Year of Publication

2015

Degree Name

Master of Science (MS)

Document Type

Master's Thesis

College

Agriculture, Food and Environment

Department

Plant and Soil Sciences

First Advisor

Dr. Ben M. Goff

Abstract

Bermudagrass (Cynodon dactylon L.) is a perennial warm-season grass that is very responsive to nitrogen (N) fertilization. Excessive N applications have negative environmental consequences and make maintaining mixed swards difficult. This study determined the effects of enhanced efficiency (EE) N fertilizers and fertilizer rate on bermudagrass yields, nutritive values, and white clover persistence. Nitrogen sources included urea, urea formulated with Agrotain® (U+A), urea with Agrotain® and dicyandiamide (SuperU), a polymer-coated urea (ESN), ESN+urea (75% ESN, 25% urea), and methylene urea (MU). In the urea formulation trial, SuperU and U+A maximized forage yields at lower N rates. The dicyandiamide in SuperU did not increase yields over U+A. Highest production efficiency was achieved at lower N rates. ESN had the lowest relative stimulate growth, which may increase clover persistence. In the clover persistence trial, the addition of N fertilizer began decreasing clover populations after 112 kg N/ha. Slow-release fertilizers (ESN, ESN+urea, MU) had higher clover percentage at the final harvest. Crude protein and in vitro digestible dry matter increased, while neutral detergent fiber and acid detergent fiber decreased with the addition of white clover. SuperU and U+A were more efficient and ESN had lower relative stimulated growth beneficial for mixed pastures.

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