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Comparison of Different Phosphorus Extractants in Soils of the Western State of Nigeria 1
Author(s) -
Oko Bernard F. D.,
Agboola Akinola A.
Publication year - 1974
Publication title -
agronomy journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.752
H-Index - 131
eISSN - 1435-0645
pISSN - 0002-1962
DOI - 10.2134/agronj1974.00021962006600050011x
Subject(s) - soil water , crop , swamp , chemistry , phosphorus , dry matter , agronomy , soil test , environmental science , ecology , biology , soil science , organic chemistry
Researchers in Western Nigeria have a problem in choosing a universally accepted extractant for soil test correlations. Many P extractants that are in use today have been adopted without sufficient investigation. In the present study, 8 different P extractants were used in extracting P from 90 surface soil samples taken from 2 different ecological zones of the Western State of Nigeria. Soil P values for the different extractants before the first crop of rice ( Oryxa saliva var. ‘OS 6 ’ upland rice) were correlated with P uptake of the first crop, cumulative P uptake (P uptake for two croppings of 8 weeks each), and with cumulative yield (dry matter for two croppings). Soil P values after first crop were correlated with P uptake of the second crop. Results suggested that different ecological zones may require different extractants, viz. Bray No. 2 (0.03 N NH 4 F + 0.1 N HC1) (r = 0.433*) for the swamp soils; Bray No. 4 (0.5 N NH 4 F + 0.1 N HC1) (r = 0.491**) for the Ikenne soils, and Bray No. 1 (0.03 N NH 4 F + 0.025 N HC1) (r = 0.383*) for the Ilora soils, but the general purpose extractant for rice in soils of the Western State was Bray No. 1 (r = 0.372***). With the swamp soils, there was a negative correlation when soil P after first crop was correlated with second P uptake. The North Carolina extractant (0.05 N HC1 + 0.025 N H 2 SO 4 ) (r = 0.462**) gave the best reliability for Ikenne soil. The Bray Nos. 1 and 2 were equally useful in both correlations for the above, as well as initial soil P with first P uptake although there was a slight preference in the former for the Bray No. 2 (r = 0.513**) over Bray No. 1 (r = 0.396*). For the 90 soil samples, Bray No. 2 (r = 0.279**) gave better correlation between soil P after first planting with second P uptake. Correlation of initial soil P with one cropping of 8 weeks was better for swamp soils, whereas in Ikenne soils more confidence could be placed on correlations with second cropping and cumulative P uptake. For the Ilora soils and with a combined group (consisting of 90 soil samples) there was little or no significant difference in using either.