ESTABLISHING ALFALFA

[yellow]

How many alfalfa mature plants per square meter does it take to produce enough toxins to kill off alfalfa seedlings? Does anyone have any info on this?

Do other legumes have similar problems?

[emiled]

It's difficult to give an exact answer on the number of plants per square metre that it takes to kill off alfalfa seedlings. All I can tell you from the research I've read and the field experiences we've had, that the age of the stand, soil type and amount of precipitation will have some bearing. Mature alfalfa plants (dead or alive)do exude a toxin that produces an allelopathic or autotoxic response to new seedlings where their establishment can be severely limited. The younger and the thinner the stand, (from our field experience) the less of a problem. Research information suggests lots of moisture on well drained soils will help leach away the undesirable toxins.

If it is an old stand, my recommendation is not to plant alfalfa for at least one year, preferably 2 or more years.

I have not seen or heard of issues on other legumes that we grow in N. Central Alberta. I do know from the literature that this allelopathic effect from alfalfa can affect some types of weeds and there are also weeds that produce toxins that will limit alfalfa production. I have also seen references to other plants in other countries (thorn apple in Australia)that can produce these effects on establishing crops.

[calenso]

Does alfalfa have the same toxic effect on other legumes? On grasses?

[emiled]

The toxic effect only effects seedling alfalfa.

[sunnyacres]

What are some of the weeds that are toxic to alfalfa seedlings?
Are there advantages and/or disadvantages to mixing creeping and tap rooted varieties as far as hay production. We have moderate saline soil and not in a high rainfall area.