Horses and cows love it, but what is alfalfa? Is it the same thing as hay? What about straw? Let’s find out!
To start, hay refers to any member of the grass or legume families that have been mown and dried as fodder, or animal feed. You can find oat hay, wheat hay, ryegrass hay, clover hay, timothy hay, alfalfa hay, and others. Straw, or stover, refers to the dried stalks leftover after harvesting grains, such as oats and rye. Straw is generally used as bedding, though it can be used as a low quality feed. Alfalfa stover makes a good bedding for rabbits, guinea pigs, and hens.
Alfalfa is a legume, like peas and beans, but it grows more like oats or barley. Native to southwestern Asia, alfalfa is primarily grown as fodder for livestock. It is either dried and baled, or fermented as silage. Many gardeners are finding that alfalfa’s deep roots and nitrogen-fixing ability make it an excellent cover crop or green manure.
Alfalfa (Medicago sativa) is a flowering perennial in the pea family. Alfalfa was first farmed, over 6,000 years ago, in Iran. Then the Persians took this valuable crop to Greece around 500 BC. The Latin name, Medicago, refers to the ancient people of Iran, the Medes. The Arabic word for this crop, al-fiṣfiṣa, is what gives us our common American name for it. The rest of the world has been calling it lucerne, but that is slowly changing as more of the world’s alfalfa crop is grown in California.
The alfalfa plant
As a perennial, alfalfa plants grow for an average of 4 to 8 years, though they can live for 20 years. These deep-rooted plants, while only 3 feet tall, can reach down as much as 49 feet to find water! I guess it’s safe to assume that they are drought tolerant. In fact, alfalfa is rated as drought-resistant, meaning it can go for long periods of time without any water at all. Most of the time, alfalfa roots only go 6 to 9 feet deep, which is still pretty impressive, when most annual vegetables only root 6 to 12 inches down. Once established, alfalfa plants create a sturdy crown at ground level. Much like sorghum, these crowns contain bud shoots that make it possible to harvest a crop only to have a new one grow.
Alfalfa is usually mown 3 or 4 times a year, but it can done up to 12 times a year, in an ideal microclimate. Overgrazing, or over-harvesting, can damage the crown. After flowering, pollinated flowers produce spiraled fruits that contain 10 to 20 seeds. Alfalfa plants uses chemicals to prevent other alfalfa plants from growing nearby. This is called autotoxicity. It is triggered after the first seeding of an alfalfa plant and it continues for the remainder of that plant’s life. because of this, crop rotation with corn, wheat, or other crops must be used before replanting an area with more alfalfa.
Nutrients in alfalfa
Alfalfa is a highly nutritious plant. It contains high levels of protein, fiber, and carotenoids. Alfalfa is highly combustible and it can cause bloating when eaten fresh, by livestock, so it is normally dried first. Alfalfa, like other legumes, also has root nodules that contain beneficial bacteria, Sinorhizobium meliloti, that are able to convert atmospheric nitrogen into a form usable by plants. You can buy alfalfa meal, as a nitrogen source, or you can grow your own.
How to grow alfalfa
Alfalfa, like wheat, can be sown in either spring or autumn. These plants need a neutral soil pH of 6.8 to 7.5 to thrive. Other factors are less important. Alfalfa uses a lot of phosphorus and potassium, but our Bay Area soil tends to have both in abundance. (See Soil Test) Alfalfa seeds are planted 1/2 inch deep and should be spaced at 6-inch intervals. When farmers plant alfalfa, they use a machine, called a drill, that inserts a single seed at the right depth and spacing, as the farmer drives over a field. Since alfalfa is sensitive to weed competition in its early development, the proper spacing is rather important.
If you are growing your own alfalfa for the first time, use 1/4 pound of seed over a 25 square foot area (or 20 pounds of seed per acre). Planting it will take some time, because these seeds are really tiny, so put on some music and wear a hat. Alfalfa does not grow well on slopes or in areas with shallow soil. [Raw, unsprouted alfalfa seeds contain chemicals that can be toxic to humans, causing lupus-like symptoms, so don’t eat them. Also, there is no scientific research to verify medical claims made about alfalfa or its sprouts. Leave alfalfa to your soil and the livestock, where it belongs.]
Alfalfa pests and diseases
Blister beetles, thrips, spider mites, weevils, armyworms, nematodes, cutworms, grasshoppers and crickets, leafhoppers, and aphids are all attracted to alfalfa. Alfalfa is prone to several root rots, such as rhizoctonia, phytophthora, and Texas root rot. Other alfalfa diseases include fusarium wilt, downy mildews, anthracnose, bacterial wilt, and verticillium wilt. Since alfalfa, along with clover, rye, and other legumes can host bean mosaic, it is a good idea to keep some distance between them and your bean crops. Also, voles, pocket gophers, and ground squirrels can be major alfalfa pests.
Alfalfa as insectary and habitat
Insectaries are plants that attract and provide for insects. Alfalfa’s purple flowers are a big favorite of honey bees and other pollinators. Commercially, alfalfa and cotton are intercropped because of predatory insects attracted to alfalfa help to protect the cotton crop. Alfalfa also provides food and habitat to over 130 bird species and many other forms of wildlife. Alfalfa flowers are responsible for the majority of the honey produced in the United States. That being said, it ends up that bees and alfalfa don’t necessarily play well together. The structure of an alfalfa flower makes it so that a western honey bee gets knocked in the head each time they land on a flower. Apparently, bees don’t like getting knocked in the head, so they sip alfalfa nectar from the side of the flower, foregoing the pollen transfer. Since it takes young bees a few knocks to the noggin to learn this trick, pollination still occurs, but only because beekeepers make sure there are plenty of inexperienced bees in the hive when they service alfalfa fields. Alfalfa leaf cutter bees do a much better job of pollinating alfalfa than honey bees.
Even if you only have a driveway or fence strip, try your hand at planting some alfalfa. It will improve the soil, attract pollinators, and it needs no care at all, once it is established.
You can grow a surprising amount of food in your own yard. Ask me how!