Effect of plant roots on chemical and biochemical properties of surrounding discrete soil zones

Abstract

Soil samples were taken from an Orthic Brown, Dark Brown, and Black Chernozemic Ah horizon and from the Orthic Dark Brown Chernozemic Ap horizons of the unfertilized part of a continuous wheat field and the fallow field of a wheat-fallow rotation, both under cultivation for 70 yr. The 2 grasses were blue grama Bouteloua gracilis and rye Secale cereale. High root densities were achieved by the end of the study, especially with blue grama. Changes in pH over time were slight but consistent; they decreased in the Black Chernozemic soil and increased in the other soils. Redistribution of labile P was caused by the presence of plant roots. The Orthic Dark Brown Ah and Ap horizon soils reacted differently to the conditions of the study. Monosaccharides always increased in the rhizosphere zone and generally decreased in the zone adjacent to the rhizosphere zone in the case of rye and in the outside zone in the case of blue grama. -from Author