Spatial and temporal variability of nutrient availability and soil acidity condition in volcanic soils

Abstract

Spatial and temporal variability of nutrient availability and the acidity are the result of soil formation conditions, management and variation among seasons. It is important to know and consider this variability to design future management practices. Therefore, the objective of this study was to evaluate the variability of nutrient availability and the acidic condition of volcanic soils, under pasture and forest, considering different spatial and temporal scales in Máfil municipality, Los Ríos Region. Two spatial scales were considered, one macro (transect of 14 km, with distance between samples of 100 m) and a micro (sampling grid at intervals of 50 m), with the seasonal variation (6 sampling dates). Soil samples were taken at 0-20 cm of soil depth. The acidic condition was assessed using pH (H₂O and CaCl₂), exchangeable Al, sum of bases, ECEC and Al saturation. Nutrient availability in soil was assessed through mineral N, available S, P-Olsen and exchange cations. Main results show there were no significant differences (p> 0.05) between sampling scales, using conventional statistical analysis for nutrient availability and acidity parameters. However, the spatial analysis shows clear differences between the scales through the different adjustment models and types of spatial dependence. Likewise, the chemical properties showed different degrees of variation given by the sampling date. N and S available showed the highest seasonal variations.