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Effects of Aluminum Toxicity and Phosphorus Fixation on Crop Growth on Oxisols in Natal
Author(s) -
Reeve N. G.,
Sumner M. E.
Publication year - 1970
Publication title -
soil science society of america journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.836
H-Index - 168
eISSN - 1435-0661
pISSN - 0361-5995
DOI - 10.2136/sssaj1970.03615995003400020025x
Subject(s) - oxisol , lime , soil water , agronomy , fixation (population genetics) , fertilizer , chemistry , phosphorus , gypsum , environmental chemistry , environmental science , zoology , soil science , biology , paleontology , biochemistry , organic chemistry , gene
Simple, routine methods for estimating exchangeable Al and P‐fixing capacity of acid soils are described. A glass‐house study on eight Oxisols revealed marked growth response of ‘trudan’ ( Sorghum sudanense ) to amelioration by lime, gypsum, and Ca silicate which is ascribed to elimination of Al toxicity rather than to improved P availability. Growth response to ameliorants took place up to the point of elimination of exchangeable Al after which a significant reduction in yield occurred. P fixation is shown to be a major fertility limitation in the soils studied. Since no apparent relationship between P fixing capacity and exchangeable Al existed and since lime did not decrease P fixation despite its ability to eliminate soluble Al, it is concluded that P fixation is the result of an adsorption reaction rather than a precipitation reaction. Although the soils studied are all capable of fixing large quantities of P considerable variation exists between them. Fertilizer recommendations based only on an estimate of available P in the soil per se could thus be in serious error.