tilling helps breaks up very compacted soils so that air and water can get down to these tiny life forms, but the downside of tilling is that most of these tiny life forms have micro-environments and soil levels that they live in, and tilling upsets these "homes" and kills many of these tiny life forms. These life forms typically recover, but it does take time. Sawyer said that we should limit the tilling of your soil to only occasional tilling and then in only one direction. Options to rototilling include the use of a large or small garden fork or simply hoeing, as it only turns the soil instead of pulverizing it.
To help keep your soil moist and protected from the hot sun, it is good to find a way that you like to keep the soil covered. Straw and grass work well for such coverings, but may cause weed problems. Half-composted leaves are free and weed-free. Commercial options include paper mulch, plastic mulch and biodegradable mulch.
Many of these tiny beneficial life forms that are good for our soil are killed by the use of chemical applications that kill off not only the intended nasty microbes, but also a wide host of microbes. If you find the use of chemicals necessary, it is best to limit the amount that is used.
To simplify this: add composted organic matter to your garden; make air and water easily available to the microbes; keep the soil relatively covered to keep sun glare off and moisture in; limit the amount of destructive chemicals; and limit the amount of tilling as much as possible.
Please seek gardening information from the University of Minnesota Extension website, www.extension.umn.edu, clicking on "Yard and Garden." Local Master Gardeners are now responding to your questions via voicemail. Call (218) 444-7916, leaving your name, number and question. Our Facebook page may also be of help.