Using Sod Crops to Improve Your Soil

Learn how rotating sod crops on your homestead can improve the soil, leading to larger harvests.


| September/October 1972



sod crop

Sod crops such as clover lead to better soil.


PHOTO: K.U. HABLER/FOTOLIA

Sod cropping as defined in this chapter is a balanced method of farming which permits maximum output of soil resources while at the same time maintaining and improving them. It is a method that contrasts with Row Cropping  in that sod cropping is basic to water and soil conservation, and essential—in rotation — for the maintenance of high level row crop production.

Without question, sod crops are the most important underdeveloped agricultural resource in the world today. This is true in spite of the fact that they have been around a long time: improved varieties such as alfalfa were known to the Persians and Romans before the time of Christ; clovers were grown in northern Europe in A.D. 800. There are at present 5,000 species of sod grasses in the world, and 1,500 of these are found in the U.S. This number does not include the hundreds of "natives" and weed varieties which agriculturalists refuse to include as economic to American fanning practice.

Due to the numbers involved, it is with some difficulty that we attempt a classification of sod cropping. Some crops are grown annually, some in rotation, and some permanently. Of the annuals, there are warm season and cool season varieties. Grasses are grown in companionship with other grasses or with legumes. And every plant species has an optimum soil and climate requirement. A high-producing sod crop may prove to be valueless on poor soil. And conversely, a sod crop considered undesirable in a productive soil-and-climatic-environment, may be highly regarded on a less desirable site: palatable short grasses like buffalo blue grama, silver bluestem, and sand dropseed are not grown to advantage on fertile sites.

Benefits of Sod Crops

Plant ecologists present the clearest perception of optimum plant development in the presentation of the Climax Growth concept. We are told that there is a subtle response between plants and changes in the environment. Individual plants become more abundant or less abundant in a community, depending upon soil and climate factors. One species is gradually replaced by another higher and more adapted variety, until finally vegetation attains the climax form characteristic of the soil and climate. This is a good explanation of why a climax sod crop is the only important soil builder of any consequence. When a native sod us plowed and put into rowcrop production, a climax has been destroyed but the soil remains productive for many years. When this happens in a humid forest situation the soil becomes unproductive after a few short years, of cultivation; the wider spacing of trees offers little root development and soil-aggregation buildup.

A sod growth, however, reaches climax as more and more topsoil is formed and accumulated. Each succession contributes to the next higher plant development. An example of California rangeland climax is illustrated below.

Climax succession is also apparent when overgrazed or cultivated land is abandoned and sod crops allowed to return: first, annual weeds (crab grass, pigweed, Russian thistle) appear; then so-called poverty grasses (wire grass, broom sedge) replace the native weeds; as the organic content of the soil increases, poverty grasses get so thick they cannot withstand their own competition. Thus, short-lived perennials like bunch grass appear and progress, finally, to semi-climax and climax grasses native to the region.





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