TY - JOUR

T1 - Organic Phosphorus in Soil Size Separates Characterized by Phosphorus‐31 Nuclear Magnetic Resonance and Resin Extraction

AU - Rubæk, G. H.

AU - Guggenberger, G.

AU - Zech, W.

AU - Christensen, B. T.

PY - 1999/9/1

Y1 - 1999/9/1

N2 - Land use and soil management affect soil organic C in whole soil and size separates, but knowledge of the accompanying soil organic P (P(0)) is limited. The objectives of this study were (i) to identify the structure of P(0) in soil size separates by solution 31P-nuclear magnetic resonance (NMR) spectroscopy, (ii) to determine the labile P(0) pool in the size separates by anion-exchange resin extraction, and (iii) to characterize the labile P(0) pool. We used soils from two long-term experimental sites, one in Bavaria (under spruce and deciduous forests, permanent grassland, and arable farming) and one in Denmark (with arable rotation and different fertilization strategies - unfertilized, mineral fertilizer, and animal manure). Total P(0) content increased with decreasing particle size. The dialyzed NaOH extracts of clay were enriched in microbial-derived teichoic acid-P and other diester-P forms compared with silt and sand. Clay from permanently vegetated soil had larger proportions of teichoic acid-P and other diester-P forms and was richer in resin extractable P(0) than clay from arable soil. There was a linear relationship between the proportion of the 31P-NMR spectra allocated to diester-P (including teichoic acid-P) and resin-P(0). Our results suggest that the highly active and easily mineralized soil P(0) was mainly associated with clay. The larger part of the clay-associated P(0) was tightly bound and not extractable. Although the composition of this P(0) remained unknown, it was probably inaccessible to rapid microbial utilization. The composition of NaOH-extractable P(0) in the clay fraction was influenced to a greater extent by land use than by fertilizer inputs.

AB - Land use and soil management affect soil organic C in whole soil and size separates, but knowledge of the accompanying soil organic P (P(0)) is limited. The objectives of this study were (i) to identify the structure of P(0) in soil size separates by solution 31P-nuclear magnetic resonance (NMR) spectroscopy, (ii) to determine the labile P(0) pool in the size separates by anion-exchange resin extraction, and (iii) to characterize the labile P(0) pool. We used soils from two long-term experimental sites, one in Bavaria (under spruce and deciduous forests, permanent grassland, and arable farming) and one in Denmark (with arable rotation and different fertilization strategies - unfertilized, mineral fertilizer, and animal manure). Total P(0) content increased with decreasing particle size. The dialyzed NaOH extracts of clay were enriched in microbial-derived teichoic acid-P and other diester-P forms compared with silt and sand. Clay from permanently vegetated soil had larger proportions of teichoic acid-P and other diester-P forms and was richer in resin extractable P(0) than clay from arable soil. There was a linear relationship between the proportion of the 31P-NMR spectra allocated to diester-P (including teichoic acid-P) and resin-P(0). Our results suggest that the highly active and easily mineralized soil P(0) was mainly associated with clay. The larger part of the clay-associated P(0) was tightly bound and not extractable. Although the composition of this P(0) remained unknown, it was probably inaccessible to rapid microbial utilization. The composition of NaOH-extractable P(0) in the clay fraction was influenced to a greater extent by land use than by fertilizer inputs.

UR - http://www.scopus.com/inward/record.url?scp=0032712757&partnerID=8YFLogxK

U2 - 10.2136/sssaj1999.6351123x

DO - 10.2136/sssaj1999.6351123x

M3 - Article

AN - SCOPUS:0032712757

VL - 63

SP - 1123

EP - 1132

JO - Soil Science Society of America Journal

JF - Soil Science Society of America Journal

SN - 0361-5995

IS - 5

ER -