A little over a decade into on-farm, real-world environmental research through the UW and Extension’s Discovery Farms program, this research program shared some of what it has learned over the last 10 years about environmental impact of farms at its December conference, held in Wisconsin Dells.
While Discovery Farms was started in 2000, program director Dennis Frame had been focused on farming and the environment for the 20 years prior to Discovery Farms’ formation, working with farms in Trempealeau County – an area filled with steeply sloped farm land. Faced with potential intrusive regulation to control runoff on farms, Frame and his colleagues found that most studies that these regulations were based relied on data from small plot trials that weren’t usually applicable on a large scale, or the regulatory levels were based on model estimates. “Model estimates are estimates,” Frame said, and not necessarily what is actually happening in the real world.
Discovery Farms research was started to have a better understanding of the amount of nutrients – nitrogen and phosphorous – leaving farm fields. “I can tell you now, after 10 years (of research), pretty close, when we look at your farming system,” Frame said, the amount of nutrients leaving.
The other charge of Discovery Farms is to identify situations that affect losses and engage producers in finding ways to reduce those losses to an acceptable level. “Going out to a farm and telling a producer ‘I know exactly how to fix that’ is not a great sales technique,” Frame pointed out, noting that approach has been tried unsuccessfully over and over again.
Discovery Farms’ goal is not to eliminate nutrient losses, he pointed out. “We will never eliminate losses (completely)… zero is unattainable.”
Frame said in his 30-year history of working with farmers, he said he has learned that farmers are problem solvers, and if they aren’t already trying to reduce nutrient and sediment losses, it’s because they don’t realize it’s a problem. He said that may be driven by farmers not having confidence in past research models and resulting estimates that didn’t take into account real-world application.
Discovery Farms research farms have included beef, swine, poultry and dairy farms – rotational grazing, organic and confinement dairy operations. They have worked with farms on the east and west sides of Wisconsin, and although there are regions they haven’t worked with yet, Frame said there is significant consistency in the data they have generated from the different areas of the state.
“We have had the real honor in the last 12 years to work with some great people who have been open and honest. They’ve opened up their farms to us because they believe in their farms and they believe in their systems.”
The Discovery Farms research has included surface water monitoring – perennial and intermittent flow, tile line monitoring and intense sampling. Farmers are not engaged in helping with sample or data collection. The research looks at when and why runoff events occur and how they can be reduced.
Amongst all the farms the program has worked with so far, Frame said they have gathered about a 100 years worth of surface water runoff data, about 49 years of tile runoff data and 20 years of in-stream monitoring data.
WHAT’S BEEN LEARNED SO FAR?
One of the key points Discovery Farms has learned so far is identifying key runoff risk factors: Snowmelt, rain on snow or frozen ground and non-frozen soils that are close to saturation. They have also pinpointed the window of high runoff risk for farms to February, March and June, with March the most critical risk period. Out of 12 months, a third of the year’s runoff occurs in March. “This isn’t rocket science… it’s poop.”
Frame noted regulatory discussions on eliminating winter spreading, expressing his concerns about narrowing the spreading window, concentrating it in the second-highest annual risk period, which is May and June. “You’re not eliminating risks (if you don’t have winter spreading), you’re moving it from winter to spring. Would we rather have some nutrients run off in winter or do we want some to run off in the spring? If every dairy in an area spread manure the same two weeks and that was followed by a 2-inch rain, would the result be better or worse?”
Early fall spreading can be advantageous before there is snow cover, he noted. “Manure decisions have a huge impact on nutrient losses, depending how and when you apply it.”
The research showed that when soil approached the saturation point, more runoff occurred. Runoff occurred on soils saturated with 35 percent moisture with as little as a quarter inch of rain. On frozen ground even less rain caused a runoff event. On soils at 25 to 35 percent saturation it took at least 0.75 inches to cause runoff, and on dry soils with less than 25 percent saturation, it took just under an inch of rain to create a runoff event.
Looking at sediment loss, the average soil loss on Discovery Farms with current research is 670 pounds per year – this is loss from the field, not loss to surface water. Phosphorus losses averaged 2 pounds per acre annually. Half of that was particulate or bound to sediment and half was just in the water column (dissolved reactive). Nitrogen averaged 7 pounds lost per acre.
MYTHS BUSTED AT BRAGGER DISCOVERY FARM
The Bragger family farm was the first Discovery Farm. It is located in Trempealeau County with significantly sloped fields. The farm consists of a dairy and poultry operation. Several important things were learned through research there, as well as myths busted:
• Farm setting is a good predictor of runoff rates. False. The farm’s setting is actually a terrible predictor of lost, Frame said.
• High slopes equal high runoff rates. False. The average runoff rate statewide is 8 percent. On this highly sloped farm, the runoff rate is 2.5 percent on ag land and 1.8 percent for woodland and grass.
• Soil test Phosphorus levels greatly affect Phosphorus loss and surface application of manure equal high Phosphorus loss. False. The average Phosphorus level in the Bragger farm’s soil was 57 parts per million (ppm) with a range of 25 to 99 ppm. Average loss of dissolved Phosphorus was about 0.14 pounds per acre. This number was expected to be much higher because of the surface applied manure and high soil test Phosphorus levels. Ninety percent of the Phosphorus losses were during storm events.
In the past it was suggested farmers should incorporate manure to reduce Phosphorus runoff, but Frame questioned whether or not that was a good approach, since incorporation would likely increase sediment losses on that area with its slopes up to 33 percent.
To reduce environmental risk from farms, Discovery Farms looked at nine factors to consider:
• Soil type: Clay soils had the highest runoff and sandy soils only ran off during snowmelt. Farms cannot change their soil type, but they can control timing and amount of tillage. They can also install tile to remove excess water. Discovery Farms saw less sediment in tile with newer systems.
• Crop state of development: It’s a key factor, but it’s uncontrollable.
• Soil quality: Farms can leave residue to build organic matter. They can practice no-till, or vertical tillage may be a consideration. Less soil disturbance and more organic matter can create macropores that allow faster water infiltration in soil.
• Surface roughness and cover: This is created through residue, tillage and manure application.
• Structural practices, such as terraces, contour farming and check dams.
• Storm duration and intensity
• Tile drainage: Data from several of the Discovery Farms sites indicated that surface runoff was driven by tile capacity, so when tiles were full there was surface runoff. In some parts of the state, tiles are picking up groundwater. Improving tile systems can reduce surface runoff.
• Snow cover: Snow depth is a poor predictor of runoff. Spring runoff events are driven by sun intensity and temperature. Early melt periods, when the sun is less intense create less runoff. When there is lots of snow at the end of March/April there is high potential for runoff. Warm, cloudy or foggy weather equals slow melt and less runoff risk. Producers can be provided with runoff risk alerts (high, medium or low), but big runoff events can’t be accurately predicted. Rain on snow might drive runoff (depends on snow depth, temperature and amount of rain). Rain on frozen ground with little snow usually greatly decreases the potential for manure to bond with the soil. Early frozen ground has open macropores that allow some infiltration of manure. In late frozen ground, after rains, the macropores are filled with ice, which blocks any bonding with the soil. All regulations/recommendations for winter manure applications should be based on conditions, not calendar dates.
• Soil moisture: Non-frozen runoff is driven by storm intensity and soil water capacity, which can be evaluated by soil moisture. The risk of runoff is greater when soil moisture is greater than 30 percent. The second highest risk period is May through June. Producers should evaluate soil moisture between 25 and 30 percent and evaluate liquid manure applications, which may influence soil moisture (13,000 gallons equals 1/2 inch of rain). Low soil moisture on clay soils equals cracks and expansion of macropores. Evaluate ground before applying liquid manure on dry soil - it may require pre-tillage with surface applications.
Another risk reduction strategy that Discovery Farms has pinpointed is ways to reduce nutrients leaving the field.
No-till creates an opportunity for decreased runoff and sediment loss, but increased dissolved Phosphorus loss. Eighty-two percent of surface phosphorus loss was in the dissolved form. No-till is part of the solution to reduce those losses, Frame said, but it is not the only solution.
Tile drainage systems are another factor for reducing nutrients leaving the field. They are a big factor in eastern Wisconsin. Tile is often the major contributor of water to streams/rivers and lakes in that area. Breaks in tile contribute a significant source of sediment and nutrients. Phosphorus loss was high in surface water, low in tile. Phosphorus and sediment in tile is greatly affected by the type/age of tile (concrete, clay, plastic, covered plastic). Nitrogen loss was low in surface water, high in tile.
Nutrient application rates are another key in reducing nutrients leaving the field, Frame noted. Over application of nutrients can generate significant nitrogen losses. Reasonable (8,000 gallons) of summer manure on hay did not generate runoff even when followed by rain within 30 hours of application. Grazing systems have a tremendous potential for nutrient/manure runoff from overwintering sites – this was influenced by stocking density and location of overwintering paddocks.
Frame pointed out that although Discovery Farms has a lot of research yet to do in the coming years, it’s clear that all types and sizes of farms need to be part of the solution to reducing environmental by agriculture – all the way down to the smallest of hobby farms.