Soil factors infl uencing nematode spatial variability in soybean

Abstract

The economic damage to Brazilian soybean [Glycine max (L.) Merr.] production attributed to Pratylenchus brachyurus has increased in recent years. The objective of this study was to determine the influence of soil properties on nematode variability in a soybean crop. Soil and root samples (0–0.20 m) were collected from 142 points in an area that was 180 by 180 m. Root samples were analyzed for nematodes, and soil samples were analyzed for chemical attributes. The data were analyzed using principal component analysis and geostatistics. The spatial variability maps of the attributes S, Ca, Mg, K, sum of bases, base saturation index, and cation exchange capacity were aligned with the water runoff direction. Soil organic matter and K were associated with very low number of nematodes in the root (NNR) (NNR £ 3614), low (3614 < NNR £ 10,496), and moderate (10,496 < NNR £ 21,248). On the other hand, the regions with high Mg, S, and soybean productivity were associated with regions with high (21,248 < NNR £ 43,648) and very high (NNR > 43,648) NNR. The findings indicated that soil chemical characteristics influence the population dynamics of the root-lesion nematode P. brachyurus.