UW Field Day Tour Focuses on Greenhouse Gases and Crop Management

Tour examines viability of greenhouse gas reductions in Wisconsin agriculture.

MADISON, Wis. – The University of Wisconsin-Extension and UW-Madison invite farmers, agronomists, crop consultants, agri-business, governmental agencies, as well as the general public, to attend a special session on greenhouse gases and crop management at the Agronomy/Soils Field Day at 8 a.m. Aug. 27 at the Arlington Agricultural Research Station on Highway 51 about 5 miles south of Arlington. The field day includes greenhouse gas tours at 8:30 a.m. and 10:30 a.m. where you can see first hand how greenhouse gases are collected across different Wisconsin cropping systems, hear about recent research discoveries and learn about the applications of this research.

Agriculture contributes almost 10% of the greenhouse gas emissions in the US, with nitrous oxide and methane being the primary greenhouse gases from agriculture. Agricultural soil management contributes 75% of the nitrous oxide emissions in the US and 34% of the methane emissions in the US come from livestock and manure. Thus, the emphasis in agricultural research has been to identify management practices that can reduce nitrous oxide and methane losses. Reduction in greenhouse gas emissions are often considered an indicator of sustainability.

Several agriculture-led efforts are underway to reduce these emissions. For example, the Innovation Center for U.S. Dairy signed a memorandum of understanding with the U.S. Department of Agriculture (USDA) Secretary Tom Vilsack to reduce greenhouse gas emissions from dairy 25% by the year 2020. Additional efforts, such as the 25×25 Coalition, are spearheading efforts to increase renewable energy production in the United States and reduce greenhouse gas emissions.

“Our current research at UW is focused on understanding what the baseline losses are, how much they vary from year to year and how different cropping systems and management practices affect those losses,” said Matt Ruark, a UW-Extension specialist and assistant professor of soil fertility and nutrient management at UW-Madison. “We are also interested in assessing the emissions in relation to the production. Depending on the agricultural system being evaluated, the emissions may be calculated per gallon of milk, per bushel of grain or per energy produced.”

The University of Wisconsin is part of three large efforts in agricultural climate change mitigation and adaption: Sustainablecorn.org, Sustainabledairy.org and the Great Lakes Bioenergy Research Center. Both Sustainablecorn.org and Sustainabledairy.org (website under construction) are multi-disciplinary and multi-state projects funded by the USDA. The Great Lakes Bioenergy Research Center is funded through the U.S. Department of Energy. Sustainabledairy.org is led by the University of Wisconsin and in partnership with the Innovation Center for US Dairy and includes quantification of greenhouse gas emissions to improve models, assessment tools and user tools. These and other tools are currently being beta-tested and may be available and promoted soon for use to quantify effects of management across the supply chain.

“The quality of these tools and our understanding of how agriculture can help mitigate effects of climate change are grounded in the quality of the research conducted at the Arlington Ag Research Station,” Ruark said. “Another important aspect to this research is to assess all the co-benefits or trade-offs that come with a reduction in greenhouse gas emissions. We do not want to sacrifice profitability, water quality or soil quality in the process.”


UW-Extension, which receives the third largest amount of federal grants in the UW System, serves Wisconsin families, businesses and communities statewide through offices in all 72 Wisconsin counties and three tribal nations, continuing education services through all 26 UW System campuses, the statewide broadcasting networks of Wisconsin Public Radio and Wisconsin Public Television, and entrepreneurship and economic development activities by county throughout the state.

Contact: Matt Ruark, mdruark@wisc.edu, 608-263-2889

Michael Fields Cover Crop Field Day (Sept. 3rd, 2014)

UW Soil Science reseCover Crops Field Day Sept 2014arch will be highlighted as part of the Michael Fields Agricultural Institute’s Cover Crop Field Day on Sept. 3rd in East Troy, WI. Graduate Student Megan Chawner will present her research results on the effects of radish as a cover crop on corn yield, nitrogen uptake and nitrogen release, soil compaction, and soil nematode populations.

Full flyer can be seen here: Cover Crops Field Day Sept 2014

Discovery Farms Field Days (8/11 and 8/28)

8112014DryRunFieldDayFlyerTwo field days are being hosted by the UW Discovery Farms program. The first is on August 11, 2014 in New Richmond, WI. Dr. Ruark will be presenting on nitrogen fertilizer efficiency, with a specific emphasis on nitrogen uptake in corn grain and corn silage. Additional presentations include an update on a Discovery Farms watershed project in Dry Run Watershed and residue and cover crop management to reduce runoff. Check out the flyer here. A dinner is included.


The second field day on August 28th is in Westby, WI, where Dr. Ruark will also be presenting on nitrogen use efficiency.

Presentations from Minnesota Cover Crop Symposium available online

Presentations from the Minnesota Cover Crops Symposium, held April 4, 2014 in St. Cloud, MN are available online at http://greenlandsbluewaters.net/resources2/covercrops-symposium.

The symposium covered many cover crop topics including an overview by Rob Myers (USDA-SARE) and presentations from government agencies, seed dealers, agronomists, and farmers, each providing a unique perspective on why and when they would use cover crops and what benefits they are looking for. It also includes my invited presentation on cover crops and nutrient management which includes resent research findings on radish, clover, and rye.

spring barley

Notes from the Nitrogen Summit: The unseen nitrogen

The most common problem for farmers and crop consultants when determining an optimal nitrogen (N) rate for corn is that they never truly know if and by how much they “over” applied their N fertilizer. Under-application of N is readily seen in corn plants through classic N deficiency symptoms of yellowing of the midrib on lower leaves, likely resulting in reduced yields (http://www.agronext.iastate.edu/soilfertility/photos/photossdef.html). There are a few metrics used to determine if N was over-applied, such as the corn stalk nitrate test (https://store.extension.iastate.edu/Product/pm1584-pdf) and end-of-season soil nitrate test. These tests require extensive sampling, only pertain to corn, and the relationship between stalk or soil nitrate values and crop yield are not well documented in Wisconsin. What I suggest here is the use of nitrogen use efficiency (NUE) calculations as simple metrics that can be used to understand how efficient you are (and can be) with N fertilizer.

The partial nutrient balance. One way that farmers and crop consultants can “see” the unused nitrogen is through nitrogen use efficiency calculations. There is no one specific calculation that is the true NUE, but instead the term NUE represents a suite of calculations that each have a specific meaning. The simplest calculation is the partial nutrient balance (PNB), which is the amount of N removed in the grain divided by the N applied (http://go.wisc.edu/1467hc). A PNB of 1 (or slightly less) is considered ideal (i.e. system sustainability). If the value is much less than one, then this indicates there are opportunities for improvement. The PNB is a calculation that can be done by all growers on a field-by-field basis as long as they know their yield and the amount of N applied. Based on average N concentrations from corn samples analyzed at the University of Wisconsin Soil and Plant Analysis Laboratory, 0.70 lb-N is removed with 1 bu of corn grain (at 15.5% moisture). Therefore, multiplying 0.70 by the yield (bu/ac) gives an estimate of the amount of N removed. This calculation can also be used to “see” a simple N budget for the field (N input vs. N output) by subtracting the N removal from the N applied; if it is negative, more N was removed than what was applied. If it is positive, this is the amount of N remaining in the soil system. However, a lot of this N can still be tied up in the crop residue and for many systems there is a limit on how close we can get this value to 1. More accurate PNB values can be determined if the actual N concentration of the grain is known.

The value of the zero-N check strip. To get a sense of how much N is available from the soil, we can use the amount of N taken up by the corn plant (ears, stalks, and leaves – the entire above ground biomass) when no fertilizer is applied. This will involve cutting a whole plant at ground level, drying, and analyzing for total N; this is obviously not a standard sample practice. This value (total N uptake in unfertilized corn) can then be subtracted from the N in the above ground biomass from fertilized corn and then divided by the amount of N applied to give us the apparent crop recovery efficiency (RE). It is called the “apparent” crop recovery efficiency because we aren’t using the N taken up in root biomass and we are making assumptions about the fate of the applied N. In this case a value of 1 would indicate that the increase in N uptake from unfertilized to fertilized was the same as the amount of N applied (this is an unrealistic system). Snyder and Bruulsema (2007) provide some context, stating that values of 0.5 to 0.8 represent corn systems under best management practices. So, the value of the zero-N check strip allows you to know how much of your N was “needed” by the crop. This is in contrast to the partial nutrient balance calculation, which doesn’t indicate anything about crop need of the fertilizer, only the N balance of your soil and cropping system.

Recovery efficiency verifies the need of the fertilizer. Different soils will supply different amounts of N. For example, in an N rate trial conducted in 2011, corn fertilzied with 150 lb/ac of N at the Lancaster Agricultural Experiment Station had a RE of 63% while corn grown at the Arlington Agricultural Experiment Station had a RE of 28%. This indicates that would want to thing about altering our N rates at Arlington because less than 30% of the N that was applied was taken up. At Lancaster, we may not be able to improve much as nearly 70% of the N applied as take up by the plant.

Comparing the RE and the PNB. A stark contrast between these two calculations can be seen with irrigated sweet corn in the central sands in 2011. Yields without N were incredibly low, leading to RE of 88%, while the PNB was only 43% (150 lb/ac of N was used in this example). The 43% PNB is quite low, indicating a lot more N is applied to the system than is removed. However, a large percentage of the N applied ended up being taken up by the crop. Thus, for sweet corn on sandy soil, the PNB alone doesn’t tell the whole story regarding efficiency and fate of the N applied.

Overall, you’ll notice that I’ve used a lot of terms like “estimate” and “apparent” throughout the past few paragraphs. These calculations are not meant to be the last word on how efficient you are with your N fertilizer, but simply provide a tool for farmers and crop consultants to assess the current state of their N management. These measures need to be conducted across many growing seasons to get a range of efficiency values across different rainfall patterns. But, if we can make the “unseen” nitrogen “seen”, this will give both farmers and consultants more confidence with continuing their current N management plan or identify fields on which improvement strategies are warranted.

For more information on nitrogen use efficiency calculations see http://go.wisc.edu/1467hc. For more general information on nitrogen in soil check out Soil and Applied Nitrogen (http://www.soils.wisc.edu/extension/pubs/A2519.pdf).

Agri-View article highlights research on nitrogen use efficiency

A recent article in Agri-View highlights key research findings on nitrogen crediting from cover crops, use of polymer-coated and nitrification inhibitors, and managing nitrogen on tile drained land. Research was presented at the 2013 Soil, Water, and Nutrient Management Meetings and presentations will be made available shortly.

Full article can be found here.

Nitrogen efficiency: Products, cover crops can improve system

Nitrogen efficiency Products, cover crops can improve system
February 19, 2014 8:30 am  •  Jane Fyksen Crops Editor

Efficient use of nitrogen in corn production makes sense.

That was evident from the big audience UW-Madison soil scientist Matt Ruark had at Corn-Soy Expo in Wisconsin Dells when he addressed the topic, including use of controlled release fertilizers and nitrogen stabilizers and cover crops that supply nitrogen to the next crop.

Noting that nitrogen use efficiency has been on a steady climb upward since the mid-1970s, Ruark still thinks growers should be tracking their nitrogen use efficiency by simply dividing grain produced by nitrogen applied, field-to-field and year-to-year.

The number goes up if yield increases with the same nitrogen rate, yield is maintained with less nitrogen, or best yet, yield goes up with less nitrogen.

Full article can be found here.

Jim Stute wows them at Crop & Pest Management Field Day

Stute 2013

Jim Stute (Department Head & Crop/Soils Educator, Rock County Extension) and Megan Chawner helped out an under-the-weather Matt Ruark at the Diagnostic Training Center’s Crop and Pest Management Field Day. As a team, we gave four hour-long workshop sessions, where we addressed current issues with cover crops and prevented planting and viewed cover crop performance in our demonstration trial. Attendance was about 65 people, which included crop consultants, fertilizer dealers, and government agency employees.

Two handouts were provided: (1) NRCS Technical Note and (2) white paper on evaluating the economic trade-offs between prevent planting payments and harvesting a planned cover crop for forage.

Four big questions asked during this workshop were: 

1) Are there any drawbacks to a rye cover crop in no-till? Preliminary research at the Arlington Agricultural Research Station shows little to no drawback to no-till corn silage yields (data here). However, there is tremendous benefit to soil by having this soil cover after a corn silage harvest. The key to good management in this scenario is to make sure the cover crop is terminated as early as possible to avoid additional competition for nitrogen and water.

2) Will annual ryegrass (aka Italian ryegrass) winterkill in Wisconsin? Annual ryegrass has been known to survive Wisconsin winters and it is important to have a plan for spring termination. Ryegrass has also been known to develop herbicide resistance. However, ryegrass remains a popular cover crop option when flying seed onto standing corn or soybean because of the relatively low seeding rate (22-33 lb/ac of pure live seed) compared to winter rye (60 to 185 lb/ac) or oats (33 to 110 lb/ac).

3) Which legumes are beneficial following winter wheat? Frost seeding red clover (early spring) or berseem/oat mixture post harvest. Crimson clover will also work post harvest, but berseem has been observed to be more consistent in stand establishment.

4) What are the known benefits of radish? Preliminary data can be found here and current research exists in Rock, Sheboygan, and Washington Counties. Preliminary results indicate that radish will increase nitrate concentrations in early season soil nitrate tests, but not enough data has been collected to quantify a nitrogen credit.

Corn University presented by Wisconsin Corn Growers Association

wcga-corn-university-summer-2013_Page_1Joe Lauer, Carrie Laboski, Francisco Arriaga, and I will be presenting at an Extension event on August 5th. This “Corn University” will cover topics of nitrogen, soil, and agronomic management of modern corn production. I will be presenting on nitrogen management of corn (including controlled-release fertilizers and crop rotations) and cover crop management. Click here for more details.

Indicators of early season performance of ESN® fertilizer

Hancock trials

Nitrogen fertilizer trials at Hancock indicate that ESN® has performed well as of 30 days after emergence (DAE). The main fertilizer treatments will be split into sub-treatments where some plots will receive additional N fertilizer applications (in 30 lb-N/ac intervals) based on rainfall events to assess how well ESN® compares to conventional fertilizer with supplemental N applied. The ESN® was applied 100% at emergence while the ammonium sulfate (AMS) and ammonium nitrate (AN) treatment were split applied (⅓ of N as AMS at emergence, ⅔ of N as AN at tuberization). At 30 DAE, the ESN® had greater average petiole nitrate concentrations across all N rates. 

(see full document here)

Presentations of the 2013 Central Sands Processing Vegetable Meeting

To check out this presentation and other presentations at the 2013 Central Wisconsin Processing Crops Meeting

Take home messaged from nitrogen and snap bean research:

1) Different snap bean varieties respond differently to nitrogen fertilizer applications.

2) Variations in rainfall timing cause huge differences in response to nitrogen

3) There is a huge nitrogen use efficiency decrease when nitrogen is applied in excess of 60 lb/ac, but any slight yield gains achieved with extra nitrogen can be justified from an economic perspective (i.e. the high economic value of the crop far exceeds the cost of additional nitrogen fertilizer)