“Soil, Nitrate, Cropping Systems” and You

Lydia Marcus-Staff Writer

As residents of Iowa, we have an interest in local agricultural practices, whether we realize it or not. In particular, the fertilizer applied on surrounding fields impacts the quality of the water we drink. Nitrate that crops do not consume may be washed out of the field and into local bodies of water, including the shallow wells that supply much of Sioux Center’s water.

The current cropping system used across most of Iowa and the Midwest—corn and soybeans are continuously rotated—requires much nitrogen fertilizer, meaning that large quantities of nitrogen are lost to the environment each year. This has consequences for water quality and ecosystem health.

Dordt College professor of environmental studies, Rob De Haan, professor emeritus of agriculture, Ron Vos and local farmer Matt Schuiteman recently published an article called “Soil Nitrate, Cropping Systems, and Economics” in the agriculture journal PLOS ONE. The article presents the findings of their five-year study of five different crop rotations and the impact each has on the amount of nitrate found in the soil afterward. In addition, the research took the economic viability of each system into account. It found that a cropping system that planted oats, alfalfa and corn successively performed the best in terms of profitability and the amount of residual nitrate in the soil.

But adopting a new cropping system requires commitment on the farmer’s behalf.

“There are many reasons that could discourage a farmer from adopting new cropping systems. The most obvious reason is money,” said junior agriculture major and Ag Club treasurer Victoria Cast. Different crop rotations often require different planting, maintenance and harvesting techniques, so switching cropping systems may require a farmer to buy new equipment.

“Another reason related to money is the markets. Farmers want to grow the crops that sell well,” said Cast. “Many times, that means interrupting the crop rotation.”

Interrupting a crop rotation means planting crops in a different order than originally planned. For example, if the farmer had planned to plant corn one year and soybeans the next, but the market price of soybeans is quite low, the farmer may choose to plant corn two years in a row.

“In my opinion, it is not the consumer’s job to encourage the farmers to adopt different cropping systems,” said Cast.

“There are so many misguided and misunderstood topics between consumers and producers that the encouragement needs to come from the university and research communities. Farmers are proud people and do not like when people who do not understand their business tell them what to do.”

However, there are ways in which consumers can indirectly promote the improvement of agriculture practices. For example, consumers can vote for public servants, city council members, state representatives or even national officials who support agriculture practices that improve water quality.

“An increase in consumer demand for products such as perennial grains will also help,” De Haan said. “Planting more perennial grains will improve water quality. We can pull perennials into the system by spending dollars on them.”

Consumers can also choose to eat less meat. Much of the corn and soybeans grown on commercial farms are used to feed livestock that are eventually butchered. Consuming less meat means the demand for livestock feed decreases, putting less pressure on farmers to grow these crops.

Cast also believes that consumers could encourage farmers by “asking questions and showing interest in what is happening on the farm level.”

De Haan concurs.

“Individually thanking farmers for doing a good job caring for the soil and water quality can have a lot of impact,” he said. “Commercial farmers don’t get thanked all that often, and they do an important job.”

One response to ““Soil, Nitrate, Cropping Systems” and You

  1. Minor nuance: “much” might be too strong of a word to describe the quantity of Sioux Center water supplied by shallow wells. Sioux Center is also supplied by an array of deep wells, which is why the water there is so hard. Tge city balances it’s supply between deep and shallow wells to provide a balance between the amount of nitrates and hardness in city water. You could find the actual ratio with a quick call to the local drinking water plant.


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