Garry J O'Leary

Horsham, Australia · Cropping Systems Modelling

The increasing acidification of soil due to pollution and agricultural management practices is a growing problem worldwide, where food production is already under threat by climate change, more frequent droughts, and soil nutrient depletion. Soil acidification is quantified by pH measurements and is a primary metric for soil health. High soil acidi...

The yield of rain-fed crops needs to increase to meet the requirements of a growing human population. One way to achieve this is to store more rain in the root zone of soils and increase its use by crops. This will be difficult where poorly structured, dense clay subsoils occur. These subsoils limit crop yields by reducing root growth, and the upta...

To better understand how climate change might influence global canola production, scientists from six countries have completed the first inter-comparison of eight crop models for simulating growth and seed yield of canola, based on experimental data from six sites across five countries. A sensitivity analysis was conducted with a combination of fiv...

There is currently great interest in employing Machine Learning (ML) methods for yield prediction in agriculture. Numerous ML methods are available from simple to very complex algorithms, including random forest (RF), support vector machine (SVM) and least absolute shrinkage and selection operator (LASSO) for yield of many crops using existing indu...

Electronic data storage is central to efficient data retrieval and analysis. The need for databases to improve interoperability of data stored is increasing beyond classical spreadsheet data analysis to modeling impacts of climate change scenarios. Management of observations from field experiments and associated synthetic data generated by simulati...

The acidification of soils in agriculture is a growing problem in the world where food production is increasingly under threat by climate change, droughts and nutrient depletion. Field pH color test kits are a cost-effective tool suitable for rapid pH assessments and are used widely in both developed and developing countries. Because the pH test ki...

Climate change impacts to crop production are likely to be greatest in semi-arid regions already constrained by marginal growing conditions. The response of temperate grain crops (wheat, field pea and lentil) to elevated CO2 (eCO2) (550 μmol mol− 1) under semi-arid field conditions was studied over 11 years in the Australian Grains Free Air CO2 Enr...

We compared Support Vector Machine (SVM) and Random Forest (RF) machine learning approaches with the widely used Jarvis-type phenomenological model for predicting stomatal conductance (gs) in wheat (Triticum aestivum L.) using historical measurements collected in the Australian Grains Free-Air CO2 Enrichment (AGFACE) facility. The machine learning-...

Intercropping is considered by its advocates to be a sustainable, environmentally sound, and economically advantageous cropping system. Intercropping systems are complex, with non-uniform competition between the component species within the cropping cycle, typically leading to unequal relative yields making evaluation difficult. This paper is a rev...

Atmospheric carbon dioxide concentrations [CO2] are increasing steadily. Some reports have shown that root growth in grain crops is mostly stimulated in the topsoil rather than evenly throughout the soil profile by e[CO2], which is not optimal for crops grown in semi-arid environments with strong reliance on stored water. An experiment was conducte...

Plant responses to rising atmospheric carbon dioxide (CO2) concentrations, together with projected variations in temperature and precipitation will determine future agricultural production. Estimates of the impacts of climate change on agriculture provide essential information to design effective adaptation strategies, and develop sustainable food...

Understanding sources of uncertainty in climate–crop modelling is critical for informing adaptation strategies for cropping systems. An understanding of the major sources of uncertainty in yield change is needed to develop strategies to reduce the total uncertainty. Here, we simulated rain-fed wheat cropping at four representative locations in Chin...

The yield of rain-fed crops needs to increase to meet the requirements of a growing human population. One way to achieve this is to store more rain in the root zone of soils and increase its use by crops. This will be difficult where poorly structured, dense clay subsoils occur. These subsoils limit crop yields by reducing root growth, and the upta...

Early vigour in wheat is a trait that has received attention for its benefits reducing evaporation from the soil surface early in the season. However, with the growth enhancement common to crops grown under elevated atmospheric CO2 concentrations (e[CO2]), there is a risk that too much early growth might deplete soil water and lead to more severe t...

A method is described for integrating crop modelling and production economics to quantify optimum applications of multiple nutrients and yield gaps. The method is demonstrated for crop production in the high‐rainfall zone of southern Australia. Data from a biophysical crop model were used to overcome the persistent problem of inadequate experimenta...

We developed a photoperiod-corrected thermal model that can predict wheat phenology based solely on the combination of photoperiod (Ppd) and vernalisation (Vrn) alleles to identify the phenological suitability of germplasm across the cropping region in southern Australia. More than 200 wheat genotypes that vary in combinations of Ppd and Vrn allele...

Reducing the number of tillers per plant using a tiller inhibition (tin) gene has been considered as an important trait for wheat production in dryland environments. We used a spatial analysis approach with a daily time‐step coupled radiation and transpiration efficiency model to simulate the impact of the reduced‐tillering trait on wheat yield und...

Using ensembles of models to study crop adaptation to changing climate appears to be an intuitive approach. For a group of similar deterministic models we expect the ensemble error would be lower than any single model mean error. By definition, increasing the number of observations to estimate the mean should reduce expected error inversely with th...

Grain number (GN) is determined by spike growth rate (SGR), fruiting efficiency (FE) and the duration of spike growth period (Ds). However, these three traits are not independent of each other and therefore quantifying their relative contribution to GN is important for improving yield potential. This study aimed to model GN as a function of SGR, FE...

Elevated atmospheric CO2 concentration (e[CO2]) stimulates biomass and yield of crops through the 'CO2 fertilisation effect'. Stimulation of biomass with supplemental nitrogen (N) under e[CO2] may influence water use dynamics, which is particularly important in relatively low yielding dryland Mediterranean regions where timing of water limitations...

Elevated CO2 (e[CO2]) can stimulate N2 fixation of legumes via increases in photosynthetic carbon supply to symbionts. N2 fixation mechanisms are highly sensitive to drought but little is known about changes in nodule metabolism under e[CO2] and water restriction. To address these challenges, N2 fixation and changes of carbohydrate and nitrogen met...

The stimulatory effect of elevated [CO2] (e[CO2]) on crop production in future climates is likely to be cancelled out by predicted increases in average temperatures. This effect may become stronger through more frequent and severe heat waves, which are predicted to increase in most climate change scenarios. Whilst the growth and yield response of s...

Maintaining high quality grain from Australian dryland production systems is under threat from three main environmental factors. These are rising atmospheric CO2 concentrations, increasing frequency of drought and higher temperatures both as average increase and more frequent heat waves. For wheat, we propose a new hypothesis and simulation model f...

Long season, winter-type canola cultivars have the potential for significantly higher yields than short-season, spring-type canola, yet until recently, breeding of new canola cultivars in Australia has focussed on spring-type canola. This has been to accommodate the typically drier, warmer conditions across the Australian cropping belt where long-s...

We tested the hypothesis that lengthening the duration between the terminal spikelet stage of development and anthesis (referred to here as the construction-phase duration, CPD) will increase yield per unit area in wheat (Triticum aestivum L.). Field experiments were undertaken at 17 sites across the high-rainfall zone of south-eastern and Western...

The potential impact of elevated atmospheric carbon dioxide concentration ([CO2]) and future climate predicted for 2050 on wheat marketing grades and grain value was evaluated for Victoria, Australia. This evaluation was based on measured grain yield and quality from the Australian Grains FACE program and commercial grain delivery data from Victori...

This chapter discusses the importance of the management of water supply within rainfed agricultural productions systems in already dry regions that face the prospect of further decreasing rainfall from climate change. It examines the interactive effects of water supply with high temperature and rising atmospheric CO2 concentrations on grain product...

Efforts to limit global warming to below 2°C in relation to the pre‐industrial level are under way, in accordance with the 2015 Paris Agreement. However, most impact research on agriculture to date has focused on impacts of warming >2°C on mean crop yields, and many previous studies did not focus sufficiently on extreme events and yield interannual...

Session A9: Optimisation and Analytics in Industry 4.0, IoT and Mechatronics Significant resources are being directed towards the development of bio-regenerative food systems by NASA and others to support long-duration space flights and to decrease the mass and volume of prepackaged supplies (Perchonok et al, 2012). The space mission is supported b...

Towards controlled-environment agriculture on Mars: why it is necessary and how it is possible Garry J O’Leary 1 and Kurt K. Benke 2,3 1 Department of Economic Development, Jobs, Transport and Resources (DEDJTR), State Government of Victoria, Horsham Centre, 110 Natimuk Rd, Horsham, Victoria, 3083, Australia. 2 Department of Economic Development...

Frost can significantly reduce production of field crops grown in Mediterranean‐type environments, where significant economic losses for Australian wheat occur annually. If non‐destructive sensors could make rapid, spatial assessment of frost damage, this could limit economic losses through timely management decisions. This paper reports on a metho...

Results Objectives • Develop an understanding of how photosynthesis of different functional group response to e[CO 2 ]. • Understanding different abiotic factors (temperature, drought, and nitrogen) associated with the photosynthetic response to e[CO 2 ]. • Understanding how photosynthetic acclimation to e[CO 2 ] is associated with leaf nitrogen.

Wheat grain protein concentration is an important determinant of wheat quality for human nutrition that is often overlooked in efforts to improve crop production. We tested and applied a 32‐multi‐model ensemble to simulate global wheat yield and quality in a changing climate. Potential benefits of elevated atmospheric CO2 concentration by 2050 on g...

A recent innovation in assessment of climate change impact on agricultural production has been to use crop multi model ensembles (MMEs). These studies usually find large variability between individual models but that the ensemble mean (e‐mean) and median (e‐median) often seem to predict quite well. However few studies have specifically been concern...

Heat waves have a significant impact on crop production and quality of many staple grains including wheat. Under climate change, changing weather patterns including greater temperature volatility are also likely to further affect yield stability. Simulation modeling provides a powerful tool to investigate the interactive effects of abiotic factors...

This study investigated crop water use of wheat grown in a dryland Mediterranean-type environment under elevated atmospheric CO2 concentrations ([CO2]). Two related cultivars, contrasting in agronomic features (cvs. Scout and Yitpi; Scout has good early vigour and high transpiration efficiency), were grown under ambient [CO2] (a[CO2], ∼400 μmol mol...

Through stimulation of root growth, increasing atmospheric CO2 concentration ([CO2]) may facilitate access of crops to sub-soil water, which could potentially prolong physiological activity in dryland environments, particularly because crops are more water use efficient under elevated [CO2] (e[CO2]). This study investigated the effect of drought in...

P-values of multiple comparisons (post-hoc Tukey´s HSD test) of growth and yield parameters of wheat at maturity among CO2 (a[CO2] and e[CO2]) and water treatments (WW, WD, DW and DD). (DOCX)

P-values of multiple comparisons (post-hoc Tukey´s HSD test) of above- and belowground biomass (sum of top and bottom root dry weight) of wheat at anthesis among CO2 (a[CO2] and e[CO2]) and water treatments (WW, WD, DW and DD). (DOCX)

P-values of multiple comparisons (post-hoc Tukey´s HSD test) of leaf gas exchange parameters among CO2 (a[CO2] and e[CO2]) and water treatments (WW, WD, DW and DD). (DOCX)

Climate change (CC) presents a challenge for the sustainable development of wheat production systems in Australia. This study aimed to (1) quantify the impact of future CC on wheat grain yield for the period centred on 2030 from the perspectives of wheat phenology, water use and water use efficiency (WUE) and (2) evaluate the effectiveness of chang...

Increased biomass and yield of plants grown under elevated [CO2] (e [CO2]) often corresponds to decreased grain N concentration ([N]), diminishing nutritional quality of crops. Legumes through their symbiotic N2‐fixation may be better able to maintain biomass [N] and grain [N] under e [CO2], provided N2‐fixation is stimulated by e [CO2] in line wit...

This study investigated crop water use of wheat grown in a dryland Mediterranean-type environment under elevated atmospheric CO2 concentrations ([CO2]). Two related cultivars, contrasting in agronomic features (cvs. Scout and Yitpi; Scout has good early vigour and high transpiration efficiency), were grown under ambient [CO2] (a[CO2], ∼400 μmol mol...

The data set reported here includes the part of a Hot Serial Cereal Experiment (HSC) experiment recently used in the AgMIP-Wheat project to analyze the uncertainty of 30 wheat models and quantify their response to temperature. The HSC experiment was conducted in an open-field in a semiarid environment in the southwest USA. The data reported herewit...

Atmospheric CO2 concentrations have been increasing from ~280 to 405 mmol mol⁻¹ air from the preindustrial era until now. As this rise is a major driver for global warming and increasing variability in weather patterns, it is predicted that the frequency and duration of heat waves will continue to increase in many arable regions during this century...

Nendel 38 | Jørgen Eivind Olesen 37 | Taru Palosuo 44 | John R. Porter 42,45,46 | Eckart Priesack 39 | Dominique Ripoche 47 | Mikhail A. Semenov 48 | Claudio Stöckle 17 | Pierre Stratonovitch 48 | Thilo Streck 33 | Iwan Supit 49 | Fulu Tao 50,44

Climate change threatens global wheat production and food security, including the wheat industry in Australia. Many studies have examined the impacts of changes in local climate on wheat yield per hectare, but there has been no assessment of changes in land area available for production due to changing climate. It is also unclear how total wheat pr...

Higher transpiration efficiency (TE) has been proposed as a mechanism to increase crop yields in dry environments where water availability usually limits yield. The application of a coupled radiation and transpiration efficiency simulation model shows wheat yield advantage of a high TE cultivar (cv. Drysdale) over its almost identical low TE parent...

The impact of elevated [CO2] (e[CO2]) on crops often includes a decrease in their nutrient concentrations where reduced transpiration-driven mass flow of nutrients has been suggested to play a role. We used two independent approaches, a Free-Air CO2 Enrichment (FACE) experiment in the South Eastern wheat belt of Australia and a simulation study emp...

The use of different downscaling methods (DSMs) to generate downscaled daily climate (DDC) data for assessing climate change impacts on wheat cropping systems was investigated. DDC data were generated from SRES A2 emission scenario simulations of seven global climate models (GCMs) using two different change factor methods, denoted as DTS and RSC, a...

Nature Plants 3, 17102 (2017); published online 17 July 2017; corrected online 27 September 2017.

Increasing atmospheric CO2 concentration ([CO2]) has profound effects on plant growth, yield and water use. Elevated atmospheric [CO2] (e[CO2]) increases above-and below ground biomass production of wheat. The increased root growth under e[CO2] may allow the extraction of subsoil water, which is especially important in hot and dry Mediterranean con...

S1 Brief description of the four downscaling methods The four downscaling methods used in the study are briefly descripted below. RCS: Raw change scaling method (RCS) is a simple CF scaling method for rapid impact assessment (Diaz-Nieto and Wilby, 2005). We used this to generate daily climate data for 2041-2060. Simulated changes in the annual mean...

Increasing the accuracy of crop productivity estimates is a key element in planning adaptation strategies to ensure global food security under climate change. Process-based crop models are effective means to project climate impact on crop yield, but have large uncertainty in yield simulations. Here, we show that variations in the mathematical funct...

Atmospheric CO2 concentrations ([CO2]) are predicted to increase from current levels of about 400 ppm to reach 550 ppm by 2050. The direct benefits of elevated [CO2] (e[CO2]) to plant growth appear to be greater under low rainfall conditions, but there are few field (Free Air CO2 Enrichment or FACE) experimental set-ups that directly address semi-a...

Nitrogen (N) input into food production is environmentally sensitive and economically significant, making efficient N use an important goal in agricultural practice and in plant breeding. In cereals, grain N concentration [N] is an important component of grain quality and nutritional value. Increasing atmospheric CO2 concentration [CO2] will not on...

Martre P, Reynolds MP, Asseng S, Ewert F, Alderman PD, Cammarano D, Maiorano A, Ruane AC, Aggarwal PK, Anothai J, Basso B, Biernath C, Challinor AJ, De Sanctis G, Doltra J, Dumont B, Fereres E, Garcia-Vila M, Gayler S, Hoogenboom G, Hunt LA, Izaurralde RC, Jabloun M, Jones CD, Kassie BT, Kersebaum KC, Koehler AK, Müller C, Kumar SN, Liu B, Lobell D...

Atmospheric CO2 ([CO2]) has been increasing since the industrial revolution and is predicted to rise from currently ~400 to ~550 ppm by 2050. This rapid increase in [CO2] enhances plant growth and yield but decreases stomatal conductance (gs), leading to enhanced crop water use efficiency. Crop responses to elevated [CO2] (eCO2) in dry-land Medite...

We compare 27 wheat models' yield responses to interannual climate variability, analyzed at locations in Argentina, Australia, India, and The Netherlands as part of the Agricultural Model Intercomparison and Improvement Project (AgMIP) Wheat Pilot. Each model simulated 1981–2010 grain yield, and we evaluate results against the interannual variabili...

To improve climate change impact estimates and to quantify their uncertainty, multi-model ensembles (MMEs) have been suggested. Model improvements can improve the accuracy of simulations and reduce the uncertainty of climate change impact assessments. Furthermore, they can reduce the number of models needed in a MME. Herein, 15 wheat growth models...

Wheat production will be impacted by increasing concentration of atmospheric CO2 [CO2], which is expected to rise from about 400 μmol mol-1 in 2015 to 550 μmol mol-1 by 2050. Changes to plant physiology and crop responses from elevated [CO2] (e[CO2]) are well documented for some environments, but field-level responses in dryland Mediterranean envir...

Maintaining grain quality of wheat under climate change is critical for human nutrition, end-use functional properties, as well as commodity value. This paper reviews the current knowledge of high temperature and elevated atmospheric CO2 on whole-grain and functional properties of wheat. It also considers the utility of contemporary crop models for...

In the High Rainfall Zone (HRZ) of southern Australia, long-season winter canola types have been commercially available only since 2011. Experiments in this region show that these varieties can provide improvements in grain yield over spring types of >20% because of their ability to make better use of the longer growing season. However, within this...

Australia’s “Direct Action” climate change policy relies on purchasing greenhouse gas abatement from projects undertaking approved abatement activities. Management of soil organic carbon (SOC) in agricultural soils is an approved activity, based on the expectation that land use change can deliver significant changes in SOC. However, there are conce...

The data set includes a current representative management treatment from detailed, quality-tested sentinel field experiments with wheat from four contrasting environments including Australia, The Netherlands, India and Argentina. Measurements include local daily climate data (solar radiation, maximum and minimum temperature, precipitation, surface...