Multiscale Spatial Variability of Potato Yield Influenced by Soil Properties.

Spatial variability of potato yield and aboveground parameters is known to be important but has rarely been studied using multiscale approach. The objective was to describe the spatial distribution of plant parameters in relation to physico-chemical soil properties using a new geostatistical approach (Coregionalization Analysis with a Drift, CRAD, Pelletier et al. 2009a, b ) that allows multiscale multivariate spatial analysis. Two agricultural sites were instrumented at 108 sampling points and two depths in loamy sands where several plant parameters (e.g. tuber, aboveground biomass, C and N contents of tubers and aboveground biomass) and soil properties (e.g. water content, gas diffusion, nitrate) were measured. Plant parameters showed spatial structures that varied at different scales. Potato yield presented a strong dominance for random distribution and smaller importance of large scale spatial variance at one site while it was randomly distributed at the other site. C and N contents aboveground presented the strongest structure at small scale while the aboveground biomass had the strongest pattern at large scale. This was consistent between sites. Correlations between plant parameters and soil properties also differed between scales, soil depths, and sites. Differences may be due to time lag measurement, different soil layering, and topography.