Submitted to: University of Missouri Agricultural Experiment Station Publication
Publication Type: Abstract Only
Publication Acceptance Date: 7/31/2013
Publication Date: 8/29/2013
Citation: Vories, E.D. 2013. Soybean irrigation management. University of Missouri Agricultural Experiment Station Publication. P. 30.
Technical Abstract: Soybean is an important crop and a major component of the agricultural economy in the Missouri Bootheel and throughout Missouri. USDA’s National Agricultural Statistics Service (NASS) reported that in 2012, 960 thousand acres of soybeans were harvested in Southeast Missouri (Butler, Cape Girardeau, Dunklin, Mississippi, New Madrid, Pemiscot, Scott, and Stoddard counties), while statewide the total was just over 5 million acres. Although the recommended planting windows for most of our commonly grown crops the in Bootheel end relatively early, soybeans have a much wider window. Farmers start planting in April once the threat of frost is past and don’t stop until after all of the wheat has been harvested and the double-crop acres have been planted in late June. Even in later July Southeast Missouri farmers plant soybeans in fields that have recently been precision graded or where an earlier crop was lost due to flooding or some other cause. Irrigation is one reason such late planting is practical. Soils with low available water holding capacities and common short-term droughts have led many producers to switch from rainfed to irrigated production even with a high annual rainfall. Another reason farmers can have such a wide range of soybean planting dates is that they can choose cultivars from a wide range of maturity groups (MG). To better advise farmers on MG selection, a multi-state project “Effect of Planting Date, Latitude, and Environmental Factors on Choice of Maturity Group in Mid-South Soybean Production” was started in 2012. The project is supported by soybean producers through the checkoff program and jointly funded by the United Soybean Board, Mid-South Soybean Board, and participating states’ Qualified State Soybean Boards including the Missouri Soybean Merchandising Council. Nine 2013 locations range from College Station, TX, to Columbia, MO, and Grover Shannon and Earl Vories collaborate on the Portageville location. Each year, four planting dates of a uniform set of 16 commercially available soybean cultivars from four different MGs (MGs 3, 4, 5 & 6) are produced in irrigated plots at each location. Observations from the plots will be supplemented with crop modeling and findings from the multi-state project will help producers select the best cultivar for their specific situation. At the conclusion of the project results will be extended to producers, consultants and agri-businesses via a MSSB/USB publication. They will also be shared with other researchers through presentations at scientific conferences and articles in research journals. Options for the management of irrigation in such a study are limited; however, both planting date and MG impact the water demands of the soybean crop and must be accounted for in scheduling irrigation. When all four MGs were planted early, the later MGs will require much more water to complete the growing season. For the more practical situation where the earlier MG was planted earlier and the later MG was planted later, the water requirements are more similar. Of course weather throughout the growing season will affect the irrigation requirement and many years rainfall will supply most of the demand for the earlier MGs planted early. However, the later planting can allow the producer to finish planting other crops before moving to soybeans. The point is that soybean planting date and MG are additional tools to be considered in the overall farm plan so that not all of the soybean acres need irrigation at the same time the rice crop is receiving the initial flood and other similar kinds of bottlenecks are avoideded.