Variability in crops implies lost production. While the very best parts in a paddock may still give less than potential yields, anything less is a sure sign of loss.

LandWISE developed a simple “crop loss calculator” called YieldEst. The purpose of YieldEst is to assess how much crop variability is costing a grower.

We have been watching establishment of the onion and pea crops at the MicroFarm. Both have shown high levels of variability, apparent very early in crop establishment. From there it can only increase.

We have visited a number of other sites this spring, looking in particular at crop establishment and seeking reasons for variations seen.  We have been a little surprised at the level of acceptance among growers; not happy but somewhat resigned.

Where does variability start? What are the most important causes? What can we do about it?

Variability starts at the start; with variations in genetic potential within seeds in a line. It is surprising how little we really know about this. We do know hybrid lines can be more uniform that open pollinated ones, mainly because they have a narrower genetic spread. But gene differences are hugely complex too. One gene can express differently depending on environmental factors. For example, we don’t know much about the effect that growing conditions of the mother plant may have on the seed we sow.

We have an idea about soil conditions for best establishment, although we wonder if we don’t over-cultivate to get a satisfactory seedbed. We hope we don’t have carry-over herbicides or weeds so growers have started using precision ag section control to get the right dose in the right place. We try not to plant if soil is too wet or too dry. Sometimes it is both in the same paddock.

We do know more about plant density and plant spacing. We know crops have a target population for best returns, and that many are sensitive to variable spacing between neighbours. Precision ag again  helps with planter controls. But maybe we are trying to plant too fast when under pressure to get seed into the ground. A lot of research has shown planting speed has a direct impact on yield, largely through spacing uniformity effects.

We know that planting equipment set up and operation has a big effect. Check planting rate is as intended. Get seed to even depth into moisture, cover it properly. Ensure every seed gets sufficient nutrients, but don’t put fertiliser too close.

There is some evidence that weather conditions straight after planting can have a big effect on emergence and establishment. Heavy rain caps weak soils, and if that dries we suffer.

If plants do emerge, they have to survive strong winds, hail, frost, birds and slugs.  And our herbicides.

And that is just getting to establishment. There is still most of the crop life to go, but it seems a fail to thrive infant never does as well as a bonny one.