Effect of organic amendment on soil fertility and plant nutrients in a post-fire Mediterranean ecosystem
Résumé
Backgrounds and aims In Mediterranean frequently
burnt areas, the decrease of soil fertility leads to regressive
vegetation dynamics. Organic amendments could
help to accelerate post-fire ecosystem resilience, by
improving soil properties and plant nutrition. This study
was conducted to assess the potential of a composted
biosolid to restore an early post-fire shrubland.
Methods About 50Mg.ha−1 of fresh co-composted sewage
sludge and green wastes were surface applied
7 months after fire on a silty-clayey soil. We monitored
over a 2-year period organic matter and nutrient transfers
to soil, nutrient responses of dominant plant species,
and ecosystem contamination by potentially toxic trace
elements.
Results Over the experimental survey, compost rapidly
and durably improved soil P2O5,MgO and K2O content,
and temporarily increased N-(NO3− + NO2−) content.
Plant nutrition was improved more or less durably depending
species. The most positive compost effect was
on plant and soil phosphorus content. Plant nutrient
storage was not improved 2 years after amendment,
suggesting luxury consumption. No contamination by
trace elements was detected in soil and plant.
Conclusions The use of compost after fire could help
for rapidly restoring soil fertility and improving plant
nutrition. The increase of soil nutrient pools after
amendment emphazised the diversity of plant nutritional
traits. Eutrophication risk could occur from high compost
and soil P2O5 content.