Losses of Solids, Moisture, Nitrogen, Phosphorus, Potassium, Carbon, and Sulfur from Laying-Hen Manure in Storage Facilities

The losses of total solids, moisture, nitrogen (N), phosphorus (P), potassium (K), carbon (C), and sulfur (S) were determined in two storage events of laying-hen manure immediately removed from three different housing systems in Iowa, USA. The three laying-hen houses were conventional cage (CC), enriched colony (EC), and aviary (AV). The houses held a nominal number of 200,000, 46,700, and 50,000 Lohmann LSL lite layers, respectively. The manure collected on belts in each house was cleaned out twice a week. A fraction of the cleaned out manure was transferred to designated storage rooms wherein losses of different components were determined in two storage events. Manure was loaded into the storage rooms over 171 days during the first storage event and over 185 days during the second storage event. The total storage periods were 202 and 245 days, respectively, for the first and second storage events. Manure was weighed, sampled, and analyzed before it was loaded into the storage rooms and at the end of each storage event. Mass balance calculations were used to determine the losses of different components. Statistical analyses show that the nutrient contents, on a wet basis, of manure loaded in CC, AV, and EC storage rooms were significantly different due to the differences in manure moisture contents. However, on a dry basis, they had no significant differences. The fresh manure cleaned out from the EC layer house was drier than that from the other two houses. Loaded-in nitrogen losses in the CC, AV, and EC storage rooms were 24.6, 12.9, and 20.8%, respectively. Nitrogen losses depended on house temperature, manure moisture, and pH. The average losses of loaded-in manure mass, moisture, and total solids during the two storage events were 27.6 ± 1.9, 33.8 ± 8.3, and 20.8 ± 7.0%, respectively. The losses of N, P, K, C, and S were 19.4 ± 13.4, 11.7 ± 5.6, 10.2 ± 6.8, 27.0 ± 6.5, and 8.3 ± 8.5% of their loaded-in amounts, respectively. The total loss of N, P, K, C, and S was 56% of the total loaded-in solids loss; thereof, the loss of N, P, and K was 7%, and C loss was 48%. The laying-hen-specific losses of N, P, K, C, and S were 0.34, 0.05, 0.08, 3.2 and 0.019 g day⁻¹ hen⁻¹, respectively. The results of this research are important for assessing impacts of stored manure on environment and nutrient losses. They can also be used to develop methodologies for the mitigation of the emissions from egg production facilities.