Impact of planting date on annual clover survival in oat

Authors: Anderson, Randal

Submitted to: Renewable Agriculture and Food Systems
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/1/2017
Publication Date: N/A
Citation: N/A

Interpretive Summary: Organic producers are interested in no-till systems, but they are concerned about controlling weeds without tillage. We proposed a complex rotation to reduce weed density in croplands, and our rotation includes a 2-year interval of cool-season small grains. This study showed that interseeding annual clovers into established winter wheat in mid-April will lead to the highest density of seedlings. However, dry conditions before wheat harvest severely reduced seedling survival. More drought tolerant clovers will be needed at this location for successful interseeding. If annual clovers can be found with more drought tolerance, this cultural tactic of interseeding will support our proposed rotation and enable producers to reduce tillage in organic farming. Systems with less tillage will be less damaging to soil health.

Technical Abstract: Interseeding annual clovers in cereal grains may help organic producers reduce the need for tillage in their cropping systems. In this study in eastern South Dakota, we evaluated seedling emergence and survival of two annual clovers in oat as affected by planting date. Berseem clover (Trifolium alexandrinum L.) and crimson clover (Trifolium incarnatum L.) were planted 0, 2, 4 and 6 weeks after oat (Avena sativa L.) planting. Berseem clover density was highest when planted 2 weeks after oat, whereas crimson clover density was the same at the first 3 planting dates. At oat anthesis, crimson clover comprised 4 to 5% of the plant community at the earliest planting dates, whereas berseem comprised 2% or less with all treatments. A dry interval during the 5 weeks preceding oat harvest reduced seedling survival of both clovers, killing more than 85% of berseem clover seedlings. Crimson clover was more tolerant of drought than berseem clover, but more than 60% of crimson seedlings still died. Oat grain yield was not affected by clover growth. Our results indicate that these clovers may not be viable for interseeding at this location. More drought tolerant clover species will be needed.