When are companion crops needed under Oklahoma conditions? 

EXPLANATION: Companion crops are not necessary for establishment of alfalfa as once believed, hence the obsolete term nurse crops. In most situations, the most profitable way to establish alfalfa is without a companion crop. 

With the advent of herbicides, the use of companion crops for weed control has decreased drastically; however, they are still useful in some situations to control soil erosion. 

Sandy soil is prone to blow when the surface dries, and blowing sand particles can destroy small alfalfa seedlings. Having a large-seeded crop that emerges quickly and has upright growth protects the soil surface and decreases the movement of the sand particles. In some cases where soils are very sandy, companion crops such as sudangrass or forage sorghum are planted in widely spaced rows several weeks before the fall planting of alfalfa. 

Another reason to have a companion crop would be on sloping areas where soil erosion by water could result. The slow top growth of alfalfa with its tap root system does not provide much protection against water erosion. 

Volunteer wheat and weedy grasses such as cheat are also effective in reducing water and wind erosion. On erosion prone areas, letting the weeds grow for a month or so provides good ground cover and increases the odds of getting a good stand of alfalfa. 

In the northern part of Oklahoma, having a companion crop could also decrease the heaving action resulting from repeated freezing and thawing of wet soils. Heaving is usually not a problem in seedling alfalfa in Oklahoma since there is usually good ground cover by alfalfa. 

ADDITIONAL INFORMATION: Companion crops actually compete with seedling alfalfa for water, plant nutrients, and light, just like weeds. Thus, the best companion crops are ones that are least competitive or ones that die a few weeks after planting alfalfa. 

Fall-sown alfalfa in Oklahoma usually has at least some volunteer wheat. These plants are frequently helpful at first and serve as a companion crop. After a few weeks wheat plants act as weeds, competing with alfalfa seedlings.

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What is the best companion crop for establishing alfalfa? 

EXPLANATION: Oat is the most widely used companion crop for spring-planted alfalfa in the USA. Oat plants are not as leafy and competitive as most other small grains. In addition, oat can be removed early and provides a valuable source of feed as well as bedding for livestock. Seeding rate for oat is usually about the same as oat grown alone (70 - 100 lb/A). 

For fall-planted alfalfa, foxtail millet, sometimes called German millet, is a good companion crop because it will provide upright growth early and then is killed by frost. Foxtail millet, sown with or before alfalfa, at 2-3 lb/A can produced up to 1 ton/A of forage in years with late freezes. 

Special plantings of crops (sometimes considered companion crops) may be necessary on very sandy soils to control wind erosion during establishment of alfalfa. A couple examples for fall-planted alfalfa include: 

-- Planting strips (usually one row) of sudangrass or forage sorghum across the field every 50 feet. The strips should be planted several weeks before alfalfa and should be oriented perpendicular to prevailing winds. These companion crops die with the first hard freeze, but the stalks continue to serve as wind breaks. 

-- Planting of foxtail millet in early summer and taking a hay crop in August. Then alfalfa is planted directly into the millet stubble (see comments on establishment of alfalfa by no-till). This millet has very little regrowth after cutting and the stubble offers little problem to most alfalfa planters.

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