Dryland corn (Zea mays L.) production in the northern Great Plains is limited by risk of crop failure due to drought conditions. Altering the row configuration and seeding rate have reduced the risk of yield loss elsewhere, but those areas typically receive greater precipitation than the annual average 300 to 350 mm (11.8 to 13.8 in) of the northern Great Plains. A study in 2007 and 2008 determined the impact of seeding rate and row configuration on dryland corn yield, yield quality and components, and precipitation use efficiency (PUE). Four sites in northeastern Montana were planted to corn (same variety) at four target rates (25,000, 37,500, 50,000 and 62,500 seeds ha?1 [10,000, 15,000, 20,000, and 25,000 seeds ac?1]) in conventional 0.61 m (24 in) spaced rows or in a skip-row configuration, with every third row skipped. Altering the row configuration had no impact on grain yield, harvest index, or grain PUE, but biomass yield and PUE were 12% and 15% greater for the skip-row configuration, compared to conventionally spaced corn. Interactions between row configuration and seeding rate were not significant (p < 0.05). Compared to row configuration, seeding rate had a greater impact on yield and showed an inverse and linear relationship, where biomass, grain yield, harvest index, and PUE for grain and biomass were 19%, 229%, 200%, 222%, and 22% greater for the lowest seeding rate, when compared to the highest. Overall results suggest that for areas with low rainfall, skip-row spacing provides a modest increase in biomass yield and that adjusting seeding rates to 27,000 seeds ha?1 (10,900 seeds ac?1) or lower will likely increase dryland corn biomass and especially grain yield, though caution is warranted in extending broadly the results of this limited dataset considering the variable nature of rainfall in semiarid environments.
