Planting Time For Early‐Season Pearl Millet and Grain Sorghum in Nebraska

Pearl millet [Pennisetum glaucum (L.) R. Br.] is a potential crop for the Great Plains, but there are few studies on production practices. The research objective was to determine the optimal planting time for pearl millet in Nebraska relative to sorghum [Sorghum bicolor (L.) Moench]. This would optimize pearl millet yields, thus increasing the prospect for pearl millet as a crop. Studies were conducted on Sharpsburg silty clay loam (fine, smectitic, mesic, Typic Argiudoll) and Ortello sandy loam (coarse‐loamy, mixed, mesic, Udic Haplustoll) soils between 1995 and 2001. Optimal planting times were determined by relating yields with calendar date, cumulative air heat units, cumulative soil heat units, and soil temperatures. Relative yields related to air or soil heat units were effective in determining the optimal planting time. Optimum pearl millet planting times were 399 air heat units or 410 soil heat units after 1 April for the Sharpsburg soil and 406 soil heat units for the Ortello soil. The optimal sorghum planting time was 308 air heat units or 307 soil heat units after 1 April for the Sharpsburg soil and 402 air heat units after 1 April for the Ortello soil. Both crops had large planting time windows, allowing flexibility in planting time. Sorghum outyielded pearl millet for May and early‐to mid‐June planting times by 0.57 to 2.32 Mg ha−1 while pearl millet had higher yields by 0.95 to 1.20 Mg ha−1 for late June and July planting times. Sorghum produced greater yields than pearl millet for most planting times while pearl millet produced greater yields than sorghum for very late planting times.