Date of Award

2013

Degree Type

Thesis

Degree Name

Master of Science (MS)

Department

Agronomy

First Advisor

Eileen J. Kladivko

Committee Chair

Eileen J. Kladivko

Committee Member 1

James J. Camberato

Committee Member 2

Brad C. Joern

Abstract

Cover crops improve soil quality through increased organic matter, biological activity, aggregate stability, water infiltration, and nutrient cycling. Slurry seeding, the co-application of cover crop seed and swine (Sus domesticus) manure, is a new practice that saves fuel, time and labor. High salinity and/or ammonia, among other components in swine manure, may reduce cover crop seed germination and limit the use of slurry seeding. Ten cover crop species were evaluated to compare the effects of swine manure components on cover crop seed germination. Seed germination percentages and rates were affected by swine manure but not by equivalent salinity levels established with Sodium Chloride. Thus, the salinity component of swine manure is not likely a large contributor to the negative effects of manure on the germination of some cover crop seeds. Pre-soaking seeds in solution had an effect on germination of cover crops, and thus a mixing period of ≤1hr is suggested for the practice. Nitrogen ammoniacal gaseous forms resulting from volatilization after manure applications had an inhibitory effect on germination of cover crop seeds and may be the driving factor reducing germination. Anaerobic like conditions also reduced germination. A rainfall event within the first week after slurry seeding may be critical in order to achieve a good establishment of the crop. Field scale trials showed that surficial slurry seeding may reduce germination by up to 50%. Surficial slurry seeding in farmer trials showed that cover crop treatments had greater yield than the matching no cover treatments, possibly due to increased nutrient cycling and other benefits from cover crops. Cover crops also reduced the yield differences between low N and high N treatments, possibly due to greater nutrient capture and cycling. Slurry seeding has potential to facilitate cover crop establishment but needs further evaluation to optimize its performance.

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