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Alfalfa

Almost certainly, Swiss farmers gave the world alfalfa. When they noticed (five hundred years ago) that their cows thrived on meadows and hay that had the most Lucerne (their common name for alfalfa), they grew more of it and have cultivated it ever since. (My books still give “Lucerne” as one of several common names used today.)

Originally a native of western Europe, alfalfa now is grown around the world for forage and hay and is the most widely-grown member of the legume family worldwide (ahead of the mighty soybean). In North America it grows across the U.S. and Canada, almost to the Arctic Circle.

Farmers prize alfalfa for hay because it is high in protein and a good complement to grass. Dairy cows give more milk when fed alfalfa hay, which can be made four times a year in the best fields. Farmers also include alfalfa in crop rotations such as wheat for a year, corn for a year, alfalfa for a year, to renew and build the soil.

Alfalfa grows so thickly that weeds struggle for enough nourishment to make seeds. Meanwhile, after its year in rotation, alfalfa leaves residues in the soil that stunt any new weeds.

Alfalfa is a perennial herbaceous legume, that is, a member of the pea family like soybeans, green beans, fava beans and many other cultivated plants (even wisteria). It goes dormant over winter, when its leaves and stems wither to the ground. In spring, new stems emerge from the main root, grow up to three feet tall, with branches that end in clusters of small, violet, pea flowers, followed by pea-like seed pods and small, hard seeds (that we sprout by the hundreds for our sandwiches).

In good conditions, alfalfa plants live twenty years and longer, ideal for farming. They do best on well-drained, neutral soils, as do the rhizobial bacteria that make their living by forming nodules on the roots of many legumes, capturing nitrogen from the air and binding it in forms that nourish the host plants, which in turn share their sugars and starches with the bacteria. This happy symbiosis is the main source of alfalfa’s contribution to soil health. Another is alfalfa’s vigorous roots, which can roam five feet deep and ten wide, opening channels in the soil for rain and improving tilth as they decay.

The herbicide glyphosate (Roundup) kills almost all plants except those with modified genes (so-called Roundup Ready crops). The U.S. Department of Agriculture has approved a Roundup Ready alfalfa that many organic growers fear will pollinate and alter their non GM alfalfa and thus render their crops non-organic. The likelihood is small, but the risk is great.

Because alfalfa grows far and wide, the National Phenology Network (USA-NPN) has designated it a “Calibration” species, meaning a plant that USA-NPN volunteers (thousands of scientists and amateurs) observe to mark events in its life cycle. For alfalfa the events include the first sign of green in spring, the first flower, the first seed pods, and the first mature seeds.

We gardeners already use our own rough kind of phenology to time our garden chores, but the data the USA-NPN collects will sharpen our timing and our successes, as well as tell us how the climate is changing.

By Mark Kane - the Groundskeeper, YourGardenShow.com

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