Phosphorous Sorption and Desorption Characteristics of Soil as Affected by Organic Residues1
- B. B. Singh and
- J. P. Jones2
The influence of seven organic residues on sorption and desorption of P by a high P-fixing soil was determined after 30, 75, and 150 days of incubation. After incubating for 30 days, all residues decreased the amount of P sorbed by the soil, resulting in higher equilibrium solution P levels. However, after incubating for either 75 or 150 days, the P content of the organic residues had a marked influence on sorption of added P and desorption of sorbed P. The critical value of P in organic residues which resulted in no tie-up of soil P was 0.3%. Sawdust, wheat straw, and cornstalks which contained < 0.3% P decreased labile soil P and increased sorption by soil after incubating for 75 or 150 days. Alfalfa (Medicago sativa), barley (Hordeum vulgare), beans (Phaseolus vulgaris), and poultry manure that contained P in excess of 0.3% decreased sorption of P. The results suggest that P fertilizer rates estimated from sorption isotherms may need to be modified following addition of organic residues.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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