ANALYSIS OF AN ION‐SELECTIVE ELECTRODE BASED METHODOLOGY FOR INTEGRATED ON‐THE‐GO MAPPING OF SOIL pH, POTASSIUM, AND NITRATE CONTENTS

Knowledge of the spatial variation of soil attributes is critical for precision agriculture. On‐the‐go soil sensors have been able to provide relatively high mapping density while assessing this variation. A new ion‐selective electrode (ISE) based approach was developed and tested for simultaneous mapping of soil pH, residual nitrate (NO3 -), and soluble potassium (K+) contents. In this article, results of laboratory experiments investigating the effects of key measurement factors on ISE performance are presented. In addition to four different soils, these factors included: soil/water ratio (SWR), quality of water used for electrode rinsing (QWR) and for ion extraction (QWE), presence of ionic strength adjuster (ISA), and solution agitation (stirring). After the targeted ion activity presented by different soils, SWR was the second most influential factor causing increased measurement variance, while the influence of QWE was only significant for pH measurements. Based on this study, the following measurement parameters were recommended: agitated purified water extraction without ISA, addition of a fixed amount of water (preferably 1:1 soil/water ratio), and use of regular (tap) water for electrode rinsing

The re-emergence of spatial reasoning within primary years mathematics education

This chapter presents a review of the re-emergence of spatial reasoning in Australasia as a potentially powerful but under-utilised bridging mechanism between real-world experiences and mathematics teaching and learning. This is the first time a chapter has been dedicated solely to spatial reasoning in the Mathematics Education Research Group of Australasia’s (MERGA’s) four yearly review and hence the chapter outlines preliminary studies that have formed the basis for the research profiled in the 2016–2019 period. The focus on primary years (Foundation to Year six) mathematics reflects a resurgence of insights from the 1980s amplified as a research focus on the interaction of spatial reasoning and mathematics development during childhood. Because mathematical concept formation is connected to interaction with the three-dimensional world in both a mathematical and non-mathematical way it will be important to spatialise the primary curriculum. The review includes coverage of the work of established Australasian research projects, along with smaller studies and literature emanating from intervention programs that are not nominally spatial, but have spatial underpinnings or spatial reasoning components. While further research is needed to explore teacher knowledge and practice, this chapter acknowledges the valuable contributions and global influence of re-emerging Australasian research