Fate of applied phosphate and sulfate in weathered acid soils under leaching conditions
1995
Lefroy, R.D.B. | Santoso, D. | Blair, G.J. (New England Univ., Armidale (Australia). Dept. of Agronomy and Soil Science)
An experiment was conducted with two contrasting acid soils: a gleyed podzolic (Aquic Haplustalf) (GP) and a red earth (Haplohumult) (RE), in open PVC columns. There was considerable movement of applied P downward in the column of the low-sorbing GP soil. In contrast, applied P moved little in the medium-sorbing RE soil. Lime and S application also had no effect on the distribution of applied P in the soil columns. The amounts of recently applied P fertiliser lost by leaching from the RE were less than 2 microg P per column or less than 2 percent of the native plus fertilizer P present in the leachate. The S, applied as Na2SO4, was completely leached out of the GP soil by 9 intermittent leachings irrespective of lime or P treatment. In the RE soil, a previous application of S resulted in a loss of 34-57 percent of the applied S after 13 intermittent leachings. Most of this S was lost during the leaching episodes. Liming enhanced leaching losses of applied S, and P application only increased S losses in the limed treatment.
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