Submitted to: ASA-CSSA-SSSA Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: May 3, 2004
Publication Date: October 5, 2004
Citation: Baumhardt, R.L., Howell, T.A., Tolk, J.A. 2004. Contrasting effects of seeding practices and irrigation on simulated grain sorghum yield [abstract]. Agronomy Abstracts, ASA-CSSA-SSSA Annual Meeting, Seattle, Washington. 2004 CDROM. Technical Abstract: Growing season weather variability of the southern High Plains complicates management of dryland and irrigated grain sorghum [Sorghum bicolor (L.) Moench]. To minimize this variability, we used long-term (1958-1999) weather records with the SORKAM crop growth model to simulate sorghum yields for various planting and irrigation practices on a Pullman soil (fine, mixed, superactive, thermic Torrertic Paleustoll). Planting date (15 May, 5 June, 25 June), population (3, 6, 12 and 16 plants m-2), row spacing (0.38 and 0.76 m), and cultivar maturity (early, medium, late) effects on sorghum yield were compared for dryland and irrigated (2.5 and 5.0 mm d-1) conditions. Under known experimental conditions, mean SORKAM yields were 4% more than measured. Based on 40 years, simulated sorghum yield increased with narrow rows. Late planted sorghum often failed to mature compared with the usual 5 June planting; however, a relationship among irrigation, planting date, and cultivar maturity emerged. Early maturing cultivars yielded more than medium and late cultivars under dryland or deficit (2.5 mm d-1) irrigation. The fully irrigated late-maturing cultivar planted 15 May yielded more than other planting date and cultivar combinations. With declining irrigation, sorghum yield can be optimized by shifting from early planted late maturing cultivars to early maturing cultivars planted 5 June.