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Fertilizer costs and increased awareness of non-point source pollution run-off amplify the pressures on farm economics. Intensive farming operations provided the impetus for our study using effluent from anaerobic thermophilically digested poultry litter as a potential fertilizer. Five fertilizer treatments were used: unfertilized control, pelletized municipal sludge, commercial crop specific products, 1x digested solids and 2x digested solids. All four applications of fertilizer were equalized for nitrogen based on commercial product recommendations. Beds treated with 2x solids accumulated higher percentage of organic matter over the 5-year period. A statistically significant increase in phosphorus was found in the solids beds in 2003. Beds with 2x solids showed statistical significance for Mg, Zn and Cu. Fertilizer trials included blueberries, tomatoes, potatoes, and sweet corn. Potato fresh weight was not significantly different in 2002 or 2003, but was in 2001. Tomato fruit number was not significantly different in 2001 or 2003, but was in 2002. Tomato fresh weight for 2x solids was not significantly different from the commercial or pelletized sludge treatments in 2002 and 2003 suggesting that tomato may discriminate between treatments. Commercial and pelletized sludge fertilizers were statistically better for sweet corn fresh ear weight and number of ears in 2002 and 2003. Blueberry yields were not significantly different between treatments for any year. As this is a perennial crop, it may be several years before a significant difference is observed. While not a total solution, our research shows the effectiveness of digested poultry litter as part of a nutrient management program; making livestock residuals a nutrient resource which offers the potential for organic use.

Increasing production of agricultural waste impacts health, economic, and environmental welfare. Thermophilic anaerobic digestion is a technology developed to treat these waste streams whereby the organic material is converted to biogas and effluent. The effluent, available in solid and liquid form, holds promise as a fertilizer. Digested (broiler litter) liquid effluent was compared to chemical and certified organic fertilizers with application rates based on soil analyses and crop recommendations. An unfertilized control and an effluent treatment at twice the recommended amount were also included. Beds treated with liquid effluent maintained higher levels of available phosphorus established from treatment in prior years with solid effluent. Beds treated with liquid effluent showed a significant increase in K, Mg, Cu, and Mn. Potato fresh weight and tuber number for 2× effluent beds were significantly better than the other treatments. Average tuber weight was also statistically significant, but organic, 2×, and 1× effluent were best. For tomato, the 2× effluent treatment was statistically better for fruit number, average weight, and total weight. In fact, the total weight per plant for the 2× effluent treatment was more than three times higher than the other fertilizer treatments. The chemical and effluent treatments were statistically better for broccoli than the organic or unfertilized control. Blueberry yields were not significantly different between treatments. As this is a perennial crop, it may be several years before a significant difference is observed. While not a total solution, our research shows the effectiveness of digested poultry litter as part of a nutrient management program, thereby making a safer, less-polluting alternative to raw livestock residuals.