UVM Implements Improvements in Soil Testing Program

Bill Jokela and Don Ross, Extension Associate Professor and Director of the UVM Agricultural and Environmental Testing Lab, Department of Plant and Soil Science, University of Vermont



The UVM Agricultural and Environmental Testing Lab and UVM Extension have made a number of changes in the soil testing and nutrient recommendations program for field crops. (They went into effect September 1, 2004). These changes expand the types of soil tests provided in the routine analysis and provide updated nutrient recommendations for field crops.

Soil Test Changes
1. Organic matter will now be reported on all samples at no extra charge. (It was formerly available as an optional test for an extra charge.) Although organic matter content is not used directly in making nutrient recommendations, it is an important soil property that affects soil tilth and quality and overall nutrient status. It is also an important parameter in for recommendations for some herbicides.

2. The full micronutrient package will be reported on all samples (at no extra charge). This includes iron (Fe), boron (B), manganese (Mn), copper (Cu), and sodium (Na), in addition to zinc (Zn), which has been included for many years. Except for Zn, no recommendations are made based on these tests. There have been no known deficiencies of Fe, Mn, Cu, or Na in field crops in Vermont. We make recommendations for boron on forage legumes, but they are not based on a soil test because the test has not proved reliable enough. However, it can be useful to monitor levels of these nutrients on your farm, and we do provide average values for Vermont soils.

3. Sulfur (S) will now be reported for all soils. Sulfur deficiency has not been well documented on field crops in Vermont, though it has been suspected in some cases. A combination of lower S from atmospheric deposition, lower S content in fertilizers, and greater S uptake with increased yields, may increase the probability of deficiency under some conditions, especially where manure has not been applied. A note of caution: Sulfur is somewhat mobile in the soil (though less so than nitrate). This means that levels can vary at different times of the year due to leaching and other soil processes.

4. We will now be reporting % base saturation. This is similar to the estimates provided by some other soil testing labs. It refers to the percent of the cation exchange capacity (CEC) of the soil that we estimate is occupied by the basic cations (positive ions), calcium, magnesium and potassium at pH 6.8. The UVM recommendations are not based on percent base saturation, although the concept applies to the adjustment of our Mg recommendation where K is unusually high.

5. We will no longer be reporting Reserve Phosphorus. This test is not currently used in our fertility recommendations and dropping it allows us to add the other nutrients with no change in sample cost.  Reserve Phosphorus is available upon request for a charge of $2.00.

In summary, results will include pH, lime requirement, organic matter, available phosphorus, potassium, calcium, magnesium, sodium, iron, boron, manganese, copper, zinc, effective CEC, % base saturation and fertility recommendations. Please contact the lab if you have any questions about our new reports. We will be modifying the report format in order to include all the results on one page.

Lab website:  http://pss.uvm.edu/ag_testing/

Changes in Nutrient Recommendations
We have updated some of our nutrient recommendations, primarily related to manure nutrients and nitrogen on grass forages. These changes reflect recent research and nutrient monitoring results in Vermont and other states.

1. We have updated typical dairy manure nutrient values to reflect current manure analysis summaries from the UVM lab. These values are used as a default for crediting manure nutrients on fields where manure has been applied but no analysis is provided. The most significant change was a 10 to 25% lower P content of dairy manure, depending on manure type.

2. Values for availability of ammonium-nitrogen in poultry manure were increased to reflect recent research results from Maryland that indicate volatilization losses are less than previously thought.

3. The fertilizer equivalency of P in manure has been changed from 80% to 100% to reflect recent research in Vermont and other states and to be consistent with other states in Northeast.

4. We made minor changes in the nitrogen recommendations for grass forages, primarily recommending additional N if a second harvest is made in the establishment year.
 

The extension publication Nutrient Recommendations for Field Crops in Vermont (Br 1390) was revised to reflect these changes. We also made a number of small editing changes and corrections. The revised publication is available in printed form for $2.50 (plus postage and handling) from Communication and Technology Resources, UVM Extension.

Don Ross                                             Bill Jokela
Laboratory Director                            Extension Soil Scientist
802-656-0138                                    802-656-0480
dross@uvm.edu                                bill.Jokela@uvm.edu


This site is maintained by Sid.Bosworth@uvm.edu, Plant & Soil Science Department, University of Vermont.

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