Salmon effected many reforms in the management of the Duke's property. From 1795 he designed Park Farm, Speedwell Farm and many other buildings on the Russell estates. The Duke was interested in the
agrarian revolution of the day: Park Farm, designed in 1795, of which the first set of buildings were completed in 1797, was regarded as a model farm, using the latest machinery and techniques. The Duke started in Woburn annual exhibitions of sheep-shearing, and during these events Salmon's work in improving
agricultural implements attracted much attention. In 1797 the
Society of Arts awarded him thirty guineas for a
chaff-cutting engine, which was the parent of later chaffcutters. In 1801 Salmon exhibited his "Bedfordshire Drill", which became the model for succeeding
drills. In 1803 he showed a new design of plough. In 1804 he brought out a "scuffler", or
cultivator, and two years later he exhibited a self-raking
reaping machine, which was described in 1808 in ''
Bell's Weekly Messenger''. In 1814 Salmon patented the first
haymaking machine. He received at various times silver medals from the Society of Arts for surgical instruments, a canal lock, a weighing machine, a humane
mantrap, and a system of earthwalls.
John Russell, 6th Duke of Bedford (who succeeded his brother the 5th Duke in 1802) conferred on Salmon the stewardship of his
Chenies estate, so that he might improve the system of plantation. He paid great attention to the proper method of pruning forest trees, for which he invented an apparatus, and made experiments to determine the best method of seasoning timber. ==Retirement==