Editor’s note: This is part three in a series of columns titled “Agriculture and the water puzzle.”
Since this series deals with water, it’s appropriate to briefly discuss this winter’s weather. Soil in the area is wet, quite wet and as this is being written, another winter storm is on the way. Many soils are saturated and there are areas on standing water. What does this mean for wheat in the ground? On the plus side, unless the weather turns off exceptionally hot and dry, there should be adequate moisture for a wheat crop. Are there concerns with standing water and saturated soils? While not ideal, the damage should be minimal if standing water infiltrates into the soil before temperatures warm and wheat resumes growth. There are two problems with standing water. The first is the loss of nitrogen from the soil. The second is a lack of oxygen necessary for root cells to respire and function properly. Cold weather minimizes that need since plants aren’t trying to grow. Time will tell how much damage may have been done. Last week we discussed were the water use comes from – the surface and groundwater we use. Today, were does that water come from?
Groundwater, is the result of the accumulation of water over hundreds and thousands of years in water permeable rock from precipitation. This rate of accumulation is the result how much precipitation falls and the intensity of events. Precipitation must be sufficient to not only infiltrate into the soil but enough to fill all soil pours – to saturate the soil – and allow gravity to push the water downward. Most rainfall events don’t contribute to groundwater. A secondary factor is the ease with which water can move downward. That is a function of the soil type; movement is easier in sandy soils, and the composition of the water bearing rock. There are other factors such as depth to groundwater, evapotranspiration rates, and temperature. The accumulation of groundwater is a slow process. The Ogallala aquifer, a large underground lake in western Kansas and states such as Colorado, Oklahoma, and Texas is critical in supplying water for an area prone to drought and heat. As long as withdrawals from pumping don’t exceed inputs, the aquifer is fine. When more is withdrawn than can be replenished you have a water deficit. It is like a checking account. You can’t take out more than you have and that is the direction the aquifer is heading towards.
Reservoirs are filled by runoff from precipitation flowing into them, typically from creeks and rivers. Rivers receive water from runoff within the state and from states upstream such as Colorado and Nebraska. Their flow is also determined by groundwater. Permanent streams and rivers are groundwater at the surface so as the groundwater declines, so does the flow in the streams.
Next week: where are we at with water in Kansas.
Dr. Victor L. Martin is the agriculture instructor/coordinator for Barton Community College. He can be reached at 620-792-9207, ext. 207.