In Kansas, Seaboard Farms has received state regulatory approval to expand the number of pigs at the grow-finish sites. Included in the approval was notification that Seaboard had purchased irrigation water rights to furnish the water needs of the pigs associated with the expansion. Several neighbors were quoted as having concerns that the increase in pig inventories would result in their water wells running dry, etc.
As an extension swine specialist in Nebraska I ran into this concern several times during the permit process for producers. My conclusion at the time was that pork production is not a large user of water when compared to irrigated agriculture.
In the case of the Seaboard permit, the approval was for an increase in inventory to 198,000 pigs. If we assume these pigs are housed in facilities with nipple drinkers, the average daily water usage per pig during the grow-finish period will be 1.5 gal/pig/day. Now pigs aren’t in the facility for 365 days per year. There are periods of time when the facility is empty and no drinking water is used. However, water is used for cleaning, etc. Cleaning water usage generally is similar to drinking water usage so I’ll use 1.5 gal/d/pig space times 365 days per year to estimate total water needs for the Seaboard site.
Water is typically measured in acre inches when discussing irrigation needs. An acre inch of water is one inch of water applied to 1 acre of cropland and equals 22,611 gallons.
198,000 pig spaces times 1.5 gal/space/day times 365 days per year equals 108,405,000 gallons or 4,794 acre inches of water. This is a large amount of water however it’s looked at.
However, compared to the needs of irrigated corn production in the region, it is a small number. If we assume that the typical irrigated corn field in SW Kansas requires 15 acre inches of water per year (it may be higher depending on the year), the water needs of the 198,000 pig spaces translates into 320 acres of irrigated corn. This is ½ section of corn yield, a drop in bucket compared to the large number of acres of irrigated cropland in the region.
Yes, pigs are in SW Kansas due to the irrigated cropping systems that have been developed in the region that allow for growing the feed grains used by the pigs and having a cropping system that benefits from the resulting animal manure. If water usage is the concern, improvements in irrigation efficiencies associated with the cropping systems is the place to start, not with banning pork production.
Thanks to Linden Olson for spotting an error in my math. The correct conversion factor is 27,000 gal per acre-inch, not 22,611. When you do the math with the correct conversion factor you come up with 266 irrigated acres of corn, not 320 acres.