ISSN:
1573-0867
Keywords:
Phosphate rocks
;
soil P tests
;
soil test calibrations
;
iron-oxide impregnated paper test
;
mixed anion exchange/cation exchange membranes test
Source:
Springer Online Journal Archives 1860-2000
Topics:
Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
Notes:
Abstract Soil phosphorus (P) tests have usually been calibrated using regression relationships between test values and crop yields for soils with a history of soluble P fertilizer use. However, the regression relationships have frequently been found to be different where phosphate rock (PR) based fertilizers have been used. Consequently, the traditional soil P tests often give incorrect estimates of soil P status of PR fertilized soils where calibrations were derived using soils treated with soluble P fertilizers. Alkaline soil tests (e.g., Olsen, Colwell) usually underestimate, while acid tests (e.g., Truog, Bray 2) usually overestimate, the soil P status of PR fertilized soils where normal calibrations are used. Several ways of overcoming this problem are discussed. Separate calibrations can be used for soluble and PR based fertilizers. In practice, this could involve mathematical modification of test values obtained with PR fertilized soils to enable use of the normal calibrations. Soil and fertilizer P models are available which use fertilizer history to derive current fertilizer recommendations and/or predict consequences of different fertilizer strategies. These could be extended to include functions describing the dissolution of PR in soil. This requires more detailed information on PR dissolution rates in different soils. Two soil tests for use with both soluble P and PR fertilized soils have recently been developed. They are the iron-oxide impregnated paper and the mixed anion exchange membrane/cation exchange membrane tests. While more evaluation is required in field situations, evidence to date indicates that both tests show promise.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00750221
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