I don’t use commercial fertilizer on my farm, so I could see no need to have a spreader. I started using a power take off broadcast/fertilizer spreader to plant “bin” oats. I broadcast the cheap oat seed onto last year’s corn ground after fitting it down, then bale the crop rather than combining it. This method allows me to mow the crop before ragweed, and other noxious weeds become a problem. The stand is good e n o u g h to nurse a hay crop and get it established. The animals enjoy the oat hay and it fits well in my farm plan.

I used my tractor to spin on the oats and hay seed and thought about my buddy’s design and yet another job the horses could do. I also found a supplier for organic pelleted fertilizer and soil amendments. Once again the broadcast spreader was used to apply these soil builders. The more I drove the tractor to do such an easy job, the more I was disgusted about burning fuel and watching my horses stand in the pasture and watch me.

Last spring, 2009, I made a trip to Jonathan Lawton’s farm. I got there in time to watch him top dress some corn with a fertilizer spreader he had built from a truck rear end and a PTO driver broadcast spreader. He built his prototype mostly from wood because he had the wood on hand. The spreader worked like a dream. The horses pulled a forecart with the fertilizer spreader hooked behind it. The rear end of the old truck turned when pulled across the ground, so a gear drive assembly was fashioned to supply power to the spreader. The fertilizer flew out of the spreader covering a 40 foot arc. In no time at all the fields of corn were top dressed, the horses were worked, and sustainable agriculture was practiced.

Inspired by my friend Jonathan, I resolved to build a fertilizer spreader of my own. I enlisted the help of my Uncle Fred, a welder and fabricator in his own right, to help me.  We acquired a rear end out of an old Jeep. We cut all the unnecessary parts off the rear end, like brake drums and such to lighten the axle and keep mud from having a place to build up. We checked the rotation of the gears to get the wheels running in the right direction and figured out the ratio needed to drive the spreader.

The ratio part still puzzles me. I know that I wanted the s p r e a d e r to turn at approximately 540 revolutions per minute while the horses pulled the spreader 4 miles per hour, the walking speed of most horses. I turned to Jonathan for the technical expertise to get this all right. I marked one tire and rolled the axle across the ground. I needed to roll it so the tire made one complete revolution while counting the number of turns the transmission/rear-end made. This took two people, one to watch the tire and the other to count the revolutions the yoke made. I also found a gear ratio stamped on the “pumpkin” of the rear end and offered all this information to Jonathan. He told me I needed two gears, one 3 inches and the other 7 or 8 inches, depending on  what I could buy. This ratio worked out to a little less than 3-to-1. I am sure there are folks out there who understand this part very well, but I am not one of them. Once you get the information I wrote about, take it to a machine shop and ask for help if you need it. I am also sure most engineers or even a student good at math, could help you with this part.