By Donella Meadows
–August 4, 1988–
Organic farmers have long believed that soils managed without chemical fertilizers produce steadier yields, year in, year out, than soils farmed conventionally. In a season when the weather happens to be perfect for chemicals, organic yields might be a little lower. But they should be higher in times of drought.
This year is the perfect time to check out that belief.
Dick Thompson raises grain, soybeans, hogs, and cattle near Boone, Iowa. He hasn’t used fertilizer or pesticide on his 300 acres in 21 years. Like any good Iowa farmer, he would never predict corn yields in early August. But when asked how his crops are doing, he has plenty to say.
“We got three inches of rain on the 16th of July that saved our necks. For us it came before the corn tassled. Some of our neighbors planted earlier; the rain came too late for them. We plant corn late, because it takes longer to get all that manure on the fields.”
Organic farmers are somewhat shielded from weather vagaries because, as Dick says, “we don’t have all our eggs in one basket.” His neighbors plant only corn and soybeans, but Dick rotates several crops to maintain soil nutrients and control insects. He may suffer a partial wipeout, but rarely a total one. Dick had a great oat crop this year — 142 bushels per acre. He had two good cuttings of hay, and his pastures are OK. His animals will be well fed.
But the corn that followed hay in Dick’s rotation got less water because the hay took it all up. The corn planted after soybeans in the rotation, though, is ten feet tall and looking good.
“We usually do all right in droughts. I think it’s because of infiltration. Once this spring we had .8 inches of rain in 15 minutes. My neighbor’s fields were ponding and running all over. The water just soaked into ours.”
Dick’s theory about infiltration makes good sense. The secret weapon of organic farmers is that mysterious, rich, black stuff called humus. Nature makes humus out of cornstalks, manure, and other organic matter plowed back into the fields. Humus absorbs and holds water like a sponge. It decomposes slowly, releasing nutrients at just about the rate plants need to take them up. Organic farmers take care to build up soil humus. Farmers who get their nutrients out of a bag tend to let humus run down.
Rhonda Janke at the Rodale Research Farm in eastern Pennsylvania has been watching the effects of the drought on comparison plots farmed both organically and convention-ally. This year there were 6 dry weeks from the 1st of June to the 17th of July. Rhonda says the organic corn was at least 6 inches taller than the conventional, though it was the same variety and planted a week later.
She also attributes the difference to infiltration. Once she timed the absorption of a 4-inch rain; it took 49 minutes to sink into the conventional plots, 11 minutes in the organic plots. She has found that organic corn has more roots, which go down deeper. They have to travel further to get the less-concentrated nitrogen in organic soil — and so they tap deeper levels of water in a drought.
Again, however, organic farming isn’t pure magic. Some rotations failed spectacularly this year. To control weeds the Rodale farm plants soybeans directly into young barley. After the barley is harvested, the beans come up before a weed can squeeze in. This year, though, the barley took all the moisture out of the soil and the beans died.
In Nebraska, where rainfall is marginal even in a normal year, things are especially tough. Warren Sahs, Superintendent of the University of Nebraska’s Research and Development Center in Mead says, “we’ll be lucky if we get half a crop.” He keeps an eye on the organic farmers in his region, though, and he says they’re faring better than most. Del Ackerlund’s 700 acres, organic for 20 years, missed some of the few scattered rains that have come through, but his corn and soybeans look fine, Warren tells me. “The difference between organic and conventional really shows up in years like this, especially in corn.”
At his experiment station Warren Sahs has run a comparison of organic and chemical farming now in its 13th year. His data show clearly that organic plots yield more reliably than conventional ones. Even in good years the organic plots outyield continuous corn grown with fertilizer, insecticide, and herbicide. In the dry year of ’83 organic yields were double conventional; in the drier year of ’84 they were triple. In ’85 with good rain the conventional yield was 103 bushels per acre; the organic yield was 117.
Organic farmers still get ridiculed by folks who haven’t paid attention to actual results out in the field. Organic farming isn’t a panacea. Like all farming it has its problems and risks. But after this year of drought, maybe it will finally be taken seriously as a sound, environmentally benign, and above all reliable way way of raising food for the world.
Copyright Sustainability Institute 1988