Submitted to: Agronomy Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/24/2006
Publication Date: 6/5/2006
Citation: Nielsen, D.C., Vigil, M.F., Benjamin, J.G. 2006. Forage yield response to water use for dryland corn, millet, and triticale in the Central Great Plains. Agronomy Journal. 98:992-998. Interpretive Summary: Dryland cropping systems in the central Great Plains nearly always suffer from lack of water because of the variable nature of precipitation. Forage production makes better use of precipitation than seed production. Forage production also does not have a critical growth stage (in which yield is more highly influenced by water use) as seed production generally does. Therefore, forage production systems may have a place in diversified dryland cropping systems. However, farmers in this region need a simple tool to evaluate the productivity of forage cropping systems under widely varying precipitation conditions. Data from a long-term dryland forage rotation (corn for silage, foxtail millet, and forage triticale) were analyzed to determine water use vs. dry matter relationships, and those relationships were used with historical precipitation records at Akron, CO to estimate the expected average yields and ranges of yield. The study determined simple linear relationships between crop water use and dry matter production, all with the same slope. But corn required 53 mm more water use than millet or triticale to start producing dry matter. Consequently, millet and triticale produced similar amounts of dry matter for a given water use, while corn produced less dry matter. Triticale had a higher probability (74%) of producing a dry matter yield of at least 4000 kg ha-1 than corn (45%) or foxtail millet (30%). While this rotational forage production system has a relatively high precipitation use efficiency (8.7 kg ha-1 mm-1), the system might benefit by the replacement of corn with a forage legume species.
Technical Abstract: Reduced and no-till dryland cropping systems in the semi-arid central Great Plains of the United States should be diversified from the traditional wheat (Triticum aestivum L.)-fallow (W-F) system to minimize disease, weed, and insect problems associated with monoculture. Forage production systems, with higher water use efficiency compared with grain production systems, may have a place in these diversified dryland cropping systems. However, farmers in this region need a simple tool to evaluate the productivity of forage cropping systems under widely varying precipitation conditions. The objectives of this study were to 1) quantify the relationship between crop water use and dry matter yield for corn (Zea mays L.), foxtail millet (Setaria italica L. Beauv.), and forage triticale (xTriticosecale Wittmack) under dryland conditions; and 2) determine the range and distribution of expected dry matter yields for these three crops in the central Great Plains based on historical precipitation records. The three crops were grown in a dryland corn-millet-triticale rotation from 1998 through 2004 at Akron, CO under no-till management. Dry matter production was linearly correlated with water use for all three crops, with regression slopes ranging from 24.2 (corn) to 33.0 kg ha-1 mm-1 (millet). Water use efficiency varied widely from year to year (0 to 32.2 kg ha-1 mm-1) for the three crops, as influenced by growing season precipitation. Averaged over all years of the study, water use efficiency was not different among the three crops. Millet and triticale produced similar amounts of dry matter for a given water use, while corn produced less dry matter. Precipitation use efficiency for the millet-triticale-corn forage rotation was 8.7 kg ha-1 mm-1, suggesting this as an efficient forage rotation for the region.