Masters Theses

Date of Award

3-1977

Degree Type

Thesis

Degree Name

Master of Science

Major

Biosystems Engineering

Major Professor

C. H. Shelton

Committee Members

J. I. Sewell, B. A. Tschantz

Abstract

A field containing approximately 12 acres of corn and located on the University of Tennessee Holston farm was selected for this study. The objectives of this study were (1) to determine the effects of soil moisture variation due to topography and soil type, (2) to determine the effects of soil moisture variation on corn yield, and (3) to compare observed soil moisture deficiency occurrence with those predicted by using a soil-moisture balance procedure. Twenty-five soil moisture access tubes were installed throughout the field after April 30, 1976, on which date the corn was planted. Weekly moisture measurements were made during the corn-growing season. Corn yield (green matter basis) was determined on August 10, 1976. Lindside silt loam had the highest average soil moisture during the growing season, followed by Altavista loam and Huntington silt loam, in that order. Corn yield was influenced little by soil moisture differences among soil types. An analysis of variance was applied to the yield data for the three months of the growing season. This analysis indicated that the soil moisture level within different elevation ranges did not significantly relate to the corn yield. Based on the results of this one-year study the following conclusions were reached; 1. The influences of soil type and elevation range on yield were not significant in this year of study probably because precipitation level was 1.6 inches above normal during the growing season. 2. Corn yield increased as moisture content approached field capacity throughout the soil profile. 3. Soil moisture was greater in sites located on level ground where frequent ponding occurred. 4. The predicted and measured soil moisture were in close agreement except during the first month of the growing season. 5. Soil moisture deficiency occurred in the upper foot of the soil profile, while moisture excess occurred at depths of two and three feet. 6. The actual number of soil moisture deficit days was 42 in contrast to 20 predicted days of soil moisture deficiency.

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