Seed Germination

The snow is still on the ground but spring is coming. When spring comes, it is important to understand what soil temperatures are doing. Knowing what to look for when you walk into a field is critical to make sure the spraying and seeding operations that need to be done in the spring occur In a timely fashion. When looking at fields, it is important to see what weeds are growing. The first thing that will likely show up in a field is winter annual growth. These weeds got started the fall before and will start to re-grow when the soil shows its first sigh of increased temperature. With the amount of moisture that we had in the fields last fall and the soil temperatures that we saw, it is likely that we will have winter annual weeds in all our fields. If the weeds are thick and start early, they can take a lot of nutrients from the ground and dry the surface of the soil out. These weeds need to be dealt with early. Soil temperatures are variable throughout the day. Taking temperatures in the middle of the day will give higher readings than the average for the soil conditions in a field. Using an average of two temperatures taken at a couple of times during the day will give a better indication of what the soil temperatures are in a field. Also, remember that there is variability in a field that is a result of soil type change and ground cover from straw and chaff. The areas that are covered with straw will warm up slower than the areas that are not covered. The first weeds to grow in the spring are volunteer canola, stinkweeds and shepard’s purse. These weeds indicate that the soil is in that 3 to 5 degree Celsius range. This temperature is enough to get most of the crops that we grow started, all be it at a slow start. Wheat, oats, barley, argentine canola and peas will start to germinate at this temperature range. Corn and beans require a soil temperature of 10 degrees Celsius to germinate so they should be planted later. Temperatures on the edge of the required germination temperatures can cause problems. When temperatures are right on the edge and we have conditions that cause the soil to drop below the minimum required temperature such as freezing nights or snowfall, the germination process stops. If the temperature stays below the critical temperature for an extended period of time, the seed will become susceptible to disease or if it stays cold long enough, the seed will rot in the ground. This is why it is a good idea to have the soil temperature warmer than the required temperature. Knowing the soil temperature is an essential part of a management plan in the spring. Colder soils have a harder time producing a healthy crop. Be aware of the soil temperatures on your farm and you will grow more bushels


By Dave Cubbon, P Ag