BU-07403     2000

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WHAT'S NEXT?

Several guidelines for managing soil biology were introduced in this chapter - encourage diversity, feed organisms frequently, don’t destroy habitat with excessive pesticides or tillage. But there were no strict numbers for how many arthropods you need, or a list of species that are essential, or a precise set of practices that will generate the "ideal" mix of soil organisms. This means that good observation skills are important to assessing the effects of practices on your farm.

Monitoring

Each farmer notices a unique set of changes as soil biological activity rises. One might notice more birds picking out earthworms behind the plow. Another might see manure pies disappearing more quickly, or reduced ponding after a rain. It takes practice to observe the activities of soil organisms. Observations such as these are essential, but there are also more systematic ways to monitor soil biology.

Assessing soil life on your farm

Soil life can be measured in three general ways: the amount of organisms, their activity, and the soil processes they influence.

The amount of organisms can be measured by directly counting them under a microscope or by estimating biomass using several laboratory methods. Activity is often monitored by measuring soil respiration (the amount of carbon dioxide given off) or decomposition rates.

The biomass (amount of organisms) does not change drastically from day to day, but activity levels respond rapidly to changes in temperature, moisture, and food. Because activity levels can change quickly, it is important to note temperature and moisture conditions when sampling.

In addition to directly measuring the organisms or their activity, it can be useful to monitor the processes they influence. These include the stability of soil aggregates, rate of water infiltration into the soil, the rate of decomposition, pest activity, and soil nitrate levels.

On-farm tests

The Monitoring Tool Box describes a soil respiration test that measures carbon dioxide, and a cotton strip test that measures the rate of degradation of a buried piece of cloth. The Tool Box also describes tests of aggregate stability and percolation (infiltration).

A simple on-farm respiration test is available from Woods End Research Laboratory (207-293-2457, http://www.woodsend.org/).

Biological activity can be observed more informally by noting how long it takes for manure or residue to disappear from a field.

Lab tests

A few commercial labs will test the number or activity of organisms in your soil. Some consultants are developing recommendations based on such tests, but the research basis for interpreting biological measures is still weak.

The future of soil biology management

There is much to learn about managing soil biology. Researchers are only beginning to understand the specific biologic mechanisms of many management practices. As research accumulates, farmers may increasingly use practices such as:

• choosing a cover crop as a biocontrol for a specific pest.
• timing tillage to give crops the best advantage from the resulting biological activity.
• managing habitats at the edge of fields to support predators of pests.
• choosing fertilizers and pesticides partially based on the non-target organisms they affect.
• choosing a source of compost and manure based on how it impacts disease or crop-enhancing organisms.

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