April 29, 2021
When considering what is required to grow a quality crop, the first and maybe most important step is emergence and establishment of a plant stand after planting. Many factors can aid or cripple how the plants emerge from the soil. These can include weather, planting equipment, tillage practices, and seed quality. The one factor that influences virtually everything to do with crop emergence is the soil type and condition. Variability of soils in a field can vary greatly and can impact soil temperature, soil moisture, and soil condition.
Soil Temperature – Corn and soybean both need certain soil temperatures in order to start the germination process. The general rule of thumb is that it is best to plant when soil temperatures are at or above 50° F. Soil temperature can be influenced by soil texture as well. Course textured soils tend to warm up quickly but can cool off quickly. Heavier soils with a higher percentage of clay or organic matter tend to warm up slower but can hold the temperature longer under cooler situations. No matter what the soil texture is, crop residue and soil moisture can also influence the soil temperature (Figure 1).
Soil Moisture – In order for a seed to germinate it needs moisture in the soil for the process to take place. A course soil texture allows for rapid movement of water through the soil profile. As temperatures warm up, the amount of water in the profile can disappear and quickly reduce germination. It is very important in course soils that planters are set correctly and good seed to soil contact occurs. Finer soil types with higher clay content tend to be wetter in the spring and can cause issues due to too much water. Too much water can cause the seed to rot instead of germinating. It can also make closing the seed slot difficult; therefore, planters might need adjusting or modifications to aid in closing the seed slot to help ensure good seed to soil content
Soil Conditions – Soil conditions can vary by soil types and can affect the seeds ability to germinate and emerge from the soil. Fine textured soils are heavily affected by the amount of moisture in the soil. Wet soils at planting can lead to uneven planting surfaces due to clods from tillage, inability to create good seed to soil contact, and crusting after planting. Crusting can be a serious issue in the spring when planting occurs in wet, silt and clay type soils. After planting, the soil can crust as wind and warm temperatures dry out the soil. This results in a seedling being unable to emerge through the crusted surface layer (Figure 2).
Figure 1. Residue can cause soils to remain cooler and wetter in the spring at planting time and can be a hinderance to emergence.
Figure 2. Soybean emerging through crusted surface.
Soil texture has a direct correlation to crop emergence. To help achieve maximum emergence, it is critical that we pay close attention to the soil conditions at planting. This means that we might have to determine when we can plant or shouldn’t plant, and make sure that our planters are set up correctly. Paying close attention to the detail can be the difference between a perfect plant stand and a bad plant stand.