By David Tenenbaum

A software program intended to reduce water pollution and soil erosion has matured into an essential production tool for farmers, says Fond du Lac County, Wis., dairy farmer Josh Hiemstra, who farms 525 acres near Brandon.

“I began using it in 2005 because I had to — I won’t lie,” he says.

The software, called SnapPlus, was created at the University of Wisconsin-Madison Department of Soil Science and introduced in 2005 under a state-federal mandate to reduce soil erosion and prevent runoff of nitrogen and phosphorus. These essential nutrients can overfertilize lakes and streams, and feed the “dead zone” in the Gulf of Mexico.

“Now I use it because it helps me make better business decisions, better environmental decisions,” says Hiemstra. “SnapPlus is a big deal for farmers.”

“SnapPlus solves several problems at once related to distributing manure and fertilizer efficiently while meeting guidelines for protecting groundwater and surface water,” says Laura Good, the soil scientist who has led development and testing of the software. “The program helps to maintain crop fertility without wasting money or endangering natural resources.”

The program is used on 3.36 million acres, or about 37% of the state’s cropland, says Good.

The crux of SnapPlus calculates nutrient requirements for cropland and pasture. The phosphorus calculation starts with a soil test, adds phosphorus from planned fertilizer and manure applications, and then subtracts phosphorus extracted by crops. The software also estimates field erosion and phosphorus runoff rates to streams and lakes.

The math may sound simple, says Good, but the real world is complex. Soils have varying structure, slope and subsurface geology — all factors that affect whether nutrients like phosphorus and nitrogen stay where needed or become water pollutants.

Conditions can change from year to year, even within a field. Cropping rotations can be variable and complex. And weather is, well, weather.

Fertilizer ranks near the top in farm expenses, but if some is necessary, more is not necessarily better. So beyond enabling farmers to heed runoff standards, SnapPlus offers a means to optimize fertility and yields, and control costs.

Any farm in Wisconsin that applies nutrients and has benefited from government cost-sharing or receives the agricultural property tax credit must write a nutrient management plan according to state-specific guidelines, which is typically done with SnapPlus. “These standards and restrictions would be rather difficult to follow on paper,” Good observes.

Although SnapPlus is produced by the UW-Madison Department of Soil Science, experts from Extension have contributed nutrient recommendations and algorithms.

SnapPlus automatically taps databases on soil types, municipal well locations, and streams, lakes and shallow bedrock, so it “knows” factors conducive to rapid movement of groundwater, Good says. “It tells you, on each field, what kind of soil you have, what kind of issues you have.”

Nutrient planning is often done by hired certified crop advisers, although many counties offer training courses to farmers who want to write their own plans.

With its triple benefit of avoiding pollution, supporting yields and reducing costs, SnapPlus “is a good use of taxpayer dollars,” Hiemstra says. “You can call the county and get support. If they can’t answer, there is a full staff in Madison. The people who are writing the program are the ones telling you how to use it and answering your questions.”

Agriculture may not get many headlines, but technology and economics are changing fast. 

“Where we are now with the economics of agriculture,” Hiemstra says, “it’s even more important for farm operators to know their costs and manage on their own. If you as a producer don’t take ownership of the information, you may be spending more than you need to spend.”

The development and optimization of SnapPlus has been supported over the years with funding from the Wisconsin Department of Agriculture, Trade and Consumer Protection; the Wisconsin Department of Natural Resources; the Wisconsin office of the USDA’s Natural Resources Conservation Service; and Hatch grants from the USDA’s National Institute of Food and Agriculture.

Tenenbaum is a University of Wisconsin-Madison communication specialist.