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Long-Term Soil Test Monitoring in Minnesota Cropping Systems

Start Date: 2012
Principal Investigator: Dan Kaiser
Organization: University of Minnesota, Department of Soil, Water, and Climate
Status: Complete

Background Info

Soil tests are used to monitor the potential responsiveness of crops to fertilizer. When fertilizer is under applied there is a risk for a decrease in soil test levels. As crop yields increase the removal of nutrients increase. Even if fertilizer is applied to replace the nutrients lost, some crop consultants still notice decreases in soil test levels. It is unclear if some of this decrease is due to changes in where a sample was taken or due to under-application itself. To improve sampling accuracy, GPS receivers can be used to mark point within fields to allow for returning back to the same spot. Monitoring soil test values at a single location over the growing season could aid in identifying problem spots when soil test levels decrease at unexpected rates. Through partnerships with crop consultants and dealers, this study monitored soil test levels at single point in a field. Throughout the growing season, soils were sampled from producer fields fertilized according to standard practices in order to gauge change in soil test levels.


Assess long-term variability in N, P, K, Zn, and pH levels at a specific point within farmer fields around the state

Evaluate the effects of crop removal and soil moisture on the consistency of soil test values over one or more years

Key Findings

More locations will be established for the 2013 growing season. In addition, we also are planning on including comparisons between field moist/slurry soil test for K in order to better understand differences between this test and the air dried test and how it may vary depending on soil properties. Since the first year was as setup year we cannot draw any firm conclusions. With the additional sites, we many expand upon the tests ran to better understand some of the variability being encountered out in the field.

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