About the Illinois Soil Nitrogen Test

Illinois is home to some of the most productive soils in the world. After the rich native prairie sod was tilled, the natural soil fertility was adequate to produce a variety of crops, and was even excessive in some cases. As cultivation of the arable land continued over time, commercial fertilizers came into use for supplementing the benefits of manuring and crop rotations, so that yields would be sufficient to meet the changing needs of the nation. The demand for fertilizers increased dramatically with the introduction of improved crop varieties selected for maximal yields with high planting rates.

Soil is the world's fundamental resource for sustained crop production. It supplies water and nutrients to the growing plant as well as serving as a physical support. Soils differ widely in their ability to supply nutrients, and these differences must be taken into account if fertilizers are to be used wisely and responsibly.

Nitrogen is the most important element that must be managed in the soil-plant system. In Illinois, the annual investment for nitrogen fertilizers exceeds $500 million, on the assumption that fertilizers largely supply nitrogen to the crop. Yet a large body of research demonstrates unambiguously from isotopic studies and unfertilized (check) plot yields that the soil is often the major source of nitrogen taken up by the plant over the growing season, and that this source is affected by soil type and management history.

Test your soil to estimate how much nitrogen will be available from soil reserves, and plan your fertilizer additions to supplement what the soil can supply. With the ISNT, you can maximize the return on your fertilizer investment, while minimizing the adverse environmental effects of overfertilization. For more information, visit http://illinoissoilntest.nres.uiuc.edu or contact the ISNT research team at isnt@nres.uiuc.edu.

ISNT History »