At the end of April, we had a big precipitation event. Many of us saw 2.5” to 3” of rain/snow fall in the course of a couple of days. What we didn’t see was flooding or even creeks that were running anywhere near capacity. And as I looked around, I didn’t see ditches running out of fields, or new erosion. As it so happened, we had a rain event that we were able to hold in our soil, even though we had some decent rains in places throughout the month. And that got me thinking about the lessons that we need to take from this and apply to how we irrigate and manage water this season.
So often for us, our rains come with such force that we are unable to capture all of the moisture into our soil profile. That is why we seldom see the sum of our moisture probe raise an amount that is equal to the rain gauge. But it is also why we manage a profile of moisture that looks at more than the top foot. We want to have room to hold onto precipitation, without runoff.
Therein lies the lesson to be learned from these April showers. AquaSystems probes are a hugely important step in managing not just our irrigations, but our field health. Probes are the reason that we wait to begin irrigation. We want to maintain room for moisture, yes, but we also want to protect ourselves from saturated soils and erosion. We also learned a couple of weeks ago from Mike about the delicate nature of keeping Potassium available. I don’t know how many of you caught it, be he made a statement about Potassium release being tied to soil moisture and soil temperature. While we can’t really control temperature, we can control how we irrigate to do the best we can to maintain a soil that is somewhere between 10% and 35% depleted.
But the other side of these lessons is a bit more obscure. I have talked about soil texture and how it relates to irrigation, but this was another good reminder that we cannot overlook irrigation rate and speed in the process. For those of you that have hills, we have soils that can hold four to six inches of available water in our 3-foot profile but can only absorb water at a rate of 0.20”-0.40” per hour. Running a pivot over it applying 1” of water leads to runoff. I have seen it happen far too many times. But what if we used pivot controls and a VRI prescription to address this issue? What if instead of applying 1” of water, we applied 0.35”, the pivot auto reversed, applying 0.35” on its way back, and then reversed again, applying 0.30” on its way to the rest of the field. We applied the same water amount but spread it out to get it to infiltrate. It added a bit of time to our circle, but if it added yield, does 1 hour more per revolution matter?
Mother Nature always shows us the right way to do things if we pay attention. Matching application rate to infiltration rate will improve yield, improve soil health, and reduce erosion. It’s not even necessarily an expensive concept to incorporate. Sure, we can build a VRI prescription around Soil Texture and Water Holding Capacity, but other factors can be just as important. As we talk about improving how and what we measure in your fields for AquaSystems, remember that the factors we are putting in play are all things we already are aware of in our fields. It’s just a matter of whether or not we are paying attention.