Birdsfoot Trefoil Uses: Planting Birdsfoot Trefoil As Cover Crop
By: Jackie Carroll
If you’re looking for a cover crop for difficult soil, the birdsfoot trefoil plant may be just what you need. This article discusses the pros and cons of using birdsfoot trefoil as a cover crop, as well as basic growing techniques.
What is Birdsfoot Trefoil?
Birdsfoot trefoil (Lotus corniculatus) is a plant with several agricultural uses. At least 25 varieties are available. Buying seeds from a local supplier ensures that you get a good variety for your area. For farmers, birdsfoot trefoil uses include:
- crop for cutting as hay
- livestock forage crop
- cover crop plant
Home gardeners grow birdsfoot trefoil as a cover crop. There are some advantages to growing this uncommon plant instead of traditional cover crops such as alfalfa and clovers. Birdsfoot trefoil plant is a good choice for difficult locations with wet or moderately acidic soil. It tolerates moderate levels of salt in the soil as well.
Birdsfoot trefoil also has some clear disadvantages. When the soil is good enough to grow alfalfa or clovers, these crops are better choices. Birdsfoot trefoil seedlings aren’t very vigorous, so the crop takes time to become established, and may become overrun with weeds before it takes off.
Growing Birdsfoot Trefoil as Cover Crop
If you’ve never grown birdsfoot in the location before, you’ll need to treat the seeds with an inoculum so that the roots can fix nitrogen. Purchase an inoculum labeled for birdsfoot trefoil and follow the package instructions, or use treated seeds. You won’t need treated seeds in subsequent years.
The best time to plant is in early spring, but you can also plant in late summer if the soil is damp enough. The seedlings need consistently moist soil as they become established. The advantage of planting in late summer is that there won’t be as much competition from weeds.
Smooth the soil and then firm it up before broadcasting the seeds over the planting area. Firming the soil with a roller as you would when planting grass improves germination by ensuring the seeds come in firm contact with the soil. Make sure the soil stays moist. A light sprinkling of soil over the top of the seeds improves germination.
Since it is a legume, birdsfoot trefoil contributes nitrogen to the soil. Although it doesn’t need nitrogen fertilizer, it may benefit from the addition of phosphorous. As long as the soil stays moist and the plot doesn’t become overrun with weeds, the crop is carefree.
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Bird’s-foot trefoil, (Lotus corniculatus), perennial herbaceous plant of the pea family (Fabaceae). Bird’s-foot trefoil is native to Europe and Asia and has been introduced to other regions. Often used as forage for cattle, it is occasionally a troublesome weed. A double-flowered form has been developed and is sometimes cultivated as a garden ornamental.
The spreading stem grows to about 60 cm (2 feet) long and bears compound leaves with three or five oval leaflets, broadest near the tip. The flowers, about 2 cm (0.8 inch) wide, are yellow, sometimes tinged with red, and grow in clusters of 5 to 10. The fruits are straight thin legumes the clustered pods somewhat resemble bird feet and are the source of the plant’s common name.
This article was most recently revised and updated by Melissa Petruzzello, Assistant Editor.
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Birdsfoot trefoil – a niche crop for wet, acidic soils
About 35 years ago, Jack Hudson of Dafter, Michigan, decided he wanted to farm. He chose to grow birdsfoot trefoil and raised as much as 1,000 acres at one point.
“I didn’t know much about farming, and I thought, ‘Well, here’s a specialty crop that I can learn in the limited amount of time that I have,’” Hudson says.
Birdsfoot trefoil worked well for Hudson. The soils in his area have a pH of 5.8 to 6.0, and trefoil will “tolerate a range of 5.5 to 7.5,” according to the National Resources Conservation Service plant fact sheet. However, trefoil does best within the range of 6.0 to 6.5 pH. This makes it a good alternative legume to alfalfa in acidic soils.
Trefoil also tolerates poorly drained soils. According to Dr. Richard Leep, a retired forage agronomist, trefoil is more resistant to many root rot diseases that affect alfalfa.
While many people find trefoil difficult to establish, Hudson says he finds it an easy crop to establish.
“If you plant it by itself, it’s not difficult to establish,” Hudson says.
It is typically grown with a grass to keep it upright, since it has a thin stem and tends to lie over. Hudson says he doesn’t find this to be a problem. If it’s used for pasture, the cows eat it anyway. When he harvests it for seed, he windrows it, which will pick it up, and then he uses a combine. Leep says that there may be a problem with lodging while making hay.
Hudson says, “A lot of times, people will plant it with red clover and timothy, or orchard grass, or something like that. It’s not as aggressive as some of those other crops. It’s slow to establish if you do that. We always do a clear seeding, 5 pounds to the acre, and we have never had a crop failure in establishment.”
Trefoil is, however, difficult to grow as a seed crop, and Hudson says he has had some crop failures harvesting the seed.
“There’s a good market for the seed. There’s a lot of seed grown in Wisconsin and southern Ontario, and there’s seed also grown in Michigan. That is generally sold to seed brokers, or buyers, and that seed is distributed throughout the U.S. and Canada,” Leep says.
But the right conditions have to be met to get a good seed crop.
“The problems are insect infestations and weather and pollination. This year was very dry, so we had a lot of small pods. Small pods give you small seeds and low germination. It’s one of the risks. If it’s too wet, we don’t get good pollination. If it’s too dry, we don’t get pods filled out. So there are lots of hazards with it,” Hudson says.
In the last five years, Hudson has cut down on seed production and rents his fields out for cattle and bison to graze. He says animals do well grazing trefoil.
Leep helped with a study where they compared the plant production and the gains of dairy heifers on three pastures – orchard grass, orchard grass mixed with trefoil and alfalfa mixed with orchard grass. The study was replicated three times.
“We found that the birdsfoot trefoil-grass yielded a little bit less than alfalfa-grass, but the animal gains were the greatest with birdsfoot trefoil,” Leep says.
Leep also did a study at the University of Michigan with dairy steers on trefoil, ryegrass and alfalfa mixed with ryegrass. Once again, the alfalfa mix produced the most forage, but animal gains were greatest with the trefoil.
Trefoil can’t be grazed as hard as alfalfa. Hudson says that he tries to leave at least 4 inches.
“If you graze it too hard, it will set the stand back. We don’t graze it right down to the ground. We’re particularly careful in the late summer and fall not to graze it back too far,” Hudson says.
If a pasture is grazed too hard, he has to use a no-till grain drill and seed the pasture to give it a boost. Otherwise, trefoil reseeds itself, and Hudson has some stands that are about 40 years old and haven’t ever needed to be replanted.
“Birdsfoot trefoil fills a nice niche. Where alfalfa cannot be grown successfully, birdsfoot trefoil can be grown successfully, and it will produce very good gains,” Leep says. FG
For more information about raising birdsfoot trefoil, check out the following resources:
- The National Resources Conservation Service plant fact sheet for birdsfoot trefoil (PDF, 96KB)
- Pennsylvania State University Extension – birdsfoot trefoil
- Purdue University Agronomy Extension – birdsfoot trefoil production
- The University of Vermont – “Birdsfoot Trefoil as a Grazing or Hay Crop”
PHOTO 1: Jack Hudson holds birdsfoot trefoil pods, which he's found works well for gain in cattle.
PHOTO 2: About 35 years ago, Jack Hudson of Dafter, Michigan, decided he wanted to farm. He chose to grow birdsfoot trefoil and raised as much as 1,000 acres at one point.
PHOTO 3: Jack Hudson and his grandson scout the fields for insects. Photos provided by Jack Hudson.
Bird's foot trefoil
Common Name: Bird's foot trefoil
Skill Level: Beginner
Exposure: Full sun
Soil type: Well-drained/light, Clay/heavy, Chalky/alkaline
Time to plant seeds: March to April
Flowering period: May to August
This spreading native perennial is normally found in grasslands. It has bluish-green, divided leaves. In spring and early summer, attractive double yellow, pea-like flowers appear, followed by black peapods of about 2.5cm. This species is ideal for a wildlife garden. Its height varies, from 5cm to 20cm, but stems can grow up to 50cm. The plant has a deep, branched root system and tolerates both wet and moderately dry conditions.
The height of the plant is variable, from 5 to 20 centimetres (2 to 8 inches), occasionally more where supported by other plants the stems can reach up to 50 cm (20 in) long. It is typically sprawling at the height of the surrounding grassland. It can survive fairly close grazing, trampling, and mowing. It is most often found in sandy soils. It flowers from June to September. The flowers develop into small pea-like pods or legumes.
The plant had many common English names in Britain, which are now mostly out of use. These names were often connected with the yellow and orange colour of the flowers, e.g. 'butter and eggs'. One name that is still used is eggs and bacon (or bacon and eggs). 
Lotus corniculatus has a broad distribution worldwide.   It is common everywhere in Britain.  It is abundant in Ireland,  and also in Northern Ireland, including County Londonderry, County Down, and County Antrim.  Habitats include old fields, grassy places,  and roadsides. 
It is used in agriculture as a forage plant, grown for pasture, hay, and silage. It is a high quality forage that does not cause bloat in ruminants.  Taller-growing cultivars have been developed for this. It may be used as an alternative to alfalfa in poor soils.
A double-flowered variety is grown as an ornamental plant. It is regularly included as a component of wildflower mixes in Europe. It can also prevent soil erosion and provide a good habitat for wildlife. 
Fresh bird's-foot trefoil contains cyanogenic glycosides,  which release small amounts of hydrogen cyanide when macerated. This is not normally poisonous to humans, though, as the dose is very low, and the metabolization of cyanide is relatively quick.  Condensed tannins are also present in L. corniculatus. 
In the traditional medicine of the Sannio regio of Italy, the diluted infusions were used for anxiety, insomnia, and exhaustion. 
The flowers are mostly visited by bumblebees.  In the Chicago Region, mostly non-native bees have been observed visiting the flowers, including Andrena wilkella, Anthidium oblongatum, Apis mellifera and Megachile rotundata.  The native bees Bombus impatiens and Megachile relativa have also been observed visiting birdsfoot trefoil flowers, though the latter only rarely. 
The plant is an important nectar source for many insects and is also used as a larval food plant by many species of Lepidoptera such as six-spot burnet and the silver-studded blue.  It is a host plant for the wood white butterfly, Leptidea sinapis. 
Birdsfoot trefoil is an invasive species in many parts of North America and Australia. It has been commonly planted along roadsides for erosion control or pastures for forage and then spreads into natural areas.   Once it has established in an area, it can outcompete native species.  The use of prescribed fire is not an effective management tool against Lotus corniculatus and herbicide is recommended to control it.