Oral Sesssion 12—Vegetable Crops Culture & Management 1 Moderator: Albert Sutherland 19 July 2005, 10:00 a.m.–12:00 p.m. Room 106
Jeffrey P. Mitchell, William R. Horwath, Karen K. Klonsky, Randal J. Southard, Rich DeMoura, Daniel S. Munk and Kurt J. Hembree
Jeff Mitchell, Charlie Summers and Jim Stapleton
146 POSTER SESSION 15 (Abstr. 022-031) Crop Protection Wednesday, 26 July, 1:00-2:00 p.m.
Edmund J. Ogbuchiekwe, Mathieu Ngouajio and Milton E. McGiffen
Field experiments were established at the University of California Desert Station in Coachella Valley from 1998 to 2000. The main plot treatments included: 1) summer cowpea used as mulch in the fall; 2) summer cowpea incorporated into soil in the fall; 3) summer sudangrass incorporated into the soil in the fall; and 4) summer fallow (bare-ground). An economic comparison of cover crop treatments and crop management programs vs. the effect on yield, crop value, value of hand weeding, costs of production and net return, and dollar investment from each treatment was determined. Among the cropping systems tested in 1999, lettuce following the incorporation of a cowpea cover crop produced the highest yield (1082.43 boxes/ha), with a net return of $883.04/ha. The return for each dollar invested in the cowpea-incorporated system was an additional $0.65 if cowpea-incorporated was chosen over cowpea mulch. In 2000, the net return from lettuce following cowpea-incorporated was much higher with 1294.23 boxes/ha and a net return of $1698.46/ha. In 1999, cantaloupe grown in the cowpea-incorporated system had the highest net return of $973.34/ha, with 874.58 boxes. An additional $0.93 was made for choosing cowpea-incorporated over sudangrass. In 2000, cantaloupe grown in the cowpea-incorporated system had even higher yields than in 1999, producing 1522.89 boxes/ha and returning over $3000.00. And an additional $0.93 was made for choosing cowpea-incorporated over sudangrass cover crop. Overall, the rate of return on investment favored cowpea-incorporated over all cover crops.
Braja B. Datta and Ray D. William
Field experiment on production systems of `Selva' day-neutral and `Totem' June-bearing strawberry was established in 1995 on the spring-killed cover crop mulched plots using randomized complete-block design. Seven soil cover treatments consisted of `Wheeler' rye (Secale cereale) and `Micah' and `Steptoe' barley (Hordium vulgare), `Micah' residue applied on soil surface, a wedge of perlite (artificial medium) placed next to strawberry row, perlite with `Wheeler' rye, and no treatment were used. During the early summer, cover crops were replanted between strawberry rows and mowed down after 6 weeks. In both cultivars, plant growth doubled during mid-summer, and `Micah'on surface produced better growth than the growth in other treatments. No significant difference was found on CO2 assimilation rate (mmol·m–2·s–1), leaflet length, and number of leaves and runners among treatments (P ≥ 0.1). Yield of `Totem' was ignored during the establishment year. In `Selva', `Micah' residue on surface produced 36% more crowns per plant and the greatest total yield than that of any other treatment. `Micah' on surface produced 50% more shoot biomass and 45% greater yield compared to `Micah' barley planted in the plot. Total `Selva' yield was 61% greater in perlite treatment than the yield in perlite with `Wheeler' rye and 31% greater than the control treatment. Comparison of `Selva' strawberry total yield and average fruit production between cover crops vs. control treatment using non-orthogonal contrast indicated no significant difference might suggests no detrimental interaction between cover crops and strawberry.
Greg D. Hoyt
The North Carolina Agricultural Research Service supported this research. Emeritus Professors Thomas R. Konsler and Frank L. Haynes provided leadership in cole crops and potatoes. Anthony D. Cole and George B. Cox provided technical
Greg D. Hoyt
An experiment was established to determine the effect of different winter cover crops residues on yields of no-till pumpkins, yellow summer squash, and sweet corn. Residue treatments of fallow, triticale, crimson clover, little barley, and crimson clover + little barley were fall established and killed before spring no-till planting in 1998 and 1999. All summer vegetables received recommended fertilizer rates and labeled pesticides. Spring cover crop growth and biomass measurements ranged from 1873 to 6362 kg/ha. No-till sweet corn yields among the various cover residue treatments were greater where crimson clover and crimson clover + little barley (mixture) were used as residue in 1999, but not significantly different in 1998. No-till pumpkins showed the beneficial affect cover crop residue had on vegetable yields when dry conditions exist. Triticale and crimson clover + little barley (mixture) residues reduced soil water evaporation and produced more numbers of fruit per hectare (5049 and 5214, respectively) and greater weights of fruit (20.8 and 20.9 Mg/ha) than the other residue treatments (3725 to 4221 fruit/ha and 11.8 to 16.1 Mg/ha, respectively). No-till summer squash harvest showed steady increases in yield through time by all treatments with crimson clover residue treatment with the greatest squash yields and triticale and little barley residue treatments with the lowest squash yields. We found that sweet corn and squash yields were greater where legume cover residues were used compared to grass cover residues, whereas, pumpkin yields were higher where the greatest quantity of mulch was present at harvest (grass residues).
Harbans L. Bhardwaj
Winter legume cover crops have been successfully used to meet N needs of many summer crops, but they are not being used extensively in Virginia and the mid-Atlantic region, especially for specialty crops such as muskmelon and sweet corn. The objective of these studies was to determine the potential of winter legume cover crops in meeting N needs of muskmelon (Cucumis melo L.) and sweet corn (Zea mays L.). Comparisons of performances of muskmelon and sweet corn, grown after lupin (Lupinus albus L.), hairy vetch (Vicia villosa Roth.), Austrian winter pea ([AWP] Pisum arvense L.), and control fertilized with 112 kg N ha–1, and unfertilized control were made during 1999, 2000, and 2001. The interactions between cover crop treatments and years were, generally, significant. The muskmelon fruit yields were 53.6, 45.0, 23.1, 13.0, and 5.6 Mg·ha–1 during 1999; 27.8, 26.3, 8.6, 5.8, and 2.2 Mg·ha–1 during 2000; and 41.1, 39.9, 25.5, 21.4, and 2.1 Mg·ha–1 during 2001 respectively for lupin, hairy vetch, AWP, 112 kg N ha–1, and control. Similar results were obtained for number and size of muskmelon fruits. The sweet corn ear yields (Mg·ha–1) were 8.5, 5.6, 3.1, 1.5, and 0.7 during 1999; 5.2, 3.9, 4.0, 4.8, and 1.2 during 2000; and 2.6, 2.4, 1.9, 2.0, and 0.9 during 2001, respectively for lupin, hairy vetch, AWP, 112 kg N ha–1, and control. White lupin and hairy vetch, as winter cover crops, were superior than AWP and 112 kg N ha–1 for sweet corn ear number and size, and plant height. These results demonstrated that winter legume crops, especially lupin and hairy vetch, can be excellent winter cover crops for meeting N needs of muskmelon and sweet corn.
Edmund J. Ogbuchiekwe, Milton E. McGiffen Jr. and Mathieu Ngouajio
Economic analysis compared the returns of cropping systems and management practices for production of fall lettuce (Lactuca sativa L.) and spring cantaloupe (Cucumis melo) following summer cover crops. The cover crop treatments included: cowpea [Vigna unguiculata (L.) Walp.] incorporated into the soil in the fall, cowpea used as mulch in the fall, sorghum sudangrass [Sorghum bicolor (L.) Moench] incorporated into the soil in the fall, and a bare ground control. Lettuce and cantaloupe were managed using conventional, integrated, and organic practices. The effect of each cropping system and management practice on crop yield, cost of production and net return was determined. In 1999 and 2000, yield and net return were greatest for cantaloupe and lettuce when the cowpea cover crop was incorporated into the soil before planting. The effect of crop management practice varied with type of cover crop. When lettuce was planted into cowpea-incorporated treatment in 1999, conventional management had the highest cash return followed by integrated crop management. In 2000, organically-grown lettuce after cowpea incorporated had the highest net return followed by integrated crop management grown under cowpea incorporated treatments. In 1999 and 2000, integrated cantaloupe following cowpea-incorporated treatment had the highest yield and cash-return. A 20% price premium for organic produce increased the net returns for the organic-grown lettuce and cantaloupe. Organic lettuce following cowpea-incorporated treatments produced a high net of $2,516/ha in 1999 and $5,971/ha in 2000. The net returns due to 20% organic premium price varied between 1999 and 2000 in cantaloupe production. They were highest for organic cantaloupe after bareground with a net return of $4,395 in 1999 and $3,148 in 2000 for organic cantaloupe after sudangrass.
Francis X. Mangan, John Howell and Stephen Herbert
125 POSTER SESSION 18 Nutrition & Photosynthesis/Vegetable Crops
S.B. Sterrett, H.E. Hohlt and C.P. Savage Jr.
Off-site movement of sediment, nutrient and agricultural chemicals from plasticulture production of green-pack tomatoes on water quality is a serious environmental concern, particularly for the clam aquaculture industry of eastern Virginia. Thus, the development of ecologically sound, economically sustainable cultural management strategies for tomato (Lycopersicon esculentum Mill.) production is needed. Two plantings were made within each of the three tomato harvest seasons [summer, bridge (late summer) and fall] in 1998 and 1999 (one summer crop in 1999). Between-bed treatments included clean culture or pearl millet [Pennisetum glaucum(L.) R. Br.] sown at bed establishment. On-bed treatments included standard plasticulture with fumigation on a 76-cm-wide bed (std), plasticulture without fumigation on a 76-cm-wide bed (std-fum), plasticulture on a 61-cmbed with fumigation (narrow) and organic mulch [wheat straw (Triticum aestivum L.) in 1998; desiccated hairy vetch (Vicia villosa Roth.) in 1999]. Total and marketable yields for the three plasticulture on-bed treatments (std, std-fum and narrow) were similar in 1998 and 1999. Yield was suppressed for the organic mulch on-bed treatments in all but the bridge plantings in 1999. Improved yield with plasticulture treatments and high market price for the summer crop in 1998 resulted in elevated crop value and return to land and management (return) compared to that of organic mulch. The return for later plantings was low, but positive. Return was negative for both bridge and the first fall crops in organic mulch in 1998. Low yields in all treatments and low prices in 1999 resulted in negative to negligible return for on-bed treatments in all but the summer planting using plasticulture. Return was consistently lower with organic mulch compared to plasticulture for the high value summer crop in Virginia with between-bed millet in 1998 and with or without millet in 1999. The use of organic mulch on the beds in this study was not economically feasible for the high value summer crops. Adjustments (desiccation of cover, control of weeds) in cultural management of the between-bed management strategy are needed before large-scale commercial implementation will occur.