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Nutrient Study Targets Increased Yields While Reducing Inputs

posted on May 17, 2013

In the next three decades, the world population is expected to grow by 30 percent from 7 to 9 billion people.  The challenge of feeding a burgeoning population on the same or – potentially -- a fewer number of acres will be one of the greatest challenges faced by farmers in the future.  

The spirit of solidarity in facing a global challenge only goes so far when your closest competitor may also be your neighbor. But one agricultural group -- whose goal is increasing profitability -- is combining the efforts of several hundred farmers to find the balance between cash and chemicals. Paul Yeager reports.


In the last 80 years there has been a 6 fold increase in U.S. corn yields.  The gains are attributed primarily, to better hybrids and the advent of chemical fertilizers.     Weather, however remains the key ingredient in agriculture’s recipe for success and in 2012 drought had a decidedly negative impact in the Corn Belt.  USDA estimates a lack of precipitation caused last year’s corn harvest to be nearly 20 percent less than the 2011 average of 147.2 bushels per acre. 

With corn at $6.00, even a two bushel per acre difference on a 300 acre farm can lead to a profit or loss of $3,600. While farmers can’t control the weather, new technologies, like precision farming, are enabling growers to maximize yields and minimize costs through the strict management of inputs.  

Tracy Blackmer, Iowa Soybean Association Director of Research: “If we just assume we know what were doing in a field we can go out and very accurately apply the wrong amount of anything anywhere.  If we didn’t know any better.”

Tracy Blakmer is the Director of Research for the Iowa Soybean Association or ISA.  Because the ISA’s members raise soybeans and corn in rotation, the association funds over 30 research projects on both crops.  Its goal is to find ways of increasing yields and production efficiency, while protecting the environment. 

Tracy Blackmer, Iowa Soybean Association Director of Research:  “I don’t know a farmer that wants to buy nitrogen they’re going to loose or don’t need.  But there’s also a lot more restrictions coming down to restrict how much you can apply. So the more we can collect more and more data that will also have the impact of improving management but also perhaps influencing future policy and regulation on fertilizers.  It would really help everybody.  It would help the environment, the government in spending and efficiency and it would help the grower.”            

Thanks to yield monitors and GPS tracking, farmers can tell exactly what part of a field is producing well and where there is room for improvement.  But those tools alone can’t determine if more nitrogen is needed, where less nitrogen is needed, or if nitrogen is even a factor.    

Ken Lund, Polk City, Iowa:  “It’s more of trying to put the dollar of fertilizer in the right place in the field and do a better job.  I don’t want to put more than what I need to grow on that crop.  But I don’t want to have a shortfall either.”

To find out how he might realize increased yields while reducing input costs, Ken Lund, who farms 2,800 acres in central Iowa, enrolled both a corn and soybean field in the ISA’s Nutrient Management Benchmarking Survey in 2011.  More than 400 farmers enrolled over 900 fields to have their soil and crops analyzed for essential nutrients and a number of micronutrients.  Because the data was shared by farmers across the state, growers could learn not only what was right or wrong in their fields but also in their neighbors.    

Tracy Blackmer, Iowa Soybean Association Director of Research:  “Growers aren’t necessarily known for being neighborly and their biggest competitor is within 50 miles.  This is a project that’s going the opposite way.  This is where growers are working together.  They’re collecting that data, they’re all benefiting from it, they’re increasing profitability on it and I believe that’s one of the competitive edge right now for US Ag.”

The first step in the Nutrient Management Benchmarking Survey involved Digital Aerial Imagery, or DAI.  Aerial photographs were taken of land enrolled in the survey to identify one “Non-stress and one “Target-stress” area in each field.  Growers took soil samples and tissue samples from crops in each area so nutrient levels could be analyzed and compared.   

Ken Lund, Polk City:  “This field has been continuous corn now for six years now and I’m interested in seeing what’s going on a little more and it’s patterned tiled.  I has tile every forty feet in it.  I’m concerned what that’s doing to my nutrients.  The soybean field was just more of a representative field of what I’ve got, a more normal field, just more representative of all of mine.”

The study allowed farmers to select the fields they wanted enrolled in the program.  It also offered growers latitude in selecting problem areas under the assumption that nobody knows a tract of land as well as the person who farms it.

Ken Lund, Polk City, Iowa:  “When I went and took the samples in the leaf tissues, I did not go to a spot in the field that was real sandy where I would have those kind of issues.  I tried to stay in a representative part of the field where the nutrients are going to make a difference.” 

As part of the program, growers met with other farmers in their area to compare notes allowing participants to not only gain knowledge about their own farming practices, but to also gain insight as to what was or wasn’t working for other farmers in the region.    

Since the study was statewide it established a benchmark that will lead to a better understanding of how weather and soil types affect the uptake of macro and micro nutrients.  And there was the added benefit that it got growers out in the field, taking tissue and soil samples, an important step towards better nutrient management.   

Tracy Blackmer, Iowa Soybean Association Director of Research:  “If every grower did just one trial in Iowa that would be over 4,000 to pick from.  Most growers agree they can find at least one thing they can do better.  But they’re doing what they’re doing because they think it’s the right or they wouldn’t be doing it.  How do you find that one thing better?  So, as were getting down to the point of trying to fine tune within a few bushels for each management practice, we’re finding out that a lot of things we thought twenty years ago, aren’t necessarily true today, with better information.” 

Tags: aerial photography GPS Iowa Soybean Association nitrogen Nutrient Management Benchmarking Survey Nutrients Phosphorus Pottasium Precision Agriculture soil testing Sulfer tissue testing


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