Throughout the world, farmers are having to address their environmental impact, particularly in relation to water quality. In this feature I've outlined my take on how the Iowan farming community is working together to curb run-off from agricultural land in the state. Their proposed approaches include use of cover crops, strip tillage and improving soil structure will have resonance with farmers all over the UK.
There is a ‘dead zone’ in the Gulf of Mexico caused by nutrient spikes and sediment run-off from farmland and other industries; Iowa’s farmers are one of the target groups charged with addressing the problem. So why are the farmers having to act?
Figures announced by the National Oceanic and Atmospheric Administration in June 2014 suggested that the oxygen-depleted, or hypoxic, zone of Gulf extends to between 4,633-5,708 square miles, which is equivalent to the state of Connecticut.
Thirty-one states feed water, via the Mississippi River, into the Gulf; all of them have strong agricultural production credentials. Iowa is one of the states galvanising its farming industry to take action to try and reverse the worrying trend.
Dean Lemke, a sixth generation farmer is also involved with the Agribusiness Association of Iowa which provides advice via 1,275 advisors and input supplies to farmers. He puts Iowa’s farming scale into context: “Iowa is a concentrated zone for food production with 36 million acres of farmland and 88,000 farmers. We produce a lot of animal protein and lead the USA in corn, egg and pork production, plus we are the second largest beef rearing state. Iowa produces more grain than Canada and more soya than China, so our state is a hotspot for nutrient run-off into water.”
Mr Lemke added that farmers need to take action, and that advisors will play a key role in changing practices on the ground.
The response from Iowa’s farming sector was to establish the Iowa Agricultural Water Alliance (IAWA) last autumn. IAWA is funded by the Iowa Corn Growers Association, Iowa Soybean Association and Iowa Pork Producers. It as a not-for-profit organisation led by Executive Director, Sean McMahon. Its establishment was prompted by the 2008 Gulf Hypoxia Action Plan. The plan established a goal to reduce total nitrogen (N) and phosphorus (P) levels by at least 45%.
Like the UK’s Voluntary Initiative, IAWA is taking an industry self-help approach via detailed guidance, in the hope that legislation can be avoided.
Commenting on IAWA’s planned approach, Sean McMahon said: “IAWA is a farmer led organisation wholly involved in adopting the Iowa Nutrient Reduction Strategy (INRS) which is targeting nine priority watersheds and wetlands across the state. Our aim is to increase farmer awareness of the INRS and the encourage them to adopt science-based practices proven to have environmental benefits.”
Such practices include anything which reduces N and P field losses into surface water. “The science-identified ‘best practices’ we are recommending were identified by the College of Agriculture and Life Sciences at Iowa State University and the Iowa Department of Agriculture and Land Stewardship partnered to conduct the scientific assessment,” he explained.
The nutrient reduction practices fall in three categories:
- · N and P management - care in nutrient application rate, timing, and method, plus the use of cover crops and reduced tillage;
- · Land use and edge-of-field practices including perennial energy crops, extended rotations, grazed pastures, and land retirement;
- · Edge-of-field practices involving drainage water management, wetlands, bioreactors, buffers, terraces, and sediment control.
“Research shows that using the nitrification inhibitor Nitrapyrin results in a corn yield increase of around 6%, plus a nitrate-N loss decrease when using a with fall [autumn] applied anhydrous ammonia. The only cost associated with this practice is the product.”
When it comes to specifically targeting phosphorus, Mr McMahon says that there are three key management practices that they are recommending: only applying the P required based on soil testing results; planting late summer or early autumn cover crops and adopting reduced tillage.
“These practices leave more crop residue on the soil surface, improve soil structure and reduce erosion and run-off,” he said.
In addition to the N and P focused recommendations, IAWA is also advocating extended rotations by including alfalfa for forage or energy crops, resulting in reduced N and P applications and related losses.
Finally, there are a range of “edge of field practices” that Mr McMahon cited as recommendations:
- · Establishing wetlands greatly reduces nitrate-N entering water courses;
- · Installing Bioreactors – a buried trench filled with a carbon source which is typically woodchips – through which drainage water flows. Microorganisms colonise on the wood chip and break down nitrate to N2 gas;
- · Buffers and saturated buffers – water is distributed to a riparian strip of trees and shrubs which absorb N and P, reducing nitrate losses by between 5-8%.
As an incentive for action, IAWA coordinates match funding for farmers to invest in water quality installations like wetlands and buffers.
“There is a real willingness to act amongst the farmers I’d describe as the early adopters and innovators, but our challenge will be to get all farmers engaged,” Mr Lemke added.
“We also have an important role in communicating about farming with the wider publics in the state; we are a food producing state, but consumers don’t appreciate that there are negatives associated with food production,” he noted.
It is clear that the 45% reduction target for N and P is in firm focus for the state’s governors, municipalities and farmers, but one thing left me worried about how far they can progress, which is that they have no targets and no timescales for meeting their long term goals; without these there is no accountability. So my question for Iowa is how long has the state got before voluntary compliance becomes compulsory legislation? A wrangle that we are dealing with her in the UK too.
About the Gulf of Mexico Dead Zone
About the Gulf of Mexico Dead Zone
The Gulf of Mexico is a large ocean basin in the Atlantic that extends to circa 600,000 square miles. Like the Mediterranean, it is partly landlocked. Thirty-one agriculturally rich states and two Canadian provinces drain into the Mississippi River and its tributaries, which in-turn feed the Gulf of Mexico. The river water carries sediment and nutrient run-off from agricultural land.
Seasonal spikes in nutrients entering the Gulf create oxygen depleted zones, whilst these zones have been known of and measured since 1985, it has roughly doubled in size. This dead zone is the largest in the world.
· Iowa Agricultural Water Alliance: http://www.iowaagwateralliance.com/
· Iowa’s Nutrient Reduction Strategy: http://www.nutrientstrategy.iastate.edu/
· Corn Nitrogen Calculator: http://extension.agron.iastate.edu/soilfertility/nrate.aspxis