The effect of soil heterogeneity on the spatial distribution of Heterodera schachtii within sugar beet fields

The beet cyst nematode, Heterodera schachtii, causes severe yield losses in sugar beet production worldwide. It tends to occur in heterogeneously distributed patches within fields. Soil texture is often regarded as the dominant soil property affecting the population density of H. schachtii. This study was based on the hypothesis that a relationship between soil texture and related soil properties and the population density of H. schachtii can be quantified with measurements of the soil's apparent electrical conductivity (ECa). The ECa, which is known to be strongly related to soil texture, was measured in four agricultural fields using the non-invasive EM38 sensor. Two of the fields showed little spatial variation in soil texture, whereas the other two were more spatially heterogeneous. Soil samples to determine the nematode population were taken either along transects or following a nested sampling design. Geostatistical methods were used to analyse the spatial distribution of ECa and nematodes. Correlations between ECa and nematode population density were moderate (R-2 = 0.47) and strong (R-2 = 0.74) in heterogeneous fields, indicating that H. schachtii prefers deep soil with medium to light textures and non-stagnic water conditions. Management maps based on ECa and soil taxation maps indicate areas with different soil-related living conditions for H. schachtii. These maps could enable farmers to improve site-specific management strategies on nematode-infested fields. (C) 2011 Elsevier B.V. All rights reserved.