Impact of Weather on Dry Forages and Pastures

Producing enough stored forage to feed livestock can be a challenge in dry years. Dry weather during the pasture "summer slump" can quickly force people to prematurely use up their stored forage supplies. Management strategies can help ensure adequate feed going into the winter. These include good alfalfa management, potato leafhopper control, rotational grazing, supplementing pastures with hay, restricting livestock to a sacrifice paddock with full feed, and the use of corn silage. The Forage Rainfall Insurance Program is available from Agricorp with an enrolment deadline of May 1.

In Ontario, first-cut yields are largely a function of temperature, whereas second and third-cut yields are more limited by available moisture. One-half to two-thirds of total yield is typically from the first-cut. First-cut yields were quite variable across Ontario in 2007, ranging from 75 to 120 per cent of a typical yield, depending on winter survival, temperatures and moisture. In extremely dry areas, second-cut yields have been reduced by up to 100 per cent. At this time, forage inventories going into the winter feeding period are difficult to predict. Spring carry-over forage inventories were above average in many parts of the province due to excellent 2006 yields. As many areas are now receiving rain, pastures may recover and reasonable third-cut yields may be possible. In southern Ontario, corn silage provides an excellent opportunity to supplement forage inventories.

Management Factors

• If there is adequate alfalfa growth to economically justify cutting, and a 30 to 40 day harvest interval can be maintained, cutting is recommended.
• Where the crop has reached the flower stage without adequate volume for harvest, there won't be a lot of additional growth even if the field receives rain. In these cases, clipping the top growth will encourage growth of new crown buds, resulting in an increase in forage yield.
• Potato leafhopper (PLH) damage on alfalfa is greatly underestimated. PLH feeding affects the transportation of fluids and nutrients in the plant and significantly worsens the effects of dry weather. New seedings are very susceptible. PLH can be managed by scouting and spraying at threshold levels, and by the use of PLH resistant varieties.
• Vigorous forage stands with good plant health resulting from good fertility, variety selection (disease resistance, persistence), drainage and weed control usually have better dry weather tolerance. Healthy plants with a good root system are better able to withstand dry conditions. Stands with chronic root and crown rots are often not able to withstand extended dry periods.
• Stands with an early first-cut harvest date generally have more summer regrowth, and may enable a successful third-cut harvest.
• Pastures that are over-grazed will take much longer to recover from extended dry conditions. Managing pastures to maintain a 3 to 4 inch (7 to 10 cm) residual will aid in plant recovery and help to retain any soil moisture.
• If feed is in short supply consider using non-traditional sources of pasture, such as summer-planted annuals, and grazing hay fields to extend the pasture.

  For more information on dry conditions and low water go to our website at www.ontario.ca/crops and click on the Adverse Weather button.

Related Links

• Dry Weather Information

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