by Gentry Sorenson, Field Agronomist • Many refer to replant insurance coverage dates when considering early planting of corn and soybeans. The earliest replant insurance coverage for corn is April 10th and the earliest replant insurance coverage for soybean in the northern part of Iowa is April 15th. Crops that are planted before those dates are not eligible for replanting payments. Before considering planting corn and soybeans this year it is more important to consider field conditions.
A couple of questions should be considered before planting.
• Is the soil in the field fit for planting?
• Is the soil dry as to avoid sidewall compaction and gauge wheel compaction?
Evaluation of those questions will help in understanding if soil conditions are fit for planting.
Additionally, soil temperatures should be above 50 degrees Fahrenheit and rising for corn and soybean planting. Soil temperatures above 50 degrees Fahrenheit is required for germination of seed. Soil temperatures can be accessed online from the previous day through the Iowa Mesonet or they can be taken in your own field to understand current soil temperatures. Assessing long-term forecasts or 10-day forecasts will also aid in understanding if warming of soil will continue or if a cooling trend may happen in the future. Factoring in those weather impacts can be important as drastic soil temperature changes can affect stand establishment. With prolonged soil temperatures below 50 degrees Fahrenheit, seedlings are at more risk for seedling diseases.
When selecting an early planted field, many target sandier soils first. Soils that are sandier often are planted earlier in the spring due to their ability to dry faster. A watchout is that sandier soils can be influenced by temperature changes on cool nights exposing the seed to soil temperature fluctuations.
After emergence air temperature should be monitored for corn and soybeans if wide temperature variations occur. Temperatures of 28 degrees Fahrenheit or lower can be lethal to above ground tissue when exposed for one to two hours. When the air temperature reaches between 32 degrees and 50 degrees Fahrenheit, the overall vigor of the plant can be influenced by temperature. For help in understanding average spring freeze dates for your county, a tool is available at https://mrcc.purdue.edu/freeze/freezedatetool. Other options on this tool include first fall freeze date and growing season trend maps.
When plants have emerged, scout your field, and evaluate plant population differences from early planted crops to later planted crops. Take some time to evaluate weed pressure and take notes on field conditions to aid decision making in the future.