The speaker line up here at the National No-Tillage Conference (NNTC) is super and the first day's program was excellent. Lots of discussion related to improving soil health through no-till. An evening session on cover cropping was particularly good with lots of advice on how to work cover crops into a no-till crop rotation program.
Dan Towery discussed how incorporating cover crops is truly a journey that can take many years--say 15--to reach what he calls the maintenance phase. He thinks of it in four phases:
- phase 1 (initialization: soil structure improves, though additional nitrogen may be needed for the cover crops initially)
- phase 2 (transition: organic matter is accumulating, microbial activity increases, phosphorus accumulates, and nitrogen is immobilized, plus there's more N mineralization)
- phase 3 (consolidation: more organic matter accumulates, more water is available in the soil, cation exchange capacity (CEC) increases, and nutrient cycling is improved)
- phase 4 (maintenance: a continuous flow of N and C in the soil, greater water availability, high nutrient cycling, with increases in N and P)
Eileen Kladivko, an agronomist at Purdue, in a super talk walked the audience through the decision matrix for selecting a cover crop mix. She mentioned a cover crop decision tool offered by the Midwest Cover Crops Council (MCCC). This is a very powerful tool that can help demystify the many considerations involved in determining what cover crop system is best in a particular situation.