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Soil Technical Info

This is a collection of information and resources available on the Web that may be of interest to you. If you know of other resources that may be beneficial, please feel free to suggest them by emailing suggestions@rockriverlab.com.

Late Season Nitrate Testing Instructions and Interpretation:

Sampling Instructions:

-Need 8" segment of corn stalk (6" above ground to 14" above ground)

-Sample 1-3 weeks after black layer has formed

-Leaf sheaths should be removed

-Stalk damaged by disease or insects should not be included

Shred or chop samples before sending to the laboratory

Wisconsin Interpretations

< 450 ppm nitrate...............Low

450-2000 ppm nitrate...............Optimum

> 2000 ppm nitrate...............Excessive

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Frequently Asked Questions (FAQs)

Will soil samples, which have been sitting in a truck for a few weeks, still produce an accurate analysis?
- Yes, pH, P, K, Ca, Mg, Zn, and Mn are OK. Soils needing nitrate analysis require immediate delivery.
Can lime and fertilizer be added simultaneously?
- Yes.
Are soil test kits reliable?
- No. Cheap and general indication of soil ph and fertility are only advantages.
- Rock River Laboratories, Inc. offers much more accuracy, such as soil pH within tenth of pH unit and other analysis within a few parts per million.
- Rock River Laboratories, Inc. offers professional staff and technicians.
- Rock River Laboratories, Inc. offers specific crop recommendations based on university research data.
- Rock River Laboratories, Inc. offers specific methodologies of soil testing, unlike kits.
Are splitting soil samples between two or more laboratories a good judge in comparing lab quality?
- No. Usually growers or crop consultants collect soil samples, mix in bucket, and then send to laboratories for comparison. Incomplete mixing is first problem. Studies conclude that mixing moist or too dry soil increases the inaccuracy.
- Rock River Laboratories, Inc. participates in the Farmers Service Association Proficiency Testing Program involving approximately 6 other laboratories. We also participate in the North Central Region Proficiency Soil Testing Program involving over 20 peer laboratories. Soil professionals run these programs from government and university.
- Sending split samples to laboratories, without knowing what procedures of analysis and extracting processes of each, is a waste of time and money. Professionally run Proficiency Programs compare apples to apples and oranges to oranges.
- Sticking with one laboratory like Rock River Laboratories, Inc. and developing a long-term relationship is recommended.
How do I sample in no-till situations?
- Soil pH tends to be lower near the surface and increases with depth. Even though nitrogen applications to surface quickly transform and become mobile, decreases in soil ph near surface are common.
- Soil sample at 0-3 inch and 3-6 inch depths to account for differences in pH.
- Lime applications may be necessary if concentration of soil acidity occur near surface.

Credits: Dr. Robert Lippert, Clemson University