When it comes to farming in Illinois we usually don’t think about it being dry in the spring. It is usually the opposite: too wet to get in the field and concerns about creating compaction, sidewall compaction in the furrow or crusting. But at times the soil can get too dry in the spring; either from lack of rain or from tillage and windy conditions. Or it rains hard, dries quickly and bakes the surface, leaving a crust that a soybean seedling can’t break through.
Planting soybeans when it is too dry creates a risk of incomplete germination. Soybeans absorb about 50% of their seed weight in water before the germination process can begin. As a result, planting into soil with inadequate moisture may result in failed germination and reduced or delayed emergence, which affects final stands.
If you find yourself planting into drier soil—go deeper. For decades the recommended planting depth was 1 to 1 ½ inches. But recent research conducted by Jim Specht, retired University of Nebraska scientist, showed that today’s soybean planting depth can be pushed to 1.75 to 2.00 inches without much concern. Add in better seedling vigor ratings, seed treatments and better equipment planters, and the risk of planting deeper is minimal.
So if you find the soil dry at the top and the soil is in good condition drop your planting depth to 2 inches. Planting deeper than 2 inches creates a risk that the seedling will not have enough energy available to emerge, especially if the surface crusts.
When thinking about increasing the depth consider the vitality and vigor of the genetics you purchased, soil texture and surface residue. Light soils and no-till soils are much less likely to crust. Row planters with row cleaners are better designed to place seed deeper in the soil while leaving the soil in better condition than a drill.
Soybean germination is fickle and more unreliable than corn. But then soybean seeding rates are typically five times greater than corn and this usually compensates for failed emergence. But in some years, dry conditions or crusting will persist in parts of the field that lead to uneven emergence and gaps in stands. Before rushing out to replace, evaluate the cause of uneven emergence, its uniformity and stand density before considering replanting.
Agronomist Dr. Daniel Davidson posts blogs on agronomy-related topics. Feel free to contact him at firstname.lastname@example.org.