What a difference a year makes. Last spring we were worried about planting into cold, wet soils. This spring, so far, has been just the opposite as we are looking at abnormally dry condition and record early warm soil conditions. Then this week we are experiencing the cooler temperatures that should have seen in early March. There has been some concern about the alfalfa fields in the area as they had broken dormancy very early this year and what affect the cold temperature might have on these fields. Alfalfa is tolerant of cold temperatures. But we must understand a little bit more about the growth and biology of alfalfa in order to make a management decision. We know that temperatures in the 25-30 degree range will cause some leaf deformation for plants just greening up. If the frost occurs at later stages the leaves will not be affected. Night time temperatures must fall to 24 degrees or lower for four or more hours to freeze top growth. This means that temperatures at or just below freezing (28 to 32 degrees) will not damage the alfalfa. The only way to tell if the alfalfa is damaged is to wait 2 to 4 days and then determine if the leaves are wilted or blackened. Unless this damage is present there is no damage to the plant. In fact, we have had snow fall on the past on growing alfalfa with no significant damage. Damage will occur mostly to the top of the growth since this is the most exposed to the cold temperatures. If damage is severe, and the alfalfa is 14 inches or more in height, a cutting should be taken. Frozen alfalfa will have no toxins in the top growth and will actually be high quality forage if harvested immediately. Regrowth will be slow so be sure that there enough plant nutrients in the form of fertilizer for the ensuing cuttings.
Another question for this year is when to start planting corn. Soil temperatures are high enough (above 50 degrees) to start germination. However, it is probably best to wait a little longer and perhaps start getting seed in the ground around the week of the 16th. Many of the farmers I talk to are waiting a few days as they can get a lot of corn planted once conditions are right. There is a popular misconception that we should be planting deeper because of the dry conditions. The theory here is that we would be putting the seed closer to any possible moisture. However, there is little or no moisture in the subsoil, so the optimum planting depth should remain around 2 inches for corn and around 1 inches for soybeans. Once we start planting deeper, we can put more stress on the corn seedlings to emerge from the soil. If we would have a major rain event, we could see soil crusting that could reduce emergence populations. Also we should keep planting populations the same, around 34,000 to 35,500 seeds per acre. Another thought for this year's planting moisture shortage is to be careful of too many tillage passes across the field. Less tillage means more moisture in the topsoil for good crop emergence. In short, plant corn the same as you have in recent years.