Correct Planting Depth is Key for Starting Corn Off Correctly
Corn planting depth affects many aspects in the developing plants life and therefore is an important factor in reaching top end yield potential. At Jacobsen Seed, we advocate a planter setting of 2.5”, ensuring the seed is placed between 2.0” and 3.0” as seed size and bumps can cause some variability within the seed trench. At this depth factors such as seed to soil contact, moisture and temperature stabilization, and nodal root development are optimized. The yield results on the left are from the 2017 Jacobsen Seed Showcase Plot in Ulmer, Iowa. The dramatically lower yield of that shallow planted corn was expected early as emergence was behind almost 30% due to poor seed to soil contact and low yield was sealed during the dry spell in June and July as the underdeveloped root structure struggled. For a planter setting that requires no additional cost and just a few minutes of time, 50+ bushels of profit were gained in this test. Be sure to check your depth often and every time a new field is started. This is especially important if directly following a tillage pass as the soil may be ‘fluffed’ and will settle causing your seed to be planted too shallow.
Planting corn at the correct planter setting of 2.5” helps to maximize the following factors
Soil Moisture and Temperature – The top 1.5” to 2.0” of soil is a zone of high variability. This zone is the first to dry out after moisture events and because corn needs at least 30% of its weight in water to begin germination that can be an issue. This drying also means that there is much more air present. Seeds planted too shallow are vulnerable to the temperature swings we often see in the spring and could possibly not give the growing point enough of a blanket to protect it from a late spring frost.
Emergence – Even emergence should always be an important goal. Seeds that struggle to germinate due to temperature and moisture issues are often behind their peers. Plants that are as little as 2-5 days behind their neighbors show reduced yield in many studies.
Nodal Root Development – Nodal Roots are the primary root system for the corn plant throughout its life but are the second set of roots to develop. Plants planted at 1.5” or shallower struggle with correct placement and formation of these essential structures. When the plant is too shallow the roots are often trying to develop in a zone of too little moisture and too much air, leading them to callous off and stop growing. This can cause root lodging or stunted corn plants.