The Drought Myth

Tonight I read the two-page article by William Albrecht titled “The Drought Myth – An absence of water is not the problem” available through the Acres USA website. The “drought myth” he’s talking about is this crazy idea we’ve gotten in our heads that droughts cause crop disasters. We think that droughts cause crop disasters because it seems like every time we have a drought, lo and behold, we have crop disasters.

But, as a wacky professor I had in college once emphatically pointed out (thanks, Dr. Goff) – correlation does not equal causation. In other words, just because one thing always happens after the other doesn’t mean that one directly caused the other. Sometimes, there’s a step in the middle–let’s call it the X-factor. It may very well be that the lack of water is affecting the X-factor that is, in turn, affecting crop performance. If we can fiddle with the X-factor, we can conceivably stop a crop disaster from ensuing. Albrecht argues that there are not one, but two X-factors at work here: soil fertility and plant protein content.

The first clue is this: During the drought of 1954, when my parents were learning to walk and talk and drive their parents crazy, corn plants in Missouri had their lower leaves yellowing. This is worth noting because typically, when plants are short on water, it’s their top, growing leaves that wilt. The older, lower leaves only suffer when there’s a nutrient deficiency. So there’s a big drought, and the plants are acting like they’ve got enough water but not enough nutrients. Why?

Albrecht says the drought causes the upper parts of the soil to dry out, so the plants’ roots grow deeper in search of water. But by the time they find it, they’ve reached deeper levels of the soil where there isn’t much fertility, and that’s where they run into trouble. They’re hungry, not thirsty. Poor things. Just imagine there being a shortage of water in your city or town–you take a very long walk to the nearest river, drink yourself silly, and look around–where’s the McDonald’s? If there’s no food waiting for you at the river, you won’t be in a very good shape at all. You did all that work and now you’re starving.

So what’s the solution? Build McDonald’s stores next to the river. In farmer terms, build soil fertility so that it reaches far down into the soil. Do this during the good years so that when a drought comes along, it doesn’t kick your ass.

But this advice seems to conflict with the second clue: When the researchers in Missouri compared three fields with varying degrees of fertilization, they found that the most fertile soils had the most damaged plants. So you’re thinking soil fertility is a good thing and then Albrecht throws this wrench in the mix–fertilize your soils and your plants will still suffer.

Apparently, the damage you see on the plants in fertilized soils looks an awful lot like the damage you see in plants that are nitrogen deficient. So there’s something very bad going on in the parts of the plant where nitrogen plays a crucial role. How come?

What Albrecht thinks is while plants in fertile soils are growing vigorously, they’re throwing lots of nitrogen-based proteins and enzymes around, both of which are not happy at high temperatures. And guess what drought brings? High temperatures. Those proteins and enzymes cook in the sun, leaving the plant with dead tissue. Not good.

So soil fertility looks like a double edged sword. You give ’em food, so they grow, only to have their growth stunted by the heat. BUT, it does seem like the benefits of soil fertility outweigh the costs. Regardless of the heat damage, corn plants in fertilized soils were far more productive than those in unfertilized soil. In the Missouri plots, the unfertilized field produced 18 bushels per acre and the plants spent 14 inches of water. In the fertilized field, the production was a whopping 79 bushels per acre, having spent only 2 additional inches of water. Plus, it’s not that the fertilized field was given more water or retained more water–it’s that the plants in the fertilized soil absorbed more available water. The whole high-temperature-damaging-proteins-and-enzymes thing is unfortunate, but there ain’t much we can do about that, is there? Fiddle with your soil fertility and the next drought won’t be such a disaster.

This applies to all you farmers out there, not just crop farmers. Albrecht left the article off with a handful of data about how rabbits fared during the same drought: Those that were fed green grass from a plot that was fertilized by manure (their own manure, if you must know) didn’t die from the heat. The other ones, which were fed timothy hay grown in various fields that were fertilized or treated with trace elements–well, those didn’t do so well. But when those remaining survivors had milk powder added to their diets, they all of a sudden stopped dying. In a similar study, rabbits that had timothy hay in their diet replaced by red clover hay also stopped dropping dead. What do red clover, milk powder, and grass from a field fertilized by manure have in common? Albrecht didn’t say, but my bet’s on nitrogen. And how exactly does nitrogen in the diet affect rabbit survival in the heat? I’ll have to dig up that info from another source.

But here’s the point: Droughts do not cause crop disasters (or livestock disasters, for that matter)–poor soil fertility does. You just don’t realize it until your soils are put to the test by the drought. Myth…BUSTED.

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