Semester

Fall

Date of Graduation

2006

Document Type

Dissertation

Degree Type

PhD

College

Davis College of Agriculture, Natural Resources and Design

Department

Horticulture

Committee Chair

William Bryan.

Abstract

growth and availability of forages. Cool-season perennial grasses are the basic source of feed for cow-calf production. Producers require information about incorporating annual forages into grazing systems during months of low productivity of the cool-season species. An experiment was conducted for two years (2004 and 2005) at Reedsville Experimental Farm, West Virginia University, to determine growth rate, herbage accumulation and quality of sudangrass, and pearl millet grown in summer and triticale and a mixture of annual ryegrass and turnips grown in the fall on the same land. Two methods of herbage control, burning and glyphosate, were used to kill existing vegetation before establishing annual forages. Three levels of N (0, 50, and 100 kg ha-1) were applied to each species. Sudangrass grown in summer produced the most forage mass and was of lower quality compared to pearl millet and naturalized pasture. Pearl millet was more susceptible to competition from other species than sudangrass. Rapid growth of both sudangrass and pearl millet occurred between 30 and 50 days after seeding. Nitrogen application increased forage mass for all forage species grown in summer and fall, and thus, resulted in greater economic return. In addition, N application hastened physiological maturity of both sudangrass and pearl millet. Forage accumulation from annuals established after glyphosate application was higher than from those established after burning. Use of glyphosate as a method of preplant vegetation control was more profitable than use of burning. Pearl millet established after burning failed to germinate due to competition from naturalized vegetation. In the fall, naturalized pasture and the mixture of annual ryegrass and turnip produced similar forage mass and more than triticale. As expected, the cost of seed and establishment cost for these fall annuals was higher than naturalized pasture. Some establishment costs were recovered when fall established annuals were harvested the following spring. Naturalized pasture that received 100 kg N ha-1 split into two equal portions and applied in summer and fall was ranked the highest in economic returns. A system where sudangrass was grown in summer and triticale in fall produced the highest economic returns when N was applied at the rate of 200 kg ha-1 and glyphosate was used as a method of preplant vegetation control. A system with sudangrass after glyphosate in summer and a mixture of annual ryegrass after glyphosate in fall produced the highest DM yields but, high cost of turnip seed lowered the economic ranking. In summer, sudangrass produced more DM than pearl millet, but the high cost of seed and high seed rate lowered its net return. Results of this study suggest that sudangrass can be used to supplement naturalized pasture in summer and triticale and a mixture of annual ryegrass and turnip in fall for both high quality and quantity. For higher productivity and economic returns, fall annuals can be harvested again in spring.

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