Crop Comments: Harness Buckwheat to Mine Complexed Soil Nutrients (for Free)

The U.S. plants significantly less acreage of this summer annual than it did a century ago. Buckwheat was once a much more widespread crop before the late Industrial Revolution introduced new technologies.

The center-point of such technologies were fertilizers based on chemical ingredients which increased productivity and profitability of staple crops like wheat, corn and soybeans. But those fertilizers were increasingly accompanied by chemical weedkillers, which buckwheat is very vulnerable to. This “advancement” substantially decimated buckwheat production.

In America, while over a million acres of buckwheat were harvested in 1918, by 1954 this crop’s acreage was pared down to 150,000. Today, American farmers grow about half that figure.

But several factors have revived interest in the culture of Fagospyrum esculentum (buckwheat’s scientific name). With extreme weather conditions becoming increasingly common, growers need to explore options to extend or introduce new forages into livestock rations. Such need encourages these crop people to introduce buckwheat to crop rotations and livestock programs.

Buckwheat claims several pluses in the realm of cropping economics – a subject which has soured in recent weeks, due to the geopolitical mess in the Middle East which has magnified fertilizer costs. Such expense worries, associated with fertilizer-hungry crops, are compounded by climate uncertainties.

F. esculentum is a moisture-loving, cool-climate, summer annual grain. Historians believe buckwheat cultivation began in Southeast Asia 5,000 – 6,000 years ago. From there it spread to Central Asia, Europe and ultimately North America in the 1600s. It’s one of the quickest-growing green manure crops, needing only four to six weeks from planting to flowering, plus another four to five weeks to seed maturity. It suppresses weeds, protects soil from erosion, attracts beneficial insects (especially honeybees) and builds organic matter.

It repels weeds through allelopathy, meaning it secretes chemicals serving as natural herbicides, thus discouraging many other plant species. Allelopathic, it may be used as a smother crop, choking out most weeds. It competes well, because it germinates rapidly and its dense canopy shades the soil.

Buckwheat’s name is derived from the seed’s appearance, similar to beech tree seeds. The German words for beech and wheat are Buche and Weiz. But rather than being in the wheat grouping, it’s actually part of the rhubarb family (technically considered a fruit). It’s slightly related to Japanese bamboo.

Agronomists at University of Wisconsin-Madison show that buckwheat’s dense canopy rapidly shades the soil, choking out most weeds while hogging solar radiation from less aggressive plant species. It fights quackgrass in the Northeast, particularly if the field has been thoroughly tilled to break up that stubborn perennial’s sod. Ideally, such fields are autumn-plowed or early spring-plowed, then disked or field-cultivated just before planting. According to weed scientists, buckwheat stands can successfully eradicate Canada thistle, sow thistle, creeping jenny and Russian knapweed.

F. esculentum also increases the bioavailability of phosphorus (P) and some micronutrients for crops following in the rotation by liberating complexed soil nutrients through acidulation.

Plants with this trait boast roots tips that secrete malic and citric acids, which chemically separate P and the traces from soil particles. Thus released, these nourish the buckwheat, usually with enough liberated elements left over to feed the rotation’s next crop.

However, buckwheat doesn’t fix nitrogen, so modest doses of manure prior to planting prove beneficial. Its mature seed averages about the same amount of protein (12% 13%) as most other small grains.

A broadleaf annual crop, buckwheat normally grows two to three feet tall, with a single succulent stem and several branches of flowers, varying in color from white or light green to sometimes pink or red. It forms a dense, fibrous root system, with a deep taproot. Most of its roots are concentrated in the top 10 inches of soil. Its biomass (total dry matter/acre) is usually 2,000 – 3,000 lbs. Very attractive to honeybees, this crop also invites wasps and parasitic flies.

It has two major shortcomings: intolerance to frost and extreme susceptibility to herbicide residue. This latter weakness caused buckwheat acreage to plummet since World War II. Many of the chemicals used to make wartime munitions were diverted to ag chemical production – a change to which buckwheat did not adapt.

Plant this crop up till July 15, particularly on land that has been unproductive, overtaken by goldenrod and burdocks.

Growers should prepare a good seedbed, but don’t pulverize it. Plant like other small grains, drilled or spun on, but only 50#/acre. Drag in lightly if spun on but, again, only 50#/acre. Buckwheat tolerates pHs of 5.0 – 6.0 as well as generally low fertility. It’s a great way to bring back abandoned fields (once any herbicide has had enough time to dissipate).

In terms of human health benefits, University of Illinois scientists found that dark-colored honey (especially that produced with nectar from buckwheat blossoms) can contain 20 times as much antioxidant as what’s found in paler honeys. Antioxidants are the body’s first defense against free radicals producing inflammation and tissue damage. Although increasing antioxidant levels won’t reverse existing free radical damage, it can prevent further cell deterioration.

Buckwheat packs antioxidant power similar to that found in vitamin C provided by ripe tomatoes.

I’ve had good luck recommending folks plant 30 – 40 lbs. of Japanese millet and 20 lbs. of buckwheat per acre. Buckwheat liberates nutrients for millet through acidulation. Its allelopathy discourages weed competition. Interestingly, allelopathy does not throw a curve to millet seedlings.

Another successful recommendation has been a blend of oats, tillage radishes and buckwheat.

I’ve recommended 5 lbs. of radish seed, 25 lbs. of buckwheat and a bushel of oat seed per acre. The buckwheat dies with the first killing frost, but by that time it will have achieved its acidulation and allelopathy missions. Then the radishes do their soil penetration thing, accompanied by the oats.

When it gets really cold, on the other end of the growing season, radishes and oats call it quits. But all three crops have done a great job of maintaining ground cover, quietly self-composting under the snow.

by Paris Reidhead