Masters Theses

Date of Award

8-1996

Degree Type

Thesis

Degree Name

Master of Science

Major

Plant, Soil and Environmental Sciences

Major Professor

Henry A. Fribourg

Committee Members

Don Tyler, John Reynolds, John Waller, Garland Wells

Abstract

Researchers have become increasingly aware of root growth and development and their importance in plant growth. Marginal soils are prime areas in which to explore roots and their ability to withstand pressures and continue growth through fragipans, slate rock, and flooding of water tables. There are many diverse soils in Tennessee which are marginal. Planting row crops on these soils can cause erosion. Planting some other species could introduce root systems that help prevent erosion. Proper land management must be used. This study was initiated in 1983 by Fribourg and Wells on marginal soils. Twelve marginal soils were selected, but enough growth for data collection was obtained on only ten of these during the first 10- year period of the study. A Memphis soil, which is not classified as marginal, was used as a control site. The same four treatments were established on all soils: 1) 'Kentucky 31' tall Fescue (Festuca arundinacea Schreb.) infested with Acremonium coenophialum Morgan-Jones and Gams, 2) ‘Guymon’ bermudagrass (Cynodon dactylon L.) for hay production, 3) American sycamore (Platanus occidentalis L.) for biomass production, and 4) loblolly pine (Pinus taeda L.) for timber production. The grasses were harvested three to five times each year. Every other row of the American sycamores was harvested at the midpoint of the study, enabling the coppice growth to be taken into consideration at the conclusion of ten years. The second harvest collected coppice and 10-yr old trees in 1993. The loblolly pine growth measurements were taken at the same time as the sycamore data. Predicted pine site indexes (25-yr basis) ranged between 20.9 and 38.9 m. Mean survival at age 11 from seed was 89 and 94% for loblolly pine and American sycamore, respectively, on those soils where stands had been established successfully. American sycamore total dry weight yields, including the first cut weights and the second cut with both coppice and 10-yr old tree weights, ranged from 4.92 to 52.70 Mg/ha with a mean of 22.12 Mg/ha. The loblolly pines had much less variability among soil types than American sycamore. This difference is best explained by the adaptable nature of the loblolly pines to many conditions, whereas the American sycamore requires greater amounts of moisture and more favorable conditions for growth. The range of the mean yields for ten years of growth for the grass species (not including Memphis, the control site, and the Ruston soil, where stands were only 8-yr old) were, for tall fescue, 21.27 to 50.98 Mg/ha with a mean of 38.30 Mg/ha and for bermudagrass, 20.89 to 42.00 Mg/ha with a mean of 28.18 Mg/ha. Bermudagrass did not get established as easily in Middle and East Tennessee as in West Tennessee because of the cooler weather. The root analyses did not show as great a correlation between the number of roots and the yield of total biomass as had been expected. This was possibly due to insufficient data. Additional research concerning the potential economic benefits for landowners who put the findings of this study into practice will help to provide the necessary financial incentives for them to change their current practices.

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