Location: Nematology LaboratoryTitle: Sunn Hemp cover cropping and organic fertilizer effects on the nematode community under temperate growing conditions) Author
Submitted to: Journal of Nematology
Publication Type: Peer reviewed journal
Publication Acceptance Date: 9/26/2012
Publication Date: 12/30/2013
Publication URL: http://handle.nal.usda.gov/10113/60952
Citation: Hinds, J., Wang, K., Marahatta, S., Meyer, S.L.F., Hooks, C. 2013. Sunn Hemp cover cropping and organic fertilizer effects on the nematode community under temperate growing conditions. Journal of Nematology. 45(4):265-271. Interpretive Summary: Plant-parasitic nematodes are microscopic worms that can cause major economic losses in vegetable crops. Conversely, free-living nematodes that feed on bacteria, fungi and other organisms cycle nutrients, are highly beneficial and can be indicators of soil health. The cover crop sunn hemp, which has been mainly studied in tropical and subtropical areas, has been shown to improve soil health, reduce numbers of plant-parasitic nematodes, and increase populations of nematode-antagonistic microorganisms. Therefore, sunn hemp was planted in Maryland as a cover crop for zucchini to determine its impact on the free-living nematode community. In 2010, sunn hemp used as a living and surface mulch increased numbers of free-living nematodes by final harvest. In 2011, when the sunn hemp was mowed and then tilled into the soil prior to planting the zucchini, there was an early season increase in the number of nematodes that feed on bacteria and fungi, and at the end of the growing season there were more free-living nematode species in plots with sunn hemp than in plots without the cover crop. Therefore, tilling the sunn hemp maintained the free-living nematode community throughout the zucchini growing season. The results are significant because they indicate that a sunn hemp cover crop tilled into the ground can promote soil health in a temperate environment. This research will be used by scientists and vegetable growers for improving soil health in vegetable production in a temperate climate.
Technical Abstract: Plantings of sunn hemp as a cover crop have been experimentally shown to improve soil health, reduce plant-parasitic nematodes, and increase nematode-antagonistic microorganisms. However, these studies have been largely conducted in tropical and subtropical regions. To investigate the impacts of sunn hemp used as a cover crop on nematode community structure and soil health in the Southeastern USA, experiments were conducted in Upper Marlboro, Maryland during three field seasons from 2009 to 2011. Field plots were established to investigate the effect of using sunn hemp concurrently as a living and surface mulch (SH) on the nematode community and compare it to bare-ground (BG) treatment plots. Additionally, organic and synthetic fertilizer treatments were added as subplot treatments to examine their impact on the nematode community. In 2010, when used as a living and surface mulch, sunn hemp increased bacterivores, fungivores and total nematodes by final harvest. In 2011, when the sunn hemp was flail mowed and then strip-tilled into the soil prior to planting the zucchini, there was an early season increase in the number of bacterivorous and fungivorous nematodes and at final harvest species richness was higher in SH than BG plots. In contrast, application of organic fertilizer did not have an early season impact, but by the final harvest, application of the organic fertilizer significantly improved all soil health parameters. Thus, strip-tilling the sunn hemp and application of organic fertilizer helped sustain the free-living nematode community throughout the zucchini cropping cycle.