Date of Award

2017

Document Type

Open Access Master's Thesis

Degree Name

Master of Science in Biological Sciences (MS)

Administrative Home Department

Department of Biological Sciences

Advisor 1

Casey Huckins

Committee Member 1

Andrew Burton

Committee Member 2

Kari Henquinet

Abstract

In the low-fertility soils of Senegal, West Africa, management of woody species in agricultural fields has the potential to improve soil fertility and crop production. However, optimal species for this purpose have not been clearly defined. Thus, the objective of this study was to evaluate the potential for two native woody species, Combretum glutinosum and Piliostigma reticulatum, to improve soil fertility. Soil samples were collected from beneath tree crowns of P. reticulatum and C. glutinosum and compared with fertilizer-amended and non-amended soil from adjacent open fields in a bioassay experiment. Two common crops, millet (Pennisetum glaucum) and maize (Zea mays), were grown in soil samples and crop growth and biomass production were measured as indicators of relative soil fertility. Maize biomass and growth parameters were greater in soils from beneath P. reticulatum as well as in field soil amended with chemical fertilizer. However, most parameters of millet growth and biomass did not respond to differences in soil chemistry. Chemical analyses determined that most soil fertility indices were greater in soil from beneath P. reticulatum and C. glutinosum than in adjacent open fields. Net nitrogen mineralization however was only significantly greater in soils from beneath P. reticulatum. While the study results indicate that both woody species can positively influence soil fertility, P. reticulatum shows greater potential for soil fertility improvement that can enhance crop production; and fertilizer treatment had a greater overall positive effect on fertility and bioassay crop production than the woody species.

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