Zone sampling is especially useful for N but has also been useful for P, soil pH, zinc, copper, sulfur and chloride. Variable rate controllers are available for whatever input needs to be varied on a farm. Liquid materials, dry materials, anhydrous ammonia, seed, ag chemicals and starter fertilizers can all be varied with any number of pieces of equipment. Seeders and planters have variable-rate attachments. Controllers can be used to vary chemical rates for herbicides, insecticides and fungicides.
Some controllers can stay in a tractor cab and can be used to control several different input rigs.
Others are specific for a piece of equipment. Good advice would be to have a unit that would be flexible for use in future needs and serviced by a company that is likely to be around for a long time. A local supplier available for servicing would also be helpful. Managing the data Data management and computer operation will be challenging for many producers who already manage many parts of their farming operation. Teaming up with a local supplier with these skills or a consultant that provides archiving and data management services would be very helpful for many producers.