Relation of fallow to restoration of subsoil moisture in an old alfalfa field and subsequent depletion after reseeding
1936
Grandfield, C.O. | Metzger, W.H.
In experiments conducted at Manhattan, Kansas, it was found that alfalfa cropping had depleted the soil of available moisture to a depth of nearly 25 feet. Clean fallow restored the available subsoil moisture to a depth of 25 feet in approximately 2 years and a subsequent seeding of alfalfa again depleted this moisture in about the same length of time. The conclusion is drawn, therefore, that 2 years of fallow were necessary to restore subsoil moisture on old alfalfa ground to a point where the roots of a newly seeded crop could penetrate through moist soil to a depth of 25 feet or more. Two years after seeding alfalfa the subsoil was depleted of moisture to a point near the wilting coefficient, making it necessary for the crop to depend on current rainfall, unless the root penetration had been deep enough to reach moisture at lower depths.
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