Submitted to: Meeting Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 6/4/2007
Publication Date: 6/21/2007
Citation: Russelle, M.P., Blanchet, K., Everett, L. 2007. Characteristics and fertilizer value of compost dairy barn manure. In: Proceedings of the National Compost Dairy Barn Conference, June 21-22, 2007, Burnsville, Minnesota. p. 75-81. Interpretive Summary:
Technical Abstract: Compost dairy barn (CDB) manure is a new manure source on dairy farms. Only two published studies report manure composition in CDBs. One determined composition in the upper 30 cm of 12 barns and the other summarized sample analyses from the entire pack depth from 6 barns. The visually apparent uniformity of CDB manure suggests that it could be sampled and analyzed before land application, making it unique compared to other dairy manure sources that are too heterogeneous to sample before the day of application. This report summarizes some of the nutrient characteristics of CDB manure from eight barns and suggests a sampling protocol. Total N concentration averaged about 10.9 g/kg and did not differ among areas in the barn or depth. Ammonium N concentration was much lower in the surface layer (0.85 g/kg) than the compact layer (2.27 g/kg). The range of C:N ratio for the entire pack depth was 11.2 to 20.9, which implies that N mineralization from CDB manure would not be limited by high C:N ratios. Phosphate (P2O5) concentration averaged 2.8 g/kg and did not vary with depth or sampling location. Potash (K2O) concentration averaged 7.4 g/kg in the surface and 6.7 g/kg in the compact layer (P=0.053) but did not differ by sampling location. Wet bulk density of the compacted manure was similar among barns, averaging 885 kg/m3. To our knowledge, this is the first report of pack density in CDBs. This suggests that farmers can estimate the amount of manure to be hauled by calculating the product of the average density we determined for the compact pack and the measured volume of the manure pack in their barn. Initial estimates of manure N availability varied two-fold, from 3.1 to 6.1 kg/Mg, but these need to be tested in the field. Ammonium-N comprised 41 to 65% of the available N and the pH of CDB manure typically is above 7.5, so ammonia volatilization may be high when the barn is emptied and during and after land application. Farmers are advised to incorporate this manure resource quickly to minimize ammonia losses. Based on this study, we recommend that farmers take samples through the entire pack in at least six sites in the barn. Sampling and analyses can be completed a few weeks before manure application, improving the likelihood of applying the most economic and environmentally sound manure rate.