Evaluation of an on-the-go technology for soil pH mapping

Abstract

Since conventional sampling and laboratory soil analysis do not provide a cost effective capability for obtaining geo-referenced measurements with adequate frequency, different on-the-go sensing techniques have been attempted. One such recently commercialized sensing system combines mapping of soil electrical conductivity and pH. The concept of direct measurement of soil pH has allowed for a substantial increase in measurement density. In this publication, soil pH maps, developed using on-the-go technology and obtained for eight production fields in six US states, were compared with corresponding maps derived from grid sampling. It was shown that with certain field conditions, on-the-go mapping can significantly increase the accuracy of soil pH maps and therefore increase the potential profitability of variable rate liming. However, in many instances, these on-the-go measurements need to be calibrated to account for a field-specific bias. After calibration, the overall error estimate for soil pH maps produced using on-the-go measurements was less than 0.3 pH, while non-calibrated on-the-go and conventional field average and grid-sampling maps produced errors greater than 0.4 pH.

Comparison of In-Field Measurements of Nitrogen and Other Soil Properties with Core Samples

“…An on-the-go pH sensing unit, which measures pH using ISE's in direct contact with soil, is commercially available. Results from this unit are well-correlated with laboratory measurements, especially when calibrated with lab-analyzed samples from the field (Staggenborg et al, 2007;Adamchuk et al, 2007).…”

Challenges in Using Precision Agriculture to Optimize Symbiotic Nitrogen Fixation in Legumes: Progress, Limitations, and Future Improvements Needed in Diagnostic Testing

“…Electrometric methods with CaCl 2 or water extracts are traditionally used for pH measurement, which require soil sample collection, extraction, and pH meter reading (Table 2). In addition to electrometric methods, solid-state pH electrodes have been successfully used for in-situ measurement of soil pH [79,96]. In this method, soil cores are analyzed within the field, using pH electrodes that are mounted into a moving vehicle [96].…”

“…In addition to electrometric methods, solid-state pH electrodes have been successfully used for in-situ measurement of soil pH [79,96]. In this method, soil cores are analyzed within the field, using pH electrodes that are mounted into a moving vehicle [96]. However, visible and near infrared (VIS/NIR) diffuse reflectance spectroscopy have potential for use as on-the-go tools to measure soil pH in a manner that is rapid, accurate, and low-cost [97][98][99].…”

Espacialização em alta resolução de atributos da acidez de Latossolo por meio de sensoriamento em tempo real

“…O conhecimento desses processos é pré-requisito para a adoção do manejo sítio-específico de solo e de planta (Adamchuk et al, 2007). No entanto, a captação da variabilidade espacial dos atributos à elevada resolução, por meio de amostragem de solo direta, demanda elevado volume de trabalho em campo que, associado ao tempo e ao custo da análise laboratorial, dificulta sua aplicação em larga escala (Machado et al, 2006 (Adamchuk et al, 2007), com baixo custo (Machado et al, 2006) e capazes de caracterizar indiretamente a variabilidade espacial de atributos de solo e de desempenho vegetal nas áreas agrícolas (Corwin et al, 2006;Adamchuk et al, 2007). Neste sentido, a condutividade elétrica aparente (CEa) tem sido utilizada na agricultura de precisão (AP) como ferramenta preditora de atributos físico-químicos do solo (Lund et al, 1999;Corwin et al, 2006;Machado et al, 2006;.…”