McSorley, R., D. R. Seal, W. Klassen, K.-H. Wang, and C. R. R. Hooks. 2009. Non-target effects of sunn hemp and marigold cover crops on the soil invertebrate community. Nematropica 39:235-245. Two field experiments were carried out in south Florida to determine the effects of summer cover cropping practices on soil nematode communities and other soil invertebrates. Treatments consisted of a summer cover crop of 'Tropic Sun' sunn hemp (Crotalaria juncea), a cover crop of 'Single Gold' marigold (Tagetes patula), or bare fallow. Following termination of cover crops in early fall, all of the plots were planted with a winter vegetable crop of yellow squash (Cucurbita pepo). Among the plant-parasitic nematodes, Quinisulcius acutus was suppressed by sunn hemp, but Helicotylenchus dihystera increased on marigold. Bacterivorous nematodes were stimulated following the sunn hemp cover crop but treatment differences did not persist through the subsequent vegetable crop. Population levels of soil mites showed a similar trend. Omnivorous and predatory nematodes were not affected consistently by cover crop treatments. Yield of yellow squash was greater following sunn hemp than marigold or fallow. Results suggest that sunn hemp is a versatile cover crop that can differentially lower numbers of some plant-parasitic nematodes and temporarily stimulate beneficial nematodes and soil mites.
