In 2008 aminopyralid (a hormonal weedkiller) found its way into manure through animals grazing on treated land.  In order to avoid any possible risk to the gardener Sinclair changed its supplier sources to ensure that any material used is not contaminated and regular laboratory checks continue to be conducted to ensure the material is herbicide free.

Another factor that has affected the look of manure is that animals are given deeper bedding than they used to be. The manure and bedding is all composted down together but the end result is more straw-like in texture and lighter in colour.

Before changing to a different looking product extensive checks on the nutrient levels, etc were done and also growing trials were conducted.  These showed that J. Arthur Bower's Farm Manure performed even better than before.  One reason for this is that the wood shavings used as bedding have proven to be beneficial in maintaining soil aeration and moisture levels.