Niveles de carbono orgánico y ph en suelos agrícolas de las regiones pampeana y extrapampeana argentina

soil organic carbon (soc) and ph are considered key indicators of soil health. the objective of this study was to determine soc and soil ph of agricultural soils (0-20 cm) in the pampeana and extrapampeana regions of argentina and to elaborate maps with both variables, using the median of each county. soil samples were taken from fields that were sampled in 2005 and 2006 at a 20 cm-soil depth and totalled 31,619 and 31,398 for som and ph, respectively. the second objective was to compare the prediction efficiency (ep) of two interpolation methods: 1) inverse distance weighting (idw) and 2) ordinary kriging method (ko). both methods produced similar maps of som and ph, but the ep was slightly greater for the ko (65 to 80%) compared to idp (63 to 79%). soil organic matter values ranged from 5.5 to 38.0 g kg-1, with values declining westward and northward and increasing to the southeast of the region. soils of most of the area presented ph values that ranged from 6 to 7.5, except for some cases in northern buenos aires, center-southern santa fe and eastern cordoba, where soil ph values ranged from 5.5 to 6. soil organic matter showed a declining tendency which indicated the need to apply management practices to revert this degradation process. the soil ph should not be limiting for crop production, but potential problems of acidity could appear in some areas.