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Nutrient use and its fate can now be tracked using the NuGIS model.

In order to account for nutrients to adequately supply crop needs, while at the same time being better stewards of our environment, it is important to maintain a balance of nutrient inputs, removals and losses. The Nutrient Use Geographic Information System (NuGIS) provides a complete collection of the components of nutrient application and utilization on a geo-tagged basis for each county in the continental United States. The NuGIS balance can also be computed on an individual basis for each U.S. watershed.

NuGIS is a free interactive model and database that can give growers a summary of the nutrient balance for their watershed or county. While it does not address nutrient balance at the farm or individual field level, farmers could use a similar approach to computing the balance for their own fields using their own records of inputs and yields. These balances help growers assess their nutrient management plan’s agronomic, economic and environmental effects. Something growers will be doing more of in the future.

NuGIS integrates multiple tabular and spatial datasets to create county-level estimates of nutrients applied to the soil through fertilizer and livestock manure applications, and nutrients removed by harvested crops. Nutrient balances and removal efficiencies are estimated for five years, coinciding with the USDA Census of Agriculture, from 1987 – 2007 and annually from 2010 – 2013. Geospatial techniques were used to estimate balances and efficiencies for 8-digit hydrologic units using the county-level data. The results of this project are shown here with interactive thematic maps.

Figure 1.  Watershed nitrogen balance map for N 2012

The NuGIS project is sponsored and managed by the International Plant Nutrition Institute (IPNI). The two primary objectives of this project are to assess nutrient use efficiency and balance in crop production, and identify weaknesses in the balance estimation processes and the datasets used for these estimations.

The NuGIS project is a cooperative effort among many people. The concept was first presented by the Potash & Phosphate Institute (PPI) in 2005, at one of the first meetings of the TFI-PPI Nutrient Use Task Force. The conceptual framework, interpretation and reviewing were a joint effort of the IPNI staff: C.S. Snyder, T.W. Bruulsema, T.S. Murrell, H.F. Reetz, S.B. Phillips, R.L. Mikkelsen, W.M. Stewart and T.L. Jensen. Quentin Rund and Ryan Williams of PAQ Interactive converted concepts and tactical approaches into numeric estimates and graphical representations. Final editing and production support were coordinated by D.L. Armstrong and K.P. Griffin of IPNI's editorial group. The project is currently coordinated by P.E. Fixen of IPNI. NuGIS is a work in progress and we welcome your comments at nugis@ipni.net

Illinois Examples of NuGIS

The following figures provide some examples of the kind of information available in NuGIS relating to the State of Illinois. Similar data are available for each state in the U.S. The first figure (Figure 1) shows the Nitrogen balance.  As an example, one watershed (Upper Sangamon) is highlighted in Figure 2.

Figure 2. Nitrogen balance display. Upper Sangamon watershed is outlined in maroon.

From the legend on the left, we see that the Upper Sangamon watershed has 31 to 50 pounds of N applied above the amount utilized. Figure 3 provides a perspective on how this N balance varies across the Midwestern states.

Figure 3. Comparison of nitrogen balance across Iowa, Illinois, Indiana, Missouri and Tennessee.

In Figure 4 the P balance for the Upper Sangamon watershed is shown to be in the range of -25 to -6 pounds per acre.  This means that more P is being removed than is being applied.

Figure 4. Phosphorus balance display. Upper Sangamon watershed is outlined in maroon.

Figure 5 shows that large areas of northwestern and southern Illinois have similar deficit P levels. But the bulk of Illinois and most of Iowa and Missouri have a balanced P status. Areas just north of the Ohio River in southeast Illinois and southern Indiana have a P balance of +26 to +50 lbs./A, indicating that P application in fertilizer and manures is greater than removal through harvest and more is at risk of being lost through surface runoff.

Figure 5. Comparison of phosphorus balance across Iowa, Illinois, Indiana, Missouri and Tennessee.

For potassium (Figure 6), the Upper Sangamon watershed is in balance (+10 to -10 lbs./A). There are no real environmental concerns with K, but we need to keep it in balance to meet crop needs and help avoid unnecessary expenses. K is also important in getting the most efficiency from other nutrients (such as N), for efficient water use and for maintaining crop health.

Figure 6. Potassium balance display. Upper Sangamon watershed is outlined in maroon.

As Figure 7 illustrates, K is in balance for most of the central Midwest. Of course that is the area where potash has been more commonly used, so we have had a good opportunity to manage soil test levels for more years.

Figure 7. Comparison of potassium balance across Iowa, Illinois, Indiana, Missouri and Tennessee.

NuGIS is a free interactive online app that can be used for any county or watershed in the U.S., and provides the most complete information available anywhere on nutrient use and nutrient balance. Versions of NUGIS are also under development for several other countries. 

I encourage you to look up your county and watershed and see how the nutrient balances for N, P and K have changed over time. Then consider your own farm and calculate your nutrient balance over the years. Are you putting on more that you are removing? Are you mining your soils by not replacing what is removed through harvest? A simple nutrient balance along with regular soil tests can help you refine and optimize your nutrient strategy.

Harold Reetz is a Certified Crop Adviser working as an agronomy consultant in Monticello, Illinois. His areas of expertise include high-yield crop production, precision farming technology, 4R plant nutrient management systems and conservation systems.