ISSN:
1573-5036
Keywords:
Eucalyptus regnans
;
microbial phosphorus
;
organic phosphorus
;
soil P tests
;
P availability
;
phosphatase activity
Source:
Springer Online Journal Archives 1860-2000
Topics:
Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
Notes:
Abstract Concentrations of labile inorganic P (Pi, dilute double acid-extractable), labile organic P (Po, bicarbonate-extractable), microbial P, and phosphatase activities were measured in Mountain Ash (Eucalyptus regnans) stands aged 0, 5, 9, 16, 40, 46, 80 and 250 years. Labile Pi, initially 34 μg g-1 at age 0 years, decreased to 2.3 μg g-1 at age 16 years, and was constant thereafter. All other indices of available P increased with stand age. Microbial P varied the most along the age sequence, from 1.8 μg g-1 at 0 years to 99 μg g-1 at age 80 years. Oxidation of organic P during the regeneration burn creates a large and readily available source of Pi for the young, developing stand. After canopy closure, the stand becomes increasingly dependent on P released by mineralization. Phosphatase activities were as high as have been recorded, and the organic pools are therefore significant stores of potentially available P. At age 80 years (for example) the amount of labile Po and microbial P in the surface 5 cm of soil was 26 kg ha-1. However, the adsorption maxima for Pi fixation were also as high as has been recorded, and so it is apparent that roots must possess specialized mechanisms of uptake to compete for mineralized P.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00010964
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