Seeding in standing water on flat lands that are irrigated by contour checks is fairly common. Successful stands are obtained throughout late summer and early fall by this method. After the land is prepared for irrigation, the field is flooded. The seed is broadcast on the water from an airplane. The land is flooded for about 48 hours. By that time, the seedcoat has been ruptured, the cotyledons have emerged, and the primary root has begun to develop. As the water is drained off, or seeps into the soil, the primary root is anchored in the mud. If the water is held too long, the seedlings may be driven to the levee by the wind.

Trefoil generally is seeded in spring in colder parts of the country. The recommended rate of seeding is 3 to 5 pounds per acre drill seeded to a depth of one-fourth inch or less.

Inoculation is essential in places where trefoil has not grown previously. Trefoil bacteria do not occur naturally in most soils.

Soil moisture should be controlled. Irrigation should be frequent enough to keep the ground moist throughout the period of seed setting and ripening. Frequent irrigation also helps to maintain a canopy of new growth above most of the seed pods and to keep the humidity high to reduce seed shattering. Trefoil stands grown for seed on Soils low in phosphorus, potash, and sulfur will often benefit from liberal applications of fertilizer containing them.

Birdsfoot trefoil, like alfalfa, responds to thin stands. In replicated tests with row-planted stands of Viking trefoil, rows spaced 6 to 24 inches apart produced 30 to 60 percent more than stands planted by broadcasting. Seed shattering increased sharply in the 24-inch, row-spaced stand.

Weedy grasses, particularly winter annual species, usually can be controlled by applying granulated or pelleted IPC, which should be applied when the ground is wet and cold. Many broad-leaved weeds can be eliminated by spraying with 4-(2,4- DB). The spray should be applied before the trefoil is cut back to start seed production.

Daylength influences blossoming and may influence setting of seed. The time of clipping back preparatory to seed production therefore is important. The recommended time to cut back in California is May 1 to 15; in Oregon, May 25 to June 5.

Regrowth to full bloom requires 30 to 35 days. Seed setting would then start about June 20 and continue to August 1 to 10. Harvest is 20 to 30 days later.

Pollinators are essential during the entire seed-setting period. If wild bees are scarce or absent, one or two strong hives of honey bees per acre should be furnished.

The first crop is usually used for seed in nonirrigated areas. Harvest follows about 25 to 30 days after full bloom.

Harmful insects and mites, such as lygus bugs and stink bugs (Pentatomidae), must be controlled.

We know of no completely satisfactory method of harvesting trefoil. Direct combining after spray curing can be done under ideal conditions. Mowing and drying in the swath for 8 to 24 hours before combining has been a successful method. Mowing and windrowing to cure and threshing from the windrow is commonly used. Mowing trefoil at night and curing it on a hard surface has been tried.

Curing in shocks and bales to be threshed by stationary harvesters and other methods have been tried, but we cannot give a good, general recommendation.

BIENNIAL yellow and white sweet-clovers are grown mainly for grazing and soil improvement. Planting practices are like those for alfalfa.

According to Samuel Garver and T. A. Kiesselbach, who worked in Nebraska, the first year's growth can be grazed or mowed for hay, but grazing gives better seed production the following year.

About 6 inches of stubble or growth should be allowed to remain for the winter. Higher seed yields are obtained when the second year's early growth is not grazed or mowed. Some of the varieties grow so tall if they are not grazed, however, that it is advisable to graze them so that the harvesting machinery can handle the growth. About 10 inches of stubble should be left to insure regrowth.

Thick stands should be avoided when sweetclover is grown for seed. The yield on dry land is reduced because of excessive competition for soil moisture. The seed yield on wetter lands is reduced because of excessive shading.

At least one plant per square foot is required to control weeds and is considered suitable for drier sites for seed production. If there is enough soil moisture, two or three plants to the square foot is better.

Sweetclover is quite drought tolerant when it is established, but it requires favorable moisture conditions in the early stages of seedling development. Moisture is needed for the companion crop as well as the sweetclover. There should be enough soil moisture the second year to provide a good vegetative growth, but drier weather favors flowering, seed formation, and harvesting.

Sweetclover requires readily available calcium. It can grow with lower levels of soil phosphorus than alfalfa. Weeds are normally controlled by the companion crop in sweetclover the first year. A spring-tooth harrow or similar tool can be used to control annual weeds in the spring of the second year if they are troublesome.

It is sometimes necessary to control the sweetclover weevil (Sitona cylindricollis). Dieldrin can be used for this purpose.

Bees at the rate of two or more colonies per acre must be provided for pollination.

Combining from windrows is a satisfactory method of harvesting.

SUMMER ANNUAL legumes include Korean and striate lespedezas (L. stipulacea and L. striata), velvet bean (Stizolobium deeringianum), cowpea (Vigna sinensis), alyceclover (Alysicarpus vaginalis), crotalaria (Crotalaria), and hairy indigo (Indigofera hirsuta).

Lupine, vetches, field pea, and Hubam sweetclovers are summer annuals in the North, although fall seeding of peas with oats is practiced on the Pacific coast.

The summer annuals generally are planted in the South from January to March and harvested in the fall.

LESPEDEZA is planted in early spring by drilling or broadcasting with pasture mixtures or grain at the rate of 25 to 30 pounds of unhulled seed per acre. The stand is maintained indefinitely by volunteering.

A crop of hay usually is cut or the stand is pastured until about July 15. If it is pastured and a dense growth persists or weeds are present, mowing may be worthwhile. The seed yield is greater if a hay crop is not taken, however. The crop should not be mowed if the lower leaves are firing or dying. Live buds should be left below the mowing line.

Lespedeza does well on a wide range of soil conditions, but responds favorably to lime on acid soils and to mixed fertilizers, particularly phosphorus, on deficient soils.

Dodder, the major weed problem in lespedezas, is controlled by burning.

There are no severe problems of insect pests or pollination.

Kobe lespedeza, a late-maturing strain of L. striata, generally is combine harvested from windrows. The Korean can be harvested standing.

THE Trifolium genus of winter annual legumes includes berseem (T. alexandrinum), large hop (T. campestre), small hop (T. dubium), rose (T. hirtum), crimson (T. incarnatum), Persian (T. resupinatum), and lappa (T. lappaceum) clovers and subclover (T. subterraneum).

The Medicagos include spotted burclover (M. arabica), California burclover (M. hispida), and little burclover (M. minima), button clover (M. orbicularis), and black medic (M. lupulina). The Melilotus genus includes sour-clover (M. indica), Hubam, Israel, and Floranna sweetclover (M. alba annua).

Also included are rough pea (Lathyrus hirsutus), lupine (Lupinus species), Austrian winter pea (Pisum arvense), and vetch (Vicia).

The last three species and Hubam sweetclover are grown as summer annuals in the northern parts of the United States and as winter annuals in the Pacific coast region, west of the Sierra Nevada and the Cascade Mountains and in the lower South.

Hairy vetch is the only one of the vetches that is winter hardy enough to be used as a winter annual in the North.

Winter annual legumes usually are planted in the South from August to November and harvested in June and July, about the same time as the small grains.

Although annuals, the small-seeded species ordinarily maintain themselves by reseeding, the key to which is their percentage of hard seed.

Common crimson clover does not normally reseed because of its low percentage of hard seed, but varieties such as Dixie do reseed, because they have a higher proportion of hard seed.

Cultivating or disking the soil after harvest sometimes helps to plant the volunteer crop.

It is common practice (except among specialized seedgrowers) to graze the crop until about a month before normal flowering time. The yield of seed may be reduced thereby, but sometimes such grazing helps to control weeds.

The tall-growing species, such as lupines, peas, and vetches, require no special management and produce more seed if they are not grazed or clipped.

CRIMSON CLOVER is seeded in the fall alone in an open, established, short grass sod or with oats or barley.

The crop can be grazed until early in March in the southern sections before it is allowed to go to seed.

Usually 10 to 20 pounds of inoculated seed are planted per acre.

Crimson clover will require fertilization with phosphorus, potassium, and sometimes boron in the South, but too much fertilization for seed production should be avoided in order to avoid excessive growth and damage from crown and stem rotting organisms.

One colony of honey bees per acre should be provided for pollination.

The clover head weevil (Hypes metes), lesser clover leaf weevil (H. nigrirostris), seed chalcid, pea aphid, and other insects may be problems.

Crimson clover sometimes is combined standing, but usually it is combined from windrows.

THE VETCHES require cool temperatures for best development. In the Southern and Pacific States, they usually respond as winter annuals and mature in late spring and early summer. In the North, where winters are severe, they usually act as summer annuals and mature late in summer or fall.