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Kathryn E. Brunson, C. Robert Stark Jr., Sharad C. Phatak and Michael E. Wetzstein

Research results are presented from a multi-year study on vegetable production in southern Georgia that compared two low-input production systems to the conventional rye cover crop technology. The low-input systems use beneficial insect principles as a substitute for conventional pesticide controls, but pesticides are used if needed. Preliminary results from the low-input systems using crimson and subterranean clovers indicate that crimson clover produces better yields and can “catch up” to the conventional rye system. The higher yields of the rye technology can be offset by the cost reductions associated with the low-input technologies. Production budgets were developed for 3 years of eggplant and 2 years of fresh-market tomato and bell pepper to reveal expected net returns under the low-input and conventional systems.

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Muddappa Rangappa, Harbans Bhardwaj and Harry Dalton

An on-farm animal manure, such as chicken manure, can be a source of nutrients for the growth and production of agricultural crops. However, use of manures at rates that are considered adequate for crop production may cause excessive accumulation of phosphorus (P) and also result in leaching of nitrogen (N), thus leading to potential pollution of ground and surface water. Composting of manures with a carbon (C) source can reduce P and N to manageable levels to support production of crops. In order to determine the potential of composted manure for crop production, we studied growth and production of sweet corn by using poultry manure composted with a carbon source of crimson clover hay or wheat straw. These experiments, conducted during 2002 and 2003, compared six treatments: 1) uncomposted chicken manure alone; 2) composted with wheat straw turned weekly; 3) composted with wheat straw turned bi-weekly; 4) composted with crimson clover hay turned weekly; 5) composted with crimson clover hay turned bi-weekly; and 6) a control with a commercial recommendation rate of N fertilizer. These treatments resulted in 9244; 13,866; 15,688; 16,734; and 11,977 marketable ears/acre, respectively, indicating significant superiority of treatments 4 and 5 over all others. Similar results were obtained for ear length, ear fresh weight, and plant height. Results indicated that composting of poultry litter with wheat straw or crimson clover hay is a viable way to utilize poultry manure for production of sweet corn and other agricultural crops. This study implies that composting of on-farm animal manure with organic material, such as hay and straw, could play an important role in development of an environmentally friendly, economically feasible, and sustainable organic production of agricultural crops.

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Francis X. Mangan, Mary Jane Else and Stephen J. Herbert

Field research was conducted in Deerfield, Mass. to study the effects of different cover crop species seeded between plastic mulch on weed pressure and pepper yield. A complete fertilizer was applied before plastic was laid on Sept. 13, 1991. Two cover crop treatments were seeded Sept. 13, 1991: white clover (Trifolium repens) alone and hairy vetch (Vicia villosa) in combination with winter rye (Secale cereale). On May 27, 1992 the vetch and rye were mow-killed with the biomass left on the soil surface. Annual rye (Lolium multiflorum) was then seeded on the same day as the third cover crop treatment. The remaining two treatments were a weedy check and a hand-weeded check. Peppers were transplanted into the plastic on May 31. Both the annual rye and clover were mowed three times over the course of the experiment with the biomass left between the plastic mulch. The white clover and annual rye were much more competitive with weed species than the dead mulch of vetch and rye. The three cover crop treatments had pepper yields that were severely depressed compared to the hand-weeded treatment. Among the three cover crop treatments, only the annual rye yielded more peppers than the weedy check.

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Steven J. Guldan, Charles A. Martin, Jose Cueto-Wong and Robert L. Steiner

Five legumes [hairy vetch (Vicia villosa Roth.), barrel medic (Medicago truncatula Gaerth.), alfalfa (Medicago sativa L.), black lentil (Lens culinaris Medik.), and red clover (Trifolium pratense L.)] were interseeded into sweet corn (Zea mays L.) at last cultivation when sweet corn was at about the V9 (early) or blister (late) stage. The effect of legume interseeding on sweet corn yield, and late-season dry-matter and N yields of aboveground portions of the legumes was determined. Sweet corn yield was not affected by legume interseeding. In 1993, legume dry-matter yields were 1420 kg·ha–1 interseeded early and 852 kg·ha–1 interseeded late. Nitrogen yields were 49 kg·ha–1 interseeded early and 33 kg·ha–1 interseeded late. In 1994, dry-matter yields were 2760 kg·ha–1 interseeded early and 1600 kg·ha–1 interseeded late. Nitrogen yields were 83 kg·ha–1 interseeded early and 50 kg·ha–1 interseeded late. In 1993, barrel medic was the highest-yielding legume with dry matter at 2420 kg·ha–1 and N at 72 kg·ha–1 interseeded early, while red clover yielded the lowest with dry matter at 340 kg·ha–1 and N at 12 kg·ha–1 interseeded late. In 1994, dry-matter and N yields ranged from 4500 and 131 kg·ha–1, respectively, for early interseeded barrel medic to 594 kg·ha–1 and 16 kg·ha–1, respectively, for late interseeded red clover.

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Wheeler G. Foshee, William D. Goff, Michael G. Patterson and Donald M. Ball

Hairy vetch (Vicia villosa Roth), common vetch (V. sativa L. `Cahaba White'), arrowleaf clover (Trifolium vesiculosum Savi `Yuchi'), crimson clover (T. incarnatum L. `Tibbee'), red clover (T. pratense L. `Redland II'), yellow nutsedge (Cyperus esculentus L.), buckwheat (Fagopyrum sagittatum Gilbert), hairy indigo (Indigofera hirsuta L.), bahiagrass (Paspalum notatum Flugge `Pensacola'), common bermudagrass [Cynodon dactylon (L.) Pers.], and centipedegrass [Eremochloa ophiuroides (Munro) Hack] were grown for 3 years in a 3 × 3-m spacing around young pecan [Carya illinoinensis (Wangenh.) K. Koch] trees. Compared to weed-free plots, all cover crops suppressed tree growth substantially, and there were no differences among cover crops in the degree of suppression. Mean trunk cross-sectional area of weed-free trees increased 26-fold by the end of the third growing season but increased only 13-fold for trees grown with any cover crop. These results suggest that cover crops, if grown in young pecan orchards to promote beneficial insects, should be excluded from the immediate area around the young trees.

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Dru Bernthal*, Elsa Sánchez and Kathleen Kelley

A field trial investigating the use of living mulches for weed management in edamame (Glycine max), also known as vegetable soybean, was conducted in 2003 at the Russell E. Larson Agricultural Research Center, Rock Springs, Pa. Edamame was direct seeded on 24-25 June 2003. Seven weeks later, the living mulch treatments were broadcast seeded. The living mulch species were white clover (Trifolium repens), buckwheat (Fagopyrum esculentum) and a control with no living mulch (bare ground). Each living mulch plot was divided into a weeded and non-weeded subplot. Weed pressure was evaluated every 2 weeks from the time living mulches were sown. Data collected included the total number of weeds present, number of different species present, number of broadleaf and grass species and number of annual and perennial species. The total number of weeds in weeded and non-weeded subplots was lowest in the buckwheat and highest in the clover. Species diversity in weeded subplots was lowest for the control and highest in clover while species diversity in non-weeded subplots was lowest in buckwheat and highest in the control. Overall, most weeds present were broadleaf annuals including pigweeds (Amaranthus spp.), shepard's purse (Capsella bursa-pastoris), common lambsquarters (Cheno-podium album) and common purslane (Portulaca oleracea). Based on this 1-year study, which will be repeated in 2004, the buckwheat treatment is likely the most effective in managing weeds in edamame field production for consideration by Pennsylvania growers.

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D.R. Earhart, M.L. Baker and V.A. Haby

Phosphorus (P) concentration in surface waters from non-point agricultural sources is an increasing resource management concern. This study was conducted at Overton, Texas, on a Bowie fine sandy loam (fine-loamy, siliceous, thermic, Plinthic Paleudults) to evaluate cool-season legumes for P uptake following poultry litter (PL) application rates on spring vegetables. Treatments were PL rate (0, 1X, 2X, 4X) and a commercial blend (CB) for comparison. Cool-season legumes, consisting of crimson clover, berseem clover, hairy vetch, and red clover, were the subplots. The vegetable crop in Spring 1995 was watermelon. The 1X PL rate was 2.2 t·ha-1 and the CB was 44.8N-0P-32.5K kg·ha-1. Dry matter yield was decreased by the 4X PL rate. Plant P concentration increased linearly as PL rate was increased. The greatest P uptake (4.1 kg·ha-1) was at the 2X rate. Hairy vetch had the greatest yield (1,875 kg·ha-1), plant P concentration (0.53%), and P uptake (9.6 kg·ha-1). PL rate increased soil P concentration at all depths. The least amount of P accumulation was from CB and was equal to the control. Hairy vetch appears to have the capability of removing a greater amount of P and reducing soil concentration when compared to the other legume species tested.

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M. Rangappa, A.A. Hamama and H.L. Bhardwaj

Although there is increasing interest in reducing the use of nitrogen (N) fertilizers due to the potential of unused N causing pollution of surface and groundwater, N is a major nutrient for plant growth. Our objective was to determine the potential of using winter legume cover crops to meet the N needs of seedless watermelon (Citrullus lanatus), a potential cash crop for farmers in Virginia. Fruit number, fruit weight, fruit yield, and fruit quality traits (flesh to rind ratio, water content, total soluble solids, sugar content, and pH) of seedless watermelons were evaluated in replicated experiments in Virginia at three locations during 1997-98 and two locations during 1998-99 following cover crop treatments consisting of crimson clover (Trifolium incarnatum), hairy vetch (Vicia villosa), crimson clover + rye (Secale cereale), hairy vetch + rye, and a bareground control treatment that received 100 lb/acre (112 kg·ha-1) of N. At all five locations, the bareground control treatment resulted in fewer fruit [1803 fruit/acre (4454 fruit/ha)], lower fruit weight [9.8 lb (4.5 kg)], and lower fruit yield [8.9 tons/acre (20.0 t·ha-1)] compared to the four cover crop treatments. The crimson clover + rye and hairy vetch treatments resulted in highest numberof fruit [2866 and 2657 fruit/acre (7079 and 6563 fruit/ha), respectively], whereas the highest fruit yield was obtained following hairy vetch [21.2 tons/acre (49.8 t·ha-1)], hairy vetch + rye [20.3 tons/acre (45.5 t·ha-1)], and crimson clover + rye [19.6 tons/acre (43.9 t·ha-1)]. Cover crop treatments did not affect the quality of watermelon flesh. The seedless watermelon fruit averaged 1.4 flesh: 1 rind ratio, 90% water content, 9.5% total soluble solids, 8.0% sugar, and a pH value of 5.9. These results indicated that legume cover crops, such as crimson clover and hairy vetch, can be successfully used to produce seedless watermelons, in a no-till system, without any use of N fertilizers with dryland conditions.

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Laura K. Hunsberger

Vegetable soybeans [Glycine max (L.) Merr.] (edamame) are growing in popularity as a niche crop grown by traditional grain producers. Edamame were grown in an organically transitional system from 2004–2005 at the University of Maryland Lower Eastern Shore Research and Education Center in Salisbury, Md. Four weed suppressing treatments were used in order to determine if this crop would grow well in an organic production system. Five varieties; BeSweet 2020S, BeSweet 292, 414F, Dixie (2004 only), and Mooncake (2005 only) were grown in a RCB design with 4 reps. The weed suppression systems included; a ground cover of commercially purchased compost in a 4-inch layer, a ground cover of straw in a 4-inch layer, New Zealand Clover applied as a living mulch at a rate of 35#/A and an untreated control. Soybeans grown in both commercial compost and clover had significantly higher yields (6,606 and 5,578 lb/acre, respectively) than those grown in the untreated control (4,283 lb/acre), but were not different from those grown in straw (5,578 lb/acre). Weed suppression system also had an affect on the pod number per plant. On average, compost, clover and straw had 49% more pods per plant than the control. Over both years, BeSweet 2020S, BeSweet 292, 414F, and Dixie all had significantly higher yields than Mooncake (5,003, 5,613, 5,522, 7,138 and 1,875 lb/acre, respectively). Variety also had an effect on pod number per plant, with BeSweet 2020S having a 37% higher pod number that BeSweet 292. It is feasible that vegetable soybeans can be grown organically or in a low input system. This value added crop could fill an important niche for both market growers and small traditional grain producers growers.

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Carl H. Shanks Jr. and Jimmie D. Chamberlain

`Totem' strawberries (Fragaria ×ananassa Duch.) were planted with clean-cultivated inter-rows or inter-rows planted with permanent cover crops of white clover (Trifolium repens L.) or `Manhattan' perennial ryegrass (Lolium perenne L.). There were no significant differences between treatments in the number of twospotted spider mites (Tetranychus urticae Koch), strawberry aphids [Chaetosiphon fragaefolii (Cockerell)], or Pratylenchus sp. or Xiphinema sp. nematodes on strawberry plants. The cover crops reduced strawberry yields relative to cultivation, although fruit size was significantly larger the second year. Root weight did not differ significantly in either year. Weight of above-ground vegetation was significantly higher in cultivated plots the first year, but not the second year.