Geostatistical and multivariate analysis of soil attributes between terrace channels in the semi-arid region

Abstract

The spatial variability of soil attributes in terraced areas is poorly studied in the semi-arid region. Considering that multivariate analysis enhances the diagnosis of spatial variability from geostatistics, soil attributes were studied in different zones between terrace channels in semi-arid region, more precisely in a retention terrace area in Canindé (Ceará, Brazil). Soil samples (n = 100) were collected at depths of 0.0 - 0.1 and 0.1 - 0.2 m for descriptive and geostatistical analysis. For multivariate analysis, samples from three zones relative to the terrace channel (Upper, Middle, and Lower) in the 0.0 - 0.2 m layer were considered, with 30 replicates. There was spatial dependence of soil attributes in the two layers studied. Near the channel, in the respective layers, there was higher clay content (13.7% and 14.7%) and higher degree of flocculation (61.3% and 71.7%) compared to the other zones. Water-dispersible clay was higher in the Upper zone (6.5% and 7.7% in the respective layers), while the Middle zone showed higher potential acidity in the evaluated layers (4.8 and 4.5 cmol_c dm^-3, respectively) compared to the other zones. In the multivariate analysis, there were highlights for the higher sum of bases in the Upper zone (18.9 ± 0.8 cmol_c dm^-3), higher sand content in the Middle zone (72.6 ± 0.6%), lower potential acidity (2.1 ± 0.2 cmol_c dm^-3) and higher phosphorus content (12.8 ± 3.0 mg kg^-1) in the Low zone. The zone above the terrace channel loses mainly clay and requires practices to increase water and nutrient retention.