Development of a Rainwater Harvesting Model for Broiler Farms to Estimate On-farm Storage Needs

Abstract

Access to water is critical for poultry production and rainwater harvesting (RWH) may reduce reliance on low-yield and poor water quality wells or municipal (city or county) water supplies to supplement water consumption and offset rising water costs. Current uses of RWH have been primarily focused on reducing stormwater runoff in urban areas and providing sources of potable and non-potable water. The objectives of this research were to develop a RWH model to estimate the main water consumption sources for a poultry farm; bird water consumption (BWC), evaporative cooling make-up water consumption (EWC), and maintenance water consumption (MWC) and to evaluate the performance of the model over a 25-year period for nine locations across the U.S. for varying storage capacities. Daily BWC was estimated using industry feed intake performance data for genetic strains of broilers. NOAA weather data was used to estimate rainfall harvested (RFH) and EWC. Equations for BWC and EWC were calibrated and evaluated using data from a poultry farm in east Alabama. Model BWC was overestimated by 15% compared to farm BWC data. Model EWC was overestimated by 453 m3 with a mean daily value of 8 m3 compared to a farm mean daily value of 3.6 m3. Equations for BWC and EWC were used to develop a RWH model that incorporated multiple user inputs. The entire model was run over a 25-year period to evaluate the performance of a 379 m3 storage capacity in Huntsville, AL and a simple economic analysis was performed for a low, medium, and high municipal water cost. The overall performance of the model was within 18.21% of total water consumption (TC) estimations for data recorded on a north Alabama farm. Economic results show that at the three municipal water costs, savings increased as water cost increased. To evaluate the behavior of the model for various locations and storage capacities, nine locations were chosen across the U.S. that represented high poultry production areas and varying climates. Six storage capacities between 189 m3 and 1,136 m3 in increments of 189 m3 were evaluated in each location over a 25-year period from 1990 to 2015. Values for TC were separated into municipal water usage (MU) and storage water usage (SU), where MU was water the farmer had to buy and SU was water the farmer did not have to buy (i.e. savings). A simple economic analysis was performed to estimate the savings over the 25-year period for a range of municipal water costs from $0.79 to $3.17 in increments of $0.26 m-3. Results showed the largest reduction in MU was increasing from a storage capacity of 189 m3 to 379 m3. The reduction in MU was reduced with each additional increase in storage capacity. All locations experienced no savings at a municipal water costs lower than $1.32 per m3. Most locations experienced maximum savings at water costs between $2.38 and $3.17 using a storage capacity of 568 m3. The model also showed that in locations with low amounts of annual rainfall, these locations would not benefit from installing RWH systems. Many farmers located in high precipitation areas could potentially benefit from installing a RWH system to supplement their current water sources and offset rising water costs. This RWH model can be used as a decision tool by farmers to determine the potential benefits of installing a RWH system to meet their farm’s needs.