The drought monitor report as of Tuesday, May 24 indicated a further expansion of worsening drought conditions. However, the rains from Tuesday through Thursday over much of the state, especially the eastern two-thirds should reflect greatly improved conditions in our area. Reports indicate from two to over six inches depending on location. While this may not eliminate drought conditions, it certainly helps. The six to ten-day outlook (May 31 to June 4) indicates normal temperatures and 33 to 50% chance of above normal precipitation. The eight to 14-day outlook (June 2 to 8) indicates a 33 to 40% chance of below normal temperatures and near normal precipitation. If this holds, it is good news. As we continue the roller coaster we are on regarding precipitation and temperature, we know how it affects us. But what are the effects crops?
• There is a concept regarding plants, in fact for living organisms, termed “cardinal.” This cardinal concept applies to everything from nutrients and plant populations to temperature and precipitation. There are cardinal minimums and maximums for say air and soil temperature or precipitation. These are the high and low extremes beyond which the plant is severely damaged or killed. There is also a cardinal optimum range between these extremes where conditions are ideally suited for plant growth. These cardinal conditions not only vary by species but also by the growth stage the plant is at.
• Most of us understand the effects of dry and/or hot conditions on plants. How important adequate soil moisture is on germination, growth, and seed production. The conditions our area was experiencing, except we yoyoed back and forth between well-above and well-below normal temperatures. Fortunately, the extremely cool conditions were before extremely sensitive crops such as cotton were planted. Cold soil and air conditions will slow corn development as it is heat driven. However, these conditions were beneficial to alfalfa and an already impacted wheat crop. For wheat already struggling from dry conditions, cooler temperatures did help the wheat mature more naturally, but the high temperatures two weeks ago certainly hurt.
Now to the effects of saturated soils on crops.
• First, plant roots need oxygen to continually explore the soil while taking up water and nutrients to transport to the rest of the plant. The results can be stunted plants with reduced yields caused by a lack of oxygen and/or diseases or even plant death. However, these effects depend on several factors.
• First, broadleaves such as soybeans or alfalfa are more susceptible to damage from saturated soils than grasses. Seedlings are more susceptible to damage than more mature plants, however, most corn, sorghum, and even soybean seed is treated with a fungicide that helps with the disease component. A major concern under sustained saturated soils is the loss of nitrogen fertilizer.
• Second, the weather after saturated soils is important. If conditions stay fairly cool and moderated, plants are better able to withstand saturated soils. The length of saturation also matters as does the depth of standing water. The longer the soils are saturated, the worse the damage. Finally, while it may seem backwards, moving water is less damaging than standing water as it helps bring in some oxygen.
Dr. Victor L. Martin is the agriculture instructor/coordinator for Barton Community College. He can be reached at 620-792-9207, ext. 207, or martinv@bartonccc.edu.
