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Greg D. Hoyt

This experiment was designed to compare best management practices for conventional and conservation tillage systems, chemical IPM vs. organic vegetable production, and rotation effect on tomatoes. Four vegetables were grown under these management practices with peppers (first year), yellow squash and fall broccoli (second year) on half of the field plots and tomatoes on the other half. For the third year, both sections of the field plots were tomatoes. The treatments were: 1) conventional-tillage with chemical-based IPM; 2) conventional-tillage with organic-based IPM; 3) conservation-tillage with chemical-based IPM; 4) conservation-tillage with organic-based IPM; and 5) conventional-tillage with no fertilizer or pest management (control). This poster describes pepper, yellow squash, fall broccoli, and tomato yields from the various treatments over the 3-year rotation. These results are for the third rotation sequence (years 79). Pepper yields were higher in treatments with chemical fertilizer and pest control. Fall broccoli yields were in the order: strip-tilled-chemical ≥ strip-till-organic ≥ conventional-tilled-chemical ≥ conventional-tilled-organic ≥ control. Yellow summer squash yields were in the order: conventional-tilled-chemical ≥ conventional-tilled-organic ≥ strip-till-chemical ≥ strip-tilled-organic ≥ control. Tomato yields were in the order: conventional-tilled chemical ≥ strip-till-chemical ≥ conventional-tilled-organic ≥ strip-tilled-organic ≥ control for each of the 3 years.

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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).

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Greg D. Hoyt

A no-till sweetcorn strip-till tomato rotation was established to determine whether a grass or legume winter cover crop would provide greater summer mulch and more soil inorganic nitrogen from residue decomposition. Sweetcorn yields improved as N rate increased in rye residue and bare soil, but only increased at the 50 kg N/ha rate in vetch residue. Strip-till tomato yields improved with all N rates for all covers. Total soil N and C were greater in both the vetch and rye residue treatments than the bare soil. Fertilizer N addition did not affect changes in total N or C percentages. Greater soil nitrate was measured beneath vetch residue at spring planting than in the rye residue or bare soil surface.

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Greg D. Hoyt

The availability of various conservation tillage (CT) practices along with a variety of cover residues creates an opportunity for farm managers to create new systems for vegetable production. We established various tillage practices and cover crop residues for CT use to determine which systems would continue to deliver high vegetable productivity. Recommendations for using CT based only on a yield perspective would lead us to conclude that full season crops could be grown with some form of CT and respectable yields would be obtainable. Tomato (Lycopersicon esculentum Mill.) production with CT is successfully being practiced in North Carolina in both the mountain valleys and Piedmont region. Because of the cooler soil temperatures with cover residue, summer and especially fall harvested tomatoes produce the least risk in obtaining similar yields as plow/disc production. Our experiments with short season vegetable crops and CT have had mixed results. Cole crops (Brassica L.) grown with CT in early spring or late fall experience soil temperatures cool enough to delay growth compared to plow/disc management. Proper selection of a cover crop residue type and the amount of cover residue can increase yield. Growing short season vegetable crops with CT during the warmest season of the year will reduce the risk of delayed plant growth and thus, decrease the time to harvest.

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Greg D. Hoyt and David W. Monks

Experiments were conducted to evaluate the effect of tillage systems and weed management on weed suppression and potato yield. Strip-tillage (ST) and conventional-tillage (CT) systems produced equal yields of Irish potato (Solanum tuberosum L.) or sweetpotato [Ipomoea batatas (L.) Lam.] when herbicide treatments were applied. Weeds in the nontreated control reduced yield of Irish potato and prevented storage root growth in sweetpotato. Excellent control of broadleaf signalgrass [Brachiaria platyphylla (Griseb.) Nash], henbit (Lamium amplexicaule L.), prickly sida (Sida spinosa L.), and common ragweed (Ambrosia artemisiifolia L.) was obtained with metribuzin + metolachlor applied preemergence at Irish potato planting, followed by sethoxydim + crop oil applied postemergence in ST and CT systems. Redroot pigweed (Amaranthus retroflexus L.) control was >98% at 4 weeks after treatment but was 73% to 84% at harvest across all herbicide treatments in both tillage systems. In sweetpotato, control of black mustard [Brassica nigra (L.) W.J.D. Koch], goosegrass [Eleusine indica (L.) Gaertn.], and fall panicum [Panicum dichotomiflorum Michx.] was >95% throughout the growing season for all herbicide treatments in both ST and CT.

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Danielle D. Treadwell, Nancy G. Creamer, Greg D. Hoyt and Jonathan R. Schultheis

A 3-year field experiment was initiated in 2001 to evaluate different organic sweetpotato production systems that varied in cover crop management and tillage. Three organic systems: 1) compost and no cover crop with tillage (Org-NCC); 2) compost and a cover crop mixture of hairy vetch and rye incorporated before transplanting (Org-CCI); and 3) compost and the same cover crop mixture with reduced tillage (Org-RT) were compared with a conventionally managed system (Conv) with tillage and chemical controls. Yield of No. 1 sweetpotato roots and total yield were similar among management systems each year, except for a reduction in yield in Org-RT in 2002. The percentage of No. 1 grade roots was at least 17% and 23% higher in Org-CCI and Org-NCC than Org-RT in 2001 and 2002, respectively, and similar to Conv in 2001 and 2004. Organic and conventional N sources contributed to soil inorganic N reserves differently the 2 years this component was measured. In 2002, soil inorganic N reserves at 30 DAT were in the order: Org-CCI (90 kg·ha−1) > Org-NCC (67 kg·ha−1) > Org-RT (45 kg·ha−1), and Conv (55 kg·ha−1). No differences in soil inorganic N reserves were observed among systems in 2004. Sweetpotato N, P, and K tissue concentrations were different among systems only in 2004. That year, at 60 days after transplanting, tissue N, P, and K were greatest in Org-CCI. In 2001 and 2004, N (4.09% to 4.56%) and K (3.79% to 4.34%) were higher than sufficiency ranges for N (3.2% to 4.0%) and K (2.5% to 3.5%) defined by North Carolina Department of Agriculture and Consumer Services recommendations for all treatments. No tissue macronutrient or micronutrient concentrations were limiting during this experiment. Reduced rainfall during the 2002 sweetpotato growing season may have contributed to the low microbially mediated plant-available N from the organic fertilizer sources. Despite differences in the nutrient content of organic and conventional fertility amendments, organically managed systems receiving compost with or without incorporated hairy vetch and rye produced yields equal to the conventionally managed system.

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E. Ryan Harrelson, Greg D. Hoyt, John L. Havlin and David W. Monks

Vegetable growers in the Mountain region of North Carolina are faced with increased land prices resulting from urbanization and reduced farm income from low-commodity prices. Local consumer use of pumpkin (Cucurbita pepo) for jack-o-lanterns and baking provides a fall market for growers to increase production and profitability on-farm. Most soils in these regions are highly erodible and susceptible to drought during the growing season. Little information is available on cultural practices for no-till pumpkin production in this region. Field studies were established to evaluate the yield response of no-till pumpkin to planting date and nitrogen (N) fertilization. Experiments were conducted at the Mountain (MRS), Upper Mountain (UMRS), and the Mountain Horticultural Crops Research Stations (MHCRS) in Summer 2003 and 2004 using no-till cultural practices. Three planting dates were established at 2-week intervals and 0, 40, 80, and 120 kg·ha−1 N treatments were applied at each planting date in a randomized complete block design. The 80 and 120 kg·ha−1 N fertilization rates produced greater yields and larger fruit size than the 0 and 40 kg·ha−1 N rates. Pumpkins planted earliest produced the greatest marketable and total yields for all N rates at all three locations. The latest planting date (9 July) and highest N rate yielded more cull fruit compared with marketable pumpkins with the earlier planting date at the Upper Mountain Research Station. This location has a shorter growing season and cooler summer temperatures than the two other locations. Although the third planting date was late for pumpkin planting, higher N rate treatments at that timing produced marketable yields comparable to earlier planting dates at the two warmer summer locations (MRS and MHCRS). In these experiments, the highest rate applied (120 kg·ha−1 N) maximized pumpkin yield. This observation would indicate that higher yields might be possible with even greater N rates.

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E. Ryan Harrelson, Greg D. Hoyt, John L. Havlin and David W. Monks

Throughout the southeastern United States, vegetable growers have successfully cultivated pumpkins (Cucurbita pepo) using conventional tillage. No-till pumpkin production has not been pursued by many growers as a result of the lack of herbicides, no-till planting equipment, and knowledge in conservation tillage methods. All of these conservation production aids are now present for successful no-till vegetable production. The primary reasons to use no-till technologies for pumpkins include reduced erosion, improved soil moisture conservation, long-term improvement in soil chemical and microbial properties, and better fruit appearance while maintaining similar yields compared with conventionally produced pumpkins. Cover crop utilization varies in no-till production, whereas residue from different cover crops can affect yields. The objective of these experiments was to evaluate the influence of surface residue type on no-till pumpkin yield and fruit quality. Results from these experiments showed all cover crop residues produced acceptable no-till pumpkin yields and fruit size. Field location, weather conditions, soil type, and other factors probably affected pumpkin yields more than surface residue. Vegetable growers should expect to successfully grow no-till pumpkins using any of the winter cover crop residues tested over a wide range in residue biomass rates.