A Method for Studying Corn Root Distribution Using a Soil‐Core Sampling Machine and Shaker‐Type Washer 1

UMEROUS methods have been employed to study the N root systems of plants in soils. Pavlychenko ( 5 ) reviewed the methods used prior to 1937 and described the soil-block washing method. Weaver and Darland ( 8 ) , studying soil-root relationships of native grasses in various soils, developed a method of sampling root systems of grasses by taking large soil monoliths of any desired depth and washing the roots contained therein free of soil. Fehrenbacher and Snider (1) used essentially the same method, as used by Weaver and Darland, to study corn root penetration and distribution in various soils. In the present study of corn roots, samples around corn hills were obtained by use of the soil-core sampling machine of Kelley, Hardman, and Jennings (3). One of these machines belonging to the Agricultural Research Service of the U.S.D.A. at Urbana, Ill., was used. The objective in using it was the development of an easier and quicker method of sampling roots by soil horizons. Soil cores for sampling roots have been used previously by Laird ( 4 ) and Fitspatrick and Rose ( 2 ) . They, however, used steel cylinders or steel pipes driven into the soil and had no convenient way of relating root development to soil profile characteristics. In addition to sampling with a power-driven core sampler, a shaker-type washer was used for removing soil from the roots. Previous methods of washing roots have depended largely on a stream of water from special hose nozzles to dislodge soil. Upchurch (7) developed a soilelution method of washing roots which avoided the loss of roots caused by directing a stream of water under pressure on a soil-root matrix resting on a screen. The shakertype washing method described here depends on gentle shaking action of a soil-root-water mixture to put the soil into suspension before it passes through a 16-mesh screen. Water under pressure is not required.