La qualité des sols en palmeraie adulte
Deux articles à paraître sur l’évaluation de la qualité des sols, en relation avec le recyclage des résidus organiques, dans European Journal of Soil Biology et Soil Research, co-signés par quatre chercheurs de l’Unité.
M.P. Carron , Q. Auriac, D. Snoeck , C. Villenave, E. Blanchart, F. Ribeyre, R. Marichal , M. Darminto, J.P. Caliman (2015). Spatial heterogeneity of soil quality around mature oil palm with mineral fertilization. Eur. J. Soil Biol., 66:24-31 (http://authors.elsevier.com/a/1Q2wc_QUfmYgog)
The African oil palm (Elaeis guineensis Jacq.) is grown on a total area of 16 million ha; but data on soil quality in mature oil palm plantations are fragmentary and data concerning biota are almost non-existent. Consequently, no well-tested sampling method is available for soil diagnoses. We studied the spatial heterogeneity of the soil around the palm by measuring comprehensive soil quality in a 24-year-old oil palm plantation. Soil quality and litter were assessed in five zones with different plant cover, and different applications of herbicide or fertilizer. Physical-chemical characteristics, macrofauna, and nematofauna were analysed. A sampling method was developed and adapted to the way the cultivation practices are implemented: sampling by zone and weighting the plot mean by the respective area of each zone. The total density of macrofauna in the litter and in the 0-15 cm soil layer followed a gradient from the harvest pathway (29 ind.m-²) to the windrow (1,003 ind.m-²). Ants (13 to 237 ind.m-²), earthworms (11 to 120 ind.m-²), Dermaptera (0 to 35 ind.m-²), Coleoptera (3 to 24 ind.m-²) and Chilopoda (0 to 43 ind.m-²) were the main taxa. The termite population was very poor (3 to 4 ind.m-²). The density of nematofauna was also heterogeneous (268 to 805 ind.100 g-1 of soil). Heterogeneity between zones was also reflected in the density of the functional groups, mainly soil engineers, detritivores and predators for macrofauna and bacterial feeders, and phytoparasites for nematofauna. The weeded circular zone around the palm had the highest soil nutrient content (P, K, Ca, Mg, Corg CEC, base saturation). Its biodiversity was average but it contained the highest density of earthworms and nematofauna. Possible relationships between chemicals and biological groups in the food web are discussed.
Keywords: soil quality; soil macrofauna; soil nematofauna; Elaeis guineensis.
M.P. Carron , M. Pierrat, D. Snoeck , C. Villenave, F. Ribeyre, Suhardi, R. Marichal , J.P. Caliman (2015). Temporal variability in soil quality after organic residue application in mature oil palm plantations. Soil Research, à paraître.
Sixteen million hectares of oil palm were recently planted with dramatic changes in land-use. Despite this, soil biodiversity in plantations has been little investigated. The present study aims to assess the effect of organic waste recycling on soil biodiversity in a mature plantation in Sumatra, Indonesia. A chronosequence was delineated while taking into account the time between the applications of empty fruit bunches (EFB) and soil sampling: 1, 3, 6, 12, 18 and 24 months were compared to control plots without EFB application. Soil physical and chemical characteristics and macrofauna and nematofauna populations were analysed. The findings highlighted three distinct periods: a first disturbance period (0-6 months) showing a marked increase in pH, potassium content, base saturation and macrofauna abundance, especially ants, while earthworm, millipede and nematode populations were substantially reduced; a resilience period (6-18 months); and a final period (18-24 months) showing an improvement in most soil fertility parameters and a high density of earthworms, millipedes and nematodes. The impact of EFB application on soil quality changed as a function of time and the present results explained the apparent discrepancy of some previous results in literature. This research is the first stage towards developing new strategies for enhancing soil biodiversity and related services for sustainable oil palm cultivation.
Keywords: soil macrofauna; soil nematofauna; fertilisation practices; Elaeis guineensis; empty fruit bunches.
Publiée : 18/11/2014