High Resolution Digital Soil Mapping Using Soil Survey and Electrical Conductivity Maps in the Argentinean Pampas.

The objective was to test the suitability of using soil survey and apparent electrical conductivity (ECa) maps to elaborate high resolution digital soil mapping (>1:2000). The study was conducted in a 65 hectares field, located within the cartographic unit (CU) Az26 based on the 1:50000 soil mapping. Three soil series were associated in this CU: Azul (Az) (60%), Semillero Buck (SB) (30%) and Cinco Cerros (CC) (10%). Soil ECa was measured at two depths, using the Veris model 3100 sensor cart system, on transects approximately 20 m apart. Based on ECa 0-30 cm measurements, homogeneous zones were delineated and named as ZECa. Additionally, soil sampling was conducted in an intensive manner, using a 50x100 m grid at a depth of 20 cm. Organic matter (OM), clay content (As) and effective depth (ED) were determinate. OM, As, ED and the interaction with ZECa were evaluated using ANOVA. An exploratory dendrogram showed that at 20 cm depth, Az and CC series (Petrocalcic Paleudoll) had higher OM and As, while in SB series both contents were lower. At Low ZECa, ED was upper and As and OM were lower than other zones. Despite at Middle and High ZECa As and OM were upper, in our work was not possible to detect statistically significant differences between zones. The highest ZECa showed lowest ED. Based on this findings, we conclude that Middle and High ZECa could be associated with As and CC series, meanwhile Low ZECa would be with SB series. The use of soil and ECa mapping allowed to determine the distribution and spatial relation of OM, As and ED at high resolution scale.