Directly behind the combine collecting this year’s soybean crop on this farm located about an hour east of Des Moines is a seeder sowing fall rye as a cover crop.
The rye won’t be harvested. It will be sprayed out in the spring as the fields are prepared for next year’s corn crop. Its value is preventing soil erosion and increasing soil fertility.
Wassenaar, 67, said he only began planting cover crops about three seasons ago, but he’s already seeing a difference.
“I am definitely seeing a reduction in the erosion and we think we’re seeing an improvement in yields,” Wassenaar said.
The rye not only anchors the soil, the roots pull up nutrients that are then gradually released back into the soil as the crop residue breaks down. “The plants look healthier — it’s just a better growing environment for the plant,” said Wassenaar, who also practises zero tillage.
Ahead of regulations
That he is noticing a benefit on his farm is a bonus, because the real push behind the strategy is an effort by Iowa corn farmers to get ahead of the regulatory curve when it comes to reducing nutrients flowing into the so-called “Dead Zone” in the Gulf of Mexico.
Planting cover crops is seen as one management practice that can help keep the soil and nutrients on the land where they do good instead of harm.
“One of the reasons that we’re doing this is we have the challenges with the hypoxia (lack of oxygen) in the Gulf of Mexico which they are blaming on fertilizer run-off in states like Iowa,” said Roger Zylstra, a local farmer and director for the Iowa Corn Growers Association.
“So Iowa has started what is actually a voluntary program — we are dedicated to finding watersheds where we can go in and get as many practices as we can in place to show that we can make a difference.
“We are trying to head off the fact that EPA might come in and say, ‘This is the way you are going to farm now,’” Zylstra said.
Late last year, the Iowa state government formalized voluntary efforts such as Wassenaar’s into a state-wide nutrient reduction strategy that identifies critical watersheds and promotes a series of best management practices to reduce nutrient loss.
The state’s strategy grew out of a Hypoxia Action Plan the federal government released in 2008, which called on 12 states along the Mississippi River to cut nutrient loads to the Gulf.
The provincial Agriculture Department worked with Iowa State University over two years to develop the strategy, which is based on using scientific assessments to identify and model the effectiveness of specific practices to reduce nitrogen and phosphorus run-off.
Zylstra said it’s important to find local solutions to the larger problem and avoid one-size-fits-all approaches. “Because we know what works in this area may not work 100 miles north of here,” he said.
In addition to cover crops, producers are working more with nitrification inhibitors that could be used for fall and spring nitrogen applications, he said. Filter strips, terraces and grass waterways are also being explored.
“It’s just the simple fact of finding the appropriate practices to put on the fields to be the most efficient in production and yet retain the nutrients in place,” Zylstra said.