Academic journal article Journal of Agricultural and Applied Economics

Subsurface Drip Irrigation versus Center-Pivot Sprinkler for Applying Swine Effluent to Corn

Academic journal article Journal of Agricultural and Applied Economics

Subsurface Drip Irrigation versus Center-Pivot Sprinkler for Applying Swine Effluent to Corn

Article excerpt

A risk-averse irrigated corn producer would be better off choosing the more expensive subsurface drip irrigation (SDI) over center-pivot sprinkler (CPS), given limited aquifer life and swine effluent and urea fertilization. A stochastic optimization using EPIC data maximized expected utility of 100 years' worth of net revenues for a quarter section. Phosphorus accumulation was more likely with the CPS than with the SDI but soil nitrogen was constant under both systems. SDI conserves more water than CPS per acre but depletes the aquifer faster because a greater area is irrigated. These results were invariant in the sensitivity analysis.

Key Words: aquifer depletion, center-pivot sprinkler irrigation, certainty equivalent, corn irrigation, mathematical programming, risk, stochastic optimization, subsurface drip irrigation

JEL Classifications: C61, C65, Q12, Q30, Q53

During the 1990s, animal feeding operations, including swine operations, became highly consolidated and geographically concentrated enterprises (Sweeten, Miner, and Tengman 2003). Usually, large swine concentrated animal feeding operations (CAFOs) locate in agricultural areas where there is an abundant supply of corn and sorghum, which are important feed components in swine production (Forster). Such is the case of Texas County, OK, which in 2002 had 1.07 million hogs and pigs, almost half of the 2.25 million in the state (U.S. Department of Agriculture-National Agricultural Statistics Service [USDA-NASS]). For that same year, the U.S. hog and pig population level was estimated at 60.4 million (ibid.). Animal production and their products are extremely important for Oklahoma agriculture. Eighty-two percent of the market value of agricultural products sold in the state in 2002 was from livestock, poultry, and their products (this percentage corresponds to $3.6 b.); in Texas County the percentage was even higher, about 92%, which corresponds to $609.1 m.

After the Oklahoma Senate passed regulations easing restrictions against corporate farming in 1991, there was an 8,130% increase in the number of hogs and pigs in Texas County between 1992 and 2002 (USDA-NASS). Although the county regained new economic life with the installation of the new swine operations, by 1998 there was controversy regarding the disposal of swine manure, and a temporary moratorium was imposed to limit construction and expansion of hog farms in Oklahoma (Hinton).

Froese estimates that a growing/finishing pig produces on average 0.28 cubic feet of manure per day. Ribaudo et al. estimated that, in 1998, there were 28.2 animal units per acre of land receiving manure in Oklahoma farms. Annually, the larger swine unit facilities located in semiarid regions can produce as much as three million gallons of lagoon effluent, according to ongoing research at Oklahoma State University. Because CAFOs produce such large amounts of manure, nearby land may be insufficient to use all the manure in a sustainable manner (Sweeten, Miner, and Tengman); this is especially true if effluent is applied using a phosphorus-based standard. According to Ribaudo et al., who used data from the 1998 ARMS hog survey, large animal farms in Oklahoma would need an additional 600 acres on average to apply manure following an N-based standard; for a P-based standard, an additional 1,253 acres would be required. The 1998 practice for farms with more that 1000 animal units was to apply manure on 139.4 acres on average (ibid.). Transporting the manure off-site is costly, and total cost to transport a ton increases with distance shipped. The great volume of manure produced usually needs to be contained in treatment or in storage facilities before it can be land-applied. Tyson provides an explanation of different facilities and the advantages each provides; he also alerts that problems related to odor and environmental quality can be mitigated if one devotes enough thought to planning and choosing an adequate facility type and size. …

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