The most accurate method to determine what is being applied is to weigh everything as it is applied to a field. Platform scales and wheel weighing systems are available at prices that farms can afford.

Currently manufacturers of manure- and fertilizer-spreading equipment do not include scales or load cells as options, but after-market solutions are becoming available. There are load cells available for use in dump trucks and trailers, semi-type trailers, including walking floor models, and mixer wagons. There are weighing systems for use on skid steers and front-end loaders that work by sensing the pressure changes in the hydraulic fluid needed to raise the bucket. Electronic control systems can accumulate the bucket loads and provide the total weight applied to the field.

Once the quantities are measured, all one really needs is a record of where each load went and the land area covered. Farm equipment in the not-too-distant future will combine load cells or other weighing technology with GPS tracking systems to document on the fly what is applied to a field and where exactly it was applied in the field.

If weighing manure is not an option, one can place plastic sheets in the path of a manure spreader and determine the net weight collected on a bathroom scale. If a plastic sheet measures 22 square feet, then the weight of manure on the sheet (in pounds) equals the application rate (tons/acre). If other size sheets or tarps are used, use the calculation below for estimating application rate.

Tons/acre = Net manure weight (lb) x Area of Plastic Sheet / 22

Author: Richard Meinert, Extension Educator, University of Connecticut