Critical Precipitation Period for Dryland Maize Production

Authors: Nielsen, David; Halvorson, Ardell; Vigil, Merle

Submitted to: Field Crops Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/3/2010
Publication Date: 7/6/2010
Citation: Nielsen, D.C., Halvorson, A.D., Vigil, M.F. 2010. Critical Precipitation Period for Dryland Maize Production. Field Crops Research 118:259-263. doi:10.1016/j.fcr.2010.06.004

Interpretive Summary: Dryland corn production in the semi-arid Great Plains ranges widely from year to year because of highly variable rainfall. Corn yields are greatly influenced by the timing of growing season precipitation. This paper reports that the 6-week period from July 16 to August 26 is the period when dryland corn yields are most influenced by precipitation. Two relationships between yield and precipitation during this critical period were found: one for dry years when the sum of available soil water at planting plus May precipitation was less than 250 mm (10 inches) and one for wet years when that quantity was greater than 250 mm. These relationships were used with long-term precipitation records from three central Great Plains locations to determine the probability of achieving a break-even corn yield during wet and dry years. Dryland corn production is risky due to the variable nature of precipitation in July and August.

Technical Abstract: Grain yields for dryland corn (Zea mays L.) production in the semi-arid Great Plains of the United States can be very unpredictable because of the erratic nature of growing season precipitation. Because inputs costs for corn production can be very high, farmers need to have a tool that will help them assess the risk associated with dryland corn production. The objectives of this work were to determine the critical period for precipitation during the corn growing season and to develop a relationship between critical period precipitation and corn yield to use as a tool to quantify expected yield variability associated with dryland corn production in this region. Corn yield data were collected at Akron, CO from two dryland cropping systems experiments (1984-2009) in which corn was grown in a wheat (Triticum aestivum L)-corn-fallow rotation. Yields were correlated with weekly precipitation amounts from planting to harvest in search of the period of time in which yield was most influenced by precipitation. Soil water contents at planting were measured either by gravimetric sampling or by neutron attenuation. Yields were found to be most closely correlated with precipitation occurring during the six-week period between 16 July and 26 August, with the relationship changing with the sum of available soil water at planting and May precipitation. The two linear relationships between precipitation during this critical period and yield were used with long-term precipitation records to determine the probability of obtaining a corn yield of at least 2500 kg ha-1 at three locations across the central Great Plains precipitation gradient. This analysis verifies the common observation in this region that dryland corn production is highly variable and risky.