High-resolution spacialization of an Oxisol's acidity attributes by on-the-go sensing

Abstract

The objective of this work was to evaluate the relationships between the apparent electric conductivity (ECa), measured by on-the-go sensing, with soil attributes and plant production, besides indirectly mapping with high resolution, the main acidity attributes of an Oxisol in South Brazil. Soil sensing was performed in two crop fields using the Veris 3100 sensor. Soil was sampled at the 0.00-0.15-m soil depth using a hand auger. The corn vigor index (VI) was measured with an optical sensor, and yield was determined using grain yield and moisture sensors. The association of soil acidity attributes with corn yield and ECa was determined with correlation and principal component analyses. ECa was associated with the VI and corn yield. Moreover, in the area with low chemical quality, ECa had a positive relationship with Ca²⁺ and Mg²⁺ contents, pH in water, base saturation, sum of bases, and cation exchange capacity; and a negative relationship with Al³⁺, aluminum saturation, and H+Al³⁺ values. In the area with better chemical quality, ECa was related to Ca²⁺ and Mg²⁺ contents, soil organic matter, and clay content.

Index terms: precision agriculture; electrical conductivity; soil fertility; site-specific management; soil organic matter; spatial variability