Field Calibration Procedures for Animal

Wastewater Application Equipment

Eileen A. CoiteAgricultural Extension Agent

Wayne County

Reasons to Calibrate

• Know application rate• Maintain uniformity across fields• Identify where/when system is lacking• Compensate for equipment aging and

component wear• Recommended at least every 3 years• New NPDES permit = Yearly

Factors that influence the need to calibrate

• Age, wear and tear on equipment– Pump wear– Nozzle wear

• Quality of wastewater– Salts and sand particles

• Clogging – most often solid set

Other factors to consider

• Excessive pressure– Greater potential for drift– Accelerated wear on sprinkler nozzle

• Nozzle wear– Increased discharge rate– Decreased wetted diameter

• Pump wear– Reduced operating pressure and flow

What you will need

• Watch• Measuring tape• Collection

containers

Other useful tools

• Wind meter• Flags

Collection Containers

• Rain gauges work well

• Uniform opening and cross section with graduated scale

• At least 4 inches deep• Same height, no more

than 36” above ground

• Above crop canopy

When to Calibrate

• Periods of low evaporation• Best before 10am or after 4pm• Days with a light wind (<5 mph

ideal)• Cool, cloudy days

– anytime with <5 mph wind velocity

Calibration Procedures

• Pull out reel, start up pump • Measure wetted diameter • Determine number of collection gauges

and spacing between – 25’ or less– Minimum of 16 gauges (more if WD >400 ft)

• Equally space gauges from gun cart to outer diameter (at least one wetted diameter from either end of pull)

Calibration Procedures

• Record starting time of collection• Allow system to pass completely

through collection gauges• Record pressure at reel and gun• Measure travel speed • Record ending time of collection• Immediately record amounts

collected in gauges

Calibration Procedures

Travel speed: Reel vs. observation

Calibration Procedures

Calibration Calculations

• Identify gauges outside effective lane spacing for overlap volume

• Superimpose these gauge volumes for overlap, add volumes together

• Calculate average application depth• Calculate deviation depth for gauges• Calculate average deviation depth

Calibration Calculations

• Calculate precipitation rate• Determine application uniformity

Uc= average depth-average deviation x 100

average depth

Calculation Exercise

• Divide into groups• Use collected example farm

information• Determine uniformity for farm

Calibration Results

• Higher values=more uniform• 70-85% uniformity is GOOD• <70 usually means system

adjustments are required– Contact irrigation dealer or Certified

Technical Specialist for assistance

Calibration Summary

• Calibrate to maintain application uniformity and identify equipment maintenance needs

• Recommended minimum of 3 years• Use proper equipment and set up• Calibrate during periods of low

evaporation, with calm wind

Calibration Summary

• Record collections immediately• Do the math• Make adjustments and seek

assistance if necessary

Who Needs to Calibrate???