Big Ag fans, pseudo clean-water groups mislead with ‘organic nitrogen’

Tile drainage increases the rate of nutrient runoff. Tile water should sit in a wetland before flowing into the waterways.

In my last article, I wrote about the high nitrate content in tributaries of the Raccoon River. A critic implied that this is a naturally occurring phenomenon because Iowa’s soil has more than 10,000 pounds of “organic nitrogen” per acre.

This is a common statement given by the supporters of Big Ag, members of pseudo clean-water groups and politicians who don’t want to admit that Iowa has a water pollution problem. But this statement is basically correct: this natural occurring “organic nitrogen” is what makes Iowa’s soil so productive. However, a scientific explanation is needed.

In my article I was discussing the nitrate problem. The element nitrogen is a gas in its natural state and comprises about 80 percent of the air. There is a lot of nitrogen gas dissolved between the particles of soil. The person referred to “organic nitrogen” — this is nitrogen that is combined with other elements and making the proteins in leaves, roots and animal material.

This 10,000 pounds of organic nitrogen and gaseous nitrogen is not absorbed by corn plants. If it were, farmers would not have to add more nitrogen fertilizer to their fields every year. Also, the “organic nitrogen” is not a major cause of water pollution. Historical data shows that nitrate pollution in Iowa’s waterways was not a problem until after the 1950s.

Mike Delaney led members of the Raccoon River Watershed Association in reviewing the procedure for testing water.

The other members of the Raccoon River Watershed Association and I were testing for nitrates, which has a chemical formula of NO3 with a negative charge. This is the compound of nitrogen that causes blue baby syndrome in infants and has been linked to some cancers in adult humans.

According to federal law, the nitrate level in drinking water must be at 10 milligrams per liter (mgm/L) or lower in order for drinking water to be safe. If this level is not met, the public must be informed about the problem. Several Iowa cities have issued such warning in the past few years and had to use bottled water for drinking.

The “organic nitrogen” in the soil must be changed into a useable form that can be taken in by corn. This is done by bacteria in the soil. On average, this amounts to about 90 pounds of useable nitrate per year being formed by bacterial action in the soil.

This is not enough nitrate to yield a good corn crop. A 200 bushel per acre corn crop requires about 160 pounds of nitrate per acre. Therefore, more fertilizer must be added to the soil. The amount of fertilizer needed and used per acre will vary with the soil type and the farmer’s discretion.

How much ammonia fertilizer will stay in the soil?

The most common fertilizer used is liquid ammonia. It is in those white-colored round tanks that roll across Iowa fields in early spring. The ammonia is also turned into nitrate by bacterial action. Sadly, however, not all of the nitrate stays in the soil, and it is not all absorbed quickly by the growing corn plants.

The farmer hopes that when fertilizer is in the soil and the corn is planted, the spring rains will come to allow the corn to grow. But the rains wash away the fertilizer. This happens because water has a positive charge and nitrate has a negative charge. The two compounds are attracted to each other, and together they run down the hills.

Tile drainage increases the rate of nutrient runoff. The tile water should sit in a wetland before flowing into the waterways.

The water often flows into field tiles and is quickly flushed into Iowa’s creeks and rivers, which carry particles of soil and nitrates. The amount of runoff is determined by many factors, but conservation practices can reduce nutrient loss as well as soil erosion.

Not all conservation practices fit all farming operations. However, all farmers can maintain grass waterways and buffer strips along streams, use “no till” practices and some of the many other management tools that reduce nutrient runoff as listed in the Iowa Nutrient Reduction Strategy program.

Corn is often planted to the river’s edge. A buffer strip is needed.

Another critic of my last article said I should not “point fingers” of blame, but we “should all work together.” The “working together” approach has not worked for 20 years or more. Environmental groups’ pleas for clean water fell on deaf ears. Lawsuits were the only thing that got the public’s and legislators’ attention.

The lawsuit pursued by the Des Moines Water Works against three northwest Iowa counties gave the water pollution problem needed attention. The voluntary Iowa Nutrient Reduction Strategy also came about because of a lawsuit.

The Nutrient Reduction Strategy says that 80 percent or more of the nutrient runoff that pollutes Iowa’s water is from farm field runoff. The strategy gives many suggestions for conservation practices, both in the field and at the edge of the field, that can reduce the problem. More of these conservation practices need to be implemented on farms in order to reduce water pollution and to reach the goal of reducing nutrient runoff by 45 percent.

The Iowa Legislature needs to address our state’s water pollution problem in a determined manner. The Republican Party seems to ignore the issue, and some state legislators deny that there is a pollution problem. Regulations need to be enacted, as they have in Minnesota and Ohio, and more money needs to be budgeted for soil and water conservation practices to help achieve the goal.

The nitrate reading in the North Raccoon River on June 7, 2017, at Jefferson, Iowa, was 14.2 mgm/L and at Van Meter, Iowa, it was 13.8 mgm/L. This data is from the USGS Water Resources website.

Mike Delaney tests for water clarity


  1. This is the article that should have been written in place of Mr. Harden’s previous article. It’s a much more detailed look at the issue, and that is greatly appreciated. This article shows that there is an understanding of some of the initiatives started by farmers geared towards conservation, and more certainly needs to be done as the author correctly stated. Mr. Vincent, an area farmer, has done so by installing a saturated buffer earlier this year. With that said, the current agricultural economic climate discourages diverting money towards conservation as profitability for the farmer is unlikely this year, and there is no help coming from the legislator because there’s no money there either. Perhaps there’s some help that can come from the private sector.


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