When it comes to seeding for swath grazing, an Alberta Agriculture and Rural Development specialist says that barley can be seeded by the middle of June while triticale, oats, and oat/barley mixtures can be seeded as early as the first week of June.
“We’ve had a nice, open spring this year and as many producers are finishing up their grain and oilseed planting, others are starting to think about seeding their swath grazing sites,” says Barry Yaremcio, beef and forage specialist, Ag-Info Centre, Stettler. “One of the more common questions we have been getting at the Ag-Info Centre is when to best seed a swath grazing crop.”
Yaremcio says several studies across Alberta and Saskatchewan tend to tell the same story. “The later you seed the less you will get. Those late-June early-July plantings miss several weeks of the best growing conditions and are likely to obtain yields that are two-thirds of a May seeded crop. For most, this is likely a loss of one ton per acre. For example, most barley varieties need approximately 1250 growing degree days (GDD) to reach the soft dough stage. Based on the average values for the Red Deer area if you seed on July 1, you are going to obtain the heat units by the end of September. Hopefully you haven’t run into a hard frost by then.
“If you back up your planting date to the middle of June you are approaching the 1,250 GDD mark by the middle of September. While you may consider seeding even earlier it is a fine line between going for the best yield and having a high-quality swath come December. Central Alberta can have enough rainfall and heat in late August and early September to cause significant spoilage. The cooler temperatures of late September tend to reduce the amount of quality loss and mould growth in the swath, particularly among those mold varieties which could be harmful.”
Aside from the big yield losses, another penalty for seeding too late can be a higher accumulation of nitrates in the crop, particularly July seeded oats. While the base levels for nitrate toxicity are likely a little too conservative when applied to swath grazing, there are so many variables that producers should take the test results seriously until they have a chance to discuss it with their vet or nutritionist.
“Less likely, but still a factor to consider, is the effect light frosts and near freezing temperatures can have on the mineral content of plant tissue,” says Yaremcio. “Cold stress on immature plants followed by a few days of decent growing weather may cause plant potassium levels to increase while sodium, calcium and magnesium tend to drop. From your cow’s dietary point of view this can be less than ideal and may cause tetany concerns.”
All of these factors lead Yaremcio to his recommendations for when to seed swath grazing sites. “Ideally, you want to plant early enough to take advantage of spring moisture, but late enough that you are swathing the crop just before the killing frosts of fall. To have the best combination of yield and quality barley and triticale should be swathed early dough, while oats must be cut in the milk stage. Research data from Lacombe indicates that in most cases, barley could be seeded by the middle of June. Triticale, oats, and oat/barley mixtures would be okay seeded as early as the first week of June.”