Root Growth in a Claypan with a Perennial-Annual Rotation
1988
Grecu, S. J. | Kirkham, M. B. | Kanemasu, E. T. | Stone, L. R. | Milliken, G. A. | Sweeney, D. W.
Drought stress occurs on claypan soils because they restrict root growth and water uptake. This research sought to determine if alfalfa (Medicago sativa L.) planted with fescue (Festuca arundinacea Schreb.) would decrease penetration resistance of a claypan soil enough to justify a regular rotation of the legume-grass mixture with annual summer crops of maize (Zea mays L.) and soybean [Glycine max (L.) Merr.]. The study was carried out in southeast Kansas on a Parsons silt loam (Mollic Albaqualf; fine, mixed, thermic), overlying clay (the claypan). Alfalfa + fescue were grown for 2 yr and disked. Maize or soybean then was planted on these plots. Control plots contained either maize or soybean for 3 yr. After 3 yr, penetration resistance, bulk density, soil-water content, and root length density were measured. Growing alfalfa + fescue had no effect on the penetration resistance or bulk density of the soil. At the beginning of the third year, plots previously planted with alfalfa + fescue had less water in the claypan than continuous plots of maize or soybean. Maize grown on continuous plots had more roots, was 0.3 m taller at tasseling, and had a greater yield (although still low due to the dry summer) than maize grown on plots previously planted with alfalfa + fescue. This increased growth was due partly to the greater amount of water available in the continuous plots. Roots of both maize and soybean penetrated the claypan to the maximum depth of observation (1.35 m from the soil surface). Root length densities in the claypan were greater for maize than for soybean. Contribution no. 87-374-J from the Kansas Agric. Exp. Stn. This paper represents a portion of the dissertation of the senior author, presented in partial fulfillment of the Ph.D. degree in the Dep. of Agronomy at Kansas State Univ.
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