Alternatives to reseeding old forage stands

By Dennis Haak, District Soil Conservationist, PFRA

In the past it has been fairly common practice to reseed forage stands every five to ten years, especially those used for hay production. Reseeding often involves numerous field operations such as cultivating, harrowing, seeding and packing. The cost of all these operations can easily reach $50 to $80 per acre.

However, recent research suggests that in many cases fertilizer, spiking, and proper weed control may restore and maintain productivity at a fraction of the cost of breaking and reseeding.

A fertilized forage stand will usually result in increased forage yield and protein content, improved soil organic matter, and possibly a longer stand life. Annual fertilizer requirements range from 30-70 pounds of nitrogen and 10-30 pounds of phosphorus (P₂ O₅) per acre. No nitrogen fertilizer is required for fields with alfalfa, sweet clover, or sainfoin, if the seeds were inoculated with nitrogen fixing bacteria. More accurate fertilizer recommendations can be obtained with a soil test.

It's usually better to band fertilizer to a two to three inch depth, than to broadcast it on the surface. Banding will reduce losses of nitrogen to the atmosphere, and increase the effectiveness of phosphorus due to its slow mobility in the soil. Banding should be done when plants are dormant. It is also better done when the soil is moist, to minimize root disturbance and plant injury. Application of higher rates of fertilizer only once every three years may be an option over annual applications.

Recent surveys suggest that most farmers do not fertilize forages. While some research suggests that fertilizer may not result in economic yield increases in dry years, most of this fertilizer will remain in the soil and be available for future years. As nutrients continue to be removed through forage harvesting, the economics of adding fertilizer should improve in the long term. Farmers may find that applying lower rates of fertilizer may still provide some benefit, and not be as hard on their cash flow situation.

Spiking is often practised when plant populations become very dense. This condition can occur with most forage species, but is common with bromegrass and crested wheatgrass. This tillage operation utilizes narrow shovels or spikes to uproot and kill up to one-half of the plant stand. The resulting lower plant population reduces the competition for moisture and nutrients by individual plants. It also allows for the release of plant nutrients from soil organic matter that was stored in the spiked soil.

Spiking should be done when plants are dormant (late fall or early spring), under moist but not wet soil conditions. One or more follow-up operations with harrows or a land leveller is usually needed to smooth out the soil surface. In some cases, combining a spiking with banding fertilizer, all in one operation, may provide an added benefit.

Very few herbicides are registered for established forage stands, due to a number of factors. Many forage stands contain both grass and alfalfa, which makes it almost impossible to develop a broad weed spectrum herbicide that will not harm the forage. Also, some herbicides leave a residue on the surface of leaves which may be harmful to cattle as forage feed.

Nevertheless, some herbicides may be useful for specific annual grassy or broadleaf weeds. Generally, perennial weeds like quackgrass are difficult to control without also killing the forage.

Weed prevention is easier and less costly than control. The following suggestions will prevent weeds from developing into widespread problems:

• Allow forage stands to regrow before winter. Do not overgraze or cut hay in fall.
• Cut hay crops before weeds set seed.
• Localized patches with poor forage or increasing weed populations should be reseeded with proper weed control in advance.

Forage stands will require reseeding when plant densities become too low or perennial weeds become too numerous. With the recent drop in the price of glypho-sate herbicide, some farmers have considered spraying out weed infested areas and then direct seeding forages. This method may provide better weed control than tillage and be less costly if several tillage operations are eliminated. However, it may not work in very thick weed infestations (e.g. quackgrass patches) due to poor seed placement.

The potential benefit of these practices may depend on circumstances unique to your land. It is always good to test a new idea on a small strip of land.

For more information on forage selection, contact the PFRA office in your district.