Pictured above is subterranean clover growing in Bermuda grass sod on our farm in north central Arkansas. This picture was taken on January 23rd, 2012 (2012 was a very mild winter.) The clover was planted in 1966.
Subterranean Clover
Subterranean clover or sub clover is an annual, winter clover that comes up from seed with the autumn rains and dies in mid-June after having buried its seeds in pods like peanuts. It originated in the Mediterranean region and is widely used as a pasture legume in Australia, north western California, and western Oregon. It is adapted to climates with mild, wet winters and hot, dry summers. In northern Arkansas the autumn rains can begin any time from late August to late December depending on the year. Our climate varies a lot from year to year. Some of our autumns are very wet and others are very dry. Some of our winters are very cold and others are very mild. The University of Aransas Extension service claims that subterranean clover is not suited for northern Arkansas. A plot of subterranean clover is located on our farm in north, central Arkansas, about twenty-five miles south of the Missouri border. We purchased this farm in 1967 from Floyd and Edna Kuhns, who had only owned it for two years. The Kuhns' had farmed in Oregon before moving to Arkansas. They thought that subterranean clover would be a good winter-forage for their livestock. They could not find seed in Arkansas so they had some seed shipped in from Oregon. They planted five acres of sub clover in the fall of 1966. They had a good stand of it when we first saw it in December of 1966. We took possession of the farm in August of 1967. In the autumn of 1967 only scattered plants of subterranean clover came up from seed. One of those plants proved to be very hardy, reseeding it’s self every year since then. It gradually spread. After fifty one years, plants from this one plant now cover an area of about one acre in our yard. This one plant must have been a mutation that is hardier than other subterranean clovers. We also have about an acre of this subterranean clover in our pastures. It continues to spread every year.
In northern Arkansas this strain of subterranean clover is one of the few legumes that will persist in heavily grazed goat pastures without being reseeded from time to time. Hop clover will also persist, but it has a very short grazing season (about 60 days.)
Sub clover does best with heavy grazing. It likes acid soils. It does best on soils with a pH of 5.5 to 6.5, but can tolerate a pH as low as 4.5. It grows six to eight inches tall. It sends out lateral branches up to four feet from a single taproot. These branches stay near the ground. They do not form roots, but they do bury seed pods. The flowers are hidden near the ground. They are self-pollinated. After pollination they grow down. The seeds are formed in pods just below the soil surface.
Subterranean clover is good at suppressing weeds and grows better than other legumes in dense Bermuda sod. All of the sub clover on our farm is growing in Bermuda sod.
In northern Arkansas this strain of subterranean clover is one of the few legumes that will persist in heavily grazed goat pastures without being reseeded from time to time. Hop clover will also persist, but it has a very short grazing season (about 60 days.)
Sub clover does best with heavy grazing. It likes acid soils. It does best on soils with a pH of 5.5 to 6.5, but can tolerate a pH as low as 4.5. It grows six to eight inches tall. It sends out lateral branches up to four feet from a single taproot. These branches stay near the ground. They do not form roots, but they do bury seed pods. The flowers are hidden near the ground. They are self-pollinated. After pollination they grow down. The seeds are formed in pods just below the soil surface.
Subterranean clover is good at suppressing weeds and grows better than other legumes in dense Bermuda sod. All of the sub clover on our farm is growing in Bermuda sod.
Subterranean clover is more tolerant of shade than other legumes. This plus the fact that it grows close to the ground, forming a very dense mass of stems and leaves, makes it good for preventing soil erosion. In California and Oregon it is used as living mulch for orchards, vineyards, and crops such as lettuce, broccoli, cauliflower, cabbage, sweet corn, zucchini, pumpkins, cucumbers, and cantaloupes. It dies and becomes a dead mulch at a time of the year when more moisture is needed by these crops.
Phytoestrogens, in some varieties of sub clover, can cause infertility in sheep. This is not a problem with cattle or goats. Most varieties, imported into the United States, are low in phytoestrogens.
There are many new varieties of subterranean clover. Most of them have been developed in Australia. Most of the research done on sub clover was done in Australia. The University of California has published a complete review of the literature available on subterranean clover. This review can be found in their on line cover crop database.
In the Autumn of 2015, we tried planting one of the new varieties of subterranean clover (Dalkeith) for which seed is available in the United States. We got a good stand the first year, but it did not come back the second year.
