ISSN:
1573-5036
Keywords:
flooded soil
;
phosphorus
;
phosphorus fertilization
;
Oryza sativa L
;
oxidized
;
reduced
;
soil solution
Source:
Springer Online Journal Archives 1860-2000
Topics:
Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
Notes:
Abstract The effect of natural and artificial reduction on P extractability from soils used for rice production and the relation of these values to response to fertilizer P were investigated. Soil solution P increased from a mean of 3.8 mg P·kg−1 soil for naturally oxidized slurries of 28 soils to 19.8mg P·kg−1 when the soils were naturally reduced. The mean values were further increased to 40.8 and 45.3 mg·kg−1 when the soils were reduced with 0.1M Na2S2O4 and 0.2M Na2S2O4, respectively. These P-values compare with 18.2 mg kg−1 when the dry soils were extracted with Bray No. 1 extractant. When the yields of rice were correlated with solution and extracted P, the R2's for the quadratic relationships were 0.40**, 0.31*, 0.34**, 0.30*, and 0.55** for the naturally oxidized, the naturally reduced, 0.1M Na2S2O4, 0.2M Na2S2O4 and Bray No. 1, respectively. The Cate-Nelson calculation confirmed the superiority of the weak acid Bray extractant and the critical value of 8.6 mg P·kg−1 soil needed for satisfactory yields of rice. There was little response of rice to added fertilizer P on soils with solution P-values greater than 0.09 mg P·l−1 in oxygenated soil slurries. Some soils with solution P of this order and high amounts of Bray No. 1 extractable P still gave modest responses to fertilizer P. Although natural or chemically induced reduction increased soil solution P, it did not improve prediction of yield response of rice to added fertilizer P.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF02370699
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