Spatial stability of a plant-feeding nematode community in relation to macro-scale soil properties

Understanding the spatial stability of the plant-feeding nematode (PFN) community in agrosystems represents a fundamental step in the integrated control of some damaging species because modifications of soil properties in intensively managed agrosystems may allow growers to manipulate the balance between pathogenic and non-pathogenic species.In the present study, we tested the hypothesis that a community of four PFN species (Criconemella onoensis, Helicotylenchus erythrinae, Hemicriconemoides cocophillus, and Pratylenchus zeae) in a sugarcane agrosystem is spatially structured according to macro-scale soil properties. This hypothesis was studied by using a sugarcane field in Martinique in which soil properties had been heavily modified by hillock-leveling in the 1970s, resulting in a great variation in soil properties over a small area (20.8 × 16.0 m). The goal of the study was to measure the temporal stability of the PFN community spatial structure and to identify the soil parameters associated with differences in nematode abundance. A systematic sampling design was used to collect data in the field that were analyzed using co-inertia and STATIS-Coa. The field study was complemented by a greenhouse experiment.The field study documented the existence of a stable spatial pattern of the PFN community, a pattern that was structured in relation to macro-scale soil factors such as soil carbon, nitrogen, and phosphorus content and soil texture. The constant spatial pattern of the PFN community results from the differences in distributions among C. onoensis and the three other PFN species. C. onoensis was consistently more abundant in the deeply-leveled areas of the field, while the other PFN species were more abundant in the non-leveled areas. H. erythrinae was consistently more abundant in those parts of the field with higher soil pH and sodium content. These results suggested that soil properties can affect permanently the competitive balance among PFN species.The observed relationships between PFN and these macro-scale factors were validated in a greenhouse experiment with different ratios of soil from the leveled and non-leveled areas of the field site.Modification of some major soil properties (pH, Na+ content, soil organic content) by cultural practices such as hillock-leveling, fertilization, and liming, could greatly affect the balance among PFN species in agricultural fields.