Currently available and recently developed sampling methods for slurry and solid manure were tested for bias and reproducibility in the determination of total phosphorus and nitrogen content of samples. Sampling methods were based on techniques in which samples were taken either during loading from the hose or from the transport vehicle after loading. Most methods were unbiased. New sampling methods for slurry from the hose were substantially more reproducible than existing methods. For practical reasons, the mechanization of sampling is desirable, and to minimize the influence of human activity on sample quality, the automation of sampling is advisable.