Nature's plows-earthworms

When I attended our Agriculture and Natural Resource Conference a few weeks ago at the MU campus, I saw several of the attendees holding a book. I finally acquired about why they had the book. I was told that Peter Scharf, our state soil fertility specialist, was giving them away. So I tracked him down to see what the book was all about. The name of the book is called "Dirt-The Erosion of Civilizations." It is written by David Montgomery, a geologist and a professor of earth and space sciences at the University of Washington.

The essence of this book is that we need to do a better job of soil protection to keep our global food systems able to supply food for an increasing population. The book is fascinating and it provided a historical perspective of how soil erosion has been the downfall of many civilizations. It also details the problems with American agriculture from the colonial times to the present.

In Chapter 2 entitled," The Skin of the Earth "he refers to Charles Darwin's fascination of with earthworms. Shortly before his death, Darwin wrote, "The Formation of Vegetable Mould through the Action of Worms, with Observations on their Habits." He had studied worms for over forty years.

Shortly after returning to England after his many travels, he noticed that a once thick layers of cinders that had been on the surface of his fields had disappeared. As he looked at his fallow soil, he noticed an abundance of earthworms. He later put terrariums in in his living room so that he could observe the earthworm activity.

He collected and weighed earthworm castings and estimated that the worms would run about 10 tons of soil and organic matter through their bodies per acre each year.

In addressing the activity of earthworms, Nyle Brady in "The Nature and Properties of Soils., states that the digestive enzymes and the grinding action in the gizzard of the worm produces this remarkable material. It is estimated that in the tropics, earthworms will produce up to 110 tons of casts each year per acre. The casts are higher in bacteria, organic matter, and available plant nutrients. In addition, the holes left in the soil by the worm activity increases soil aeration and drainage. Earthworms the size and stability of soil aggregates. This increases water holding capacity and improves infiltration after rainfall.

In addition to the cinder removal, Darwin noted that one of his fields had been littered with rocks. In digging a trench, he discovered that the rock layer had been covered with a fine soil. As he dissected earthworms, he observed that the gizzards contained small rocks and sand. In addition, the acid in the earthworm stomach matched the humic acid found in these soils. Humic acid is a principal component of humic substances, which are the major organic constituents of soil (humus), peat, and coal.

In his landmark book, Darwin is quoted as saying, "The plow is one of the most ancient and valuable of man's inventions: but long before he existed, the land was regularly ploughed, and continues to be plowed by earthworms. It may be doubted whether there are many other animals which have played so important a part in the history of the world, as have these lowly organized creatures."

Since earthworms are so important in building and maintaining soil fertility, there are many things that can reduce their activity. Conventional tillage practices which include disking and field preparation, drought, poor drainage, too much soil acidity, and erosion will impact these soil macro organisms. No-till and Conservation tillage will increase the activity of earthworms. Soil testing and liming will reduce soil acidity.

Although earthworm activity is important in cultivated fields and pastures, they can also be very important in gardening. They can improve the soil and they can reduce home vegetable scraps into a very useful soil amendment.

Vermiculture is the process of using earthworms to decompose kitchen scrapes. Such systems usually use kitchen and garden waste, using "earthworms and other microorganisms to digest organic wastes. This includes all fruits and vegetables (including citrus and other "high acid" foods), vegetable and fruit peels and ends, coffee grounds and filters, tea bags (even those with high tannin levels), grains such as bread, cracker and cereal (including moldy and stale), eggshells (rinsed off), and leaves and grass clippings (not sprayed with pesticides).

For resources on how to use worms for composting, just click on the link to the Missouri Alternatives Center for vermicomposting. This link can be found at http://agebb.missouri.edu/mac/links/index.htm.

This link has a variety of resources including constructing a worm composting bin (University of Arkansas) and vermiculture resources (North Carolina State University). There are step by step instructions on how to get the process to work more efficiently. Keeping the worms from getting to hot or too cold will insure better composting.

The University of Missouri Extension office is open Monday-Friday located in Kennett, Missouri at 233 North Main Street. Contact 573-888-4722 with questions or comments. MU is an equal opportunity/ADA institution.