Austrian Winter Pea Research Articles

The Use of Winter Annual Legume Cover Crops in a Wheat-Grain Sorghum Rotation in South Central Kansas

ABSTRACT Winter annual legumes in humid regions of the country can have a positive effect on subsequent corn (Zea mays) and grain sorghum (Sorghum bicolor) crops, mainly through N contribution of the legume and, in some cases, soil improvement. However, water use by the cover crop in drier regions has the potential to reduce yields in subsequent crops. This study was initiated in central and south-central Kansas to look at both the agronomic and economic implications of adding a winter annual legume cover crop to a winter wheat (Triticum aestivum)-grain sorghum rotation. Experiments included researcher-managed on-station trials and cooperative (i.e., farmer-managed) trials with farmers using hairy vetch (Vicia villosa) and Austrian winter pea (Pisum arvense). Results showed that in good rainfall years, establishment of cover crop was adequate, and no significant difference occurred between sorghum yields following cover crops versus following wheat with fertilization. On-station trials showed a significant nitrogen (N) contribution from hairy vetch and benefits to sorghum. During years with low rainfall, cover crop establishment was poor, N contribution from the cover crop was low, and grain sorghum yields were reduced because of water use by the cover crop. Variable costs were similar between cover crop and fertilized treatments, but gross returns and, consequently, net returns were lower in the cover crop plots because of this yield reduction. For cover crops to be attractive options for farmers in this part of Kansas: they must be used also for livestock feed and/or for early spring grazing; other cultivars or management systems that use less water must be developed; experiments must be conducted to ascertain benefits of cover crops during the second rotation cycle; and the price of N fertilizer must increase to the point that use of alternative sources is economical. Also, the use of cover crops by farmers in regions of variable rainfall should not be “recipe driven” but “response driven”, using cover crops in years where rainfall is adequate, and not planting or destroying stands during dry years to conserve water for the cash crop.

Shifts in substrate utilization potential and structure of soil microbial communities in response to carbon substrates

The Biolog assay is a popular tool for estimating carbon (C) substrate utilization potentials of microbial communities of natural habitats, but its ecological relevance has been questioned. In this study, impacts of simple and complex C substrates on microbial community Biolog activities were assessed to determine if the resulting utilization potentials reflected the amended substrates. A silt loam soil was amended on an equal C-basis with glucose, cellulose, lignin, hydroxyproline, gelatin, or residues from either triticale ( X Triticosecale Wittmack) or Austrian winter pea ( Pisum sativum L.) and incubated for 80 days. Mean utilization of Biolog carbohydrates, amino acids, and polymers were determined at 3, 7, 21, 35, 49 and 80 days following incorporation of each substrate to soil. In addition, microbial biomass C (MB C) and community fatty acid methyl ester (FAME) profiles were determined at each sampling point to assess community size and structure. Soil amended with lignin maintained similar levels of MB C, Biolog activities, and FAME profiles relative to a non-amended control soil. Soil amended with glucose had higher MB C levels relative to non-amended soil and soils amended with cellulose, lignin, and plant residues. Communities from glucose-amended soil utilized Biolog carbohydrates at high rates but exhibited low utilization potentials for amino acids and polymers. Principal components analysis of FAME data revealed greater amounts of fungal markers in soil amended with glucose during the first 21 days of the incubation. In contrast, soils amended with plant residues had relatively high Biolog activities for all three types of substrates and contained a greater diversity of FAMEs compared to communities from the glucose treatment. Hydroxyproline and gelatin amendments had the greatest impact on the microbial parameters measured. Highest values for MB C, Biolog activity, FAME richness, and diversity were found in either or both treatments at most sampling dates. Biolog polymer utilization was particularly elevated in soil amended with gelatin, which was similar in structure to the Biolog polymer collagen. Positive impacts of hydroxyproline and gelatin on microbial communities may be due to the N content of these treatments; however, triticale and winter pea residues had very similar impacts on soil communities, despite winter pea legume having 1.5 times more N compared to the triticale residue. Together, the Biolog and FAME data revealed successional patterns in microbial communities over time. For example, an increase in carbohydrate utilization in cellulose-amended soil at day 49 corresponded to increases in FAME richness and diversity, with elevated amounts of the fungal fatty acids 18:1ω9 c and 18:3ω6 c detected in this soil.

Interseeding Cover Crops into Soybean and Subsequent Corn Yields

Organic producers in the northeastern USA have difficulty establishing cover crops after soybean [Glycine Max (L.) Merr.] harvest. We interseeded species into soybean on an organic farm without livestock to identify cover crops that do not interfere with soybean harvest, provide significant ground cover, and increase subsequent corn (Zea mays L.) yields. Foenugreek (Trigonella foenum‐graceum L.), rye (Secale cereale L.), wheat (Triticum aestivum L.), strawberry clover (Trifolium fragiferum L.), and Austrian winter pea (Dolichos lignosus L.) did not meet establishment and height requirements at the time of harvest. White clover (Trifolium repens L.), red clover (Trifolium pratense L.), barrel medic (Medicago lupulina L.), alfalfa (Medicago sativa L.), annual ryegrass (Lolium multiflorum L.), and creeping red fescue (Festuca rubra L.) met these requirements and generally provided >30% ground cover. Interseeded grasses provided the most biomass (0.5–1.1 Mg ha−1) at spring plowdown. Interseeded legumes did not establish well in 1996–1997 and produced only 0.1 to 0.2 Mg ha−1 biomass in 1997. Corn yielded more following Dutch white clover (7.2 Mg ha−1) and medium red clover (6.7 Mg ha−1) than following no cover (5.7 Mg ha−1) in 1996 but yielded the same in 1997 (5.7, 6.3, and 6.2 Mg ha−1, respectively). Corn yielded less following annual ryegrass (5.3 Mg ha−1) and creeping red fescue (5.1 Mg ha−1) than following no cover in 1997. More research is needed to identify conditions that would reduce the risk of poor establishment of interseeded legumes or reduced corn yields following interseeded grasses.

Winter Wheat Yield Depression from Legume Green Fallow

AbstractIncreases in N fertilizer costs have caused some farmers to consider the use of a legume during the fallow phase of a wheat‐fallow system as an alternative N source for dryland wheat. Farmers need to know how this system will affect winter wheat (Triticum aestivum L.) production and economic returns. The objectives of this research were (i) to determine the effect of legume green fallow on subsequent winter wheat yields and economic returns and (ii) to determine optimal legume termination dates during the legume phase. Wheat yields following three legumes [Austrian winter pea, Pisum sativum L. subsp. sativum var. arvense (L.) Poir.; spring field pea, P. sativum L.; and black lentil, Lens culinaris Medikus] were compared with wheat yields following fertilized traditional summer fallow. Legume biomass, biomass N, and water use were measured at four termination dates during the green‐fallow phase of the rotation. Wheat yields following the annual legume were reduced, compared with traditional summer fallow, by 400 kg ha−1 at the earliest legume termination date and by at least 1050 kg ha−1 at all other dates. Economic analysis indicates that in drier than normal years, that returns are maximized when the legume is not grown during the fallow phase. In 1996, a wet year, returns were maximized when the legume was terminated at the second termination date or after 70% of the potential maximum legume water use. We found that 88% of the variability in winter wheat yield could be explained by legume water use the previous year. In general, the competitiveness of legume green fallow with winter wheat fallow is highly weather‐dependent and inconsistent. At current fertilizer costs, legume N (in this system) was too expensive to be considered a reasonable alternative to chemical fertilizer.

Rate and Timing of Nitrogen Fertilization on Yield and Gross Revenue of Fresh Market Tomatoes Following a Winter Legume Cover Crop

ABSTRACT Using a winter annual legume cover crop to supply the N needs of fresh market tomatoes (Lycopersicon esculentum L.) can be beneficial to the long-term productivity of the soil and an efficient utilization of resources. Successful production is related to fruit size, quality, yield, and timing to market highs. Mineralization of N from legumes must occur at rates and timing corresponding to optimal fruit development of the crop. The objective of this study was to determine if successful vine-ripened fresh market tomato production could occur using a winter legume cover crop to the supply the N needs. A two-year study investigated the rate and timing effects of supplemental N on yield and revenue of tomatoes following an incorporated winter annual legume cover crop of Austrian winter pea (Pisium sativum subsp. arvense). Treatments consisted of 0, 67,134,202 and 246 kg N (mulched ha)−1 applied all preplant or preplant + two split N injections of 34 kg N (mulched ha)−1 each at early fruit set and 10 d...

Registration of ‘Granger’ Austrian Winter Pea

Registration of ‘Granger’ Austrian Winter Pea

Winter Cover Cropping Influence on Nitrogen in Soil

AbstractWinter cover crops may affect the short‐ and long‐term N availability in soil depending on the quantity, quality, and degradation rate of biomass returned to the soil. We examined the effects of several cover crops on soil inorganic and organic N levels in a winter cover crop‐silage corn (Zea mays L.) double‐cropping system that was initiated in 1987. High biomass N concentrations (BMN) in the above‐ and belowground biomass of the leguminous cover crops corresponded to high levels of inorganic N and water‐soluble N, but low levels of water‐soluble C and carbohydrate compared with the nonleguminous cover crops. The BMN above which there was net N mineralization 4 wk after residue incorporation was 17.9 g N kg−1. The organic N from the aboveground biomass degraded rapidly. The first‐order rate constants for the degradation of organic N and C in the cover crops were significantly correlated. This, coupled with a significant correlation between the soil organic N (SON) levels and cumulative biomass C added, indicated the importance of biomass C inputs in organic N retention in the soil. The cover crops had variable short‐ and long‐term effects on soil N availability. Whereas rye (Secale cereale L. cv. Tetra Petkus) and annual ryegrass (Lolium multiflorum Lam. cv. Billion) were ineffective in increasing soil inorganic N levels, they were more effective than hairy vetch (Vicia villosa Roth subsp. villosa), Austrian winter pea (Lathryrus hirsutus L.), and canola (Brassica napus L. cv. Santana) in increasing SON accumulation because of a higher biomass potential and a larger input of biomass C.

Evaluation of Cover Crop Mixtures for Use in Vegetable Production Systems

Planting polyculture mixtures of cover crops can optimize the benefits of their use. Thirteen polyculture mixtures of cover crops were evaluated in Columbus and Fremont, Ohio, to find a species mix that would establish quickly for erosion control, overwinter in Ohio, contribute sufficient N and have a C : N ratio between 20:1 and 30:1 to optimize N availability for subsequent crops, be killable by mechanical methods, and have high weed control potential. All of the mixtures in Columbus had achieved 30% ground cover 1 month after planting, but only four of the mixtures achieved this in Fremont due to poor conditions at planting. Above-ground biomass (AGB) accumulation in the mixtures ranged from 3631 to 13,642 kg·ha-1 in Columbus, and 449 to 12,478 kg·ha-1 in Fremont. Nitrogen in the AGB ranged from 74 to 269 kg·ha-1 in Columbus, and 10 to 170 kg·ha-1 in Fremont. Weed cover in the cover crop plots ranged from 1% to 91% eight weeks after cover crop kill in Columbus, and 12% to 90% seven weeks after cover crop kill in Fremont. Because one or more species in each screened mixture was determined not to be suitable, none of the mixtures was optimum. However, information gained about performance of individual species within the mixtures is also useful. `Nitro' alfalfa (Medicago sativa L.), ladino clover (Trifolium repense L.), subterranean clover (Trifolium subterraneum L.), Austrian winter peas [Pisum sativum ssp. Arvense (L.) Poir], and annual ryegrass (Lolium multiflorum Lam.) did not overwinter dependably in Ohio. Tall fescue (Festuca arundinacea L.), perennial ryegrass (Lolium perenne L.), and orchardgrass (Dactylis glomerata L.) did not compete well with taller, more vigorous species, and were not persistent in the mixtures. Medium and mammoth red clover (Trifolium pratense L.), annual and perennial ryegrass, and white and yellow blossom sweetclover [Melilotus alba Desr., and Melilotus officianalis (L). Desr.], were not killable by mechanical methods. Individual species that established quickly, were competitive in the mixtures, overwintered dependably, and were killed by mechanical methods were rye (Secale cereale L.), barley (Hordeum vulgare L.), crimson clover (Trifolium incarnatum L.), and hairy vetch (Vicia villosa Roth.)

Grass–Legume Bicultures as Winter Annual Cover Crops

AbstractGrass‐legume bicultures as winter annual cover crops may combine the N scavenging ability of grasses and the biological N2 fixation capacity of legumes to improve N management in crop production systems of the southeastern USA. A 3‐yr field experiment was conducted on a Norfolk loamy sand (fine‐loamy, kaolinitic, thermic Typic Kandiudults). The focus of this research was to examine the differences among legume monocultures and grass‐legume bicultures with regard to early spring dry matter (DM) and N accumulation, and related effects on soil inorganic N levels and subsequent corn (Zea mays L.) yield. Austrian winter pea [Pisum sativum L. subsp, sativum var. arvense (L.) Poir.], crimson clover (Trifolium incarnatum L.), commonve tch (Vicla saava L.), and hairy vetch (Vicla villosa Roth) were grown in monoculture and in bicultures with rye (Secale cereale L.), oat (Arena satira L.), and wheat (Triacum aestivum L.). Aboveground plant material was harvested in early March, late March, and mid‐April. Biomass was separated into component species and analyzed for total N and C concentrations. Averaged over 3 yr, legume component DM accumulation in monoculture and biculture ranged from 0.87 to 2.53 Mg ha−1, with a ranking of Austrian winter pea < hairy vetch < commonv etch < crimson clover. For the same period, the grass component DM accumulation ranged from 1.31 to 2.28 Mg ha−1, in the order rye = oat < wheat. Three‐year mean N accumulation values for the legume component followed the same relative ranking and ranged from 24 to 93 kg N ha−1. Grass factor N content ranged from 18 to 39 kg N ha−1 in the order rye < oat < wheat. For all bicultures, the average C:N ratio over the 3‐yr experiment was >30, suggesting that net N mineralization would occur from the decomposing cover crop residues. Profile soil inorganic N (0 to 90 cm) was greater in legume monoculture than in grass‐legume biculture treatments, indicating the ability of grasses to capture soil N. Corn yield was affected by the treatments in 1 of 3 yr, with greater yields following a legume monoculture than a grass‐legume biculture. Collectively, these results suggest that grass‐legume bicultures as winter annual cover crops have the potential to utilize residual soil NO3 and thereby minimize leaching while adding fixed N to cropping systems in the southeastern USA.

Cover Crop Response to Late-Season Planting and Nitrogen Application

Cover crops aid in reducing precipitation runoff, soil erosion, and N losses in highly sloped, mountainous regions. Corn (Zea mays L.) producers in states with late spring warmup and early winters have limited success when planting cover crops following harvest. Studies were conducted from 1992 through 1995 in southern and northern West Virginia to evaluate the groundcover ability of several late-planted cover crops and their dry weight response to fall N application. In most years, vetch (Vicia villosa Roth cv. Common) and Austrian winter pea (Pisum sativum var. arvense L. Poir cv. Austrian winter) produced the least groundcover and dry matter of all species evaluated. Rye (Secale cereale L. 'Abruzzi' and 'Wheeler') was the most reliable and winter-hardy cover crop, regardless of location. Initial soil nitrate-N concentrations at planting averaged 12 ppm in soils with continuous corn-production and no history of manure application (southern experiment) and 40 ppm in soils with similar rotation and a history of manure application (northern experiment). Nitrogen application did not consistently increase the likelihood of cover crop survival, but increased dry matter for some cover crops on soils with low initial N levels. At the southern location, Abruzzi rye planted alone and common rye in combination with common vetch responded positively to additional N application in 3 out of 3 and 2 out of 3 yr, respectively. 'Pastar' rye (1992-1993), common rye (1993-1994), wheat (Triticum aestivum L.) (1994-1995), and barley (Hordeum vulgare L. 'Barsoy') (1994-1995) also responded positively to N application at the southern location. Cover crops did not respond to additional N application at the northern location on soils high in initial N fertility. Corn producers in mountainous, highly sloped land should consider methods for planting cover crops earlier to ensure plant survival and to protect soil during the winter.

Winter Cover Crop Effects on Soil Organic Carbon and Carbohydrate in Soil

AbstractWinter cover crops may increase soil organic carbon (SOC) levels or reduce their rate of depletion. Selection of appropriate cover crops to increase SOC requires an adequate knowledge of the quality and quantity of plant biomass produced and its rate of decomposition in soil. This study examined the SOC and carbohydrate concentrations in soil as affected by several leguminous and nonleguminous cover crops after 6 yr of a corn (Zea mays L.) cover crop double cropping system in a temperate, humid region. The vegetation in the control treatment without cover crops was primarily shepherd's‐purse [Capsella bursa‐pastoris (L.) Medikus]. The cover crops had a variable effect on SOC and soil carbohydrate concentrations due to a significant difference in total organic C and carbohydrate produced by the cover crops. The buried bag technique showed that the biomass C from the aboveground biomass of the cover crops decomposed rapidly in the soil with a half‐life averaging 30.9 ± 9.4 (SD) d in 1992 and 55.2 ± 7.8 (SD) d in 1993. The decomposition of carbohydrate in the aboveground biomass in the soil was also rapid with an average half‐life of 40.0 ± 13.1 (SD) d in 1992 and 50.5 ± 11.8 (SD) d in 1993. The overriding cover crop effect on SOC and carbohydrate was due to the magnitude of the C inputs from the cover crops. With more than 4 Mg ha−1 of top biomass, cereal rye (Secale cereale L.) and annual ryegrass (Lolium multiflorum Lam.) were better suited as winter cover crops for building SOC levels in this region than Austrian winter pea (Lathyrus hirsutus L.), hairy vetch (Vicia villosa Roth), and canola (Brassica napus L.).

Cover crops can increase lettuce drop

Although cover crops contribute many benefits to organic and conventional agricultural systems, they may play a significant role in the epidemiology of soil-borne diseases. A 2-year study shows that Sclerotinia minor, which causes lettuce drop disease, is a pathogen of phacelia, lana woollypod vetch and Austrian winter pea cover crops. Greenhouse and field inoculations failed to result in S. minor infections of oilseed radish, barley and fava bean cover crops. It appears these three cover crops can be safely incorporated into lettuce rotations without increasing the occurrence of lettuce drop.

Comparison of Interseeded Legumes and Small Grains for Cover Crop Establishment in Cotton

AbstractWind erosion of soil is a potential problem in unprotected cotton (Gossypium hirsutum L.) fields on the Southern High Plains of Texas during winter and early spring. Our objective was to determine which winter annual forage legumes and small grains may be successfully established by fall interseeding into standing cotton. Thirteen plantings were made over 6 yr at three locations. Both cotton and the interseeded forages were grown under rainfed conditions. The forages were winter wheat (Triticum aestivum L. emend. Thell.), rye (Secale cereale L.), Austrian winter pea [Pisum sativum subsp. pisum var. arvense (L.) Poir.], hairy vetch (Vicia villosa Roth), subterranean clover (Trifolium subterraneum L.; 5 cultivars), rose clover (Trif. hirtum All.; 3 cultivars), crimson clover (Trif. incarnatum L.; 2 cultivars), red clover (Trif. pratense L.), berseem clover (Trif. alexandrinum L.), and barrel medic (Medicago truncatula Gaertn.; 2 cultivars). Successful stands of wheat, rye, winter pea, and hairy vetch were obtained in 69% of the plantings, but in only 53% for the other forages. Establishment of the small‐seeded legumes (clovers and medics), which must be planted at a shallow depth, seemed to be governed by the timing of effective rainfall events after seeding. Establishment of the larger‐seeded wheat, rye, winter pea, and vetch was less dependent on timely rainfall after planting. Of these winter annuals, wheat and rye were the most dependable in producing a soil cover.

Fall-planted Cover Crops Support Good Yields of Muskmelons

Four cover crops {alfalfa (Medicago sativa L. `Kansas Common'), hairy vetch (Vicia villosa Roth), Austrian winter pea [Pisum sativum subsp. arvense (L.) Poir], and winter wheat (Triticum aestivum L. `Tam 107')}, alone and in combination with feedlot beef manure at 5 t·ha–1 were evaluated for 2 years to determine whether sufficient N could be supplied solely by winter cover cropping and manure application to produce high-quality muskmelons (Cucumis melo L. `Magnum 45') in an intensive production system using plastic mulch and drip irrigation. Among the legumes, hairy vetch produced the most biomass (8.9 t·ha–1) and accumulated the most N (247 kg·ha–1). Winter wheat produced more biomass (9.8 t·ha–1) than any of the legumes but accumulated the least N (87 kg·ha–1). Melon yields produced using legume cover crops alone were similar to those receiving synthetic N fertilizer at 70 or 100 kg·ha–1. Melons produced on plots with cover crops combined with beef manure did not differ significantly in yield from those produced on plots with only cover crops. Legume cover crops alone, used with plastic mulch and drip irrigation, provided sufficient N for the production of high-quality muskmelons.

Phacelia, Lana Woolly pod Vetch, and Austrian Winter Pea: Three New Cover Crop Hosts ofSclerotinia minorin California

A 2-year field and greenhouse study identified three cover crops as new hosts for Sclerotinia minor. Pathogenicity was established by planting 4-week-old transplants of six cover crops and lettuce (Lactuca sativa) into sand amended with sclerotia. After 4 weeks of incubation in a greenhouse, phacelia (Phacelia tanacetifolia), Lana woollypod vetch (Vicia dasycarpa), and Austrian winter pea (Pisum sativum L. subsp. arvense) exhibited disease symptoms, as did lettuce, and S. minor was reisolated from the diseased cover crop plants. To assess susceptibility in a field situation, seven cover crop species, lettuce, and fallow treatments were placed for two consecutive years into randomized, replicated field plots infested with sclerotia. In both the 1993 and 1994 experiments, disease was observed on phacelia, Lana woollypod vetch, purple vetch (Vicia benghalensis), Austrian winter pea, and lettuce. Oilseed radish, barley, and fava bean did not become diseased. When lettuce was planted after cover crop incorporation, phacelia, Lana woollypod vetch, and Austrian winter pea plots had significantly higher lettuce drop incidence than fallow plots in the first year. In the second year, only phacelia plots had significantly more lettuce drop. In a commercially planted lettuce field, lettuce drop incidence was significantly higher 1 year in plots previously planted to phacelia. This is the first report of S. minor as a pathogen of phacelia, Lana woollypod vetch, and Austrian winter pea cover crops in California.

Effects of Green Manures on Verticillium Wilt of Potato

Two field studies were conducted to investigate the effects of green manure treatments on Verticillium wilt of potato (cv. Russet Burbank) caused by Verticillium dahliae. Each study involved the use of a sudangrass (Sorghum vulgare var. sudanense 'Monarch') green manure treatment and a fallow treatment for either 2 or 3 years prior to growing potato. In addition to sudangrass, comparisons also were made with several green manure treatments, including Austrian winter pea (Pisum sativum 'Austrian winter'), two cultivars of rape (Brassica napus var. napus 'Dwarf Essex' and 'Bridger'), rye (Secale cereale), oat (Avena sativa 'Monida'), and corn (Zea mays 'Jubilee'). Verticillium wilt of potato was best controlled after green manure treatments of either sudangrass or corn ; after these treatments, yields were increased above all other treatments. Wilt was most severe when potato followed the fallow treatment and intermediate following rape, Austrian winter pea, oat, and rye. Wilt incidence was positively correlated with V. dahliae colonization in apical stems but was not significantly related to other pathogens (Pratylenchus neglectus, Colletotrichum coccodes, Rhizoctonia solani Ag-3) or to effects of green manure treatments on preplant nutritional effects of N, P, or K.

RESPONSE OF SWEETPOTATOES TO WINTER COVER CROPS

Rye, wheat, hairy vetch, ryegrass, and Austrian winterpea were evaluated for effects on weed control and sweetpotato production. Sweetpotatoes were transplanted into these cover crops after the cover crops had been killed with glyphosate and mowed. One-half of each plot was treated with clomazone herbicide and one-half was not treated. Plots with rye residues contained fewer goosegrass, rice flatsedge, ground cherry, and smooth pigweed plants than other cover crop plots. Sweetpotato plant vigor was greatest in the rye plots. Goosegrass, crabgrass, groundcherry, and eclipta were controlled in cover crop plots treated with clomazone. Sweetpotato plant vigor was better in the plots treated with clomazone than in plots with a cover crop only. Highest yields of no. 1 grade and total marketable sweetpotatoes were in rye and ryegrass cover crop plots, with or without clomazone. Sweetpotatoes grown in Austrian winterpea plots without clomazone produced the lowest yields. There was an increase in yield of sweetpotatoes in all cover crop plots treated with clomazone.

Cover Crop Production for Several Planting and Harvest Dates in Eastern Nebraska

AbstractSpecies used for cover crops vary greatly in their growth response to water availability, soil temperature, length of growing period, day length, and related environmental factors. Few reports compare growth of different species at different times during the growing season. This 4‐yr field experiment at Lincoln, NE, compared growth of some 20 species as affected by planting date and length of the growth period. All species were planted as early as possible each spring, with a second seeding in early summer (25 June–17 July). Additional seedings were made at other times in most years. All plots were periodically sampled for dry matter production until maturity or frost. At most samplings, growth of soybean [Glycine max L. (Merr.)] was equal to or greater than (sometimes double) that of the next species. In most situations, hairy vetch (Vicia villosa Roth) also performed well. Field pea (Pisum sativum L.) or Austrian winter pea [P. sativum L. subsp. sativum var. arvense (L.) Poir.] and fava‐bean (Vicia faba L.) grew very rapidly for the first 60 to 90 d after planting. Lespedeza [Kummerowia stipulacea (Maxim.) Makino] grew relatively well when seeded in early summer, as did tinga pea (Lathyrus tingitanus L.) and cowpea [Vigna unguiculata (L.) Walp. subsp. unguiculata]. Rye (Secale cereale L.) was usually intermediate, and small‐seeded legumes generally exhibited relatively slow growth the first 60 d. Results suggest that certain large‐seeded, cool‐season legumes would produce best for early spring seeding before row crops or summer fallow, whereas some warm‐season species would be better suited for summer seeding after small grain harvest. Soybean and hairy vetch were well suited for almost all situations in this environment.

Legume Cover Crop Contributions to No‐Tillage Corn Production

AbstractWinter cover crops can supply N to the next crop, reduce erosion and N leaching, and conserve or deplete soil moisture. To identify optimum corn fertilizer nitrogen (FN) rates following cover crops, we evaluated hairy vetch (VT: Vicia villosa Roth), Austrian winter pea [PE: Pisum sativum L. subsp. sativum var. arvense (L.) Poir.], crimson clover (CR: Trifolium incarnatum L.), and wheat (WH: Triticum aestivum L.) winter cover crops in the U.S. Coastal Plain and Piedmont for no‐tillage corn (Zea mays L.) at four FN rates (topdressed NH4NO3) over 4 yr. Parameters evaluated included cover crop yield and N content, corn N uptake, and corn grain yield. On the Coastal Plain, VT, PE, CR, and WH topgrowth averaged 205, 180, 170, and 40 kg N ha−1, respectively, and ≈40% less for the Piedmont. With no FN, grain yields were generally greater after legumes than after no cover crop, and lowest after WH, with the best yields after legumes with 90 to 135 kg FN ha−1. Synergistic responses occurred when FN was applied after legumes. Non‐N‐limited grain yield increases averaged 2 Mg ha−1 (Coastal Plain) and 0.5 Mg ha−1 (Piedmont), and were not directly related to cover crop N. With no cover crop, FN needed for maximum yield averaged 80 kg ha−1 (Piedmont) and 135 kg ha−1 (Coastal Plain). After WH, FN needs increased 15 to 30 kg ha−1, but decreased 10 to 75 kg ha−1 after legumes. Hairy vetch provided the most consistent increases, with average grain yield of 10.6 Mg ha−1 (Coastal Plain) and 8.2 Mg ha−1 (Piedmont), and an economic optimum FN rate of 127 (Coastal Plain) and 66 kg ha−1 (Piedmont).

Cotton Yield and Fiber Quality Response to Green Manures and Nitrogen

AbstractThe quantity and availability of N from green manures will considerably affect the N management of a succeeding cotton (Gossypium hirsutum L.) crop. This study was conducted to determine the N supplying capacity of crimson clover (Trifolium incarnatum L.), Austrian winter pea [Pisum sativum subsp. arvense (L.) Poir.], and rye (Secale cereale L.) to cotton and their influence on cotton yield and fiber properties. Green manure treatments (and a fallow check) with fertilizer N levels of 0, 56, 112, and 168 kg ha−1 were compared for 3 yr on a Norfolk loamy sand (fine‐loamy, siliceous, thermic Typic Kandiudult). Soil moisture at planting was similar among the four green manuretr eatments. At the 0 N level, the legumes generally had higher soil NO3‐N than rye or fallow. Cotton grown following clover and pea with 0 kg ha−1 added N had petiole NO3‐N levels similar to those of rye and fallow with 56 kg N ha−1. Fertilizer N had no influence on cotton yield in the pea winter cover treatment. A quadratic regression equation best described the lint yield response following clover. For both rye and fallow treatments, yield plateaued at 56 kg N ha−1. Green manures had little influence on fiber properties. The results indicate that legumes supply adequate but not excessive N for modern cotton production and that incorporation of rye into the production system does not affect N fertilization requirements.