( Alysicarpus vaginalis ) (74%) and hairy indigo ( Indigofera hirsuta ) (64%) cover crops ( Linares et al., 2008 ). Thus, the sunn hemp allelopathy carryover should be considered when selecting it as a cover crop. Sorghum-sudangrass ( Sorghum ×drummondi ) is a
; Haramoto and Gallandt, 2004 , 2005 ; Matthiessen and Kirkegaard, 2006 ; Mojtahedi et al., 1991 ). This study was therefore undertaken to determine the effects of several brassica cover crops and sorghum sudangrass on nutrient cycling, weed suppression
plots were 612 ft 2 (25.5 ft long by 24 ft wide). Whole plot treatments were ‘Mancan’ buckwheat, ‘Iron & Clay’ southernpea, black oats, ‘Grazex II’ sorghum-sudangrass, or a no-cover crop (control). The subplot treatment was planting time of lettuce
to create partial budgets for five summer fallow treatments: sunn hemp, velvet bean, cowpea, sorghum-sudangrass, and use of tillage to manage weeds preceding a summer squash crop. Partial budget analyses are used to evaluate the relevant costs and
. capitata ) are annually produced ( Elwakil and Mossler, 2016 ; USDA-NASS, 2014 ). A major advantage of sunn hemp over many cover crops, particularly sorghum-sudangrass (SSG) [ Sorghum bicolor (L.) Moench], is that it is a poor host for fall armyworm
and potentially cycle it to the following crop. Delgado et al. (2007) reported other benefits from summer cover crops grown with limited irrigation and observed a 12% to 30% increase in total yield and marketable tubers when potato followed sorghum-sudangrass
; Reynolds et al., 2000 ). Sorghum–sudangrass hybrids contain the cyanogenic glycoside dhurrin that, when hydrolyzed, yields cyanide, a nematicidal compound ( Widmer and Abawi, 2002 ). Brassicaceae species contain glucosinolates that react with myrosinase
production, particularly in the southeastern United States. In onion production on muck soils in Michigan using brassica ( Brassica sp.) cover crops or sorghum × sudangrass (sudex) resulted in similar weed suppression and soil fertility regardless of the
Summer cover crops can produce biomass, contribute nitrogen to cropping systems, increase soil organic matter, and suppress weeds. Through fixation of atmospheric N2 and uptake of soil residual N, they also contribute to the N requirement of subsequent vegetable crops. Six legumes {cowpea (Vigna unguiculata L.), sesbania (Sesbania exaltata L.), soybean (Glycine max L.), hairy indigo (Indigofera hirsutum L.), velvetbean [Mucuna deeringiana (Bort.) Merr.], and lablab (Lablab purpureus L.)}; two nonlegume broadleaved species [buckwheat (Fagopyrum esculentum Moench) and sesame (Sesamum indicum L.)]; and five grasses {sorghum-sudangrass [Sorghum bicolor (L) Moench × S. sudanense (P) Stapf.], sudangrass [S. sudanense (P) Stapf.], Japanese millet [Echinochloa frumentacea (Roxb.) Link], pearl millet [Pennisetum glaucum (L). R. Br.], and German foxtail millet [Setaria italica (L.) Beauv.)]}, were planted in raised beds alone or in mixtures in 1995 at Plymouth, and in 1996 at Goldsboro, N.C. Biomass production for the legumes ranged from 1420 (velvetbean) to 4807 kg·ha-1 (sesbania). Low velvetbean biomass was attributed to poor germination in this study. Nitrogen in the aboveground biomass for the legumes ranged from 32 (velvetbean) to 97 kg·ha-1 (sesbania). All of the legumes except velvetbean were competitive with weeds. Lablab did not suppress weeds as well as did cover crops producing higher biomass. Aboveground biomass for grasses varied from 3918 (Japanese millet) to 8792 kg·ha-1 (sorghum-sudangrass). While N for the grasses ranged from 39 (Japanese millet) to 88 kg·ha-1 (sorghum-sudangrass), the C: N ratios were very high. Additional N would be needed for fall-planted vegetable crops to overcome immobilization of N. All of the grass cover crops reduced weeds as relative to the weedy control plot. Species that performed well together as a mixture at both sites included Japanese millet/soybean and sorghum-sudangrass/cowpea.
Improving soil quality and suppressing weeds are two challenges facing strawberry growers. Cover crops, such as perennial ryegrass (Lolium perenne) and sorghum-sudangrass (Sorghum sudanense), have been used in rotation with strawberry in the Midwest. The objective of the field study was to investigate the effects of various cover crops on soil quality and weed populations for strawberry production. The experiment was established in 1996 at the Iowa State Univ. Horticulture Station, Ames, in plots that previously were planted continuously in strawberry for 10 years. Nine treatments were arranged in a randomized complete-block design with three replications. Treatments included cover crops of Indian grass (Sorghastrum avenaceum), switchgrass (Panicum virgatum), big bluestem (Andropogon gerardii), black-eyed susan (Rudbeckia hirta), marigold (Tagetes erecta `Crackerjack'), sorghum-sudangrass, perennial ryegrass, strawberry (Fragaria ×ananassa `Honeoye'), and bare soil (control). Data from 1998 showed that both annual and perennial cover crops were established more readily (higher treatment-plant populations and less weed populations) than in 1997. Water infiltration rates were highest in bare soil plots and lowest in P. virgatum plots. Bare soil plots and S. sudanense plots had the lowest percent soil moisture.