Large volumes of generated animal manures necessitate knowledge of how its production and storage affects composition, losses, and utilization potential. Stratification of liquid dairy manure was the main source of observed variability within outdoor uncovered manure storage, during a yearlong monitoring of 24 physicochemical manure parameters. Coefficient of variation (CV) ranged from 4% to 24% for plant nutrients and 33% to 89% for biogas feedstock parameters. Nitrogen (N) volatilization losses during storage between manure additions were ?10% mo^-1 of total Kjeldahl nitrogen (TKN). Acetic acid was up to 100% of total volatile fatty acid concentration. Bioavailability and solubility of manure parameters, reflected in ratios of volatile solids to total solids (VS:TS), total ammoniacal nitrogen to total Kjeldahl nitrogen (TAN:TKN), and dissolved phosphorus to total phosphorus (O-PO₄:TP) ratios, was high. There was substantial pathogen survival during the study, with an increased count with added manure. Manure temperature changes and precipitation levels likely played a major role in mineralization and volatilization rates of nutrients and reduction of solids, especially in surface levels of manure in storage. Study results underline the importance of sampling method, timing, and location within stored manure to obtain representative samples unless thorough mixing is previously applied.