Harrowing(redirected from Harrow (tool))
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a method for shallow cultivation of soil and care of agricultural crops. It is accomplished by toothed or disk harrows and revolving hoes. Harrowing protects the soil from rapid drying and improves its air and water penetrability, which facilitates the intensification of beneficial microbiological processes and accumulation in the soil of nutritive substances absorbed by the plants. For these reasons, fall-plowed fields, bare fallow, and winter crops are harrowed in early spring. Harrowing before the sowing of spring crops is done to level the surface of the field. Harrowing after sowing is used to destroy weed sprouts and to break up the soil crust before the appearance of shoots and around the shoots. (Revolving hoes or latticed harrows are best used for this purpose.)
On fallow fields and in preparing the soil under cultivation for winter crops, harrowing is used to level the surface of the field and to preserve moisture in the soil. Plowing and cultivation are usually conducted simultaneously with harrowing. In regions with little snow (for example, in Eastern Siberia), where the ridged surface of the field plowed for fall crops intensifies drying of the soil, autumn harrowing is practiced.
The quality of harrowing depends on the moisture of the cultivated layer of soil and on the equipment and technique of performance. Good crumbling is provided for by physical readiness of the soil (when it contains 60–70 percent of its total water capacity). Harrowing overdried or overmoist soil may be harmful. An increase in the speed of cultivation provides better friability but increases pulverization of the soil. Harrowing across the plowing or diagonally to it provides better friability and leveling of the surface. Indicators of high-quality harrowing are a well-crumbled surface layer of soil and a low degree of pulverization, a level field surface, and a maximum number of destroyed weed sprouts.
REFERENCESObshchee zemledelie. Edited by S. A. Vorob’ev and D. I. Burov. Moscow, 1964. Pages 188–89.
Korolev, A. V., S. K. Navrotskii, and M. P. Fedoseeva. Obshchee zemledelie s melioratsiei. Leningrad, 1967. Pages 144–46.
S. A. VOROB’EV