Two research locations in the coarse-textured soils of Central Minnesota highlight the sensitivity of the region to groundwater impacts, but also show how eager farmers are to come up with solutions that reduce the presence of nitrate-nitrogen below very stringent levels.
The Clean Water Fund generated by the Clean Water, Land and Legacy Amendment sales tax approved by Minnesota voters presents a number of opportunities to protect or remediate groundwater resources impacted by surface runoff.
The Minnesota Department of Agriculture (MDA) has proposed $14.77 million to do everything from supporting the current network of well monitoring, to underwriting research on Best Management Practices (BMPs) to offering technical assistance (including the state’s share of the innovative, farmer-led research program called Discovery Farms Minnesota) and even a low-interest loan program to help farmers adopt fertilizer BMPs.
Nitrate reduction field tour
About 50 people participated in a tour of two locations and listened to presentations from researchers, crop consultants and others, on Thursday, Sept. 12.
MDA research, carried out with the full cooperation of farmers across the state, and followed with interest by many more who raise crops and livestock, shows the potential to correct problems by further development of the BMPs.
In particular, the research expands beyond offering volume recommendations, and would consider the best possible form of nitrogen, timing of its application and the placement of the nutrient in relation to the row and where the seeds are. A number of relatively minor adjustments can mean big nutrient savings for the farmer, and significant reduction of losses.
The timing of the field day was appropriate, coming in the midst of a series of listening sessions on the MDA’s proposed new Nitrogen Fertilizer Management Plan. Listening sessions continue with a meeting in Wadena (Tuesday, Sept. 17, 6-8 p.m.), St. Cloud (Wednesday, Sept. 18, 1-3 p.m.), Rochester (Monday, Sept. 23, 6-8 p.m.) and Roseville (Wednesday, Sept. 25, 1-3 p.m.). The Minnesota Corn Growers Association urges farmers to attend one of these meetings and become familiar with the proposal and offer feedback.
On the farm
In central Minnesota, coarse textured soils lead to a greater “sensitivity” to loss of nutrients and non-agricultural chemicals, that can more easily reach groundwater than in areas that have finer, clay-bearing soils.
The first stop for the tour, in Rice, Minn., showcased the farm of the Schlichting and Wojtanowicz families, where they raise corn, soybeans, edible beans and potatoes on irrigated land. Recently they added alfalfa for its agronomic and environmental benefits.
“I remember 20-25 years ago this was considered low-end, prairie sand country that wasn’t worth anything,” said Diane Watonowicz, a co-owner of Prairie Farm in Rice. “With the right kind of stewardship and the right kind of things going back into the soil, it has become productive land, and that wasn’t always the case. So it’s important to be careful, so it can continue to be that, not ‘mining’ our land, but moving forward.”
Practices adopted at Prairie Farm include:
- Using low-pressure irrigation equipment to gear the timing and volume of fertilizer exactly to the needs of the growing crop.
- Stabilized urea — a biodegradable coating makes it like a time-release pill that lasts the 90 days that the corn crop grows from seedling to black-layer, according to Rick Gilbertson, Prairie Farm’s long time crop consultant.
- Taking a small, but significant portion of their land and establishing four-year alfalfa stands, which Prairie Farms intend to rotate through all 22 of their separate land holdings that make up approximately 5,000 acres. The corn (or potatoes — another crop requiring nitrogen inputs) that follows the alfalfa then gets a bump in nitrogen, meaning less commercial fertilizer needs to be applied. Alfalfa scavenges any nitrogen present in the soil and then, once the crop is taking off, the alfalfa roots decay and release nitrogen for subsequent crops to use.
Measuring the optimum amount of fertilizer
The second stop of the day was Rosholt Research Farm in Westport, a 30-acre parcel purchased by the Pope County Soil and Water Conservation District that now serves as the home for research conducted in cooperation with Stearns County Soil and Water Conservation District, University of Minnesota, MDA and the Prairie Lakes Coop, a local CHS service center.
Joshua Stamper, a fertilizer management expert at MDA, has placed more than 100 suction lysimeters — a device that works like a straw sitting in liquid when you hold your finger over the end — underneath the crop-growing area of the parcel. The research team applies a vacuum and collects the samples held in the tubes once a week. This gives a picture over time of what the optimum amount of fertilizer would be for corn-following-soybeans, corn-on-corn and soybeans-following-corn in the outwash sandy soils typical in Central Minnesota. An on-site weather station allows researchers to look at results in the light of precipitation, drought, evapo-transpiration and other conditions.
Stamper’s most recent theory is that 168 pounds of nitrogen represented the economic optimum, while the agronomic optimum only produced one more bushel per acre. The current study is designed to go for four years, and has plots ranging from 80 to 280 lbs nitrogen, along with a control plot where none is applied.
To emphasize the development of BMPs beyond just volume recommendations, Stamper noted that when corn develops from germination to V-4 (the stalk has four fully articulated leaf nodes) an acre will have up to 54 miles of roots system. But in the time between V4 and V8, that explodes to 15,700 miles of roots under a single acre of corn crop.
Stamper noted that not everyone is set up to irrigate, which allows the ultimate in “spoon-feeding,” or split application. Jeremy Drewitz from Prairie Lakes Coop says the process of establishing exactly how much N to use has gotten a huge boost from maps based on near-infrared (NIR) and LIDAR technology, which can show how well plants are growing mid-season, as well as indicating topography. Small drone aircraft can now be used to create very highly detailed maps.
Adaptive Nitrogen Management Program
Another program supported through Legacy Amendment funds shows the positive outcome that can result from farmers working in close partnership with researchers. The Adaptive Nitrogen Management program uses basal stalk sampling, as well as LIDAR and NIR to help farmers establish the optimum nitrogen rates in their most challenging fields. Based on the On-Farm Network model developed in Iowa, farmers in Becker, Hubbard, Wadena, Todd and East Otter Tail Counties have flocked to the program.
“We find that 80 percent of these farmers, after taking part, have found significant ways to change their fertilizer practices,” said Luke Stuewe, an MDA soil sicentist who works on the program.