Tillage, Matric Potential, Oxygen and Millet Yield Relations in a Layered Soil

Abstract

ABSTRACT INTERPRETIVE SUMMARY WET soils caused by intensive rain or a series of rainy days affect plant growth in the Southeastern At-lantic Coastal Plains. In this region, certain groups of soils with compact layers compound the effects of soil wetness by impeding downward gaseous diffusion, water flow, root growth and, thus, the development of plant root systems. In a study of soil water, soil oxygen and plant growth relationships, millet growth was unaffected when the soil 02 concentration was greater than 15 percent. At 02 levels less than 15 per-cent in the soil, millet growth de-creased as 02 concentrations of the soil were decreased. In a Varina loamy sand soil, 02 concentrations decreased as soil matric potential increased within the range of -2 to -80 mb. Below this range « -80 mb), 02 did not vary with matric potential. These data suggest that the aeration status of this soil may be inferred from measurements of soil water status. Deep tillage improved soil aeration, and deep-rooted plants in deep-tilled soil were less affected by poor aeration than were shallow-rooted plants in conventionally tilled soil.