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Evaluations of soil phosphate status by pot experiments, conventional extraction methods, and labile phosphate values estimated with the aid of phosphorus‐32
Author(s) -
Williams E. G.,
Knight A. H.
Publication year - 1963
Publication title -
journal of the science of food and agriculture
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.782
H-Index - 142
eISSN - 1097-0010
pISSN - 0022-5142
DOI - 10.1002/jsfa.2740140805
Subject(s) - phosphate , bicarbonate , phosphorus , chemistry , extraction (chemistry) , yield (engineering) , soil water , a value , soil test , zoology , environmental chemistry , agronomy , chromatography , soil science , environmental science , biology , biochemistry , organic chemistry , materials science , metallurgy
The implications of the quantity and intensity aspects of soil P status have been studied over a range of 4° contrasting acid soils by examining (a) interrelationships and (b) correlations with the yield and P uptake of oats from pot cultures receiving no added P, for (I) the so‐called L value, (2) readily‐soluble P (P x ) extracted by six conventional methods, and (3) the total (solid + liquid phase) P (P q ) involved in these extractions. The L value, representing the quantity of isotopically exchangeable P sampled by the plants in the pot cultures, and the P q value were estimated with the aid of added 32 P. The results emphasise the importance of the intensity factor, especially in relation to yield, and show that the success of conventional readily‐soluble P values as criteria of P status depends largely on avoidance of attack on unavailable P, coupled with reflection of intensity through variation from soil to soil in the proportion of P x to P q . The highest crop correlations, especially with yield, are therefore given by mild extractions at intermediate p H , with fairly short extraction periods, relatively inactive anions, and a fairly narrow extractant/soil ratio, such as in the lactate and bicarbonate methods.