The Hay Knife.
Before the age of the modern tractor hay and straw mobile bailer, hay and corn sheeves were held in ricks. These ricks were built in what was called a Rickyard, or at the corner of a field which had easy access.
The Hay Knife traditionally styled in high carbon steel with Hardwood Handle. At the start of the 19th century, agriculture was very labour intensive. Everything was done by hand - sowing, reaping, turning and gathering hay took a long time. Tools like a Hay Knife when in the hands of a skilled farm worker, who cut the hay into blocks called a "Truss" each truss weighed about 56lbs in old hay or 60lbs in new hay. This man was called the "Haytier", from which over the years the surname of Hayter has derived.
Some haytiers were freelance workers who travelled around the smaller farms, where a farmhand did not have the time or the skill as a haytier. In a lot of cases these men were attached to a Corn chandlers business.
The last time I used a tool such as this was to cut silage from a pit silage heap. I do understand Jim Ricketts had one in his old collection in Cookham Dean.