Red clover blossoms in a field

Cameron Ogilvie, Cora Loucks, Heather Beach, Peter Johnson, and Ralph Martin. 2020. Survey of interseeded red clover management and perceived challenges by Ontario wheat growers. Canadian Journal of Plant Science. doi:10.1139/cjps-2020-0039.
Research summary by Cameron Ogilvie

Key Messages

  • According to farmers, the top disadvantage of interseeding red clover is nonuniform stands
  • Growers using higher red clover seeding rates, tillage, and wider winter wheat row spacing were less likely to report issues with nonuniform stands
  • Future research should evaluate the impact of red clover seeding rate, tillage, and winter wheat row spacing on stand uniformity

Fewer and fewer Ontario farmers are frost seeding red clover into winter wheat. Red clover fits well in in the rotation and has many benefits – improving soil health, suppressing weeds, providing a nitrogen credit for the following corn crop. But patchy stands are a challenge for growers because they undo many of the benefits farmers look to receive from planting red clover. Previous research hasn’t shown any silver-bullet solutions.

To address this, researchers from the University of Guelph went to Ontario wheat farmers for answers. In the summer of 2017, they distributed a survey with the help of farm organizations and agronomists. The survey asked questions about farmers’ wheat and red clover management and invited perspectives on the cause of patchy red clover stands. They received 142 responses across the province, mainly from southwestern Ontario.

What they found

When asked about the disadvantages of interseeding red clover, 75% of farmers said nonuniform stands. Red clover seeding rate appeared to affect stand uniformity. Half of the farmers who seeded at 10 kg ha-1 or greater identified nonuniform stands as an issue; this increased to 78% for farmers using a rate less than 10 kg ha-1.

When it came to winter wheat management, the number of farmers identifying nonuniform stands as an issue decreased as tillage increased. Several farmers also commented that they believed their no-till system was to blame for patchy red clover stands. They thought crop residue was preventing good seed-soil contact, and earthworms or other soil biology might be burying or eating red clover seeds. Some farmers commented that when another crop in their rotation required tillage (eg. edible beans) their red clover had better success.

Farmers were also more likely to identify nonuniform stands as an issue in narrower compared to wider winter wheat row spacings. Competition between the wheat crop and red clover was also a commonly cited explanation for patchy red clover stands.

Why it matters

These survey results suggest that increasing red clover seeding rates, tillage, and widening winter wheat row spacing may improve success with interseeding red clover into winter wheat. Intuitively these make sense, but survey results are not enough on their own to guarantee success. Part of the challenge with the survey was that certain management practices were clearly dominant (eg. 97% of farmers broadcasted red clover seed) leaving alternative practices not well represented. Future research should test whether red clover seeding rates, tillage, and wider wheat row spacing do improve red clover stand uniformity.

How they did it

Researchers developed an online questionnaire with 41 questions on objective and subjective aspects farmer experiences interseeding winter wheat with red clover. The survey was distributed to farmers through personal communication, newsletters, and over social media. The researchers received 199 survey responses; 20 responses were removed because they were either outside Ontario, did not identify their county, or did not have experience interseeding winter wheat with red clover. This left 179 respondents: 142 who were currently practicing interseeding winter wheat with red clover, and the rest who had previous experience. Descriptive statistics were analyzed in Microsoft Excel, and quotations were sorted by themes according to the survey ID numbers.

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