Soil Texture and Irrigation

Soil Texture & Irrigation from Central Valley Ag on Vimeo.

by Keith Byerly

by Keith Byerly

Earlier this week, I was filling out a form for an AquaSystems grower for the NRCS and a cost share program he is involved in. I was providing the information for available water and refill points for his field. I put the agronomic knowledge that we had for the field in 4” increments on paper for this grower to turn in. The next day I got a call from the NRCS, they wanted to know how we had arrived at our numbers because they didn’t match the numbers they had. So I gave him a very simple, one-word answer: Science.

I will be the first to admit that when it comes to Soil, there are a lot of things that we don’t understand. Some of which are potassium release, certain aspects of the microbial activity, and so on. But there many things that we do understand, one of those being soil texture. For those of you that follow along with me on a regular basis, we have talked about how EC mapping is the first step in this process. It helps us identify soil variability so that we can identify soil differences in our field. Once we have the soil variability identified, and we decide where we want a probe, we take the next step which is textural analysis. We want to look at that soil and understand the exacts of Sand, Silt, and Clay. Giving us a relatively narrow window to see what our water holding capacity is – and it is much, much more accurate than a soils map.

But then what? I can assure you if that’s all that there is to it, everybody would be pulling a texture analysis and using it in irrigation management. That’s where the next steps come in. Research work that we have been doing involves Core analysis for things like compaction, water infiltration rates, soil texture changes within the core, and much more. These core will help us better understand the soil, and take our management to the next level.

MoistureProb

When I say next level, I’m talking about turning this information into actionable motion. In this case, we are talking about VR Irrigation. Because at the end of the day, irrigation rates aren’t really affected by yield goal or population as much as they are on our soil. It’s all about accurately creating a map that shows our soil texture, and our other factor that affects how fast water goes into the soil, and how deep it goes in when it does infiltrate.

VRI prescriptions can be as simple as a zone map. But my take home is that like so many things in precision ag; more good data leads to more good results. If we can layer our AquaSystems Moisture Probe with the EC Map, and the Elevation, and a textural analysis sample, we can parlay all of that into a VRI equation that is more efficient, more sustainable, and perhaps, most importantly, more profitable in the end. And those are the things I want you to be thinking about when it comes irrigation management this season. Not just the moisture probe, but the complete game and the ultimate results that we are after.