More on alternative sources of nitrogen

Editor’s note: This article is from the archives of the MSU Crop Advisory Team Alerts. Check the label of any pesticide referenced to ensure your use is included.        

In last week’s Landscape Alert, I discussed the need for small nursery growers to consider additional fertilizer sources of Nitrogen because of limited availability of ammonium nitrate in bagged quantities due to regulatory and liability concerns of suppliers. In the article, I mentioned that growers should consider soil pH reaction in looking at alternative N sources. Relying on information from an Extension web site, I mentioned that potassium nitrate has a neutral soil pH reaction. Landscape Alert team member Al Gaus noted that potassium nitrate is actually a basic soil reaction, which will increase soil pH. In order to prevent any further confusion, I present a summary table of fertilizer properties for various Nitrogen sources from the Western Fertilizer Handbook, provided courtesy of Dr. .(JavaScript must be enabled to view this email address), MSU Dept of Crop and Soil Science. Note that adding 100 lbs of potassium nitrate has the same liming effect as the addition 29 lbs of calcium carbonate. The table also indicates the acidifying effect of ammonium-based N source in calcium carbonate equivalents. For example, if a grower added 100 lbs diammonium phosphate, they would need to add 58 lbs of calcium carbonate to offset the acidifying effect of the fertilizer.

Soil reaction of common nitrogen fertilizer sources        

Nitrogen (%)

Equivalent Acidity 1

Equivalent Basicity 2

Urea

45-46%

71

0

Ammonium nitrate

34%

62

0

Monoammonium phosphate

11%

58

0

Diamonium phosphate

16-18%

70

0

Ammonium sulfate

21%

110

0

Calcium nitrate

15.5

0

20

Sodium nitrate

16%

0

29

Potassium nitrate

13-14%

0

26

1. Equivalent acidity = lbs of calcium carbonate needed to offset acidifying effect of 100 lbs of fertilizer product
2. Equivalent basicity = lbs of calcium carbonate needed to produce equivilent liming effect as 100 lbs of fertilizer production
Source: Western Fertilizer Handbook

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