Date of Award

2007

Level of Access

Campus-Only Thesis

Degree Name

Master of Science (MS)

Department

Plant, Soil, and Environmental Sciences

Advisor

Ivan J. Fernandez

Second Committee Member

Stephen A. Norton

Third Committee Member

Bryan Dail

Abstract

The use of organic residual materials, such as biosolids, is a common practice in agriculture while its use in forests is not. Currently in Maine, U.S., forest utilization of biosolids is regulated to specific limits that are based on agricultural experience with these materials. Recent regional interest has arisen in utilizing biosolids in forests. Research that has investigated biosolids amendments in forests has been region-specific and has primarily utilized either aerobically or anaerobically digested biosolids. Few studies have reported on the use of lime-stabilized biosolids in forests, especially in the northeastern U.S. The combination of an existing market interest in forest utilization of these materials and a lack of fundamental data addressing forest ecosystem response prompted a multiyear study. The objectives of this study were to (1) evaluate spatial and temporal soil pH response through a highly replicated sampling regimen that focused on the uppermost soil depths (2) measure changes in soil chemical response throughout the soil pedon (3) investigate treatment effects of trace element chemistry in the amended soil and (4) monitor foliar chemical response as a indication of initial biotic response to treatment. Eighteen plots were established in two phases at loading rates of 0 (control), 4.5, 6.7, 13.4, 20.2,26.9, and 33.6 Mg CCE ha-1 with the lowest rate representing the current regulated loading limit for forest biosolids applications in Maine U.S. Samples of the O-horizon and upper 5 cm of the mineral B-horizon were collected on a seasonal basis to characterize the temporal and spatial pH response to treatment. Foliage samples and full-pedon soil cores were collected annually to assess treatment effects on foliar nutrient concentrations, soil exchange chemistry, and soil trace elements. Initial response to treatment was characterized by significant neutralization of acidity in the O-horizon that migrated down into the upper mineral B-horizon over time. Soil pH response varied with loading rate and was primarily affected by chemical properties of the biosolids. Notable effects on soil chemistry included increases in O-horizon exchangeable Ca that resulted in corresponding decreases in exchangeable H and Al. Significant loading of trace metals was not apparent at any soil depth one-year after treatment. In general, foliar response corresponded to changes in soil exchange chemistry as Ca was the most notable nutrient increase in foliage. The lime-stabilized biosolids used in this study have potential for use in forest soil pH and nutrient management. However, future research should attempt to quantify tree growth response following forest biosolids applications and should also continue to monitor changes in soil chemistry. This research serves as a foundation for future studies that evaluate the usefulness of these materials in forest fertilization as well as for future regional C sequestration efforts.

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