The drought monitor report as of Tuesday, May 30 indicates exceptional drought in our area continuing with really no change from last week. Overall, in the western half of the state and extreme Southeast Kansas, conditions continuing a bit more.
Remember this is as of this past Tuesday. The six to 10-day outlook (June 6 to 10) indicates a 40 to 50% of leaning below normal for temperature and a 33 to 40% chance of leaning to above normal precipitation. The eight to fourteen-day outlook (June 8 to 14) indicates a continued 40 to 50% chance of below normal temperatures and a 33 to 40% chance of leaning to above normal precipitation.
It is definitely a more favorable forecast for our summer crops. Rainfall patterns appear to be returning to a more “normal” pattern.
While planting of summer crops was off to a slow start, some recent rains and an advancing calendar has seen a flurry of activity planting corn, the start of soybeans and soon grain sorghum. There are a fair number of cornfields in the two to three leaf stage.
Some fields of soybeans are exhibiting true leaves. The oat fields, more than typical for our area, are growing and some are heading out. The oat will contribute valuable hay for the area. If you take a close look at many of the corn fields, you may notice pale green to yellow green plants. Looking as if the plants are suffering from a nutrient deficiency. So, what’s going on?
First, a little background will help. There are seventeen essential nutrients for plants to complete their lifecycle. We won’t list them all here, but the macronutrients by chemical element abbreviation are: C, H, O, N, P, K, Ca, Mg, and S. C, H, and O are supplied by carbon dioxide and water, what the plant needs to make sugar during photosynthesis.
The others are taken up by actively growing roots as they explore the soil. Of these, N, K, and S are readily available in the soil solution and move by mass flow to the roots as water is taken up. P, Ca, and Mg are much less readily available as they diffuse to roots along a concentration gradient. That’s why producers often band phosphorus at planting to have a concentrated zone of P making it easier root uptake.
Diffusion is slower when soils are cooler. All nutrient uptake is and uptake is further slowed by drier soils, especially soils with higher clay content.
So, what does this have to do with yellower corn plants?
After germination and emergence, you may notice growth is typically slow for the first several weeks and then about V6, about twelve inches, plants enter a grand growth phase and growth is rapid. As the plant first emerges it is relying on stored food reserves in the seed to establish itself.
As leaves emerge, the plant starts to obtain energy through photosynthesis. The plant is also devoting much of its energy to establishing a root system to explore the soil for water and nutrients. Especially under conditions like we have had with cooler temperatures and a lack of adequate soil moisture, the process is slower and there is a lag.
Rain and typical temperatures will alleviate the problem shortly and there should be no effect on yield. Producers do a very good job of making sure adequate soil fertility is in place, especially for the macronutrients.
Dr. Victor L. Martin is the agriculture instructor/coordinator for Barton Community College. He can be reached at 620-792-9207, ext. 207, ormartinv@bartonccc.edu.
