Submitted to: University of Missouri Agricultural Experiment Station Publication
Publication Type: Abstract only
Publication Acceptance Date: 7/16/2008
Publication Date: 9/2/2008
Citation: Vories, E.D. 2008. Predicting the Suitability of Fields for Rainfed Corn Production. Delta Center 47th Annual Field Day, Portageville, MO., University of Missouri. p. 1. Interpretive Summary:
Technical Abstract: Timely irrigation of corn increases yield and reduces earworm damage and aflatoxin production. However, the costs of fuel, fertilizers, and other crop inputs have increased greatly in recent years and many producers cannot afford the investment required to be able to irrigate all of their fields. With increased demand for corn to meet the need for ethanol fuels more farmers will probably try to produce corn without irrigation. It would be useful to know which fields have the greatest likelihood of profitable rainfed production without having to risk crop failure to find out. As the adoption of precision agriculture methods becomes more widespread, much information is available about the properties of production fields. Sensors can collect site-specific data of spatially variable soil properties, offering more timely results and the higher spatial resolution than methods that involve soil sample collection and laboratory analysis. Researchers are also developing new sensors and refining methods for interpreting the findings from current sensors. Relating those measurements to spatially referenced yield should indicate trends regarding which properties impact yield most under rainfed conditions, and allow the development of indices to apply to other fields without corn yield data. A field study was initiated at the University of Missouri Delta Research Center Marsh Farm in 2007 to investigate the factors impacting corn yield in a rainfed production system. The combination of alluvial and seismic activity over the years has resulted in highly variable soils in the field, like most fields in the region. The county Soil Survey shows areas of Tiptonville silt loam, Dundee sandy loam and silt loam, and Reelfoot loam and sandy loam within the 12-acre field. Initial measurements included spatially referenced soil apparent electrical conductivity (ECa) and elevation. A corn crop was produced without irrigation and harvested with a combine equipped with a calibrated yield monitor. The yield data were "cleaned" to remove erroneous data points. The 2007 growing season was relatively dry, with less than 4 inches of rain recorded during June and July and nearly 2 inches of that recorded on July 1. With the sandy soil texture, significant drought stress was observed. The information from the county soil survey was not sufficient to describe the yield differences observed in the field. Similarly, the range of yield values that could be predicted from only elevation and ECa was not sufficient to adequately describe the observed yields. The study is continuing in 2008 with additional information being collected as time allows. Identifying the fields best suited to rainfed corn production will reduce the risk to farmers, allow more efficient use of energy and fertilizers, and provide additional bio-fuels for everyone.