IMPACT OF LONG-TERM LAND APPLICATION OF BROILER LITTER ON ENVIRONMENTALLY RELATED SOIL PROPERTIES

The largest portion of Alabama's rapidly growing poultry industry is g eographically concentrated in the Sand Mountain region of northern Ala bama. The result is that large amounts of waste are applied to relativ ely small areas of agricultural soils. A study was conducted to determ ine the effects of long-term broiler waste (litter) application on env ironmentally related soil conditions in the region. The region has an average annual rainfall of 1325 mm, which is evenly distributed throug hout the year, a thermic temperature regime, and soils in the region a re of the Ultisol order. In each of four major broiler-producing count ies, three pairs of sites consisting of long term (15-28 yr) littered and nonlittered fields on matching soil series and maintained under pe rennial tall fescue (Festuca arundinacea Schreb.) were sampled. Soil c ores were taken to 3 m or lithic contact and depth-incremented samples (0-15, 15-30, and each subsequent 30-cm interval) were analyzed for o rganic C, total N, NO3-N, pH, electrical conduc- tivity, and acid-extr actable P, K, Ca, Mg, Cu, and Zn. Litter application increased organic C and total N to depths of 15 and 30 cm, respectively, as compared wi th nonlittered soils, whereas pH was 0.5 units higher to a depth of 60 cm under littered soils. Significant accumulation of NO3-N was found in littered soils to or near bedrock. Extractable P concentrations in littered soils were more than six times greater than in nonlittered so ils to a depth of 60 cm. Elevated levels of extractable K, Ca, and Mg to depths greater than 60 cm also were found as a result of long-term litter use. Extractable Cu and Zn had accumulated in littered soils to a depth of 45 cm. These findings indicate that long-term land applica tion of broiler litter, at present rates, has altered soil chemical co nditions and has created a potential for adverse environmental impacts in the Sand Mountain region of Alabama.