Compost Treatments Interact with Other Factors To Affect Red Radish Production

Abstract

Spent mushroom substrate and yard waste compost each were applied to the soil surface at two depths (equivalent to 2.5 or 5 cm) and then incorporated in order to study effects on spring and fall production of red radishes (Raphanus sativus L.). Other variables examined were radish cultivars and, in one fall experiment, the presence or absence of the herbicide trifluralin. Spent mushroom substrate gave seasonally-variable results, including a distinct negative effect on yield when applied at 204 Mg.ha⁻¹ (a layer 5 cm deep) for fall production. Yard waste compost improved yield as compared to unamended soil when trifluralin was used; however, no benefit was demonstrated in the absence of the herbicide. Hybrid cultivars produced higher yields overall than open-pollinated cultivars, but there was some overlap between specific cultivars, and compost x cultivar interactions were evident in two of three experiments. Spent mushroom substrate is not recommended as a soil amendment for radish production when stand establishment occurs under hot, dry conditions. Further research is needed to determine the potential usefulness of yard waste compost as a soil amendment for field production of radish in the absence of a phytotoxic herbicide. Chemical name used: 2,6-dinitro-N,N-dipropyl-4-(trifluoromethyl)benzenamine (trifluralin).