The long growing season of the southeastern Coastal Plains allows planting of a second crop after
spring-planted maize (Zea mays L.). Second crops have been shown to reduce erosion and prevent
leaching of nutrients and pesticides. Maize grown with a second annual crop might also have a yield
advantage over mono-cultured maize. Seven tillage/cropping systems were compared. They included
disking for weed control, disking for seedbed preparation, or no disking. Double-cropped treatments
included sunflower (Helianthus annuus L. ), soybean ( Glycine max. L.), a cover crop [crimson clover
(Trifolium incarnatum L.) ] or no double crop. Double-cropped soybean yields did not respond to
irrigation. They averaged 0.63 Mg/ha over 4 years. This is less than half of the local non-double-cropped
yields. Sunflower yields averaged 0.89 Mg/ha, also less than non-double-cropped yields
(1.0-2.5 Mg/ ha). The best continuous maize yields (7-8 Mg/ha) were from treatments with disking
in some phase of the operation. Treatments with lower maize yields generally had higher plant nutrient
contents. Double-cropped maize yields significantly (P < 0.10) outyielded mono-cropped maize
yields in two of the three years. In 1984, a dry year, the minimum tillage treatment had lower
tensiometer readings than the conventionally tilled treatment
