Even with an everyman’s body of 5’7”, 194 pounds, Lorenzo Pietro Berra (1925-2015) was one of America’s greatest athletes and was a cog on ten world championship teams with the New York Yankees. He was also one of our more courageous citizens, volunteering for the D-Day invasion as an 18-year old and later earning the Purple Heart during the invasion of southern France. Yogi was born in St. Louis to Italian immigrants and did not speak English until he was 10 years old. Perhaps this is why his “Yogi-isms” are at once dyslexic and absurd but also colorfully descriptive (the title of this essay is one).
A strange feeling of “déjà vu all over again” came over me as I glanced at a recently-released scientific journal article about two weeks ago. The title of this article was “Nitrate Loss in Subsurface Drainage from a Corn-Soybean Rotation as Affected by Nitrogen Rate and Nitrapyrin,” published May 3, 2019 in a reputable journal. (Nitrapyrin is a fertilizer additive that slows the conversion of ammonia to nitrate in a fertilized field by killing the bacteria that facilitate the process.) The article’s authors are people whose work I have admired and cited many times, but I’ll just be honest, this latest paper did not present much new information. Here are some of their other titles:
- Nitrate Losses through Subsurface Tile Drainage in Conservation Reserve Program, Alfalfa, and Row Crop Systems (1997)
- Nitrate Nitrogen in Surface Waters as Influenced by Climatic Conditions and Agricultural Practices (2001)
- Nitrate Losses to Surface Waters Through Subsurface Tile Drainage (2001)
- Corn Production on a Subsurface-Drained Mollisol as Affected by Time of Nitrogen Application and Nitrapyrin (2003)
- Nitrate Losses in Subsurface Drainage from a Corn-Soybean Rotation as Affected Time of Nitrogen Application and Use of Nitrapyrin (2003)
- Corn Production on a Subsurface-Drained Mollisol as Affected by Fall versus Spring Application of Nitrogen and Nitrapyrin (2005)
- Nitrate losses in Subsurface Drainage from a Corn-Soybean Rotation as Affected by Fall and Spring Application of Nitrogen and Nitrapyrin (2005)
- Nitrogen Applicaton Timing, Forms, and Additives (2008)
- Nitrate Losses to Surface Water Through Subsurface Tile Drainage (2008)
Now, I wish to say a few things before proceeding further. Firstly, my intention here is not to impugn the character of these researchers, and you should know my scientific reputation will never approach theirs. Secondly, although we are cautioned against self-plagiarism, we all (including myself) borrow from our own work and tend to advance incrementally. This provides continuity between proposals, journal articles and graduate students. Rare indeed is the paper that doesn’t include some form of “further research is needed” in the conclusion. It would probably be better if we said what Yogi said: “It ain’t over ‘til it’s over.” Or at least until we say it’s over, unfortunate as the case may be.
As would be expected, there are common themes in the above listed papers that are present in the 2019 paper. Here are three:
- Nitrate concentration and load in tile drainage water increased as N (application) rate increased.
- Nitrate concentration and loads in tile drainage can be tempered by applying the recommended rate of fertilizer N.
- Nitrapyrin did not reduce nitrate in drainage water or improve corn yield.
Now I’m guessing that if you’re reading this, you probably already knew #1 and #2 above. There still is some uncertainty surrounding #3, but there is very little evidence this fertilizer additive has improved water quality even though it has been around since the 1970s. But public dollars still support its use, so go figure. Call me crazy if you must, but I just don’t see a fertilizer additive solving a continental scale problem caused by major alterations of hydrology and an important biogeochemical cycle. Be forewarned, if you quote me on this, I will be forced to respond with a Yogi-ism (“I didn’t really say everything I said.”)
Maybe unfairly, I would like to contrast the research surrounding nitrogen pollution (of which I am a part) with the human genome project. It took scientists 13 years to completely map our DNA. After this was finished, researchers and physicians went about developing gene therapy and molecular medicine, designing drugs, and curing diseases. They didn’t go back and remap the human genome for the fun of it. After forty or fifty years, we’re still publishing papers (using public funds, in some cases) that aim to pinpoint the best amount of nitrogen to put on a corn field. Why? Well, I think the answer can only be that the practitioners and the body politic have failed to embrace the science around N rates, and since the laws of nature haven’t changed all that much since the 1970s, we’re left saying the same thing over and over. I guess all you can do is “Take it with a grin of salt.”
Before I finish here I want to show you a little data. I looked at the past 20 years’ (1999-2018) of statewide data for three things: amount of nitrogen harvested in the grain (Grain N), amount of nitrogen leaving the state in its streams (Stream N) and the amount of stream water leaving the state (Q). The graph below shows how much each has increased since 1999. Harvested Grain N has increased 29%; stream N, 73%; and water, 83%.
As far as the increased Discharge (Q) linking to Stream N, there are those that want to look at that graph and say that Stream N is a weather-driven phenomenon. Nitrate (N) is a water soluble pollutant and it stands to reason that more water means more movement of soluble contaminants from the land to the stream network. This is what we call the “transport limited” portion of contaminant hydrology. What this data shows, however, is that the precipitation we get is encountering a practically inexhaustible (at least from weather) supply of nitrogen on the landscape. It’s inexhaustible because we saturate the landscape with this nutrient to maximize Grain N. This is the other side of the contaminant hydrology coin: supply limitation.
With much more N leaving in both the streams and the grain, it begs the question, where is all the N coming from? One possibility is from soil stocks that have been built up over the years, but I tend to doubt that. I’m more open to the possibility that farmers are using larger amounts of commercial fertilizer, but I have not seen any data that shows this is increasing. I am most curious about the increased number of hogs contributing to these data.
In 2002, Iowa had 14 million hogs. Now we have 23 million. And since a hog’s lifespan is ~6 months, this means we have roughly 18 million more hogs per year reaching maturity. A feeder pig excretes about 27 grams of nitrogen per day; thus the hog population increase results in an extra 189 million pounds of N milling around the Iowa landscape. Interestingly, the 73% increase in Stream N since 1999 amounts to 339 million pounds, in the ballpark (get it?) of the extra 189 million generated by the larger hog population. I think the time has come to look at hog populations as the driver of increased Iowa stream nitrate over the past 20 years. As Yogi advised, “When you come to a fork in the road, take it.” So I’m going to do that.
Thanks for reading, and please remember, “Half the lies they tell about me aren’t true.”
Image credit for featured photo:
By Unknown – Baseball Digest, front cover, September 1956 issue. , Public Domain, https://commons.wikimedia.org/w/index.php?curid=15346062