Masters Theses

Date of Award

5-2006

Degree Type

Thesis

Degree Name

Master of Science

Major

Environmental and Soil Sciences

Major Professor

Joanne Logan

Committee Members

Richard G. Buggeln, Jaehoon Lee, Paul Denton

Abstract

Crushed gypsum wallboard (CW) is a plentiful calcium and sulfur rich product that has been used as a soil amendment. CW is an excellent source of Ca and S that can help improve soil structure, increase infiltration rate, ameliorate subsoil acidity, and decrease surface crusting enabling the soil to supply more water to the crop through infiltration and better conditions for root growth. However it may cause magnesium deficiency in certain crops. In this study ground gypsum wallboard as a soil amendment at varying rates was investigated on typical Tennessee soils planted with fescue, tobacco, and sweet potato. Data collected included crop yields and soil physical and chemical properties such as bulk density, water content, pH, Ca, Mg, and K. Five experiments were conducted, pm fescue sod, tow on tobacco, and one on sweet potatoes. Tobacco and fescue experiments were conducted at the University of Tennessee Highland Rim Research and Education Center, experiments with fescue and sweet potatoes were conducted at the Tennessee State University Research and Demonstration Farm, and an experiment with tobacco was conducted at the University of Tennessee Research and Education center at Greeneville. In the fescue experiments CW was surface applied to fescue sod at three rates (0, 22, and 45 Mg/ha) in fall 2004. In the tobacco experiments, CW was surface applied and incorporated into the soil at three rates (0, 22 and 45 Mg/ha incorporated) and applied to the surface without incorporation at the 22 Mg/ha rate in spring 2005. in the sweet potato experiment, CW was applied a the same treatments as with tobacco, with an addition 22 Mg/ha treatment of a CW and wood mixture (CWW) incorporated into the soil, in spring 2005. In all cases, the CW treatments were compared to a no CW check. Results showed no detrimental effects of CW on crop yield. Soil pH was generally decreased by CW, but the decreases were small (0.1 to 0.3 pH units), and not detrimental to crop growth. Soil Ca was shown to increase at the soil surface with CW. In most cases, there was also an increase in subsurface Ca. A definite increase in exchangeable soil Ca was found from early season to after season soil samples at the surface and subsurface depths, indicating the much of the gypsum may have remained in the solid phase at the early sampling date. The Ca movement suggests the dissolution and leaching of gypsum had occurred in a short period of time, less than one year after application. The total increase in exchangeable Ca was less than the total Ca added, indicating that a large proportion of the gypsum added was still in the solid phase and available for continued dissolution over time. Soil Mg levels were found to be deficient in both fescue experiments at HR and TSU. K levels were shown to decrease when CW was applied, especially in the fescue and sweet potato experiments at TSU. Soil water content increased slightly and soil strength decreased, in some cases significantly, which could be beneficial to plant growth. Bulk density showed little decrease when CW was incorporated into the soil. From the results obtained by this study, using CW as a soil amendment not only helps waste management but can benefit the soil for a long period of time. Future studies should conduct plant analyses for possible deficiencies caused by the high rates of CW, collect more water data, and conduct the study for more than one year. It is probable that the short time frame in which the study was conducted may have prevented the effects of CW from being fully expressed.

Download
Files over 3MB may be slow to open. For best results, right-click and select "save as..."

Included in

Life Sciences Commons

Share

COinS