Texas High Plains agriculture, largely dependent on water from the Ogallala aquifer for irrigation, exemplifies semiarid agricultural regions where irrigation is used at nonsustainable rates of extraction. Integrating crop and livestock systems has been suggested to conserve water and to achieve other environmental and economic goals compared with monoculture systems. From 1998 to 2008, two large‐scale systems, with three blocks in a randomized block design, compared irrigation water, productivity, chemical inputs, and specific pests of (i) a cotton (Gossypium hirsutum L.) monoculture, and (ii) an integrated three‐paddock system that included cotton in a two‐paddock rotation with grazed wheat (Triticum aestivum L.) and rye (Secale cereale L.) and the perennial variety WW‐B. Dahl old world bluestem (OWB) [Bothriochloa bladhii (Retz) S.T. Blake] in a third paddock for grazing and seed production. All paddocks were irrigated by subsurface drip. Angus crossbred beef steers (Bos taurus; initial BW 229 kg; SD = 33 kg) grazed 185 d from January to mid‐July each year. During the 10 yr following the establishment year, cotton lint yield was similar and averaged 1370 kg ha−1 for both systems. Bluestem seed yield averaged 25 kg pure live seed (PLS) ha−1. Steers gained 139 kg on pasture and 0.79 kg d−1. Per hectare, the integrated system used 25% less (P < 0.001) irrigation water, 36% less N fertilizer, and fewer other chemical inputs than monoculture cotton. Integrated production systems that are less dependent on irrigation and chemical inputs appear possible while achieving goals of sustainability, fiber production, and food security.

Fossil fuel-derived inputs can increase cow-calf production per unit of land or labor but can raise financial and environmental concerns. Eleven US cow-calf systems from nine ecological regions in Iowa, South Dakota, Tennessee, and Texas were analyzed to determine quantities of energy used and carbon (C) emitted due to fossil fuel use (excluding emissions from soils and biota) and to determine how management and environment influenced those quantities. Total energy and C cost, calculated cow 21 or ha 21 , were highly correlated (0.99). Energy use cow 21 and ha 21 varied greatly across systems, ranging from 3 000 to 12 600 megajoules (MJ) ? cow 21 ? yr 21 and from 260 to 20 800 MJ ? ha 21 ? yr 21. As stocking rate increased, MJ ? cow 21 increased at an increasing rate. Differences in quantity of fertilizer accounted for most variation in energy use. Fertilizer allowed higher stocking rates but reduced energy efficiency of liveweight marketed. Compared to intensive, higher stocking rate systems, rangeland systems based on native or naturalized forages used little or no fertilizer, but used more energy cow 21 for crude protein (CP) supplementation, fencing, and pickup trucks. Across all systems, energy used to produce winter feed ranged from 0% to 46% of total energy. Northern systems used higher percentages of total energy for winter feed and fed for more days year 21 , but southern systems that included large amounts of bermudagrass (Cynodon dactylon L.) hay used the most MJ ? cow 21 for winter feed. Systems with high MJ ? cow 21 were vulnerable to shocks in energy prices. Reducing energy use and C emissions from cowcalf operations is possible, especially by reducing fertilizer and hay use, but would likely reduce productivity ha 21. Forages with high nitrogen use efficiency, locally adapted plants and animals, and replacement of hay with unfertilized dormant forage and CP supplementation could reduce energy use. Resumen Insumos derivados de los combustibles fósiles pueden incrementar el costo por unidad de tierra o trabajo dentro del sistema vacabecerro pero a la vez pueden incrementar las preocupaciones financieras y medioambientales. Once sistemas de producción vacabecerro de 9 regiones ecológicas de Estados Unidos ubicadas en Iowa, Dakota del Sur, Tennessee, y Texas se analizaron para determinar las cantidades de energía consumidas y el carbono (C) emitido debido al uso de combustibles fósiles (exceptuando las emisiones inherentes al suelo y al medioambiente), y a la vez determinar como el manejo y el medioambiente afecta estas cantidades. El total de energía y costo de carbón C, calculado por vaca o hectárea fue altamente relacionado (0.99). El uso de energía por vaca y hectárea tuvo una gran variación en los sistemas, fluctuando de 3 000 o 12 600 MJ ? vaca 21 ? añ o 21 y de 260 a 20 800 MJ ? ha 21 ? añ o 21. Mientas, la densidad animal incrementaba MJ ? vaca 21 también se incrementó a una tasa a la alza. Las diferencias en cantidad de fertilizante fueron las que provocaron una mayor variación en uso de energ...

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