The Staple Triad: Grain, Legume, Oil

Every farming culture that has fed itself without a shop arrived, independently, at the same three crops. A grain for calories, a legume for protein, an oil for fat. Alik Pelman's triad is wheat, fava and olive, all three rainfed, all three grown in his part of the world for thousands of years. He says roughly half of humanity's calories come from this class of crop, and that the three store without refrigeration and take little space. Those are his numbers, from his own account, and they match the historical record on every continent.

The triad is not a menu. It is the answer to three separate nutritional budgets that a plan has to fill at once, and it is the reason the staple block takes most of the ground in lesson 303.

Why three, and not one or two

One crop cannot feed a person. Grain alone gives calories and a protein that is low in lysine. Legume alone gives a better protein but a protein that is low in methionine, and usually not enough calories. Eaten together in the same day, each supplies what the other lacks, and the pair is a complete protein. That is the whole reason rice and beans, or maize and beans, or wheat and fava, recur across the world.

Oil is the third budget. Neither grain nor bean carries much fat, and a body needs fat for density, for warmth and for the fat-soluble vitamins. Oilseed and oil tree crops are the densest food a farm stores, and in Pelman's table a single line, the olive oil, carries about 59 of his 70 grams of daily fat.

Why the staples get the land

The crops that feed you are the crops that take the ground. Pelman has said the land hogs are the seed crops, wheat, rice, corn and the legumes, and not the vegetables. That sounds backwards to anyone who has only gardened, where the vegetable bed is the big effort, but the arithmetic from lesson 302 holds: vegetables are mostly water, a few kilograms per square metre, while the dry staples are the calorie and the protein and they need the broad ground and the rainfed field. On Pelman's farm the staples are about 80 percent of the cultivated area and the garden about 20.

The same triad, different crops

The members change with climate, the shape does not. The Mediterranean answer is wheat, fava and olive. Mesoamerica answered with maize, beans and squash, and oil from sunflower and amaranth. East and Southeast Asia answered with rice, soybean and sesame, and soybean is remarkable because it fixes its own nitrogen and returns protein and oil at once. India runs a whole family of triads, millet with pigeon pea and groundnut in the dry belt, rice with lentil and mustard on the irrigated plain. Dry Africa answered with millet and sorghum, cowpea and bambara groundnut, and oil of groundnut and sesame. The cold north answered with rye or barley, pea or bean, and the oil of rape and flax.

If you live where the Mediterranean crops grow, take Pelman's triad and be done. If you live in a short season or a wet one, choose the members that will ripen on your ground: perhaps oats or rye for the grain, fava or field pea for the cool season legume and common bean for the warm, and hazelnut or sunflower or flax for the oil.

The store is part of the triad

The three store. Pelman says the seed crops keep five years or more, and that fava is notable because you can leave it in the field for a year and come back and it is still there. The grain and the bean, kept dry and cool and clean, keep for a decade. This is the whole reason the triad carries a household through a winter and through a bad year, where a garden of fresh vegetables cannot. A subsistence store is a dry room holding the same three crops the field grew, rotated first in first out, and the goal is to lay by two years of them by about year five.