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Soil phosphorus status and fertilizer use in select agricutural soils in Nicaragua
viii, 123 leaves : illustrations ; 28 cm.
A survey of small, medium and large Nicaraguan producers indicated a heavy reliance on imported complete fertilizer. Analysis of soils sampled from the large-scale commercial producers found low P retention in the lowland heavy clay soils. These soils contained high amounts of plant available P as indicated by four soil P testing methods, Texas A&M, Bray I, Mehlich III and Olsen. These same methods extracted less P from soils from Pacific coast volcanic lowlands and central highland uplands, indicating significant P retention in soils of these two regions. These findings are supported by a greenhouse study in which an indicator crop grown in the lowland clay soils demonstrated no response to added P. A high response in the indicator crop was observed in the volcanic lowland and central highland soils. Correlation between the four P extraction methods and plant response in the volcanic lowland and central highland soils was high, indicating all methods were adequate for these soils. A statistical correlation of the P quantities extracted by the four methods from all soils in the study found that all methods correlated well, indicating that all methods are adequate for the soils in the study. A phosphorus fractionation method found lowland-clay soils were dominated by the Ca-P fraction. The predominant fractions in volcanic lowland and central highland soils were Fe-P and Al-P.
Issued also on microfiche from Lange Micrographics.
Includes bibliographical references (leaves 89-95).