Dealing with moisture stressed perennial forages

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Source: Alberta Agriculture and Forestry

Determining the right time to cut a hay stand could mean the difference between harvesting a second cut or the stand becoming dormant.

“A lack of sufficient moisture stresses plants, and that is certainly apparent this spring,” says Karin Lindquist, forage and beef specialist with Alberta Agriculture and Forestry.

“Plants that do not get enough moisture are usually stunted and are forced to set seed earlier than normal. Management considerations – for hay production especially – when faced with such issues are timely.”

All plants strive to produce seed regardless of present conditions. Plants experiencing stress from lack of moisture are at risk of dying. As a result, they need to produce seeds as soon as they possibly can. Once they have accomplished this stage, they go dormant – usually for the remainder of the year.

Lindquist says that it is a distinct disadvantage to allow plants to reach seed set when growing a forage stand for hay or pasture. “Even when moisture is adequate later in the growing season, it is unlikely the mature plants will regrow. If any regrowth does occur, it will primarily be from tillers.”

“Alfalfa plants that are cut when they reach 30% to 50% bloom – one plant with an open blossom compared with three to five other plants – or grasses when they are almost ready to flower, will be encouraged to restart regrowth. By the time the rains arrive, the plants will be able to take full advantage of the sudden arrival of moisture to provide greater yields than the previous first cut.”

She notes that when cutting short and moisture-deficient hay crops, the volume of hay to be harvested may be insufficient. “Some of that cut forage may need to be left behind to break down.”

Attempting to harvest as much hay as possible from the swaths carries risk of kicking up soil into the bales, and that can cause white mould issues that are only realized once those bales are fed to livestock.

“While the hay may cause some feed refusal, soil-borne molds typically do not contain mycotoxins,“ she says. “However, feed quality can certainly be reduced by 10 to 20% or more.”

Lindquist adds that fertilizing forage stands when there is a lack of moisture is a waste of money. “At least a half-inch, 1.25 cm, of rain is needed in less than 12 to 24 hours for fertilizers to be able to dissolve and get absorbed by the roots. Fertilizer left on the soil surface without the timely rains can result in almost half of the fertilizer to be lost to the atmosphere.”

Contact

To connect with the Alberta Ag-Info Centre:

Hours: 8:15 am to 4:30 pm (open Monday to Friday, closed statutory holidays)
Toll free: 310-FARM (3276)

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