Planting Depth

One inch to 1.5 inches is the ideal planting depth where tillage is used. Where tillage is used, the soil should be free of large clods to insure good seed-soil contact and good seed coverage. Shallow planting (3/4 to 1 inch) in late April promotes more rapid emergence than deeper planting. However, be aware of the increased exposure to herbicides, which may damage young seedlings. In late April, soil temperatures at 1-inch depth are 3 to 8 degrees warmer than at 2-inch depth. After May 15, the air temperatures are higher and the probability of crusting increases. It is a poor practice to plant deeper than 1 to 1.5 inches because a crust may form above the seed and reduce emergence. It takes the combined pressure of many plants to break through the crust. In the process, many of the hypocotyls are broken, and the seedlings do not emerge. When planted at a 1-inch depth, the seed is more likely to be inside the crust layer. As the seed swells in the germination process, the soil crust is broken and a higher percentage of plants emerge. On some crusting silt loam soils, deep planting results in 25 to 50 percent mortality during emergence. Where soil crusting is a problem, no-till planting and crop residue are preferred. Adequate crop residue prevents the formation of soil crust and aids in stand establishment. Three-fourths- to 1-inch seeding depth is ideal for no-till seeding.