“Traditionally, forage stands have been terminated in the fall by using one of three approaches – tillage only, herbicide application combined with tillage and herbicide application followed by direct seeding into sod,” says Mark Cutts, crop specialist at the Alberta Ag-Info Centre. “The main advantage of fall termination is the ability to establish a good seedbed with tillage or – in the case of direct seeding – allowing the sod to decompose.”
While spring termination of hay land is an option, producers need to be aware of a number of factors that will affect its success. The ability to manage these factors will influence the success of seeding annual crops into spring-terminated hay land.
“One factor that must be managed properly is soil moisture,” says Cutts. “In many areas of the province, conservation of spring moisture is essential for crop establishment.”
Utilizing multiple tillage operations to prepare a seedbed will reduce available soil moisture. The preferred method of establishing annual crops in spring-terminated stands is a herbicide application followed by direct seeding into sod.
Cutts says that producers also need to be aware that spring termination of hay land will delay the date of seeding. “For herbicide applications to be effective, sufficient plant material must be present.”
Grasses should be at the three to four leaf stage, and legumes need to be actively growing to allow for good herbicide coverage. Seeding will also be delayed three to five days after the herbicide application to allow thorough translocation into the plant. This will result in seeding delays of two to three weeks as compared to a fall-terminated stand.
Control of the forage species in the hay stand is essential in order to reduce yield loss due to competition with the growing crop. A high rate of glyphosate – up to 720 g of active ingredient per acre – can be applied to the hay stand once sufficient growth is present. If regrowth of the forage species occurs after emergence of the annual crop, producers then need to assess the weed spectrum and determine if a suitable in-crop herbicide option exists.
“Establishing good soil to seed contact is critical to the success of the seeded crop,” he says. “With sod seeding the most consistent results have occurred with cereal crops compared to a smaller seeded crop, such as canola. The larger seed size associated with cereals allows seeds to be placed beneath the thatch layer into soil where good soil-to-seed contact occurs.”
Cutts adds that evaluating the fertility of the soil is important. “Nutrient levels are commonly deficient on older hay stands and will need to be addressed when seeding an annual crop. It is recommended producers collect a soil sample to properly evaluate fertility requirements.”
“Seeding annual crops into spring terminated hay land poses a number of challenges and is a riskier option as compared to seeding into fall terminated hay stands,” he says. “To manage these risks, producers need to recognize these challenges and adopt the appropriate crop management techniques.”