Alex B Mcbratney

Alex B Mcbratney
The University of Sydney · Sydney Institute of Agriculture

FAA PhD DSc DScAgr

About

737
Publications
341,430
Reads
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44,219
Citations
Introduction
Trying to figure out how soil ticks or tocks Hoping to make soil more secure for sustainable development
Additional affiliations
January 2017 - December 2017
The University of Sydney
Position
  • Managing Director
January 1989 - present
The University of Sydney
Position
  • Head of Department

Publications

Publications (737)
Article
Full-text available
Soil organic carbon (SOC) sequestration is the transfer of CO2 from the atmosphere into soil organic matter. It, therefore, relies on photo- synthesis and plant-derived carbon (C) input, which usually occurs through biomass production. Janzen et al. (2022) reminded us that when calculating SOC sequestration potential, we should recognise the source...
Article
A fifty-four per cent of the global population is estimated to live disconnected from the natural environment. Furthermore, a large majority of our community unknown how significant is the soil in their life, e.g. the provider of food, energy and medicine, etc. Strengthening this connection is one relevant action toward Soil Security, referred to a...
Article
Full-text available
Improving the amount of organic carbon in soils is an attractive alternative to partially mitigate climate change. However, the amount of carbon that can be potentially added to the soil is still being debated, and there is a lack of information on additional storage potential on global cropland. Soil organic carbon (SOC) sequestration potential is...
Article
Full-text available
Since the early 2000s, digital soil maps have been successfully used for various applications, including precision agriculture, environmental assessments and land use management. Globally, however, there are large disparities in the availability of soil data on which digital soil mapping (DSM) models can be fitted. Several studies attempted to tran...
Article
Full-text available
Recent reviews have identified major themes within regenerative agriculture—soil health, biodiversity, and socioeconomic disparities—but have so far been unable to clarify a definition based on practice and/or outcomes. In recent years, the concept has seen a rapid increase in farming, popular, and corporate interest, the scope of which now sees re...
Article
Full-text available
Soils deliver multiple ecosystem services (ES) that are essential for life on Earth, such as – among others - water and climate regulation, nutrient cycling, and biomass production. Understanding society's perception of the benefits provided by soils can provide valuable insights regarding the human-nature relation. However, despite soil's many con...
Article
An increasing number of soil spectral libraries are being developed at larger extents, including at national, continental, and global scales. However, the prediction accuracy of these libraries was often fairly poor when used on local scales. This study evaluates different strategies to improve the model accuracy of a regional spectral library for...
Article
Full-text available
Quantitative assessment of soil functions requires the characterization of soil capability and condition. Mid-infrared (MIR) spectroscopy has been suggested as a viable alternative to the wet chemistry method. However, the extensive set of soil properties that can be well predicted have yet to be explored. The USDA MIR spectral library contains app...
Article
Although soil degradation has become a global phenomenon that might severely threaten the provision of a large range of ecosystem services, not much is known about the economic value of soil functions such as carbon sequestration and rainfall water infiltration. Knowing these values would be an important input into the recently developed concept of...
Article
Not only do soils provide 98.7% of the calories consumed by humans, they also provide numerous other functions upon which planetary survivability closely depends. However, our continuously increasing focus on soils for biomass provision (food, fiber, and energy) through intensive agriculture is rapidly degrading soils and diminishing their capacity...
Article
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Soil microbial interactions are crucial in performing ecosystem functions. The microbial co-occurrence network could shed a new understanding of microbial functioning as affected by land management. Current studies on microbial community interactions mainly considered surface soils, thus the understanding of the microbial interactions and functions...
Chapter
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Pedometrics is concerned with the application of mathematical and statistical methods to the study of the distribution and genesis of soils. Here, we describe the main areas that pedometric research addresses: distribution of the soil pattern in character space, spatial and spatio-temporal soil variation, quantitative evaluation of the utility and...
Article
Full-text available
Background and objectives Flour millers often produce several flour types from a single wheat grist. Consequently, different specifications characterize each flour. For example, French standards specify six different flour types, each classified by ash content. The proportional blending of different flour streams from a single wheat grist achieves...
Article
Full-text available
Pedometrics, the application of mathematical and statistical methods to the study of the distribution and genesis of soils, has broadened its scope over the past two decades. The primary focus of pedometricians has traditionally been on spatial and spatio-temporal soil inventories with numerical soil classification, geostatistical modelling of spat...
Preprint
Full-text available
Soil organic carbon sequestration (SOCseq) is considered the most attractive carbon capture technology to partially mitigate climate change. However, there is conflicting evidence regarding the potential of SOCseq. The additional storage potential on existing global cropland is missing. SOCseq is region-specific and conditioned by management but mo...
Article
Citizen science is becoming a significant contribution to large scale soil surveys. TeaComposition is a citizen science project introducing the Tea Bag Index (TBI) method to students in Australia to support research on soil decomposition using tea bags (green and rooibos). Soil microbial driven decomposition is an essential soil function that relea...
Article
Full-text available
Background and objectives Flour millers are faced with constraints of having to meet proximate specifications, usually defined by supply contracts, while trying to maximise yield. The study investigated the application of response surface methodology (RSM), in a commercial scale flour mill, as a means of maximizing yield while meeting quality const...
Article
Full-text available
Soil ecosystem services (ES) provide multiple benefits to human well-being, but the failure to appreciate them has led to soil degradation issues across the globe. Despite an increasing interest in the threats to soil resources, economic valuation in this context is limited. Importantly, most of the existing valuation studies do not account for the...
Article
While the use of pesticides continues to rise worldwide, our understanding of the pervasiveness of associated contamination and the health risks humans may be exposed to remain limited to small samples size, based on the geographic scales, the exposed population, or the pesticide types. Using our recent mapping of global pesticide use, we quantify...
Article
Full-text available
The assessment of changes in soil condition and capability requires the identification of a reference state specific to each soil class. This study develops a framework for mapping soil classes that can be used as a reference state. It identifies soil classes that should have undergone similar historic anthropedogenesis, and differentiate, within e...
Article
Full-text available
Soil is a complex system in which biological, chemical and physical interactions take place. The behaviour of these interactions changes in spatial scale from the atomic to the global, and in time. To understand how this system works, soil scientists usually rely on incremental improvements in the knowledge by refinement of theories through hypothe...
Article
Self-citation is a common practice in soil science publications, but can we find a common behaviour in soil science papers, and are there outliers? Here we investigate self-referencing (referencing earlier papers on which a researcher is an author or co-author) for papers published in nine leading soil science journals (Soil Biology and Biochemistr...
Article
Soil entities are generally defined based on soil properties, using morphological, genetic, or utilitarian criteria. Alternatively, soil entities could be characterized by groupings of homogeneous soil-forming factors under the assumption that the dominant soil-forming processes occurring over a time period within each group are similar, and theref...
Article
Full-text available
Digital convergence is helping us to better understand and study the soil. Fixed and mobile sensors, and wireless communication systems aided by the internet produce cheap and abundant streams of digital soil data which can readily be used for modeling and information generation. Here we explore the ways in which digital science and technology have...
Article
Full-text available
In this study, a map of soil parent material is created to support the delineation of soil properties and classes of the Narrabri Shire, NSW. Currently, available information in this study area is geological and lithological maps at a scale of 1:250 000 to 1:1 000 000. These maps are not detailed, and the description in some areas is not accurate....
Article
Full-text available
Pesticides are widely used to protect food production and meet global food demand but are also ubiquitous environmental pollutants, causing adverse effects on water quality, biodiversity and human health. Here we use a global database of pesticide applications and a spatially explicit environmental model to estimate the world geography of environme...
Article
Biochar is recommended as a soil amendment for its positive influence on soil hydrological properties that results in improved soil fertility and crop yield. Much research in the last decade has been conducted in field and laboratory conditions on the effect of biochar on the hydraulic properties of the soil. However, reported results in the litera...
Article
Soil slaking is a highly relevant property in erosion risk management and soil physics in general. Despite its importance and close relation with known soil chemical and physical properties such as soil organic carbon content, pH, sodium content, and soil aggregate stability, it is still underutilized mainly due to the lack of practical methodologi...
Chapter
In digital soil spectroscopy, similarity or distance metrics between soil spectra are necessary for a large number of applications, such as for assessing the reliability of a spectrometer over repeated scans, to search for a similar soil sample based on spectra from a large database, to classify spectra into groups of similar characteristics or mor...
Chapter
Measurement protocols for the same material often vary from laboratory to laboratory. Similarly, while the same spectrometer or sensor can be used between laboratories, the difference in terms of sensor or spectrometer manufacturer is likely to introduce additional variation in the recorded spectrum.
Chapter
Usually, spectra are obtained for all the soil samples available, but only a subset of these samples are sent to the laboratory for chemical and physical analysis. The reason is that spectra are fast and cheap to retrieve, while a single soil analysis (e.g. for soil clay) is relatively slow, and significantly more costly, to obtain. One must select...
Chapter
The most common way of estimating soil properties from pre-processed spectra is by calibrating a statistical model. If the response of the spectra at a particular wavelength follows the Beer-Lambert law, the degree of reflectance at a particular wavelength is proportional to the concentration of a soil property. In this case, a linear model can be...
Book
Full-text available
This book provides a didactic overview of techniques for inferring information from soil spectroscopic data, and the codes in the R programming language for performing such analyses. It is intended for students, researchers and practitioners looking to infer soil information from spectroscopic data, focusing mainly on, but not restricted to, the in...
Article
Full-text available
Hypotheses are of major importance in scientific research. In current applications of machine learning algorithms for soil mapping the hypotheses being tested or developed are often ambiguous or undefined. Mapping soil properties or classes, however, does not tell much about the dynamics and processes that underly soil genesis and evolution. When t...
Article
Soil is a three-dimensional volume with property variability in all three dimensions. In Digital Soil Mapping (DSM), the variation of soil properties down a profile is usually harmonised by the use of the equal-area spline depth function approach. Soil observations at various depth intervals are harmonised to predetermined depth intervals. To creat...
Article
There is a growing interest in the use of soil composition as a form of evidence in food provenance, forensics, biosecurity, and archaeology. Given a soil sample of unknown origin, we should like to know the likely geographical source of that material. In this study, we investigated whether data provided from a rapid and non-destructive sensor can...
Chapter
R provides a convenient and flexible data-analytic environment for soil spectral data. R is a programming language and a software facility for data manipulation, statistical analysis and graphics. R is an implementation of the S language developed at Bell Laboratories (Venables et al. 2009) in the 1980s. While R is an integrated environment for dat...
Chapter
This chapter describes the datasets and R packages used in the book. A total of five datasets are provided and described. They originate from several studies and are made available through a book-associated R package. Most R functions used in this book are either provided in the text or available online in R packages.
Article
Full-text available
Soil aggregate stability is a useful indicator of soil physical health and can be used to monitor condition through time. A novel method of quantifying soil aggregate stability, based on the relative increase in the footprint area of aggregates as they disintegrate when immersed in water, has been developed and can be performed using a smartphone a...
Article
Digital Soil Mapping and Assessment (DSMA) has progressed from challenging traditional soil science paradigms, through small scale prototyping, to large-scale implementation capturing quantitative measures of soil attributes and functions. This paper considers the future for DSMA in the context of a highly uncertain world where high-quality knowled...
Article
Mapping soil resources at a national scale in large countries such as India is a challenge because of limited soil data available and efforts to collect them. Legacy soil information shows promise; but, there are still challenges that need to be addressed. In this study, we deliver the first digital maps of key soil properties down to 2 m depth acr...
Article
Full-text available
Human disturbances to soils can lead to dramatic changes in soil physical, chemical, and biological properties. The influence of agricultural activities on the bacterial community over different orders of soil and at depth is still not well understood. We used the concept of genoform and phenoform to investigate the vertical (down to 1 m depth) soi...
Article
Full-text available
Soil structure is an important physical property that can be degraded by soil tillage, but methods for quantifying soil structure are both few and time consuming. We developed a method for multistripe laser triangulation (MLT) scanning to quantify soil structure that can be accomplished quickly (15 min of scanning per A horizon exposure) in the fie...
Article
Full-text available
The uptake of machine learning (ML) algorithms in digital soil mapping (DSM) is transforming the way soil scientists produce their maps. Within the past two decades, soil scientists have applied ML to a wide range of scenarios, by mapping soil properties or classes with various ML algorithms, on spatial scale from the local to the global, and with...
Article
Full-text available
Australia has advanced the science and application of Digital Soil Mapping (DSM). Over the past decade, DSM in Australia has evolved from being purely research focused to become 'operational', where it is embedded into many soil-agency land resource assessment programs around the country. This has resulted from a series of 'drivers', such as an inc...
Article
This paper provides a history of the investigation of the soils and organic matter of Deli in Sumatra, Indonesia, for growing tobacco in the early 20th century and an interpretation based on current data, knowledge and understanding. We first review some early chemists and agrogeologists’ investigations on the soils of Deli to increase tobacco prod...
Article
Full-text available
The use of complex models such as deep neural networks has yielded large improvements in predictive tasks in many fields including digital soil mapping. One of the concerns about using these models is that they are perceived as black boxes with low interpretability. In this paper we introduce the use of game theory, specifically Shapley additive ex...
Article
Full-text available
Indonesian peatlands are critical to the global carbon cycle, but they also support a large number of local economies. Intense forest clearing and draining in these peatlands is causing severe ecological and environmental impacts. Most studies highlighted increased carbon emission in the region through drought and large‐scale fires, further acceler...
Preprint
Full-text available
Soil aggregate stability is a useful indicator of soil physical health and can be used to monitor condition through time. A novel method to quantify soil aggregate stability, based on the relative increase in the footprint area of aggregates as they disintegrate when immersed in water, has been developed and can be performed using a smartphone appl...
Article
Soil organic matter is important for nutrient exchange in the soil environment, carbon sink, and soil fertility. Soil scientists usually estimate the amount of organic matter in a soil from its carbon content using the 1.724 conversion factor. The origin of this conversion factor is conventionally attributed to Jacob Maarten Van Bemmelen, a Dutch c...
Article
Knowledge of the spatial variation of soil is important in modern agricultural management. To attain this knowledge, ground-based samples are required in combination with many ground-based, air-borne and space-borne sensors from the Internet of Things. Compared to traditional grid and simple random sampling that are designed for fixed sensors, adap...
Preprint
Full-text available
Abstract. The use of complex models such as deep neural networks has yielded large improvements in predictive tasks in many fields including digital soil mapping. Once of the concerns about using these models is that they are perceived as black boxes with low interpretability. In this paper we introduce the use of game theory, specifically SHAP val...
Article
Full-text available
Data sharing and collaboration are critical to solving large-scale problems. The prevailing soil data-sharing model is based on different groups sending their data to a lead party. This model is of a centralised nature and, consequently, results in the participants ceding control and governance over their data to the lead party. Here we explore the...
Preprint
Full-text available
The uptake of machine learning (ML) algorithms in digital soil mapping (DSM) is transforming the way soil scientists produce their maps. Machine learning is currently applied to mapping soil properties or classes much in the same way as other unrelated fields of science. Mapping of soil, however, has unique aspects which require adaptations of the...
Article
Full-text available
The application of machine learning (ML) techniques in various fields of science has increased rapidly, especially in the last 10 years. The increasing availability of soil data that can be efficiently acquired remotely and proximally, and freely available open-source algorithms, have led to an accelerated adoption of ML techniques to analyse soil...
Article
Since the turn of the millennium, digital soil mapping (DSM) has revolutionized the production of fine resolution gridded soil data with associated uncertainty. However, the link to conventional soil maps has not been sufficiently explained nor are the approaches complementary and synergistic. Further training on the digital soil mapping approaches...
Article
Agricultural pesticides can become persistent environmental pollutants. Among many, glyphosate (GLP) is under particular scrutiny because of its extensive use and its alleged threats to the ecosystem and human health. Here, we introduce the first global environmental contamination analysis of GLP and its metabolite, AMPA, conducted with a mechanist...
Article
The formation and stability of aggregates are crucial for soil function. Here we seek to understand the influence of microbial processing on the formation of aggregates in a structurally homogeneous microcosm, treated with two different types of organic matter - glucose and cellulose. The results demonstrated that decomposition of organic matter tr...
Article
Full-text available
Many initiatives try to integrate data from different parties to solve problems that could not be addressed by a sole participant. Despite the well-known benefits of collaboration, concerns of data privacy and confidentiality are still an obstacle that impedes progress in collaborative global research. This work tackles this issue using an online-l...
Preprint
Full-text available
Data sharing and collaboration are critical to solving large scale problems. The prevailing soil data-sharing model is based on different groups sending their data to a lead party. This model is of a centralised nature and, consequently, results in the participants ceding their control and governance over their data to the lead party. Here we explo...
Article
Full-text available
Available georeferenced environmental layers are facilitating new insights into global environmental assets and their vulnerability to anthropogenic inputs. Geographically gridded data of agricultural pesticides are crucial to assess human and ecosystem exposure to potential and recognised toxicants. However, pesticides inventories are often sparse...