Comparison and Evaluation of Laboratory Methods of Obtaining an Index of Soil Nitrogen Availability1
- D. R. Keeney and
- J. M. Bremner2
An evaluation of incubation and chemical methods of obtaining an index of soil N availability showed that incubation procedures involving estimation of the total mineral N produced on incubation of soil under aerobic conditions at 30C for 14 days or estimation of the ammonium N produced on incubation of soil under waterlogged conditions at 40C for 7 days provided a good index of the availability of the N in Iowa soils to ryegrass. It also showed that the results obtained with these soils by a chemical procedure involving estimation of the N extracted by boiling water and potassium sulfate solution were closely related to N uptake by ryegrass and indicated that this procedure deserves consideration as a routine method of obtaining an index of soil N availability. Air-drying and air-dry storage of soil samples had marked effects on the results obtained by the incubation methods studied, but had little effect on the results obtained by the chemical methods found to provide a good index of soil N availability.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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