PO 54: Know how to calculate total animal manure production on a livestock farm.

Load records and manure spreader calibration calculates manure production based on what has been spread.  There are three methods used to do this.

1. Using truck scales.
• Most accurate, works for solid, semi-solid, and liquid manures.
• Weigh tractor and spreader empty (record each axle weight), and then weigh full.  Full weight – empty weight = manure weight
• Determine application area: measure length and width of application pattern; multiply to get area; and divide by 43,560 (ft²/acre) to get acreage covered.
• Calculate rate: divide manure weight by application acreage; divide this by 2000 to get tons/acre.
2. Method 2: using plastic sheets
• Works for solid and semi-solid manure; requires 3 same-size sheets or tarps and three 5-gallon buckets.
• Determine tarp and pail weight (put one sheet in each bucket; weigh).
• Stake sheets at different intervals along the spread line; apply manure as normal.
• Collect, weigh, and determine rate: put tarp with manure into bucket and weigh; subtracting the original weight of the bucket and tarp.  Take the average of the weights and convert to the rate (see http://nmsp.css.cornell.edu/publications/factsheets/factsheet18.pdf).