Have you observed any interesting anomalies with water use and water penetration the last few years?
We have been observing some interesting changes in water movement in soil, on a very widespread scale, with many different soil types, and with different management systems. At this point, we have not been able to determine any commonalities based on the soil profiles.
Water is behaving very differently in soils and plants than it did eight to ten years ago.
A decade ago, if we got one inch of rainfall, crops would have adequate moisture for up to three weeks, depending on soil type, stage of growth, crop, and local climate, of course. In the last few years, particularly the last three, if there is no rainfall for a week, crops begin expressing drought stress symptoms.
While there may be problems with less vigorous root systems in some cases, this does not appear to always be the case.
Soils are drying out extraordinarily rapidly after a rainfall. It is often possible to be in the fields cultivating in about twenty to twenty-five percent of the time window required to properly dry in the past.
An example - This spring, a farmer we work with in Iowa was cultivating a corn field with a belly mounted cultivator when he drove into a saturated spot. The front wheels of the tractor dropped immediately. He backed out, and returned to look at it two days later. In those two days, the soil went from being saturated to hard and dry, the cultivator broke it up into hard chunks. Even five years ago, what happened in two days, would have taken at least eight to ten days of drying weather.
At the same time, crops seem to be absorbing water much less efficiently than they should. Or possibly, water is no longer “quenching the thirst.” More water is required to maintain plant health, growth, and vigor, as much as 20-30 percent more. This seems to be less true of irrigation water atfirst. It seems there may be a downward spiral, which, once it begins, irrigation water becomes much less efficient as well.
At this point, these observations raise more questions than we have answers for. These are important questions though, questions we need to find answers for, or our fresh water demands for food production may increase to even greater levels than they are today.