Variability

Variability from Central Valley Ag on Vimeo.

by Mike Zwingman

by Mike Zwingman

As Keith promised you all in his latest installment, I’m here today to nerd out over some possible explanations of the variability you might be seeing in your fields right now.  If you’re seeing patches of soybeans, for example, that look quite more yellow than most others in your field, that’s variability (and hint: it probably is going to take more than just a soil sample to tell you).  Or perhaps you’re seeing patches that seem forever young while the leaves otherwise drop—that’s variability too (and might just be of the sort that can be explained by the data from a sample).

It probably won’t surprise you too much to hear that while variability happens, ideally, it shouldn’t.  Ideally, all our plants should mature at the same rate, just like ideally, all our plants should emerge at the same rate.

Given these two simple facts—that 1) variability in our fields is less than desirable, and 2) variability has different causes—we are best to do some sleuthing for our own good fortunes.  So grab a magnifying glass, gumshoe, and let’s get to it.

But you don’t really need a magnifying glass.  Just go out and take a look-see at your fields.

Variability in our fields comes from differences in the soil, or, more accurately, the differences in how plants experience their own little microenvironment in the soil.  We can generally break down the soil characteristics that can influence variability into three categories: physical properties of the soil, chemical properties of the soil, and biological properties of the soil.  Physical properties include things like soil type, compaction, relative age (as in how weathered it is), erosion, slope, elevation, and etc.  Chemical properties concern the amount of nutrients available in the soil and their various forms.  Biological properties center around how many and what kinds of microbiological populations are present.

Soil that does not boast uniformity within or among these properties can lead to variability among our plants.  How quickly or not a plant matures depends in part on how effectively that plant was able to use its resources and the quality of the soil environment the plant is in greatly influences that effectiveness, or lack thereof.

So back to your sleuthing.  If you’re seeing variability in your fields, there’s something amiss in the soil.  The question is what as there are multiple soil characteristics that might in fact be amiss.

The answer depends on the direction of your problem.  If you’re seeing patches that are more mature than the rest of your fields, that would point to a problem with the physical or biological properties of the soil in which those plants reside.  Plants that mature too quickly are often experiencing stress due to lack of moisture, which might be caused by, among many things, compaction (a physical property), or a lack of organic material (a biological property).  Plants that mature too slowly are also experiencing stress, but in this instance due to a nutrient deficiency (a chemical property), which can cause sugars to essentially get caught in the stem and choke off certain signals for the plant to mature.  (Sometimes you can actually feel the knot of stuck sugars in the stem by rolling it between your fingers.)

Untitled-2Importantly, a soil sample can only shed light on variability caused by the chemical properties of your soil.  If your variability is caused by physical or biological properties, a soil sample will tell you none of it.  Thus the need to investigate the variability you see in your fields in order to get a correct and useful answer.

The future will offer us better ways of managing for variability, like multi-hybrid planters.   For the time being though, we can still manage quite well by letting the investigations we conduct this season guide our management next season.  So like I said, go take a look—even the most obvious spots of variability in your fields hold important answers to maximizing the quality of your harvest in the future.