Document Type

Thesis - Open Access

Award Date

2020

Degree Name

Master of Science (MS)

Department

Agronomy, Horticulture, and Plant Science

Second Advisor

Peter Sexton

Keywords

Cover crops, Nutrient cycling, Residue quality, Soybean sulfur, Winter rye

Abstract

Winter rye (Secale cereale L.) has become an important cover crop in South Dakota; yet, concerns over negative impacts on cash crop yields is one important limitation to the widespread adoption of winter rye in cropping systems. Two field studies were implemented at the Southeast Research Farm near Beresford, SD investigating the impacts of five seeding rates (0-90 kg ha-1) and termination timings (April 19th- May31st) with the objectives of examining the roles of winter rye management practices on soybean production and yield from nutrient cycling of nitrogen (N) and sulfur (S) in the agroecosystem. Plant, residue, and soybean samples were collected at critical points to observe changes in nutrient fluxes between sinks in the agroecosystem while fiber concentrations of rye and residue materials were analyzed to understand how management practices influenced the dynamics driving nutrient turnover. Delaying rye termination beyond May 13th resulted in dramatic increases in rye biomass leading to greater nutrient uptake and lower residue quality while seeding rate did not affect biomass production until 90 kg ha-1 was applied. Later termination dates and the 67-90 kg ha-1 seeding rates contributed to greater nutrient immobilization in crop residues and slower nutrient release as compared to earlier terminations and the 22-45 kg ha-1 seeding rates. This resulted in a decreased soybean S in both studies at later terminations and higher seeding rates; however, high fertility soils at the research location contributed sufficient S to alleviate impacts on grain yield. Yield was unaffected by seeding rate treatment while later termination timings produced a yield advantage possibly as a result of delayed soybean development.

Format

application/pdf

Number of Pages

178

Publisher

South Dakota State University

Rights

In Copyright - Educational Use Permitted
http://rightsstatements.org/vocab/InC-EDU/1.0/

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