Evaluation of Cover Crop Slurry Seeding On Germination Rates Under Controlled Conditions and Field Trials.

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 in swine manure may reduce cover crop seed germination and limit the use of slurry seeding. Ten cover crop species were evaluated under controlled environmental conditions to compare the effects of swine manure and salinity on cover crop seed germination. Seed germination percentages and rates were affected by swine manure but not by equivalent salinity levels established with NaCl. 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. Soaking seeds in manure for up to 4 hr did not inhibit and sometimes accelerated germination compared to the control, but soaking periods of 24 hr delayed germination. In field mini plots mixtures were slurry seeded into shallow cracks formed by drill. Germination in seeds that received some rain within 5 days of slurry seeding was not delayed or reduced, but those with the first rain at 7 to 14 days were inhibited to varying degrees. Field scale trials on producers’ fields were conducted in Putnam County, Indiana, in which annual ryegrass was slurry seeded with an Aerway unit with splash plates. Lack of fall rain severely reduced germination and growth, however, any germination was concentrated in small divots formed by the aerway, where the slurry mixture tended to accumulate. Further analyses of manure components such as ammonia are recommended for a better understanding of the effects of slurry seeding on cover crop germination.