A Few Comments on Corn and Soybean Planting

Richard Taylor, Extension Agronomist; rtaylor@udel.edu

At least here in northern Delaware, soil temperatures, as well as air temperature, remain low enough to slow corn emergence. One thing you can do to help improve emergence and speed up emergence is to carefully monitor seeding depth. Where possible try to plant corn between 1 and 1.5 inches deep to help improve the chances that the soil temperature will be above the minimum 50° F. needed for corn to germinate. If planted deeper than this when temperatures are marginal for germination, chances are emergence will occur over a fairly long period of time resulting in as much as a 2 leaf difference in the stage of growth of corn by side-dress time. A two or more leaf difference in growth stage is enough to change the younger corn plant from a yield contributor to a yield competitor, essentially making the younger corn plant the equivalent of a weed in the corn field. If planted shallower than 1 inch, the corn crown will not develop at the proper depth making it susceptible to early season environmental stresses.

Another valuable tool in helping warm the soil, especially in no-till and reduced tillage fields, is the use of row cleaners or row sweeps that will clear trash off the soil surface overtop the seed row. This will allow the sun’s rays to warm the soil quickly and for the soil to dry faster, also allowing it to warm quicker. Rapid, even germination is essential for maximum yield potential.

Where you are tilling soil before planting either corn or soybeans, avoid tillage operations in the very wet areas of the field or in those fields that tend to stay wet longer in the growing season. Plant your better, well-drained fields first since these have a higher yield potential and can return higher profits to you. The ideal planting dates for maximum corn yields is between April 20 and around May 10. Your better, higher yielding fields are best planted during this time frame to improve overall farm yield averages.

For soybeans, early season planting can be a successful way to both spread out the planting season and spread out harvest season. In studies done a number of years ago we showed that group IV and V beans do best if planted the earliest, followed by group III beans that produce the best yields when planted by May 15. In any case, soil temperatures in many areas are still cold enough to warrant the use of a fungicide on the soybean seed to improve emergence. In our studies, we found that the fungicide seed treatments really helped with germination and final stand counts when planting in April. Usually by early May, soil temperatures have warmed enough to not require the seed treatment.

Another caution on both a full-season and double-crop soybean crop is to make sure the soil test potassium (K) levels are in the medium or optimum range. Although potash prices are still quite high, adequate soil test K levels are essential to maintain the soybean crops ability to tolerate stress during the growing season. If you didn’t apply K to your wheat or barley crop last year and your soil test K levels are on the low side, consider adding enough K to support the soybean crop. A 40 bu/acre soybean crop removes about 90 to 100 lbs of potash (K2O) per acre while an 80 bu/acre wheat crop will have removed about 100 to 120 lbs of potash per acre.

Tags: , ,

Comments are closed.