Berseem or Egyptian Clover (Kennedy and Mackie, 1925; McLeod, 1982)

Trifolium alexandrinum L. (Duke, 1981).

According to Knight (1985), the wild parent of berseem clover has apparently become extinct; however, Duke (1981) suggests that Trifolium berytheum Boiss. & Bl., native to Israel, Lebanon, and Syria and fully interfertile with berseem, may be the wild progenitor. Egyptian landraces of berseem clover include Miscawi, Saidi, and Fahl (Graves et al., 1989). Kennedy and Mackie (1925) reported that there are four distinct agricultural varieties of berseem clover grown in various localities and differing in rapidity of growth, number of cuttings per season, height of plant, and amount and method of irrigation required. They are Miskawi, Khadrawi, Saidi and Fahl.

Miskawi (Muscowi U.S.D.A.) is the variety most commonly grown in Egypt. It is preferred in the delta region of lower Egypt where there is an abundance of water for winter irrigation but none in summer. It is a basal or crown-branching type and can be cut 5 or 6 times during its life (Graves et al., 1989).

Kennedy and Mackie (1925) mention that Khadrawi (Kadrawi U.S.D.A.) resembles Miskawi in habit of growth but requires more water. It is said to have a longer vegetative period and heavier yield.

Saidi (Saida U.S.D.A.) is characterized by having a long root system which enables it to withstand drought. It is somewhat intermediate in growth between Miskawi and Fahl. This variety is the berseem of upper Egypt; it is grown on the basin lands and sown in the mud after the Nile flood. Saidi branches both basally and on the stems and can be cut two or 3 times (Graves et al., 1989).

Kennedy and Mackie (1925) state that Fahl (Fachl U.S.D.A.) is used where water is not available after sowing and where the land is to be used immediately after cutting the crop. The land is overflowed by the Nile during the autumn months and when the water subsides a layer of mud is deposited. The seed is sown in the mud. No further irrigation is given and only one cutting of green fodder is obtained. 'Fahl' is a stem-branching type and can be cut only once (Graves et al., 1989).

The two varieties commercially available in California are 'Multicut' and 'Bigbee.' Other varieties include 'Fahl' (single cut), 'Miscawi' (Egypt), 'Sacromonte,' and "Tunisian common" (Graves et al., 1987). 'Multicut' has the best growth rate in the Central Valley and irrigated desert valleys of southern California. 'Bigbee,' a variety from the southern U.S., grows more slowly than 'Multicut' but is more winter hardy (Miller et al. 1989). In general, cultivars of berseem clover that exhibit basal branching (e.g., 'Miscawi', 'Bigbee', 'Multicut') can regrow from repeated cuttings (Knight, 1985).

In Foggia, southern Italy, Martiniello et al. (1996) conducted a pot study to evaluate the effect of mowing regime on various Italian and Egyptian accessions of berseem clover. The Italian forms (Sacromonte and the landraces Population 14 and Population 22) and the Egyptian forms (Giza 10, multifoliate, and Synt variety) all showed greatest percent mortality of plants when subjected to early (4th internode stage) mowing. Giza 10 appeared especially sensitive and Sacromonte particularly tolerant (P<0.05) and was significantly more so than all other accessions tested except Population 14.

Seed is small (Miller, 1988). Kennedy and Mackie (1925) state that the seed is slightly smaller than that of red clover and about the same size and shape as that of crimson clover, egg-shaped, reddish brown, and about one-twelfth of an inch long (2 mm.). On the average there are about 200,000 seeds per pound (Graves et al. 1987), or about 440 seeds/gram (Graves et al., 1989). Most seeds are yellow; about 10 to 15% of the seeds are purple.

Berseem can germinate when the soil surface is moderately dry, and can emerge from a greater depth than can white clover (Duke, 1981).

Berseem clover is an erect-growing, non-reseeding annual legume with oblong, slightly hairy leaflets lacking a watermark. It has hollow stems and a short taproot. Flowers are yellowish white, self-sterile, and clustered in dense elliptical heads about 1 in long. Each floret produces one roughly-spherical yellow seed (Graves et al., 1987). Berseem clover flowers are self sterile and are pollinated by honeybees (Knight, 1985).

Berseem clover does not withstand extreme heat or cold and is the least winter hardy of the cultivated clovers (McLeod, 1982). It should not be grown in areas where winter temperatures commonly go as low as 6 degrees C or lower (Knight, 1985). The most cold-hardy variety is cv 'Bigbee' (Graves et al., 1987), but 'Multicut' has withstood temperatures as low as 24 F without damage (Graves et al., 1987). In general, berseem sown early in autumn resists frost much better than that which is late sown (Kennedy and Mackie, 1925). Among the Egyptian landraces, 'Miskawi' does not do well with intense heat; late sowings result in reduced number of cuttings that may be made due to injury from summer weather; however, it appeared to be the most cold resistant (Kennedy and Mackie, 1925).

Berseem clover is considered native to the Mediterranean region, Near East, and India (Duke, 1981); Knight (1985) however, stated that the wild parent of berseem clover has apparently become extinct. Berseem has been introduced to California and the southern U.S., especially Florida. However, it does not volunteer in these areas. Its tolerances range from the Boreal Wet through Subtropical Moist Forest Life Zones (Duke, 1981). Berseem clover can be grown as a summer annual in areas with cool, moist summers. It does best as a winter annual in areas with long, warm winters and no frost danger (Knight, 1985). Berseem clover grows in most of the U.S. and does especially well along the Gulf coast and in the Yuma, Rio Grande, and Imperial valleys of the Southwest (McLeod, 1982). It performed sporadically after its introduction to California (1896), Texas (1916), and Florida (1950) (Graves et al., 1989), and it should not be grown as a winter annual in areas where winter temperatures commonly go as low as 6 degrees C or lower (Knight, 1985). Berseem clover does best below 65 m (2,500 ft) in elevation (Knight, 1985). 'Miskawi' is best adapted to regions of mild winter where irrigation is practiced (Kennedy and Mackie, 1925).

Berseem clover is said to tolerate from 3.8 to 16.6 dm of precipitation (15-65 inches) (mean of 17 cases, 8.7 cm (34.25 inches)). It is said to require from 25-30" of irrigation, from which should be deducted the amount of rainfall received (Munoz & Graves, 1988). McLeod (1982) states that berseem thrives under irrigation; Kennedy and Mackie (1925) stated that it requires almost the same quantity of water as alfalfa applied in the same manner and at the same intervals of time. The irrigation schedule should follow that of fall-planted alfalfa according to Graves et al. (1987). Too-frequent irrigations were found to retard the development of roots and stems. Lighter soils (presumably soils with better tilth) require fewer irrigations (Kennedy and Mackie, 1925). Berseem tolerates moderate periods of waterlogging in the soil (Graves et al., 1987).

An appropriate irrigation regime would include: (1) light, frequent irrigations to germinate seeds - two weeks; (2) after seedling stage - heavier weekly irrigations until the first late fall rains; (3) no irrigation is needed in the winter unless a dry period of more than three weeks occurs, or unless the soils are sandy; (4) spring irrigations to start as soon as soil drying begins and to continue until final cutting is made or seed formation is completed. The above irrigation requirements for the San Diego coast and inland areas will require approximately the following schedule (Graves and Munoz, 1986):

Berseem clover can tolerate more soil moisture than either alfalfa or white sweetclover and is similar to alfalfa in drought tolerance (Knight, 1985). 'Bigbee' is similar in drought tolerance to alfalfa but can withstand a little more soil moisture than alfalfa (Zahradnik, 1985).

Fertilizer needs of berseem clover are similar to those of alfalfa (Graves et al., 1987). Phosphate fertilizer and sometime sulfur is needed. Single super phosphate (0-25-0-10) applied yearly at 200 kg/ha (200 kg/ha x $200/ton = $40/ha) will normally provide this need (Graves and Munoz, 1987). Because San Diego County soils are usually deficient in phosphorus, spread 200 to 500 lbs/acre of single super phosphate (0-25-0) before soil preparation (Graves and Munoz, 1986).

Berseem tolerates soil pH ranging from 4.9-7.8 with a mean of 15 cases of 6.8 (Duke, 1981) and has been noted as tolerating basic to acidic soils (Munoz & Graves, 1988). It has been mentioned as alkali tolerant (Kennedy and Mackie, 1925; McLeod, 1982) and is said to do best on slightly alkaline soils (Zahradnik, 1985; Knight, 1985).

Berseem clover tolerates loam to clay soils (Munoz & Graves, 1988); it has been said to do best on medium loam soil (Knight, 1985; Zahradnik, 1985). Experiments in the Imperial Valley with berseem indicate that tight, heavy soils are not well adapted to this crop, but the lighter loamy and silty soils produce good crops. Loose river sand deposits yielded poorly. In the Imperial Valley, those soils containing large quantities of very fine sand or silt produce the best crops of berseem. The Imperial Valley soils which produce good crops of alfalfa are best adapted to berseem (Kennedy and Mackie, 1925).

Adequate phosphorus helps ensure shade tolerance of berseem clover in agroforestry systems (Hazra and Tripathi, 1986).

Kennedy and Mackie (1925) stated that berseem is tolerant of salinity or alkalinity and used in reclamation of "salty" land in Egypt. Graves et al. (1987) stated that it tolerates moderate salinity.

Berseem clover is susceptible to glyphosate (Bugg, pers. comm.).

Berseem clover can be grown as a summer annual in areas with cool, moist summers. Berseem clover does best as a winter annual in areas with long, warm winters and no frost danger (Knight, 1985). Compared to other clovers, 'Bigbee' berseem grows more vigorously in the fall and spring (Zahradnik, 1985). Flowering begins in May, and seed is ripe by late July. When the crop reaches a height of 16 to 20 in, buds from 1 to 2 in long develop from nodes, and the crop is ready for biomass harvest (Graves et al., 1987). Berseem clover flowers are self sterile and are pollinated by honeybees (Knight, 1985).

Seeding rates (using drill) have been given as 10 lbs/acre (Zahradnik, 1985), 15-20 lb/acre (McLeod, 1982; Graves et al., 1987), 15 to 25 lbs/acre (Miller et al., 1989), 17-22 lb/acre (Munoz & Graves, 1988), and 20 lb/acre (Miller, 1988). If seed is to be broadcast, a rate of 20 lbs/acre has been recommended (Zahradnik, 1985); pre-inoculated seed should be broadcast at 25 to 30 lbs/acre (Graves and Munoz, 1986). On medium soil at the Imperial Valley Experiment Station, excellent stands resulted from drilling 12 lbs/acre. On heavy or poorly-conditioned soils, as much as 20 lbs/acre may be required. Excessive seeding rates produce excessively-thick stands which prevents tillering and spreading of the root crowns (Kennedy and Mackie, 1925).

Seed should be sown at a depth of 1.3-2.5 cm (about 0.5 to 1 in) (Duke, 1981).

The seedbed should be well worked and firm, much like that used for seeding alfalfa. This usually consists of a discing or plowing, harrowing to break up the soil clods and floating the surface with a drag. Broadcast the inoculated seed on this smooth seedbed and cover lightly with a chain drag and firm the seedbed with a cultipacker roller (Graves and Munoz, 1986). Cultipacking ensures better seed-to-soil contact and moisture conservation (Zahradnik, 1985).

On heavy soils not so well adapted to berseem, the stand and subsequent growth is much improved by corrugating the surface in the direction of the flowing water. In this manner, the whole of the soil is sub-irrigated or saturated by capillarity, avoiding the detrimental effects of flooding. These corrugations are only 4 or 5 inches high, and offer no obstacle to the mower (Kennedy and Mackie, 1925).

Berseem should be seeded during early fall (Graves et al., 1987; Munoz & Graves, 1988; Miller et al., 1989). This has been translated as early October for much of California (Miller, 1988). In the Imperial Valley, late September or early October are preferable times of seeding. When a crop of seed only is desired, spring seeding in February may be practiced (Kennedy and Mackie, 1925). In San Diego County, seeding Dates are: September 1-15, inland areas to 1,500 feet elevation and September 15-30 for the coastal areas of San Diego County (Graves and Munoz, 1986).

Rhizobium type "R" (Nitragin Co.) is the recommended inoculant for berseem (Burton and Martinez, 1980; Munoz & Graves, 1988) which is the same type used for crimson clover (Zahradnik, 1985). However, superior strains of Rhizobium were found in Tunisia by Burton during 1981 (Graves et al., 1989). As a result, Duke (1981) suggests that Special Culture "No. 1" for Trifolium should be used. Seed should be pellet-inoculated before planting. (Graves et al., 1987). Inoculation of bur clover and berseem clover seedlings with the bacterium Azospirillum brasilense Strain CD accelerated the development of nodules. There was also an increase in root surface area and nutrient uptake according to Yahalom et al. (1989).

Patterson et al. (1990) reported on a pot study with berseem clover and alfalfa. For berseem clover, dual inoculation with Rhizibium and the mycorrhizal fungus Glomus macrocarpum Tul and Tul led to 22% increase in dry weight, 20% increase in N content, 9% increase in P content, and fewer but larger root nodules, by comparison with berseem clover seedlings that received only Rhizobium.

During 1925, seed was obtained commercially in Imperial Valley, Australia, and Egypt (Kennedy and Mackie, 1925). 'Multicut': breeder seed will be maintained by the Dept. of A&RS, U.C. Davis. Foundation seed can be obtained from the Foundation and Plant Materials Service, Parsons Seed Certification Center, UC Davis. Adequate quantities of foundation and certified seed were available for autumn planting in 1989 (Graves et al., 1989).

In general, fall-seeded berseem clover flowers from April through May (Duke, 1981). 'Multicut' bloomed ten days later than Bigbee (Graves et al., 1987).

Once established berseem will grow vigorously and reach a height of 18 inches by the end of January (Miller et al., 1989). A crop may be matured from early sown berseem (Sept.- Oct.) in 50 days from seeding while late sown (Nov.-Dec.) may require 70 to 90 days to produce the first crop (Kennedy and Mackie, 1925). Seed set of fall-seeded berseem occurs during June (Duke, 1981).

Seed production is abundant (Kennedy and Mackie, 1925; Graves et al., 1987) with 1500 kg of seed per hectare produced in a 1987 foundation seed field. Very little is hard seed (Graves et al., 1989). Unlike alfalfa, the most vigorous berseem produces the best and heaviest crops of seed. One field of light soil in the Imperial Valley produced seed at the rate of 792 lbs/acre, but less than half of this amount was secured from the heavy soils of the Experiment Station (Kennedy and Mackie, 1925). In Egypt, the average yield of seed for 'Miskawi' (1925) was 360 lbs/acre (Kennedy and Mackie, 1925).

Berseem clover is an erect-growing, non-reseeding annual legume with oblong, slightly hairy leaflets lacking a watermark. It has hollow stems and a short taproot; flowers are yellowish white, self-sterile, and clustered in dense elliptical heads about 1 in long; and each floret produces one roughly-spherical yellow seed (Graves et al. 1987). The landrace 'Saidi' tends to be decumbent rather than erect (Kennedy and Mackie, 1925).

Bugg et al. (1990) found that cv 'Bigbee' reached a height of 24.0 +/- 1.2 inches (mean +/- S.E.M.) in southern Georgia, and Graves et al. (1987) mention that 'Multicut' is taller than 'Bigbee.' Miller et al. (1989) state that berseem will reach a height of 18 inches, whereas in Arizona, berseem clover can attain 95-105 cm (about 37 to 41 inches) (Knight, 1985). 'Miskawi' is a rank grower sometimes attaining a height of five feet (Kennedy and Mackie, 1925). Cv 'Multicut' reached 57.1 +/- 3.2 cm (mean +/- SEM) in a Mendocino Co. vineyard (Bugg, unpublished data).

Berseem roots do not extend as deeply into the soil as those of alfalfa but are mainly restricted to the first two feet; however, 'Saidi' has "a long root system" according to Kennedy and Mackie (1925). The species is mentioned as having a short taproot (Graves et al., 1987). Inoculation of berseem clover seedlings with the bacterium Azospirillum brasilense Strain CD accelerated the development of nodules. There was also, according to Yahalom et al. (1989), an increase in root surface area and nutrient uptake.

Seeded areas should be sprinkle irrigated, if necessary, to establish a vigorous stand before cold weather begins (Miller, 1988).

Cultivars of berseem clover that exhibit basal branching (e.g., 'Miscawi', 'Bigbee', 'Multicut') can regrow from repeated cuttings, and these produce more regrowth if mowed before bloom than if mowed after (Knight, 1985). In fact, mowing of berseem clover during February may be essential to control weeds (Bugg, pers. comm.). Berseem can be mowed several times for forage and then ploughed under as green manure (yielding 33-66 kg/ha of nitrogen), or it can be allowed to produce seed following the final cutting (Knight, 1985). Crude protein contents of berseem clover remained stable through successive mowings (28-30%, slightly higher than crimson clover or alfalfa) (Knight, 1985). Berseem clover seed yields exceed 1,100 kg/ha in Arizona (Knight, 1985). Most varieties of berseem clover do not normally reseed and reestablish well, but the Italian variety 'Sacromonte' has done so in Mississippi (Knight, 1985).

Cultivars of berseem clover that exhibit basal branching (e.g., 'Miscawi', 'Bigbee', 'Multicut') can regrow from repeated cuttings (Knight, 1985). They are very responsive to mowing or grazing; will resprout quickly from the crown (Miller, 1989); and can be mowed frequently for weed control or for animal feed (Miller, 1988). In fact, mowing may be essential to control weeds (Bugg, pers. comm.). According to Munoz & Graves (1988), berseem should be mowed each time it reaches 16 inches; however, according to Miller et al (1989), it should be cut every time it regrows to 14 to 18 inches during the late winter and spring season (5 or 6 times). With five or six cuttings, 'Bigbee' and 'Multicut' berseem clovers apparently fixed 272-400 kg/ha of N while obtaining 50-235 kg/ha from soil. When over 150 kg/ha of soil nitrogen was available per year, nitrogen fixation declined steeply (Williams et al., 1990). Berseem produces more regrowth if mowed before bloom than if mowed after (Knight, 1985), and crude protein contents remained stable through successive mowings (28-30%, slightly higher than crimson clover or alfalfa) (Knight, 1985). Berseem clover can be mowed several times for forage, and then ploughed under as green manure (yielding 33-66 kg/ha of nitrogen), or allowed to produce seed following the final cutting (Knight, 1985). With 'Bigbee', grazing or cutting should begin when the stand is 10 inches high and basal shoots are visible (Zahradnik, 1985). 'Fahl' can be cut only once (Graves et al., 1989). According to Graves et al. (1989), 'Miscawi' can be cut 5 or 6 times; however, Kennedy and Macki (1925) suggest cutting it from 4 to 8 depending on the amount of water used and the height of the crop when cut. 'Saidi' can be cut two or 3 times (Graves et al., 1989).

Berseem clover can be mowed several times for forage and then ploughed under as green manure (yielding 33-66 kg/ha of nitrogen), or it can be allowed to produce seed following the final cutting (Knight, 1985). If the crop is to be used for green manure, the cuttings may be transferred directly and turned without composting (Graves and Munoz, 1986).

The multiple-cut varieties can be harvested 5 or 6 times at four week intervals from January or February until June or July. The first three cuttings are made in the vegetative stage while the later harvests are made during bloom beginning in May (Graves et al., 1987).

Mowing when the plants are about 9 inches high causes new shoots to initiate. For early-sown berseem this cutting should be made about the first of January. 40 or 50 days later, the second cutting may be made. If no seed production is desired, three more harvests may be made by June 1st when the hot weather usually curtails growth. When seed is desired, only three cuttings are made. Seed should be ready for harvest after the first week in June. When berseem is grown on light soil under favorable conditions, it should be cut every 30 days after about the first of February at which time it should be about 24 inches in height. Before cutting, basal shoots will already have been initiated (Kennedy and Mackie, 1925).

Mowing is scheduled when the plants attain 16 inches or the basal sprouts are 2 to 3 inches long. The harvesting of small areas may be done with a garden-type tractor with a front sicklebar attachment. Larger fields are usually cut with a greenchop windrower or rear-mounted tractor sicklebar attachment (Graves and Munoz, 1986). In favorable years, early-sown 'Miskawi' can sustain its first cutting in fifty days. If conditions are less favorable, it may take seventy days (Kennedy and Mackie, 1925).

Mower heights should be set no lower than 7.5 cm for best regrowth (Duke, 1981).

Berseem is used for forage in the eastern Mediterranean region and subtropical areas. It can be green-chopped, grazed, or used for silage and by all measures its quality is excellent (Duke, 1981; see also Munoz & Graves, 1988; McLeod, 1982). As detailed by Graves and Munoz (1986), berseem affords other uses as well: green manure (see also McLeod, 1982), renovating old clover or alfalfa stands, and as a "break crop" in rotations, for disrupting weed and other pests' life cycles. It can be mowed several times for forage and then ploughed under as green manure (yielding 33-66 kg/ha of nitrogen), or it can be allowed to produce seed following the final cutting (Knight, 1985). For greenchop, the cuttings may be loaded and taken directly to the livestock feeders. The cuttings can be used for silage by mixing with grass cuttings, hay, or straw to produce the proper moisture content for silage fermentation (Graves and Munoz, 1986). Clippings can be used in compost preparation or as green manure on adjacent areas (Miller et al., 1989).

In an early account of use of berseem clover in California, Kennedy and Mackie (1925) include brief accounts of the importance of the plant in the Nile Valley, Palestine, southern Italy, and in Victoria, Australia. Salient points in the bulletin include the high production, salt tolerance, and frost sensitivity of the crop. In addition, the authors discuss the difficulty of separating sourclover seed from berseem seed, once a field becomes infested.

Berseem clover can be grown in combination with white clover, oat, or rye (Duke, 1981). Mixtures of 'Multicut' Berseem clover and annual ryegrass combine advantages of both plant species by providing early winter production as well as extending the availability of high quality forage through late spring (Graves et al., 1989).

'Multicut' berseem and annual ryegrass were planted in mixtures in field trials at Davis. Annual ryegrass alone yielded about half as much biomass as 'Multicut' alone. The mixtures of 50% and 75% 'Multicut' with ryegrass yielded as much as 'Multicut' alone (13,800 lbs/acre dry matter). 'Multicut' became dominant in all mixtures by the third harvest. The frost-tolerant cultivar 'Bigbee' can be included with 'Multicut' as an insurance against freezeout. In trials at Davis it was noted that 'Bigbee', because of its shorter stature, appeared to contribute progressively less to the mixture after the first harvest (Graves et al., 1987).

Late maturation makes berseem clover tricky to use in relay-intercropping schemes with summer vegetables because of potential competition with the cash crops for light, nutrients, and water (Bugg, pers. comm.).

On heavy, infertile soil of the Imperial Valley Experiment Station, berseem yielded 10 to 12 tons of green fodder to the acre in addition to a crop of seed. Light soil near El Centro produced in four crops of berseem 23.5 tons of green feed to the acre by April 16 after which a seed crop of 792 lbs/acre was harvested (Kennedy and Mackie, 1925). 'Multicut' berseem germplasm out- performed annual ryegrass, a commonly used winter and spring forage grass, during four years of field testing under supplemental irrigation in the Central Valley (Morey and Marchant, 1977).

According to Graves and Munoz (1986), the following production schedule can be obtained with a September 15 seeding in San Diego County:

'Bigbee' can yield up to 4 tons/acre.

In Mississippi State University tests, 'Bigbee' ranked first out of 20 clovers, including 'Tibbee' crimson and 'Yuchi' arrowleaf, producing slightly more than 4 tons of dry matter per acre in three cuttings (Zahradnik, 1985). Cv 'Burton' (now called 'Multicut') consistently outperformed other varieties and strains over four years of trials in the Central Valley of California, under supplemental irrigation. Yields ranged from 11,000 to 14,100 lbs of dry matter/acre, averaging 13,300 lbs (Morey and Marchant, 1977). Graves et al. (1987) found in field trials that 'Multicut' produced up to 14,000 lbs/acre dry matter and that 'Bigbee' suffered a yield disadvantage compared to 'Multicut' of 10 to 50% in field trials. 'Multicut' also produced more winter forage than 'Bigbee.' Biomass harvests were made on May 15-16, 1991 for cover crops seeded during October, 1990, in a replicated study (r=4) at Blue Heron Vineyard, Fetzer Vineyards, Hopland, Mendocino County, California. Dry above-ground biomass for 'Bigbee' was 8.5+/-0.8 Mg/ha, Mean +/- S.E.M. When weed biomass was added, the sum was 8.6+/-0.7 Mg/ha (Bugg et al., 1996).

Total N contribution of berseem can range from 50-400 lb/acre (Munoz & Graves, 1988). Cv 'Burton' (now 'Multicut') fixed 300 lb/acre/yr of atmospheric nitrogen in four years of field testing of 'Multicut' berseem germplasm under supplemental irrigation in the Central Valley (Morey and Marchant, 1977). In a five-year study on an irrigated Yolo loam, Williams et al. (1990) found that total annual nitrogen fixation ranged from 275 to 400 lb N/ac for 'Multicut' and from 150 to 350 lb N/ac for 'Bigbee.' With five or six cuttings, irrigated 'Bigbee' and 'Multicut' berseem clovers apparently fixed 272-400 kg/ha of N while obtaining 50-235 kg/ha from soil. When over 150 kg/ha of soil nitrogen was available per year, nitrogen fixation declined steeply (Williams, 1990). In trials at Cal Poly - Pomona, nitrogen fixed was consistently lower than that measured at Davis (Yolo County), and ranged from 158 to 214 lbs per acre. This lower fixation was attributed to higher residual nitrogen in the soil (Graves et al., 1987). In Georgia, berseem clover replaced up to 97 kg/ha of N in corn and sorghum production; mean above-ground N-content was 110 kg/ha (McVay, Radcliffe, and Hargrove, 1989). At plowdown, available N from berseem cover crops can be estimated by multiplying harvested fresh weight of cover crop from a sixteen square feet (4 x 4 ft.) sample plot by 13 (to estimate lbs of N/acre) (Miller et al., 1989).

Crude protein contents of berseem clover remained stable through successive mowings (28-30%, slightly higher than crimson clover or alfalfa) (Knight, 1985). Graves and Munoz (1986) presented the following production schedule, obtainable with a September 15 seeding in San Diego County:

 

Kirchmann and Marstorp (1991) of Sweden provided foliar chemical analysis for some cover crops used in California, all at 101 days of age.

Thus, Persian clover contained 2.2% N, berseem 2.52% N, and subterranean clover 3.02% N.

In Sweden, Marstorp and Kirchmann (1991) reported the following values for stems and leaves of several legumes harvested from the field 100 days after emergence. and later used as green manure:

 

Walter Graves (pers. comm.) stated that farming systems that rely on berseem as a forage legume rather than alfalfa may require less water.

No specific information is available on the effects on soil of berseem clover. The species has a relatively short taproot, so should be less able to affect soil at depth than are some other legumes (Bugg, pers. comm.).

All kinds of stock and poultry feed on berseem and prefer it to alfalfa. In fields of alfalfa and berseem mixed, cattle and horses select the berseem, leaving most of the alfalfa until the berseem has been grazed to the ground. Replacing alfalfa with berseem showed an increase in butter fat per cow daily of more than 10%, and there are no problems with butter or milk having unusual flavor. Bloating (tympanitis) from feeding berseem when covered with dew is very rare in Egypt and Australia and not serious when it does occur. In the Imperial Valley, no bloating with berseem has occurred although it is reported for alfalfa (Kennedy and Mackie, 1925). Berseem can be direct pastured, but some caution has to be observed to reduce the potential of bloat (Graves and Munoz, 1986). Crude protein contents of berseem clover remained stable through successive mowings (28-30%, slightly higher than crimson clover or alfalfa) (Knight, 1985). Zahradnik (1985) asserts that 'Bigbee' is a palatable and nutritious legume and confirms that crude protein concentration is slightly higher than crimson clover or alfalfa and that berseem does not cause bloat.

Kennedy and Mackie (1925) mentioned that many (unspecified) pest insects can build up on berseem clover with potential adverse effects to other crops should these pests disperse. To prevent excessive build up, irrigation of berseem in Egypt is stopped by law by the end of April. Weevils which attack berseem severely in Egypt have not yet appeared in the Imperial Valley. The Chalcis fly, found attacking alfalfa seed in this region, has not attacked berseem. In southern Georgia, Bugg et al. (1990) found relatively few aphids or lady beetles associated with berseem, but extremely high densities of a bigeyed bug, Geocoris punctipes, an important beneficial generalist predator, during late May and early June. Flowers of berseem attract bees (Munoz & Graves, 1988).

Kennedy and Mackie (1925) stated that berseem had been attacked by plant-parasitic nematodes in the Imperial Valley, but like alfalfa, it carried nematodes in limited numbers. Baltensperger et al. (1985) evaluated 9 germplasm sources, and found that all were severely galled by Meloidogyne spp. Duke (1981) listed 12 types of plant parasitic nematodes as being associated with berseem.

Whitehead (1992) stated that in a pot study, burr medic and several other annual Medicago spp. (e.g. barrel medic) showed good resistance to the lucerne (alfalfa) race of stem nematode (Ditylenchus dipsaci). Subterranean clover was deemed very resistant, rose clover resistant, and berseem susceptible.

Kennedy and Mackie (1925) stated that no fungal pests of berseem were known, but Duke (1981) listed 12 fungi, 2 bacteria, 1 virus (cucumber mosaic), 2 parasitic plants, and 12 types of plant parasitic nematodes as being associated with berseem. Duke (1981) mentions berseem as tolerant of virus.

Kennedy and Mackie (1925) stated that when berseem is sown early on light soil, ordinary weeds are controlled by its dense growth, but when grown on hard soils or when the stand is thin, weeds may continue. Mallow (Malva) and Lamb's-quarter (Chenopodium sp.) have persisted in berseem fields in the Imperial Valley. Sourclover (Melilotus indica) has become established in the Imperial Valley and is persistent in fields of berseem on heavy or hard soils. Mixed seed of sourclover and berseem are almost impossible to separate. Contaminated berseem fields should not be harvested for seed. Dodder (Cuscuta) attacks berseem in Egypt but has not as yet appeared on berseem in California. Mowing of berseem clover may be essential to control weeds (Bugg, pers. comm.). Graves et al. (1987) stated that berseem is a fairly strong competitor with winter weeds during establishment and by the third cutting is often weed-free. In fall-seeded 'Bigbee' berseem plots, weed above-ground biomass in mid-May was 0.2+/-0.1 Mg/ha, Mean +/- S.E.M. (3.4% of the weed biomass in control plots) in Mendocino County, California (Bugg et al., 1996). Dominant winter annual weeds were chickweed, shepherds purse, rattail fescue, and annual ryegrass. In the same trial, per cent vegetational cover data for berseem during May was 98.8+/-1.3 (Mean +/- S.E.M.) (Bugg et al., 1996).

Berseem clover is heavily fed upon by rabbits (Bugg, pers. comm.).