Soil particulate organic matter effects on nitrogen availability after afforestation with Eucalyptus globulus

Mendham Daniel S., Heagney E.C., Corbeels Marc, O'Connell Anthony M., Grove Tim S., Mc Murtrie Ross E.. 2004. Soil particulate organic matter effects on nitrogen availability after afforestation with Eucalyptus globulus. Soil Biology and Biochemistry, 36 : 1067-1074.

Résumé : We examined the hypothesis that changes in the quality and/or quantity of soil particulate organic matter (POM) after afforestation of pasture land with Eucalyptus globulus Labill. plantations caused increased nitrogen (N) immobilization and a decline in N availability. The quantity of POM was measured on soils from 10 paired pasture/plantation sites in south-western Australia. Net mineralization of C and N were measured over a 14-day incubation of POM, whole soil, and a mix of POM (33%) and whole soil (67%) at 25°C and optimal moisture content (matric potential of 25 kPa). There was no significant difference in total organic C between pasture and plantation. However, the POM fraction C was higher in plantation soils (75%) than under pasture (62%), reflecting the coarser nature of organic inputs under plantation. Total soil N concentration was 20% lower under plantation compared to pasture, and the proportion in the POM was higher (74% compared to 57% for pasture soil). The C:N ratios in POM under both pasture and plantation, and in the whole soil under plantation were around 19, but C:N ratios of whole soil under pasture was 17. Average C mineralization was 13% lower in plantation relative to that in pasture soil. The isolated POM fraction had 18% higher C mineralization rate than that in whole soil. The change in net N mineralization with afforestation was marked, with 50% lower net N mineralization in plantation than pasture whole soils. Net N mineralization in the isolated POM fraction was also about 50% of that in the whole soil for both pasture and plantation soils. Although, the pasture and plantation POM had similar C:N ratios, the net N mineralization was 2-fold greater in pasture POM than in plantation POM, suggesting that biochemical characteristics other than the C:N ratio had the main influence on net N mineralization rates. The POM fraction did not significantly immobilize N from the whole soil when placed in a mixture of POM and whole soil, suggesting that N immobilization was not the main mechanism for POM to influence N availability in these soils. © 2004 Published by Elsevier Ltd.

Classification Agris : P35 - Fertilité du sol
F08 - Systèmes et modes de culture

Auteurs et affiliations

• Mendham Daniel S., CSIRO (AUS)
• Heagney E.C., UNSW Sidney (AUS)
• Corbeels Marc, CIRAD-CP-UMR SYSTEM (BRA)
• O'Connell Anthony M., CSIRO (AUS)
• Grove Tim S., CSIRO (AUS)
• Mc Murtrie Ross E., UNSW Sidney (AUS)

Source : Cirad - Agritrop (https://agritrop.cirad.fr/535917/)

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