Phosphorus Dynamics of Pinyon-Juniper Soils following Simulated Burning
- Leonard F. DeBano * and
- Jeffrey M. Klopatek
The objective of this study was to determine the effect of a simulated prescribed fire on P compounds in a Lithic Ustochrept soil supporting a pinyon-juniper woodland in Arizona. Soil, litter, and duff collected from beneath pinyon pine (Pinus edulis E.) and Utah juniper [Juniperus osteosperma (Torrey) Little] and adjacent interspaces were used to reconstruct laboratory microcosms in clay pipes that were burned when soils were wet or dry. Soil temperatures were monitored continuously throughout the microcosms during burning. Total, bicarbonate-extractable (BEP), microbial, and organic P; phosphatase activity; and organic C were measured in the soil, litter, and duff before and immediately after burning and 45 and 90 d later. Soil texture, pH, and CaCO3 equivalents were also determined on unburned soils. Organic P and phosphatase activity were significantly higher in unburned juniper soils than under pinyon and interspaces. Total P and BEP were higher in unburned juniper litter than in pinyon litter. Organic P made up <35%, and BEP <5%, of total soil P. About 50% of total P was lost from the litter during burning. Burning significantly increased BEP in pinyon and juniper soils, but the increases were short-lived and became statistically insignificant after 45 d. Phosphatase activity was significantly reduced in pinyon pine and juniper soils when burned dry. Burning over wet soils did not affect phosphatase activity or the concentration of P compounds.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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