Economic Comparison of a Monoculture Cotton System and Integrated Crop-Livestock Systems in the Texas High Plains.

Depletion of the Ogallala Aquifer threatens the viability of irrigated agriculture in the Texas High Plains.  We carried out two long-term experiments designed to evaluate integrated crop-livestock systems as alternatives to cotton (Gossypium hirsutum) monocultures typical of the region.  Both experiments were randomized block designs with three blocks.  The first experiment compared two irrigated systems: 1) cotton monoculture (395 mm irrigation yr^-1); and 2) integrated system (300 mm) that included one paddock of perennial ‘WW-B. Dahl’ old world bluestem (hereafter bluestem; Bothriochloa bladhii), and a two-paddock rotation of rye (Secale cereale) -cotton-wheat (Triticum aestivum)-fallow.  The second experiment included: 3) non-irrigated system composed of a native grass mixture and a two-paddock rotation of cotton-foxtail millet (Setaria italica); 4) “buffer-irrigated” system (44 mm) the same as #3, but with an additional paddock of irrigated bluestem; and 5) irrigated perennial forage system (229 mm) consisting of one paddock of bluestem and two paddocks of bermudagrass (Cynodon dactylon).  After 10 yr of the first experiment, gross margin of the monoculture (#1) and integrated system (#2) were nearly identical ($264 ha^-1), but the integrated system used 25% less irrigation water and 36% less N fertilizer.  System #2 was more profitable during the first 4 yr, but adoption of ‘FiberMax’ cotton varieties in year 5 increased lint yields and the monoculture was more profitable for 4 of the next 6 yr.  In the second experiment, irrigation and profitability decreased relative to the first experiment.  Opportunities exist to improve profitability of the low-irrigation systems (#3 to #5), including harvesting excess forage for hay, increasing grass seed harvests, and reducing fertilizer and herbicide use on non-irrigated pastures.  In general, perennial forages provided lower-cost but lower-quality grazing, compared to annuals.  Integrated crop-livestock systems can conserve natural resources and have potential to compete economically with cotton monocultures in the region.