ABSTRACT

Cotton in some poorly-drained Atlantic Coastal Plain Flatwoods soils is susceptible to black root (an abiotic disease). Those soils have greater concentrations of total salts and Cl than upland coastal plain soils. Affected cotton has black roots, mottled leaves, S-Shaped petioles, and flowers with a protruding stamen that retains little pollen. When the disease is severe, plant growth, development, and lint yield are limited. Applications of broiler litter (manure + bedding) are effective in increasing lint yield in affected soils, but inorganic fertilizers are not. The objectives of studies reported here were to determine the length of time an application of broiler litter is effective, to elucidate the effective ingredient in litter, and to determine if other amendments are effective. Field research at four locations indicated that an application of 4 tons of broiler litter/acre is effective in maintaining yield for 2 years (crops). Field research also indicated that an application of 6 ton of well decomposed gin trash increased lint yield in the current year, even though gin trash did not appear effective in a greenhouse experiment. Increasing irrigation water salt and chloride concentrations decreased cotton growth and boll weight in the greenhouse. Broiler litter and leachate from broiler litter greatly increased growth, boll weight and boll count, while gin trash, broiler feed, and cow manure had some positive effects. Inorganic ammonium-N and nitrate-N did not diminish black root or affect growth or yield of cotton. The "active" ingredient in broiler litter was shown to be in the manure not in the pine shaving bedding material. It is in a water soluble fraction of the litter and appears to have its origin in broiler feed. Black root remains a disease with an unclear cause and one practical solution (broiler litter). At the present time, the best practical recommendation is to apply 3 to 4 tons of broiler litter/acre every 2 years to fields in the flatwoods that have a history of black root. The reason that broiler litter is effective remains unknown.