Myth Buster Box
An Ongoing Series on Ag Myths & Ways of Deflating Them
➔ Myth: Nitrogen Fertilizer & High Yields are Inextricably Linked ➔ Fact:
When German chemating fertility. That’s not surprising, given How Much is Enough? ists Fritz Haber and how historically purchased fertilizer has In recent years, due to more accurate soil Carl Bosch develbeen relatively affordable, as well as easy tests, advances in precision application techoped a way to manufacture nitrogen fertilto obtain and apply. nology, and general awareness of the economic izer in the early part of the 20th century, they One clue to Pioneer’s surprising results and ecological costs of applying too much truly revolutionized the way agriculture is may have emerged from a set of four Unifertilizer, land grant universities have reduced undertaken on the planet. Nitrogen makes versity of Illinois studies showing that, on their recommendations for how much nitrogen the biological world go ‘round. Just about average, 67% of nitrogen-based fertility corn farmers need to apply. However, take a every ecosystem in the world — from corn gets is sourced naturally from soil, not look at any extension service bulletin on corn pristine wilderness to a Midwestern cornfertilizer. This has major economic impliproduction, and it’s clear the same narrative field — has its productivity limited by the cations: one of the reasons an increasing rules: more nitrogen fertilizer equals higher amount of nitrogen available to it. There’s number of “conventional” crop farmers have yields, and thus higher profits. always been plenty of nitrogen present in been showing up at soil health workshops However, a recent field trial by, of all placthe atmosphere, but it needs to be converted put on by LSP and other groups is that they es, the seed giant Dupont Pioneer, is throwing to ammonia before it is accessible to plants. are looking to cut their reliance on nitrogen a wrench into that equation. A 17-year study In fact, for most of the world’s history, fertilizer, which, because it is derived from experimented with varying how much nitrogen only lightning or specialized bacteria had fossil fuels, has experienced sharp price was applied to corn. The rates ranged from the the ability to convert atmospheric nitrogen spikes in recent years. full land grant university recommendation to into biologically usable forms. Animals can As the “Soil Health” section on pages zero. Both continuous corn and corn rotated also produce ammonia by eating plants and 16-26 of this Land Stewardship Letter with soybeans (soybeans in the rotation can excreting manure. shows, the farmers who belong to LSP’s add nitrogen to the soil naturally) were tested. The Haber-Bosch process changed all Soil Builders’ Network have been utilizing that: for the first time, humans had cover cropping, rotational grazAfter the tenth year, rotated corn that received no the ability to bypass natural sources ing, no-till, diverse rotations, nitrogen fertilizer had virtually no difference in yield and cutting-edge composting of nitrogen-based fertility and crank it out on a massive, industrial scale. methods to build soil’s innate when compared to its fully fertilized counterpart. Humans have taken over a once ability to create its own fertility. natural cycle, and as a result there is They are also utilizing biologroughly double the rate of nitrogen ically-based soil tests that go Not surprisingly, corn yields on the zero input into the terrestrial nitrogen cycle. A beyond conventional nitrogen-phosphorousnitrogen plots took a major hit the first several huge chunk of that increased input is the potassium (NPK) monitoring to determine years. Even when rotated with soybeans, not result of crop farming’s reliance on nitrogen exactly what life is present in their fields applying nitrogen to corn caused yields to fertilizer. Corn, in particular, is a nitrogen and what role it can play in growing healthy, plummet by 40%. However, in a turn of events hungry plant. High corn yields are so closely productive plants. that surprised Pioneer agronomists, after the tied to the amount of nitrogen available that In other words, we may have taken over tenth year of the study rotated corn that refarmers are often tempted to over apply the nitrogen cycle, but that doesn’t mean we ceived no nitrogen fertilizer had virtually no fertilizer as insurance. This is a problem: can’t give back some control. difference in yield when compared to its fully annual crops take up only about half of the fertilized counterpart. nitrogen applied to a field, according to Pioneer is quick to not draw too many conMore Information studies done in agricultural regions around clusions from this study, and it admits that this • “How Much Nitrogen Fertilizer Does the world. As we report on pages 22-26 of is a non-replicated trial. However, in a written Corn Need?” Aaron Smith, University of this Land Stewardship Letter, lost nitrogen update on the study, company researchers took California-Davis, https://bit.ly/47gqFyG makes its way through the soil profile and great pains to make it clear it was carefully • “How much nitrogen does corn get into our water, where it becomes a pollutant done. “This outcome is unusual and the reason from fertilizer? Less than farmers think,” in the form of nitrate. for it is unknown,” they reported, adding that, University of Illinois, phys.org/news/2023That’s one reason why, in April 2023, “Further investigation is warranted. This study 05-nitrogen-corn-fertilizer-farmers.html the Land Stewardship Project joined 10 remains ongoing.” other groups in filing a petition calling Let’s be clear: studies like this do not Myth Buster Series on the Environmental Protection Agency discount the idea that plants need nitrogen to Tired of accepting “conventional to use its emergency authority under thrive. But they help highlight the fact that wisdom” as gospel? Check out LSP’s the Safe Drinking Water Act to address rotating crops provides huge benefits and Myth Buster series on a variety of topics at nitrate pollution in the karst region of sometimes we don’t give soil and natural landstewardshipproject.org/myth-busters. southeastern Minnesota (see page 25). processes in general enough credit for gener-
The Land Stewardship Letter
No. 2, 2023
5
