What is maize good for?

Two pieces of work on maize I recently came across are unconnected as to aim and place, but nevertheless make for an interesting combined story. One asks how far maize yield can actually be pushed by the environment; the other, how far we should define its success by yield anyway.

The first study is a systematic analysis of more than 14,000 yield observations across sub-Saharan Africa. It finds that maize generally produces more grain than pearl millet, even in relatively dry environments. That complicates the familiar story that the traditional, hardy millet simply “beats” the relative newcomer, more pernickety maize in marginal conditions. And you know how much we love complicating a conventional story here.

But, heaping complication upon complication, there is a catch: maize’s performance is much less consistent. Its high yields are associated in part with hybrids and the input packages that accompany them, whereas pearl millet produces yields that are lower, sure, but also more stable. And grain weight leaves quite a lot out anyway: millet brings higher levels of iron, zinc and protein. The authors therefore argue that comparing cereal crops by yield alone can obscure their actual advantage to farmers, under their own conditions. That’s been a recurrent theme with us here, actually, come to think of it.

The Philippine experience described in the second study makes a similar point from the farmer’s side of the equation. In Laguna, farmers evaluating maize varieties did not rank them simply by how many tonnes they produced. They cared about taste, culinary uses, familiarity, nutritional value, market prospects and climate resilience as well as yield. The authors recommend involving farmers in local testing and breeding efforts, rather than treating them as merely the final recipients of fancy new varieties.

Put together, the two stories suggest a useful way of thinking about the potential, and the limits, of maize — and indeed any other crop for that matter. Maize is remarkably productive and adaptable, and the evidence does not support writing it off completely in dry conditions. But its apparent superiority depends strongly on what we measure, where we grow it, and what we put into the system.

A tonne of maize produced with expensive hybrid seed and inputs is not necessarily a better outcome than a more modest but more dependable harvest of millet; nor is a variety that comes out on top in a yield trial necessarily the variety a farmer most wants to eat, sell or grow next year.

Maize can do a great deal, but its real potential emerges only when yield is considered alongside stability, inputs, nutrition, markets and, ultimately, what the people growing and consuming it really want.

Sometimes, in some places, even maize can be an opportunity crop. Other times, not so much. And that goes for millet too.