Legumes are amazing plants. They are unique in their ability to gather nitrogen from the atmosphere and convert it to a form beneficial to the plant. The legume achieves this through the activity of bacterial colonies, (nodules), which form on the roots when the proper strain of rhizobia bacteria is present in sufficient number in the soil upon germination of the legume seed. Some legumes are very efficient at gathering nitrogen and convert enough to supply their own needs as well as those of surrounding plants.
All legumes bear fruit in the form of a pod containing seeds. These plants may be annuals, perennials, or biennials, and include some shrubs and trees. Legumes also include a great number of ornamental plants and plants valued as sources of such products as dyes, drugs, resins, perfumes and wood. They also include some of the most important of all food and forage crops, such as; clovers, peas, beans, alfalfa, peanuts, and soybeans. Many legumes are exceptionally rich in proteins and are practically the only non-meat source of some of the amino acids essential to mans diet. Unfortunately, not all legumes are beneficial. Some can be aggressive weeds (such as Kudza) and many are poisonous to grazing livestock (loco weed, crolateria, etc.).
Before low-priced nitrogen fertilizer greatly reduced their usage, many legumes were utilized as green manure crops. Increased fertilizer prices, along with our recent concern and awareness of ground water nitrate levels and stream pollution due to erosion runoff, may result in tremendous demand for legume crop seeds in the coming years.
Many legumes are utilized in pure stands or in combination with grasses for grazing and/or hay production. When utilized in combination with grasses, legumes increase forage yield and protein content, improve palatability and digestibility of grassland forage, supply nitrogen, improve soil structure, and can substantially increase carrying capacity of pastureland. However, if legumes are to co-excist with grass and be productive, the grass/legume mixture requires good soils with good to excellent drainage and relatively high pH values. While legumes provide their own nitrogen they are generally heavy users of other nutrients, in particular potassium and phosphorous.
Inoculation is the practice of introducing commercially prepared rhizobia bacteria into the soil. This may be accomplished by applying the proper amount and strain of bacteria to the seed prior to planting or by metering the inoculant into the furrow at planting. All legumes should be inoculated before planting. While most soils contain rhizobia bacteria, the strain may be poorly suited to the legume in question (improper strains can be lazy or parasitic to the host crop). Even in those instances where a specific legume crop, such as soybeans, are grown continuously on a particular field, it's a good practice to inoculate. The population of rhizobia bacteria in any given soil is strongly influenced by environmental factors. Heat, dryness, low organic matter, and acidity are detrimental to the survival of rhizobia bacterium. Producers are definitely not penalized by an overabundance of rhizobia in the soil. On the other hand, if populations are inadequate, legumes may starve from a lack of nitrogen.
Korean lespedeza (Lespedeza stipulaces) was introduced to this country in 1919 from Korea. Day-length and temperature influence the vegetative growth, floral initiation, and seed maturation. It is a short day cultivar. That is, plants remain vegetative until day length shortens sufficiently to initiate flowering. When Korean lespedeza is grown at more northern latitudes, floral initation and seed maturation are delayed because its critical photoperiod occurs late in the season. If taken too far north, frost will kill plants before they mature seed. In the more southern latitudes, the high temperatures become the limiting factor in the use of Korean lespedeza. High temperatures reduce the number of days between flowering and maturity. Vegetative growth is retarded when seedlings emerge before the day-lengths in spring are equal to or greater than the critical photoperiod. Thus, Korean lespedeza has a rather narrow band of adaptation; from northeast Oklahoma, through eastern Kansas, to southern Iowa and east to the Atlantic Ocean.
Unlike red clover or alfalfa, Korean lespedeza is a warm-season annual legume. Capable of producing nitrogen in excess of its own requirements, Korean lespedeza is an excellent supplement to cool-season pastures in eastern Kansas. In spite of the fact that it is an annual, Korean lespedeza is very persistent. Natural reseeding from hard seed results in good stands year after year as long as competition is not too severe.
Kobe Lespedeza is resistant to bacterial wilt and tar spot, unlike Korean Lespedeza. The major concern with Kobe is that it matures later in the season than Korean and so may not produce seed before the first killing frost. Kobe usually produces acceptable amounts of seed if not subjected to an unseasonably early frost.
Birdsfoot trefoil (Kitus corniculates L.) grows on many varied soil types, from clay to sandy loams. It will grow on shallow, infertile, acid, or mildly alkaline soils, mined land, and tolerate water logged conditions. However, it is most productive on fertile, moderately well drained soils having a pH of 6.4 or higher.
In Kansas, birdsfoot trefoil is limited to the eastern 1/4 of the state. Only the "Empire" type cultivars should be used.
Mature plants of birdsfoot trefoil have many well-branched stems arising from a single crown. Under favorable conditions the main stems may obtain a length of 24 to 36 inches. The leaves are compound and alternately attached on opposite sides of the stem. During darkness, the leaflets fold around the petiole and stem. When cut and dried for hay, the leaves wrap around the stems, giving the impression of excessive leaf loss.
The inflorescence is an umbel (like a carrot) having four to eight florets. Flower color ranges from light to dark yellow and may be tinged with orange and red stripes. Pollination of flowers is dependent upon insects. Ten to fifteen seeds are borne in long cylindrical pods, which turn brown to almost black at maturity. Three to five pods are attached at right angles to the end of the flower stem and are arranged so that they impart the appearance of a bird's foot. Pods ripen 25 to 30 days after pollination. They split along both sides when mature and twist spirally to scatter the seed.
Birdsfoot trefoil possesses a well developed tap root system that penetrates deeply. There are numerous lateral branch roots in the upper 15 inches of soil. Roots have the ability to produce new shoots and roots.
The nutritive value of birdsfoot trefoil is equal to or exceeds that of alfalfa. Hay yields are usually 50% to 80% that of alfalfa.
Use and Management:
In Kansas, usage of birdsfoot trefoil for pasture far exceeds its utilization as hay or silage. Once established and properly managed, it is very persistent and can increase pasture yield four to five fold. Birdsfoot trefoil blooms intermittently throughout the summer. It often sets seed on low-growing stems, even when closely grazed. This ability to reseed itself greatly enhances its ability to persist year after year. Birdsfoot trefoil pasture can be stockpiled because it retains its high quality leaves on mature growth. Also, birdsfoot trefoil continually produces new shoots from axillary buds as the stems mature.
Rotational rather than continuous grazing is preferred. Rotational grazing systems allow long periods of photosynthesis to build root carbohydrate reserves between defoliation periods. Since carbohydrates reserves stored in the roots are relatively low under warm to hot growing conditions, the rest periods provided by rotational grazing are very important in Kansas.
When utilized for hay, birdsfoot trefoil can provide two or three crops per year depending upon growing conditions. While pure stands provide excellent quality forage, associated grasses contribute to higher forage yields by filling in vacant areas. Grasses in association with birdsfoot trefoil also reduce lodging, decrease severity of soil heaving, and speed hay harvesting and curing. Non-competitive grass that are of high quality, such as timothy, do not depress the forage yields of birdsfoot trefoil, and generally result in greatest success.
Hairy vetch (Vicia villosa) is cold-hardy annual legume adapted over a wide area of the United States. Hairy vetch tolerates poorly drained and acid soils much better than most other legumes. Plants are vining with stems that attain lengths of two to six feet. The stems bear pinnate leaflets and terminate in tendrils that wrap tightly around surrounding plants. Purple flowers are borne in clusters and pods are elongated and compressed. Seed is round or oval and grayish black in color. The name hairy vetch is a misnomer as plants are nearly hairless.
Hairy vetch seeds shatter quickly after pods mature. However, it is fairly "soft-seeded" (having little or no seed dormancy) and does not dependably reseed and therefore should be replanted every year.
Hairy vetch can increase carrying capacity and quality of grass forage substantially, as-well-as reduce the need for commercial nitrogen fertilizer. With nitrogen fertilizer prices expected to escalate in price in coming years, hairy vetch usage will likely increase.
Use and Management:
Hairy vetch is widely utilized for pasture and hay. In Kansas, hairy vetch is often seeded with winter rye or winter wheat for winter pasture. The following spring this mixture is either grazed out, or cut for hay, haylage or silage. Rye generally produces more forage in the fall than does wheat, however, wheat can provide up to two weeks longer grazing in the spring. Hairy vetch used in this manner serves to increase both forage yield and quality.
Likewise, hairy vetch can be seeded into permanent pasture to increase carrying capacity and forage quality. In pasture situations, grazing of hairy vetch should not begin until the plants are at least six inches tall. It should not be grazed lower than the lowest leaf axil as axillary buds will be removed, greatly slowing regrowth. If hairy vetch is utilized for hay, the optimum yield and quality is obtained when cut in the early bloom stage.
Recently, much attention has been given to using hairy vetch as a biological nitrogen producer for row crops. In this system, hairy vetch is seeded in pure stands and is grazed through the winter and early spring. It is then treated with an appropriate contact herbicide and corn or grain sorghum is no-tilled into the vetch. Hairy vetch utilized in this manner can produce 80 to 100 lbs. nitrogen per acre for subsequent crops.
Crown vetch (Coronilla varia L.) is a long-lived perennial legume which spreads by creeping under-ground rootstocks. It possesses a deep penetrating taproot and numerous branch roots. Stems are hollow, semi-decumbent and may reach a length of four feet. Flowers range in color from white to purple with various shades in between. Seeds are borne in pods that are divided into 3 to 12 single seeded sections. Seeds are mahogany in color and are rod-shaped.
Crown vetch is widely renowned for its ability to hold soil on severe slopes and is widely used on highway right-of-ways. Valued for erosion control on steep embankments, mine spoil areas and other disturbed sites; crown vetch is potentially an important forage species for eastern Kansas. Is also serves as an ornamental ground cover.
While established plants are tolerant of moderately acid and infertile soils, it is best suited to well-drained, fertile soils with a pH of 6.4 or higher.
Use and Management:
In Kansas, crown vetch is most commonly utilized for pasture. Forage yields are equal to or superior to other more commonly grown pasture legumes. Improper grazing management can greatly reduce stand persistence. Rotational grazing, with rest periods sufficiently long enough (30 to 40 days) to replenish carbohydrate reserves in the roots, are necessary to maintain stand productivity.
When utilized for hay, two harvests per season may be attempted. Seasonal trends of carbohydrate reserves in the roots are similar to those of alfalfa. The first hay crop should be taken when crown vetch is in full bloom. This allows better regrowth as the number of axillary buds producing regrowth is highest at this time.
In addition to crown vetch's utilization as a forage legume, it is also widely used for erosion control, highway beautification, ornamental ground cover and wildlife plantings.
Winter Field Peas
The winter field pea (Pisum sativum) is a cool-season annual legume with sufficient winter hardiness for the southern 1/2 if Kansas. Similar in appearance to the garden pea, winter field peas are vining with seeds borne in pods. Flowers are purple and seed color is mottled gray. Root growth is massive providing excellent erosion control and soil improvement.
Well-drained clay loam soils of limestone origin are best for field pea production. Soil drainage should be good to excellent as field peas will not tolerate water-logged conditions. Therefore, heavy clay soils should be avoided. High temperatures can severely injure the crop. Field peas perform best in cool temperatures when rainfall is fairly abundant during the fall, winter and spring months.
A very versatile crop, winter field peas are utilized for hay, silage, crop rotation, cover crop and soil improvement. Planted in late summer (August/September) the crop protects the soil from erosion during the winter and spring months and then can be turned under as a green manure crop.
Use and Management:
In Kansas, winter field peas are most often used as a cover crop, protecting the soil from erosion during the fall and winter. The following spring (late March or April) the peas are turned under as a green manure crop. In this management system, much greater benefit will be achieved if plants are allowed to reach maximum growth. Forage yields often double by delaying harvest from early March until April. Winter field peas managed in this manner will provide roughly 40 lbs. nitrogen for subsequent crops.
Winter field peas produce a forage of very high quality. When peas are utilized as a forage legume, best performance is obtained by growing them in association with small grains. Winter pea/small-grain combination provide excellent grazing, hay, or silage. The grain stems help support the pea vines, reduce lodging and make a better balanced feed. For optimum hay or silage production and quality, harvest should begin when the first pods begin to appear.