Barley yield response to irrigation and potential profits in the Texas High Plains

Summary

Irrigated winter barley (Hordeum vulgare L.) can be a profitable alternative to some low profit major crops in the Texas High Plains. A six-year evaluation of yield response related to total spring irrigation water, applied by surface methods (furrow), and seasonal precipitation resulted in a multivariate function explaining 74% of the yield variation. Predicted yields varied from a low of 3.69 Mg ha⁻¹ to a maximum 6.18 Mg ha⁻¹ with 0 and 389 mm, respectively, based on average monthly precipitation quantities. Precipitation is skewed to less than average in th semi-arid Texas High Plains. Using modal precipitation amounts of 40% of average precipitation, yield estimates were reduced to 2.29 Mg ha⁻¹ with zero spring irrigation and to 5.63 Mg ha⁻¹ at the peak with 450 mm. A second multivariate yield response function related to alternative timings of single and multiple spring irrigations explained 76% of the variation in yields. Among all combinations of 1, 2, 3, and 4 spring irrigations, irrigation water-use efficiency was estimated to be highest with one application at the boot stage of development. All other single and combinations of multiple irrigations resulted in lower water-use efficiencies. A comparison of enterprise budgets of four irrigation timing alternatives and levels of application indicated highest profit over variable costs, $ 287 ha⁻¹, was attained by applying a total of 307 mm in three spring applications at the boot, head, and milk stages. A lower level of 217 mm applied at boot and milk stages was $ 12 ha⁻¹ less profitable and a higher level of 425 mm was $ 24 ha⁻¹ less profitable. When fixed costs of irrigation facilities, land, and machinery were considered, returns to management and risk were highest, $ 101 ha⁻¹, with 217 mm. Using 40% of average precipitation, profits were reduced $ 65 ha⁻¹ with 217 mm and $ 69 ha⁻¹ with 307 mm spring irrigation levels.