FEATHER MEAL, A SEMI-SLOW-RELEASE NITROGEN-FERTILIZER FOR ORGANIC FARMING

Plant nutrition in organic farming is based entirely on decomposition of organic materials, and release of excess N superfluous to the micro bial population. Feather meal (FM), a by-product of the poultry proces sing industry, which contains 15% N as non-soluble keratin, is a poten tial organic N fertilizer. The objective of this study was to determin e the rate of N mineralization and changes in microbial activity follo wing the application of FM to soil. Soils were incubated with FM for 8 weeks at 30-degrees-C and optimal water content, and analyzed periodi cally for inorganic N, rate of CO2 evolution, counts of microbial popu lations, and activity of dehydrogenase and protease. Approximately 45, 55 and 65% of fertilizer N were released after 1, 2, and 8 weeks, res pectively. Total number of bacteria increased due to the addition of F M after only 1 d, with a second pulse obtained at 14 d. Dehydrogenase activity followed a similar response cycling. Cellulose hydrolyzing ba cteria and proteolitic bacteria increased later, between 5 and 21 d, p robably due to secondary microbial decay products. Microbial biomass N at 5 to 7 d accounted for 10 to 14% of total FM-N, therefore the slow release of N from FM was due in part to its resistance to decompositi on and in part to microbial biomass build-up and secondary decompositi on.