During the past week, many area dairy producers have been trying to dodge rain storms in an effort to harvest alfalfa companion crops of oats or oat and pea mixtures. It’s always a relief to me when these crops get harvested and the alfalfa is given a fightin’ chance to really get established before winter. I get very nervous when I see alfalfa established with a cereal that is to be harvested for grain and straw.
Using small grains to establish alfalfa is a long-standing tradition with Wisconsin forage producers. The advantages of using a companion crop are well documented and include excellent early season weed control, soil erosion protection, and the opportunity to harvest additional forage in the form of a small grain crop. On poorly drained soils, a companion crop can take-up excess soil moisture resulting in a less favorable environment for alfalfa seedling diseases such as phytophthora root rot, aphanomyces root rot, and pythium.
The point to remember is that a companion crop is always in competition with the alfalfa. The competition is for soil moisture, nutrients, and light ----- the three basic ingredients needed for a plant to grow. Because of this, anytime a companion crop is used the alfalfa stand is compromised. Thus, producers need to limit this competition but at the same time need to maintain the inherent advantages for using a companion crop and harvesting additional quality forage. Proper selection of companion crop species and varieties, and a timely harvest are the keys in accomplishing this goal.
Let’s talk about harvest time of the companion crop. Basically, there are three choices. The small grain can be ensiled or baled at the boot to early heading stages, or it can be harvested for grain in late-summer and the straw baled. Removing the companion crop early as silage or hay is clearly the option of choice if only the well-being of the alfalfa stand is considered. By doing so, the competition is removed early in the summer and the original goals of harvesting additional forage, obtaining early season weed control, and reducing the risk of soil erosion during the establishment phase are achieved. Also, another cutting of alfalfa is available before summer’s end.
What happens if we decide to harvest the companion crop for grain and straw? For the underseeded alfalfa stand, only bad things can happen from mid- to late-summer. These include:
1) severe moisture and light competition
2) lodging of the small grain and subsequent smothering of the alfalfa plants
3) insect infestations that injure or kill alfalfa plants (such injury usually goes undetected because of the standing small grain crop)
4) smothering of alfalfa plants if straw windrows are left in the field too long after grain harvest (it has also been suggested that a significant amount of insect damage occurs under the windrows), and
5) significant competition from volunteer small grain grass growth after the small grain harvest.
Many seeding-year alfalfa stands have been lost from one or a combination
of any of these factors.
|This alfalfa under oats looks good now but there's lots of time for things to go wrong. From the standpoint of the "money" crop, the oats should come off now.||This 1997-seeded alfalfa shows the effects of not being able to get the straw off in a timely fashion. Fields like this are not hard to find.|
Some producers are in the situation where they need or want the grain or straw and/or do not have the storage capabilities to remove the companion crop for silage. There are options for alfalfa establishment in these situations without using the small grain as a companion crop. First, continue to grow the small grain crop but manage it for maximum economic grain and straw yields. This is easier to accomplish when alfalfa is not underseeded. Second, establish your alfalfa without a companion crop in the spring where conditions permit or seed alfalfa during late summer following a winter or spring cereal grain harvest. Farm and research experience confirm that both of these establishment methods can be successful if proper management practices are followed.
Perhaps the time has come that more Wisconsin dairy producers consider establishing alfalfa without a companion crop. Until recently, this was a difficult statement to make simply because there were few good weed control options. In the past few years, both Pursuit and Select have been registered for new alfalfa seedings. Poast Plus has always been effective for grass control. According to Dr. Gordon Harvey, UW Weed Management Researcher, the herbicide Raptor may eventually be added to the new seeding alfalfa herbicide list. This year’s field plots at the Arlington Research Farm look very good. For many dairy producers, harvesting the small grain silage seems to be more of a chore than a welcomed forage source. Small grain silage often causes some real headaches from the standpoint of separating the silage from other high-moisture forage inventories. This seems to be especially true for producers who are harvesting more corn silage. Direct seedings of alfalfa offer the advantages of harvesting more high quality forage during the establishment year and increasing overall whole farm alfalfa dry matter yields.
Finally, I would remind producers that in any companion
crop situation, alfalfa is the “money” crop. Establishment costs
can only be regained when they are spread over several years of a vigorous
and productive stand. Time and money lost from an establishment-year
failure is never recaptured.