Papers by Michael Bomford
Acta Horticulturae, 2013
Diurnal temperature flux tends to be greater inside high tunnels than outdoors, which may stress ... more Diurnal temperature flux tends to be greater inside high tunnels than outdoors, which may stress plants and reduce yield. We monitored annual and diurnal air temperature flux in a double layered high tunnel for 17 months in 2006-2007, and then tested the ability of translucent polyester row covers to moderate air and soil temperature in the same high tunnel in late winter and early spring of 2010 and 2011. Minimum, average, and maximum soil and air temperatures were recorded hourly in covered and uncovered beds growing Spinacia oleracea (spinach), and Brassica napus var. pabularia (kale). The high tunnel increased diurnal temperature flux from an average of 12°C in summer and 7.8°C in winter to about 15°C year-round. Row covers moderated diurnal temperature flux inside the high tunnel during that late winter and early spring monitoring periods: early morning temperature under row covers was warmer than without row covers; and afternoon temperature was cooler. The high tunnel gave 4.3°C of frost protection and elevated daily minimum air temperature by up to 7.4°C on the coldest monitoring days. Row covers inside the tunnel gave an additional 3.1°C of frost protection and elevated daily minimum air temperature by up to 4.9°C on the coldest monitoring days. Daily minimum air temperature under row covers, T cov , was a linear function of minimum temperature in uncovered beds, T in (T cov =0.85T in +2.60; R 2 =0.98), which was a linear function of daily minimum temperature outside the high tunnel, T out (T out =0.77T in + 3.30; R 2 =0.98). Row covers had a less pronounced effect on soil temperature, giving only 2.0°C of frost protection, but soil temperature rarely fell below freezing inside high tunnels during the monitoring period. Daily peaks in air and soil temperature, respectively, averaged 1.6 and 1.7°C lower under row covers than in uncovered beds. Crop yields were 35% higher under row covers. The reduced temperature fluctuation and yield increases associated with row cover use holds promise for greater production of cool season greens in high tunnels.
sulcatus (Coleoptera: Curculionidae) climbing ability by fluoropolymer, talc dust, and lithium gr... more sulcatus (Coleoptera: Curculionidae) climbing ability by fluoropolymer, talc dust, and lithium grease
individual sections: organic certification, the organic corn marketplace, marketing, profitabilit... more individual sections: organic certification, the organic corn marketplace, marketing, profitability management, fertility, and post-harvest handling. Additionally, readers who wish to do further research on the subject will find a collection of resources listed in the last chapter. Additional information on fertility needs and practices can be found in the resource section of this handbook.
Sweet potato (Ipomoea batatas L.) and sweet sorghum (Sorghum bicolor L.) are promising crops for ... more Sweet potato (Ipomoea batatas L.) and sweet sorghum (Sorghum bicolor L.) are promising crops for advanced biofuel production because they are better suited than corn (Zea mays L.) to low input production on small farms in the south. They can be considered advanced feedstocks only if lifecycle greenhouse gas emissions are less than 50% of basoline baseline emissions. Both sweet potato and sweet sorghum are multifunctional crops, with potential to simultaneously produce human food, animal feed, and biofuel feedstock. Kentucky State University is exploring the potential for organic production techniques and decentralized processing systems to reduce lifecycle greenhouse gas emissions of energy produced from these crops at a range of small farm scales. In 2009 biointensive production - a garden-scale strategy relying entirely on human labor - gave the greatest return to energy investment among the farm scales tested. Tractor-based small farm systems gave an inferior energy return in 200...
Journal of the Entomological Society of British Columbia, 2005
As part of a project to develop tools for the physical exclusion of flightless root weevils, adul... more As part of a project to develop tools for the physical exclusion of flightless root weevils, adult black vine weevils (BVW), Otiorhynchus sulcatus (F.), were placed in open enclosures with smooth walls of glass, plastic or aluminum to test their ability to escape by climbing. Enclosure walls were left untreated or were treated with substances known to reduce insect climbing ability: fluoropolymer, powdered talc and lithium grease. No BVW escapes were observed under dry conditions, but all treatments allowed some escapes under wet conditions, suggesting that moisture helps BVW adults scale treated surfaces. The results help explain the ability of root weevils to overcome physical barriers under field conditions.
Journal of the Entomological Society of British Columbia, 2000
Aphids accumulate near exclusion fences designed to intercept Delia radicum (L.) movement into fi... more Aphids accumulate near exclusion fences designed to intercept Delia radicum (L.) movement into fields. Aphid accumulations increase with increasing fence height, but are not affected by fence overhang length. Overall aphid levels are higher in small (4.3 m square) enclosed plots than in unenclosed plots. Enclosing large (38 m square) plots does not alter overall aphid catches, but does alter aphid distribution within enclosures. In large enclosures aphid accumulations are higher at enclosure perimeters than interiors, with the highest accumulations near enclosure corners. This concentric distribution is not observed in unfenced areas, and is not altered by the addition of a trap crop outside an enclosure. Key words: Myzus persicae; Delia radicum; physical control
HortScience
Polycultures are thought to offer yield advantages over monocultures when net competition between... more Polycultures are thought to offer yield advantages over monocultures when net competition between plants of different species is less than that between plants of the same species. Planting density and crop ratios may both alter these competitive effects. To observe such effects, dicultures of basil (Ocimumbasilicum L.), brussels sprout (Brassica oleracea L.), and tomato (Lycopersicumesculentum Mill.) were grown organically at a range of ratios and densities (1–47 plants/m2) over two field seasons. Relative land output (RLO) values were calculated from field data and from modeled yield-density-ratio surfaces. Both methods showed yield advantages from polyculture at high planting densities (RLO = 2.20 @ top density), but not at low densities. Dicultures offered a 19% yield advantage, on average. Competition for resources was compared by measuring canopy light interception and soil moisture content, showing tomato to be the most competitive crop, followed by brussels sprout, then basil...
HortScience
Commercial vegetable growers in Kentucky have used high tunnels for year-round production for the... more Commercial vegetable growers in Kentucky have used high tunnels for year-round production for the past decade. They suggest it is a more energy-efficient and economical means of supplying off-season vegetables to the region than trucking field-grown produce from warmer regions. In 2005, we erected a 9 × 12-m high tunnel, designed to comply with National Organic Program standards, at the Kentucky State University Research Farm. We recorded the retail cost of each component, and estimated its embodied energy using published figures for common building materials. The materials used for construction were valued at $2830, and contained 59 GJ of embodied energy. The frame and plastic cladding accounted for 36% and 24% of the total capital cost, and 28% and 37% of the embodied energy, respectively, with other components accounting for the remainder. Assuming that the frame, plastic cladding and other components last 20, 4, and 10 years, respectively, the average cost of the tunnel is $328/...
HortScience
Weed control is a major challenge confronting growers transitioning to organic vegetable producti... more Weed control is a major challenge confronting growers transitioning to organic vegetable production. Organic standards require that growers manage weeds without synthetic herbicides while maintaining or enhancing soil quality. In 2005, we evaluated the effects of two seedbed preparation methods and six weed management tactics, compatible with organic standards, on soil quality indicators, weed pressure, and yield of edamame soybean [Glycine max (L.) Merrill]. Seedbed preparation was conducted with either a moldboard plow and roto-tiller or a spading machine. Weeds were managed by a) regular hand weeding, b) pre-emergent flaming, c) post-emergent incorporation of 100 g of corn gluten meal/m2, or weekly passes from crop emergence until row closure with d) a spring-tine weeder, e) a rolling cultivator, or f) a between-row flame weeder. Dominant weeds were smooth pigweed [Amaranthus hybridus (L.)], goosegrass [Eleusine indica (L.) Gaertn.], and giant crabgrass [Digitaria sanguinalis (L....
As part of a project to develop tools for the physical exclusion of flightless root weevils, adul... more As part of a project to develop tools for the physical exclusion of flightless root weevils, adult black vine weevils (BVW), Otiorhynchus sulcatus (F.), were placed in open enclosures with smooth walls of glass, plastic or aluminum to test their ability to escape by climbing. Enclosure walls were left untreated or were treated with substances known to reduce insect climbing ability: fluoropolymer, powdered talc and lithium grease. No BVW escapes were observed under dry conditions, but all treatments allowed some escapes under wet conditions, suggesting that moisture helps BVW adults scale treated surfaces. The results help explain the ability of root weevils to overcome physical barriers under field conditions.
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Papers by Michael Bomford