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  • Resin P  (1)
  • mixed anion exchange/cation exchange membranes test  (1)
  • 1
    Electronic Resource
    Electronic Resource
    Evaluation of soil phosphate status where phosphate rock based fertilizers have been used (1993)
    Springer
    Nutrient cycling in agroecosystems 35 (1993), S. 67-82 
    Details
    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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  • 2
    Electronic Resource
    Electronic Resource
    Development and evaluation of an improved soil test for phosphorus. 2. Comparison of the Olsen and mixed cation-anion exchange resin tests for predicting the yield of ryegrass grown in pots (1992)
    Springer
    Nutrient cycling in agroecosystems 33 (1992), S. 135-144 
    Details
    ISSN: 1573-0867
    Keywords: Mixed cation-anion exchange resin P ; Olsen P ; phosphate rocks ; P sorption capacity ; P sources ; Resin P ; ryegrass ; soil testing
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract A glasshouse experiment was conducted on four soils contrasting in P sorption capacity and exchangeable Ca content with perennial ryegrass using six phosphate rock (PR) sources and a soluble P source applied at four rates (including a control). After three harvests (11 weeks) replicate pots of each treatment were destructively sampled and Olsen P and mixed cation-anion exchange resin (Resin P) extractions carried out. The remaining replicated treatments were harvested another seven times (during 41 weeks). Yields (for the last seven harvests) were expressed as percentages of the maximum yield attainable with MCP. In general, the Resin P test extracted more than twice as much P as the Olsen test. There was a significant increase in Resin P with an increase in the amount of each P source in all four soils, but Olsen P values were not significantly different for soils treated with different rates of each phosphate rock. The abilities of the Olsen and mixed resin soil P tests to predict the cumulative dry matter yield from 7 harvests and the relative yield of ryegrass were compared. Correlations between measured yield (for the last 7 harvests) and soil test for each soil, and relative yield and soil test for all four soils were assessed by regression analysis using Mitscherlich-type models. When dry matter yields were regressed separately against soil test values for each soil, the Resin P consistently accounted for 18–28% more of the variation in yield than did Olsen P. For Resin P a single function was not significantly different from the separate functions fitted to MCP and PR treatments. However, for Olsen P the separate functions for the MCP and PR treatments varied significantly from the single fitted function. The Resin P test (R2 = 0.84) was a better predictor of relative yields over this range of soils than the Olsen test (R2 = 0.75). Two regression models based on the regression of relative yield for MCP treatments against either Olsen or Resin were developed. These models were then fitted to the relative yield data on soils fertilized with PRs only. The Olsen P model was found to be a poorer predictor (R2 = 0.41) than the Resin P model (R2 = 0.73) because it underestimated the observed yield of the PR treatments.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01051168
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    Paper (German National Licenses)
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