Anne Verhallen, Soil Management Specialist – Horticulture, OMAF and MRA, Ridgetown
Recent cool temperatures make it seem like it is still spring – but summer is just around the corner. As those early crops like peas, radish etc. are harvested, consider planting a cover crop. High prices for soybeans may be luring you to double crop but consider the cost. Here is a wonderful opportunity to give something back to your soil – to ensure long term productivity through the use of soil building cover crops.
Common warm season options include:
Pearl Millet
Considerations:
- A warm season grass with tremendous growth potential, relatively drought tolerant
- Plant shallow, preferably with a drill, 9-12 kg/ha
- Requires some nitrogen to achieve maximum growth
- Be prepared to mow every 4 to 5 weeks if you want manageable residues, leave at least 20 cm of growth to ensure regrowth
Sorghum Sudan
Considerations:
- Another warm season grass with tremendous growth potential, relatively drought tolerant
- Plant shallow, preferably with a drill, 15- 25 kg/ha
- Requires some nitrogen to achieve maximum growth
- Be prepared to mow every 4 to 5 weeks if you want manageable residues, leave at least 20 cm of growth to ensure regrowth
- Can be cut and baled or ensiled for livestock feed. Delay cutting if it has been exposed to freezing temperatures.
Buckwheat
Considerations:
- Warm season broadleaf
- Very frost sensitive
- Aggressive growth habit, good at shading and suppressing weeds
- Sets seed in less than 6 weeks
- Do not include in mixtures
- Drill in seed at 45- 50 kg/ha
- Fairly tolerant to most vegetable herbicide carryover i.e. Dual, Sencor, Command, Treflan
Dry soils are a common challenge when establishing summer cover crops. Where possible use a drill to seed to ensure good soil to seed contact. Control volunteer wheat to reduce competition with the cover crops as they establish.
There are always other options for summer cover. Summer seeded wheat or cereal rye will cover the ground, not go to seed and put down an extensive root system. Spring cereals will grow but growth may be sparse. Avoid brassicas like cover crop radish or mustard during the heat of the summer as they do not tolerate hot temperatures well and will tend to bolt and flower.
Mixtures of cover crops are another early summer option. Poor growth from cool season cover crops like peas, brassicas and spring cereals is compensated by more aggressive growth from warm season cover crops in the mix like sorghum, beans, millet and others.
For more options take a look at the Midwest Cover Crop Council’s Cover Crop Decision Tool at http://mcccdev.anr.msu.edu/VertIndex.php.