For Liquid manure, take a sample each time the storage is emptied. Manure applied from a storage emptied in spring will be different from the manure applied from the same storage emptied in late summer. Agitate the storage completely. In a plastic pail collect samples from various depths of the storage, as it is being emptied. Mix 10 to 20 of these samples thoroughly and transfer a portion to a plastic jar. The jar should only be half full to avoid gas build-up and explosion. Seal it tightly and put it in a plastic bag that is securely tied. Refridgerate or freeze until shipping.
Sampling Solid Manure
For solid manure, take a sample every time the storage is emptied until a trend becomes evident. Then you can sample every few years or when you make a major change in manure source or in management. These can include changes to ration, bedding or storage methods.
Solid manure is more difficult to sample randomly. On clean cement or plywood, take samples (a forkful) of manure from various loads leaving the pile or from various parts of the pile. Chop the manure with a shovel or fork and mix the samples together as thoroughly as possible.
Divide the manure into 4 portions and discard 3. Continue mixing and dividing the manure until you can fill a plastic jar or shipping container - about half a litre. Place the tightly covered sample in a plastic bag and store in a cool place until shipping.