November 1981
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Journal of Dairy Science
Six two-stage animal waste storage simulators were designed, constructed, and used to measure the distribution and retention of nutrients during winter storage of liquid animal wastes from a dairy herd. Effects of surface aeration and pH buffering plus aeration on nutrient distribution and retention were deter- mined. Nutrients retained during simulated untreated (control) storage were total solids 99%, volatile solids 97%, total nitrogen 89%, and ash 100%. Aeration increased degradation of volatile solids but did not reduce total nitrogen retention appreciably in unbuffered systems. Aera- tion increased transfer of soluble nutrients to the low-solid stage. Buffering of waste at a pH from 6 to 7 with phosphoric acid effectively retained nitrogen in a system in which mild aeration was applied to the high-solid stage. From 30 to 42% of the total nitrogen was recovered in the second low-solid stages demonstrating the significance of the liquid phase as a valuable fertilizer resource for irrigation. Appreciable synthesis of protein by microflora apparently occurred through utilization of ammonia as a nitrogen source in the nonbuffered system. Odor intensity indexes of liquids in the surface layer were reduced by aeration of that layer. Oxidation-reduction poten- tials appear to be a reliable indication of degree of malodor production.