Masters Theses

Date of Award

5-2020

Degree Type

Thesis

Degree Name

Master of Science

Major

Plant Sciences

Major Professor

Virginia R. Sykes

Committee Members

Gary Bates, Xinhua Yin, David M. Butler

Abstract

The benefits of including a cover crop within corn and soybean production systems has been well-documented. However, there are many cover crop species which have not been examined for their suitability to Tennessee production systems. The objectives of this study were to 1) compare regional adaptability and impact on soil attributes and cash crop effects of select cover crop species and, 2) evaluate the forage quality and impact on soil attributes, and cash crop effects of using these cover crops as a spring forage. Sixteen cool-season annual species including legumes, cereals, and brassicas were evaluated for two seasons at three University of Tennessee AgResearch centers: East Tennessee Research and Education Center (ETREC), Middle Tennessee Research and Education Center (MTREC), Research and Education Center at Milan (RECM). Two cash crop rotations were used to represent common production systems in the Mid-South: soybean / cover crop / corn (S/cc/C) and soybean / cover crop / soybean (C/cc/S). Two management systems were included in this study: dual-use (cover crop harvested prior to cash crop planting) and single-use (cover crop chemically terminated before cash crop planting). Forage plots were only included at ETREC and MTREC. Cover crops were established at two different times in the fall and were evaluated for cover crop performance (ground cover, biomass at termination), forage value (yield, quality) , soil attributes (nutrients, pH, cation exchange capacity, moisture), and cash crop value (yield, quality). Cereals were a better fit in the S/cc/C rotation, as these species produced greater season-long ground cover and biomass at termination than the no-cover control. All species had good forage nutritive values in either crop rotation but covers in soybean/corn did not produce as much biomass as C/cc/S covers. The species produced 1936 to 3880 kg ha-1 of biomass and could be used as a spring forage in the C/cc/S rotation. No significant soil attribute or cash crop effects were observed. Through these studies, cover crop species were identified that are adapted to Tennessee corn/soybean and soybean/corn rotation systems and dual-use cover cropping was determined to provide high-quality forage without reducing short-term ecological benefits of cover cropping.

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