Cover Crop Seed Germination As Affected by Swine Manure Under Controlled Conditions.

Cover crops improve soil quality through increased organic matter, biological activity, aggregate stability, water infiltration, and nutrient cycling. Understanding the germination characteristics, thresholds and limits of different cover crop species is important in the adoption and increased use of cover crops as a sustainable farming practice. Co-application of swine manure (Sus domesticus) and cover crops, known as slurry seeding, represents an opportunity to expand the use of cover crops as it can be a means of saving fuel, time and labor. Slurry seeding represents a promising practice if manure-seed interaction is properly understood. Cover crop species were evaluated under controlled environmental conditions to compare the effects of salinity, manure immersion/interaction, and manure components on cover crop seeds germination. Seed germination was greatly reduced 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 germination; germination percentages for all species in salinity conditions of 5.0-8.5-11.0 mS•cm-1 ranged between 80-100% germination, a reduction of 20% could be acceptable in the slurry seeding practice. Immersion periods of <1 hr in manure, resulted in no negative effect in all species germination rates and percentages and in some cases germination rates actually increased (faster germination). Based on results Cereal Rye and Oilseed Radish with a mixing time of <1 hr. represents the best species to be used for slurry seeding.