Skip-row and plant population effects on sorghum grain yield

In environments with limited rainfall, skip-row configuration (planting one or a group of rows alternated with rows not planted) under rainfed conditions may increase yield of grain sorghum [Sorghum bicolor (L.) Moench] due to conservation of soil water between widely-spaced crop rows that is not accessed until late in the growing season. A field study was conducted over 10 siteyears in Nebraska from 2005 through 2007 to evaluate effects of row configuration and plant population on grain yield and yield stability. Three row configurations including all rows planted with a 76-cm row spacing (s0), alternate rows planted (s1), and two rows planted alternated with two rows skipped (s2) were evaluated with two plant populations. At the site with the greatest precipitation of 496 mm skip-row configuration reduced grain yield by 20 to 30% compared with s0. At low precipitation sites of 319 mm with larger soil water deficits, grain yield increased 5 and 123% with s1 and s2 compared to s0. The s0 treatment outperformed skip-row configurations when mean yield was above 4.5 Mg ha^-1. Skip-row configurations also had greater yield stability than conventional planting. Skip-row configuration will be advantageous to a producer if the total in-season available water (initial total profile water + growing season precipitation) is <675 mm.