One of the prominent features of no-till system is the accumulation of crop residues left on the soil surface. Although the technical recommendation for sampling soil for testing purpose states that the crop residues should be removed from the soil surface, it is not feasible when sampling the soil with a geo-referenced hydraulic soil-coring probe. The soil samples may also be mixed with the crop residues when they are taken without removing these residues from the soil surface, which happen frequently. The objective of this study was to evaluate the effect of removing the crop residues on soil test results. Soil sampling was carried out with and without the crop residues presence. It was carried out on sandy and clayey soils, sampled with a soil auger or a geo-referenced hydraulic soil coring probe. The effect of crop residues on soil test results was not expressive. It changed according to the type of soil sampler used, the crop residue, and the clay content. By using the hydraulic sampler, it was possible to detect differences on the organic matter (OM) content of the soil sample as a function of the sampling technique, but it did not occur by using the soil auger sampler. On the crop residues presence, the OM content increased 4g kg-1 (sandy soils where soybean was cropped) and 5g kg-1 (clayey soils where corn was cropped). Except for the organic matter content, the sampling techniques tested did not affect the soil test results interpretation of the other variables analyzed.
soil sampling; fertilizer recommendation; organic matter; no-till
