Barley (Hitchcock, 1973).

The scientific name is Hordeum vulgare L. (Hitchcock, 1971).

Hockett (1990) recounted that barley has been found at archeological sites 9,000-10,000 years old, and that the modern 4-row form probably was derived from a 2-row type that led to Hordeum vulgare ssp. spontaneum, a wild-type weedy barley.

There are many varieties of barley from which to choose. The National Seed Storage Laboratory, U.S. Department of Agriculture, Fort Collins, Colorado, maintains seed for 25,284 landraces, cultivars, and wild species of barley. (Moseman and Smith, 1985). Twenty-four varieties are listed by the Southern Seedsman's Association (Bugg, pers. comm.). Few varieties of barley or oat are adapted coast to coast (Stoskopf, 1985). The choice should be based on climatic suitability (Slayback, pers. comm.). The spring or North Africa type of barley is used in California (Poehlman, 1985). Cultivated varieties of barley include 6-rowed and 2-rowed types. In two-row types, all kernals are symmetrical, but in 6-row types, 2/3 are twisted, i.e., those from the lateral rows of the spike. The lateral kernals are smaller and weigh 13-20% less. Kernal weight in barley ranges from 5 to 80 mg (Reid, 1985). Six-row varieties of barley do not necessarily produce low numbers of tillers, but tiller mortality is high when they produce many (Fukai et al., 1990). Some barley varieties are susceptible to lodging at high sowing densities, e.g. cv 'Beecher' (Fukai et al., 1990).

The following account is from Hitchcock (1971). The spike is erect or nearly so, 2-10 cm long, excluding awns, the three spikelets sessile; glumes divergent at base, narrow, nerveless, gradually passing into a stout awn; awn of lemma straight, erect, mostly 10-15 long. In the two-rowed barley varieties, the lateral spikelets are sterile; in the six-row forms, all the spikelets produce large seed.

Barley seedlings are vigorous and excellent competitors against weeds (Slayback, pers. comm.).

Barley is a an annual grass with erect culms, 60 to 120 cm tall; blades flat, mostly 5 to 15 mm wide, with the auricle well developed; spike erect or nearly so, 2 to 10 cm long, excluding awns; the three spikelets sessile; glumes divergent at base, narrow, nerveless, gradually passing into a stout awn; awn of lemma straight, erect, mostly 10 to 15 cm long (Hitchcock, 1971). Cultivated varieties of barley include 6-rowed and 2-rowed types. In two-row types, all kernels are symmetrical, but in 6-row types, 2/3 are twisted, i.e., those from the lateral rows of the spike. The lateral kernels are smaller and weigh 13-20% less. Kernel weight in barley ranges from 5 to 80 mg (Reid, 1985). Barley roots attain a depth of as much as 1.8-2.1 m on deep soils. The deepest roots are of seminal origin, whereas the upper soil is usually explored by adventitious roots (Reid, 1985). At common seeding rates, barley usually develops from one to six stems or tillers per plant (Reid, 1985). Barley (0.2% outcrossing) is mainly self-pollinated (Stoskopf, 1985).

Barley requires a mild winter climate and grows better in dry, cool climates than in hot, moist areas (Poehlman, 1985). It is well adapted to high altitudes with cold, short seasons (McLeod, 1982). The species possesses moderate resistance to cold (Madson, 1951), but winter barleys are less winter hardy than winter wheats, triticale or cereal ryes (Anderson and Reinbergs, 1985; Stoskopf, 1985). A temperature of -8 degrees Centigrade or lower is required to kill seedlings of barley (Stoskopf, 1985). Barley is also susceptible to damage by hot, dry weather that occurs during reproduction (Stoskopf, 1985). Hockett (1990) found that barley grows best under cool, dry conditions, but can withstand hot, dry or cold and wet weather.

Barley is grown over a broader environmental range than any other cereal (Poehlman, 1985). Archeological findings from the Nile Valley of Egypt suggest that barley has been cultivated for at least 18,000 years (von Bothmer and Jacobsen, 1985). The two-rowed barleys probably originated in Asia in part from a species called Hordeum spontaneum Koch; the ancestor of the 6-row barleys is unknown (Hitchcock, 1971). Few varieties of barley are adapted coast to coast (Stoskopf, 1985); geographic suitability will vary among varieties or cultivars (Slayback, pers. comm.). In general the species does poorly in hot, humid climates (Poehlman, 1985). It is not persistent in the wild, but beardless barley occasionally occurs in grain fields and along roads from Connecticut to New Jersey, in South Dakota, Montana, Colorado, Utah, New Mexico, and Colorado (Hitchcock, 1971).

Barley can tolerate moderate droughts (McLeod, 1982; Poehlman, 1985) and is therefore superior to oat in semi-arid areas (McLeod, 1982). Nonetheless, it is usually irrigated when grown as a cover crop (Slayback, pers. comm.). Higher seeding rates of oat or barley may be appropriate where rainfall is heavy (Stoskopf, 1985), but low sowing densities do not necessarily lead to less water use because vegetative growth will be increased (Fukai et al., 1990). High-density plantings of barley were better at suppressing weeds than were intercropped barley and field pea. Weed suppression appeared to be due to competition for soil moisture. Weed populations were not reduced, but weed biomass was (Mohler and Liebman, 1987).

Hockett (1990) found that barley grows best under cool, dry conditions, but can withstand hot, dry or cold and wet weather.

Barley has a low requirement for lime (McLeod, 1982). Jobidon et al. (1989) tested barley, oat, and wheat-straw as mulches for black spruce (Picea mariana) seedlings in greenhouse trials. The mulches of barley and wheat enhanced foliar phosphorus content, but mulches did not affect mycorrhizal infection or growth of black spruce. All mulches decreased manganese content of the seedlings, however.

Noble et al. (1990) found in hydroponic studies that varieties tolerant of boron excess are more susceptible to deficiency syndrome.

Barley tolerates alkalinity, but does not grow well on very acid soils (McLeod, 1982), e.g., below pH 6.0 (Stoskopf, 1985).

This grass does well on well-drained, fertile loams or light, clay soils (Poehlman, 1985); is best adapted to loam soils with good drainage (McLeod, 1982); and can tolerate loam to heavy soils (Madson, 1951).

Barley has the highest salt tolerance of all cereal crops (McLeod, 1982). Many wild species of the genus Hordeum can also be found in saline habitats (von Bothmer and Jacobsen, 1985). Barley is used for reclamation of saline soils. The main mechanisms of salinity tolerance are salt exclusion and salt dilution (Anderson and Reinbergs, 1985). 6-row, smooth-awned cultivars of barley are typically more salt tolerant than are 2-row, rough-awned cultivars (Hocket and Nilan, 1985).

Stassart and Bogemans (1990) in Belgium found that summer barleys had better Na tolerance than winter. Better ion selectivity and less need to shunt sugars to roots.

Based on laboratory experiments, Salim (1991) compared one cultivar each of triticale (cv 'Drira'), wheat (cv 'Persian Black'), cereal rye (cv 'Aus'), and barley ('Pallidium'). Seedlings were grown for 23 days following germination under steadily increasing NaCl concentration or with 1/2-strength Hoagland's nutrient solution (control). Ultimate NaCl concentrations were 75 and 150 mM in the other treatments. Shoot growth values, expressed as percentages of the control values, were as follows:

According to Baldridge et al. (1985), Diallate, Triallate and Trifluralin are pre-emergence herbicides used to reduce incidence of wild oat in barley stands; barban can be used post emergence for the same purpose. Barley shows good tolerance of 2,4-D and MCPA amine and ester formulations, bromoxynil, triallate, difenzoquat, trifluralin, diclofop, and chlorsulfuron. Fair tolerance is observed for diallate and barban, and poor tolerance of dicamba.

Barley is an annual cereal grass (McLeod, 1982). In California, flowering is from April through July (Munz, 1973). Barley has a flexible reproductive system that mainly involves inbreeding (0.2% outcrossing (Stoskopf, 1985), but has the potential for cross pollination (von Bothmer and Jacobsen, 1985). Barley varieties usually have a greater ability than oat varieties to produce tillers (Stoskopf, 1985). Six-row varieties of barley do not necessarily produce low numbers of tillers, but tiller mortality is high when many are produced (Fukai et al., 1990).

Hockett (1990) found that barley matures faster than other cereals. Winter hardiness is not as good as for cereal rye or wheat, but is better than for oat.

Recommended seeding rates are typically from 60-90 lb/acre (Madson, 1951; McLeod, 1982; Miller et al. 1989), with Finch & Sharp (1983) favoring the high rate and Hofstetter (1988) suggesting 100 lb/acre. However, Baldridge et al. (1985) recommend only 27 kg/ha. High seeding rates may be appropriate where rainfall is heavy (Stoskopf, 1985). Low sowing densities do not necessarily lead to less water use because vegetative growth will be increased (Fukai et al., 1990). Some barley varieties are susceptible to lodging at high sowing densities, e.g. cv 'Beecher' (Fukai et al., 1990).

Intercropped barley and field pea were no better at suppressing weed mustards (Brassica kaber) and white mustard (B. hirta) than was a dense monoculture of barley. The main mechanisms of weed suppression were shading (especially by the pea) and competition for nitrogen (especially by the barley) (Liebman and Robichaux, 1990).

Seeding depth for barley or oat should be no greater than 5 cm (2 in). Shallow seeding is possible in areas with high soil moisture and leads to more rapid emergence and lessened incidence of root rot disease (Stoskopf, 1985). Other depths mentioned are 3/4-2.5 inches (McLeod, 1982) and 2-6 cm (Baldridge et al., 1985).

Seeding depth for barley or oat should be no greater than 5 cm (2 in). Shallow seeding is possible in areas with high soil moisture and leads to more rapid emergence and lessened incidence of root rot disease (Stoskopf, 1985).

To seed barley, use drills with disk or double-disk openers. Hoe- or furrow-type drills are used in arid regions with no irrigation (Baldridge et al., 1985). Barley or oat is usually planted in rows 15 to 20 cm apart (Stoskopf, 1985).

In general, barley requires reseeding each fall (Finch & Sharp, 1983). Seeding dates range from October - January (Madson, 1951). Slayback (pers. comm.) suggests that winter varieties may be sown from September through February, and spring varieties from April-May. Plant after November 1 to avoid warm temperatures if nematodes are a potential problem (McKenry, pers. comm.).

Barley is not a legume and requires no inoculation with rhizobia. (Bugg, pers. comm.)

Barley seed is usually available at low cost (Slayback, pers. comm.).

Many varieties are readily available (Slayback, pers. comm.).

Days to heading (flowering) vary among barley cultivars. Some examples include: 'Corvette': 84; 'Grimmett', 'Beecher', '2I Bon', and 'Gus': 97; 'Piroline': 104; and 'Triumph': 110 (Fukai et al., 1990). Cv 'Proctor' appears to require about 90 days to flower (Wych et al., 1985). According to Munz (1973), flowering of barley can range from April through July. As with other cereal grains, mowing and irrigation can be used to postpone and prolong flowering of barley (Menke, J., pers. comm.).

Barley produces a greater biomass and does it quicker than do the other cereals (Miller et al. 1989). Days to maturity vary among varieties (Slayback, pers. comm.).

Hockett (1990) found that barley matures faster than other cereals. Winter hardiness is not as good as for cereal rye or wheat, but is better than for oat.

In the U.S.A., mean grain yield from 1978-1980 was 2,684 kg/ha, with a total production of 8,680,000 tons, 5.2% of the world production (Poehlman, 1985). By contrast mean yield was 4,312 kg/ha in the Federal Republic of Germany (Poehlman, 1985). Under irrigation and with 336 kg N/ha added, barley seed yields can attain about 3,800 kg/ha (Baldridge et al., 1985). Under dryland conditions, maximum yield was about 1,700 kg/ha with 112 kg N/ha added (Baldridge et al., 1985).

Safe storage of seed requires that moisture content must be 14% or less; this may necessitate drying of seed prior to storage (Baldridge et al., 1985).

Barley is an annual with erect growth (Hitchcock, 1971). Tillering occurs at the base (Finch & Sharp, 1983); barley varieties usually have a greater ability to produce tillers than do oat varieties (Stoskopf, 1985), and there is moderate to heavy density of growth (Madson, 1951), barley and oat have the poorest resistance to lodging of the cereals (Stoskopf, 1985), but barley, oat, and rye do better in this respect than do 'Blando' brome or 'Zorro' fescue (Bugg, pers. comm.).

Barley can grow up to 30 inches in height, but maximum height varies with cultivar (Slayback, pers. comm.). Cv 'UC 476' attained a height of 94.6+/-6.2 cm (Mean +/- S.E.M.) in Mendocino County (Bugg et al., 1996).

Barley has a strong, fibrous root system that aids in erosion control (Slayback, pers. comm.). Roots attain a depth of as much as 1.8-2.1 m on deep soils; the deepest roots are of seminal origin, whereas the upper soil is usually explored by adventitious roots (Reid, 1985). Roots of barley produce more total monosaccharides than do those of alfalfa (Angers and Mehuys, 1990).

Hockett (1990) found that root systems of Indian barleys varied among varieties, with depth of roots ranging from about 142 cm for a mesophytic (adapted to moderate moisture) variety to about 192 cm for a xerophytic (drought-adapted) type.

A temperature of 17.6 degrees Fahrenheit is required to kill seedlings of barley (Stoskopf, 1985). Barley is easy to get establish even during cold weather (Miller et al., 1989), and seedlings have excellent vigor (Slayback, pers. comm.).

Of the cereals, barley and oat have the poorest resistance to lodging (Stoskopf, 1985). Barley is usually more competitive than oat (Stoskopf, 1985).

As with other cereal grains, mowing and irrigation can be used to postpone and prolong flowering of barley (Menke, J., pers. comm.).

Barley can be plowed in as green manure in spring (Hofstetter, 1988); its residue breaks down more slowly than that of cereal rye (Finch & Sharp, 1983). It should be incorporated before April 1 to avoid warm temperatures if nematodes are likely to be a problem (McKenry, pers. comm.).

The following is based on the account by Baldridge et al. (1985). Barley is usually harvested by direct combining or by swathing prior to combining. Barley is physiologically mature when kernal moisture declines to about 40%, but kernels are largest if harvested at 35%. Storage should be at 14% moisture or lower. However, allowing barley to stand until the safe level is reached typically leads to shattering; shatter-resistant cultivars are especially important in the Southwest, where relative humidity can drop quickly following maturation.

To seed barley, use drills with disk or double-disk openers. Hoe- or furrow-type drills are used in arid regions with no irrigation (Baldridge et al., 1985).

Barley can be cut for hay/silage, or harvested for grain. (Hofstetter, 1988); it can be plowed in as green manure in spring (Hofstetter, 1988) or grown as a cover crop (McLeod, 1982). It can be grazed lightly in winter or spring (Hofstetter, 1988). Barley produces abundant biomass quicker than the other cereals and can be used prior to cash crops that are seeded in early spring (Madson, 1951); it can often be grown where other cover crops cannot (Miller et al., 1989). In Central Valley vineyards, it can be matured before vine shoots emerge, thus lessening potential for frost injury (McKenry, pers. comm.). Barley is used for reclamation of saline soils; the main mechanisms of salinity tolerance are salt exclusion and salt dilution (Anderson and Reinbergs, 1985). Oat is usually preferred over barley as a companion crop (Stoskopf, 1985).

Raderschall and Gebhardt (1990) grew three winter crops (barley, rapeseed, and Italian [annual] ryegrass) as catch crops following fava bean (cv 'Alfred') in order to evaluate their abilities to accumulate residual nitrogen. Accumulation of nitrogen was as follows (kg/ha): barley ('Cosina'): 36.2, rapeseed (cv 'Buko'): 52.1, and Italian [annual] ryegrass of Welsh origin (cv 'Deltex'): 22.9. Carbon/Nitrogen ratios were: barley: 20.3, rapeseed: 22.0, and Italian [annual] ryegrass: 31.0. Dry matter (biomass) accumulation was (tons/ha): barley: 17.2, rapeseed: 25.4, and Italian [annual] ryegrass: 14.8. Rapeseed was superior in retaining nitrogen that might otherwise be leached as nitrate. However, the residues of Brassicaceae such as rapeseed tend to break down and re-release N quicker than do those of grasses (Poaceae).

Winter cover crops, including the annual grasses barley, 'Blando' brome, and cereal rye, and various annual clovers and medics, are suggested for Californian vineyards with the aim of producing a sod-like condition. Ideally, cover crops should be low growing, require little or no mowing, and be self re-seeding. Their functions should be to reduce tillage and dust, provide habitat for predators that attack spider mites, improve water penetration, and provide nitrogen (Christensen, 1971).

Liebman and Robichaux (1990) found that intercropped barley and field pea were no better at suppressing weed mustards (Brassica kaber) and white mustard (B. hirta) than was a dense monoculture of barley. The main mechanisms of weed suppression were shading (especially by the pea) and competition for nitrogen (especially by the barley).

In a pot study, barley responded favorably to lentil green manure, with a non-N effect being 42% of the N-based effect (Janzen and Schaalge, 1992).

Barley is usually more competitive than oat, and for this reason, oat is usually preferred over barley as a companion crop (Stoskopf, 1985).

High-density plantings of barley were better at suppressing weeds than were intercropped barley and field pea. Weed suppression appeared to be due to competition for soil moisture. Weed populations were not reduced, but biomass was (Mohler and Liebman, 1987).

In trispecific mixes (pea - barley - white mustard), 'Century' variety of field pea performed well even with high soil nitrogen. The smaller 'Alaska' pea did well in such mixtures with high water and low nitrogen (Liebman, 1989).

Inclusion of barley, oat, or rye in a mix of cover crops along with vetches and bell beans appears to reduce infestation by the weed common fiddleneck (Amsinckia intermedia) (Bugg, 1990).

McGowan and Williams (1973) in Yolo County, California, in a replicated field study, grew subterranean clover (cv 'Woogenellup') in conjunction with barley (cv 'CM67'). Subterranean clover was established November 10-11 at an initial density of 100 clover plants per square meter (equivalent to a seeding rate of 10 kg/ha) in combination with barley sown and thinned to various densities (100 (control), 33 50, 200, or 400 plants per square meter) or with several alternative techniques to delay barley germination or emergence: (1) soaking with CCC (2-chloroethyl trimethylammonium); (2) seed coating with paraffin; (3) deep (10 cm) sowing; or (4) seeding of barley delayed by one or three weeks. In the final treatment, barley was clipped to a height of 2 cm 12 weeks after sowing. At the highest seeding density, barley reduced light transmission by 49%. This light reduction apparently was the principal cause for reduced subterranean clover biomass production and number of seeds per plant.

Barley grows faster in the winter and produces more vegetation than do other reseeding annuals (Finch & Sharp, 1983). Oat does not produce as much dry matter as barley, rye, or wheat (Miller, 1984). Dry matter yield was 2,570 lb/acre when cut May 9 from a stand seeded the previous fall (Hofstetter, 1988). Dry-matter estimates by Williams and Doneen (1960) indicated 3100 lb/ac at boot stage, 5830 lb/ac at flowering, and 6760 lb/ac at medium dough stage. In small plots, total dry matter at times of heading and mid grain-filling (kg/ha) for various barley cultivars was as follows: 'Corvette': 7,590, 11,980; 'Grimmett': 8,800, 10,100; 'Beecher': 8,250, 11,770; '2I Bon': 8,940, 10,630; 'Gus': 7,600, 9,250; 'Piroline': 9,900, 9,960; and 'Triumph': 11,000, 10,720 (Fukai et al., 1990). Raderschall and Gebhardt (1990) found that barley ('Cosina') produced 17.2 Mg/ha. In Mendocino County, cv 'UC 476' produced 12.9+/-2.6 Mg/ha (Mean +/- S.E.M.), and yielded the greatest biomass of all 32 cover crops assessed, which was statistically greater than the biomasses produced by 'Oregon Common' annual ryegrass, 'Blando' brome, or 'Zorro' fescue but not than oat or cereal rye (Bugg et al., unpublished data).

Hofstetter (1988) wrote that nitrogen content is 3.5% and that there was up to 38 lb of N per acre. Williams and Doneen (1960) estimated that total aboveground N content was 83 lb/ac at boot stage, 93 lb/ac at anthesis, and 81 lb/ac at medium dough stage. Jobidon et al. (1989) tested barley-, oat-, and wheat-straw mulches in field trials in eastern Quebec forest plantations. The mulches reduced soil nitrification, apparently through the production of five phenolic acids. Growth rate and foliar nitrogen content were higher for black-spruce seedlings with mulches. There were no other significant differences in nutrient status.

Raderschall and Gebhardt (1990) grew three winter crops (barley, rapeseed, and Italian [annual] ryegrass) as catch crops following fava bean (cv 'Alfred') in order to evaluate their abilities to accumulate residual nitrogen. Accumulation of nitrogen was as follows (kg/ha): barley ('Cosina'): 36.2, rapeseed (cv 'Buko'): 52.1, and Italian [annual] ryegrass of Welsh origin (cv 'Deltex'): 22.9. Carbon/Nitrogen ratios were: barley: 20.3, rapeseed: 22.0, and Italian [annual] ryegrass: 31.0. Dry matter (biomass) accumulation was (tons/ha): barley: 17.2, rapeseed: 25.4, and Italian [annual] ryegrass: 14.8. Rapeseed was superior in retaining nitrogen that might otherwise be leached as nitrate. However, the residues of Brassicaceae such as rapeseed tend to break down and re-release N quicker than do those of grasses (Poaceae).

Barley straw contains nutrients in the following amounts (lbs/ton of hay) 4-6 of P2O5, 21-42 of K2O, 2 of S, 8 of Ca, 2 of Mg, 0.008 of Cu, 0.26 of Mn, and 0.04 of Zn, and has a C/N ratio of 58 (Parnes, 1990). Anger and Mehuys (1990) found that cropping with barley led to higher soil carbohydrate concentration than with alfalfa. This may have been due to the greater root biomass of barley and its greater ratio of carbon to nitrogen, leading to slower decomposition of barley roots. Ansari (1990) found that for barley, increasing salinity led to decreasing Ca and K concentrations and increasing Na and P.

Raderschall and Gebhardt (1990) grew three winter crops (barley, rapeseed, and Italian [annual] ryegrass) following faba bean (cv 'Alfred') in order to evaluate their abilities to accumulate residual nitrogen. Accumulation of nitrogen was as follows (kg/ha): barley ('Cosina'): 36.2, rapeseed (cv 'Buko'): 52.1, and Italian [annual] ryegrass of Welsh origin (cv 'Deltex'): 22.9. Carbon/Nitrogen ratios were: barley: 20.3, rapeseed: 22.0, and Italian [annual] ryegrass: 31.0. Dry matter (biomass) accumulation was (tons/ha): barley: 17.2, rapeseed: 25.4, and Italian [annual] ryegrass: 14.8. Rapeseed was superior in retaining nitrogen that might otherwise be leached as nitrate. However, the residues of Brassicaceae such as rapeseed tend to break down and re-release N quicker than do those of grasses (Poaceae).

Williams (1966) found that increase in infiltration rate of irrigation water was inversely related to the nitrogen concentrations of nonleguminous green manures at the time of incorporation by disking. Barley (Hordeum vulgare cv 'Atlas 40', cereal rye (Secale cereale cv 'Svalof Fourex'), annual ryegrass (Lolium multiflorum), and soft chess (Bromus mollis cv 'Blando') significantly improved infiltration rate in a loamy, well-drained soil, but mustard (Brassica nigra) did not.

McGowan and Williams (1973) found that subterranean clover depleted soil moisture more than barley did. On March 27th, 19 weeks after sowing, maximal soil moisture was observed when barley was sown at the highest density and grown alone (ca 7.5% at 5-15 cm soil depth, ca 9.9% at 15-30 cm), i.e., without subterranean clover. Lowest soil moisture levels were obtained when subterranean clover was grown alone (ca 6.2% in the 5-15 cm soil stratum, and ca 8% in the 15-30 cm stratum). Presence of barley in mixes with subterranean clover did not accelerate soil moisture depletion over that observed with subterranean clover alone.

Raderschall and Gebhardt (1990) grew three winter crops (barley, rapeseed, and Italian [annual] ryegrass) following fava bean (cv 'Alfred') in order to evaluate their abilities to accumulate residual nitrogen. Accumulation of nitrogen was as follows (kg/ha): barley ('Cosina'): 36.2, rapeseed (cv 'Buko'): 52.1, and Italian [annual] ryegrass of Welsh origin (cv 'Deltex'): 22.9. Carbon/Nitrogen ratios were: barley: 20.3, rapeseed: 22.0, and Italian [annual] ryegrass: 31.0. Dry matter (biomass) accumulation was (tons/ha) : barley: 17.2, rapeseed: 25.4, and Italian [annual] ryegrass: 14.8. Rapeseed was superior in retaining nitrogen that might otherwise be leached as nitrate. However, the residues of Brassicaceae such as rapeseed tend to break down and re-release N quicker than do those of grasses (Poaceae).

Barley can improve water infiltration rate in soil (Williams and Doneen, 1960). Williams (1966) found that increase in infiltration rate of irrigation water was inversely related to the nitrogen concentrations of nonleguminous green manures at the time of incorporation by disking. Barley (Hordeum vulgare cv 'Atlas 40', cereal rye (Secale cereale cv 'Svalof Fourex'), annual ryegrass (Lolium multiflorum), and soft chess (Bromus mollis cv 'Blando') significantly improved infiltration rate in a loamy, well-drained soil, but mustard (Brassica nigra) did not.

Williams and Doneen (1960) found that on soils of medium to fine texture, barley green manure improved infiltration. Effect increased as barley matured.

McGowan and Williams (1973) found that subterranean clover depleted soil moisture more than barley did. On March 27th, 19 weeks after sowing, maximal soil moisture was observed when barley was sown at the highest density and grown alone (ca 7.5% at 5-15 cm soil depth, ca 9.9% at 15-30 cm), i.e., without subterranean clover. Lowest soil moisture levels were obtained when subterranean clover was grown alone (ca 6.2% in the 5-15 cm soil stratum, and ca 8% in the 15-30 cm stratum). Presence of barley in mixes with subterranean clover did not accelerate soil moisture depletion over that observed with subterranean clover alone.

Poehlman's (1985) account indicated that the largest use of barley grain is as animal food, primarily to supply carbohydrates and protein. As with other cereal grains, barley is deficient in the amino acid lysine and relatively high in the sulfur-bearing amino acids methionine and cystine.

Bird cherry - oat aphid (Rhopalosiphum padi) is an important pest of barley. In Denmark, the economic injury level is 70% of stems infested, or about 7 aphids per stem (Hansen, 1991).

McKenry (pers. comm.) stated that barley is host for a Meloidogyne javania race that is a problem on Thompson Seedless grapes and a minor host for Meloidogyne arenaria. In problem areas, barley should be planted after November 1 and incorporated before April 1 to avoid the warm soil temperatures that favor nematode build-up. Barley appears to be deleterious to populations of Pratylenchus vulness, but field tests are still needed.

Seeding depth for barley or oat should be no greater than 5 cm (2 in). Shallow seeding is possible in areas with high soil moisture and leads to more rapid emergence and lessened incidence of root rot disease (Stoskopf, 1985).

Long-term barley monoculture led to development of soils that suppressed barley, wheat and oat. A Pythuim sp. fungus was implicated (Olson and Gerhardson, 1992).

Intercropped barley and field pea were no better at suppressing weed mustards (Brassica kaber) and white mustard (B. hirta) than was a dense monoculture of barley. The main mechanisms of weed suppression were shading (especially by the pea) and competition for nitrogen (especially by the barley) (Liebman and Robichaux, 1990).

Barley is usually more competitive than oat; therefore, oat is usually preferred to barley as a companion crop (Stoskopf, 1985).

Smeda and Putnam (1988) grew cover crops of cereal rye (cv 'Wheeler'), wheat (Triticum aestivum L. cv 'Yorkstar'), and barley (cv 'Barsoy') amid 2-year-old stands of strawberry (Frageria X ananassa Duchesne Rosaceae; cv 'Midway' or 'Guardian'). There were also control plots with no cover crops seeded. The cover crops were planted in mid September and killed during early or late May with applications of the graminicidal herbicide fluazifop-butyl. All cover crops showed better weed suppression than the control, but the only significant differences among cover crops indicated that barley was inferior to rye or winter wheat. There were no significant differences among treatments in yield of strawberries.

Jobidon et al. (1989a) tested barley-, oat-, and wheat-straw mulches in eastern Quebec forest plantations of balsam fir/birch. The mulches inhibited red raspberry (Rubus idaeus) and reduced mean weed cover by 41%, apparently through the production of five phenolic acids. Liebman (1989) found that high-density plantings of barley were better at suppressing weeds than were intercropped barley and field pea. Weed suppression appeared to be due to competition for soil moisture. Weed populations were not reduced but biomass was (Mohler and Liebman, 1987).

Inclusion of barley, oat, or rye in a mix of cover crops along with vetches and bell beans appears to reduce infestation by the weed common fiddleneck (Amsinckia intermedia) (Bugg, pers. comm., 1990).

Weed above-ground biomass (dry) in plots seeded to cv 'UC 476' in a Mendocino County vineyard on May 15-16 was 0.043+/-0430 Mg/ha (Mean +/- S.E.M.) which was less than 1% of the weed biomass recorded for the control plots. Dominant winter annual weeds at the site were chickweed, shepherds purse, rattail fescue, and annual ryegrass.; Vegetational cover by the barley was estimated as 87.5+/-6.6 % (Mean +/- S.E.M.) (Bugg et al., 1996).

Wild oat (Avena fatua) is probably the most difficult weed affecting barley (Hockett, 1990).

Konesky et al. (1989) used outdoor pot culture in Vancouver, British Columbia, in determining that different barley cultivars showed differing competitiveness against wild oat (Avena fatua L.) under high and low soil phosphorus concentration regimes. Based on several response variables (shoot dry matter, mean numbers of shoots per plant, mean shoot P, and P utilization efficiency), 'Fairfield' was highly competitive against wild oat under both high and low P regimes. 'Betzes' was highly competitive at low P but only moderately so at high P. 'Steptoe' was moderately competitive at high P but poorly so at low P. 'Laurier' and 'Bonanza' were moderately to poorly competitive under both P regimes.