Evaluation of EC-5 soil moisture sensors for real-time determination of poultry manure or litter moisture content

Moisture content (Ψ) of poultry manure or litter is an important property of the material. Relating manure or litter Ψ to its ammonia (NH3) emission is conducive to assessing and/or controlling real-time ammonia emissions from the manure or litter. However, means to measure manure or litter Ψ on a real-time basis is lacking. This study was carried out to characterize the operational performance of a commercially available soil moisture sensor for measuring Ψ of meatbird (broiler and turkey) litters and laying-hen manure. The Ψ tested ranged from 27.1% to 65.7% for broiler litter, 22.8% to 56.1% for turkey litter, and 11.0% to 75.0% for layer manure. Bulk density (ρ) ranged from 318 to 468 kg m-3 (20 to
29 lb ft-3) for the broiler and turkey litters and from 151 to 943 kg m-3(9 to 55 lb ft-3) for laying-hen manure. Linear regression equations were developed to relate the sensor output to Ψ and ρ for the meat-bird litters and to Ψ for the
laying-hen manure, all yielding good fit (R2 =0.95 – 0.99). An uncertainty analysis performed on the developed calibration equations revealed average errors in the Ψ estimation of ±7.1% estimated value for the poultry litters and ±6.7% estimated value for the laying-hen manure. Litter temperature was found to have a small impact on Ψ measurement by the sensor, 0.31% of measured mV per °C (0.17% per °F) deviation from the mean operating temperature over the range of 4°C to 24°C (39°F to 75°F). Results of the study indicate that when properly calibrated, the soil moisture sensor offers a reasonable means for real-time measurement of poultry litter or manure moisture content.