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Toowoomba, Australia

Viscarra Rossel R.A.,CSIRO | Adamchuk V.I.,McGill University | Sudduth K.A.,U.S. Department of Agriculture | McKenzie N.J.,CSIRO | Lobsey C.,Agri Science Queensland
Advances in Agronomy

This chapter reviews proximal soil sensing (PSS). Our intent is for it to be a source of up-to-date information on PSS, the technologies that are currently available and their use for measuring soil properties. We first define PSS and discuss the sampling dilemma. Using the range of frequencies in the electromagnetic spectrum as a framework, we describe technologies that can be used for PSS, including electrochemical and mechanical sensors, telemetry, geographic positioning and elevation, multisensor platforms, and core measuring and down-borehole sensors. Because soil properties can be measured with different proximal soil sensors we provide examples of the alternative techniques that are available for measuring soil properties. We also indicate the developmental stage of technologies for PSS and the current approximate cost of commercial sensors. Our discussion focuses on the development of PSS over the past 30. years and on its current state. Finally, we provide a short list of general considerations for future work and suggest that we need research and development to: (i) improve soil sampling designs for PSS, (ii) define the most suitable technique or combination of techniques for measuring key soil properties, (iii) better understand the interactions between soil and sensor signals, (iv) derive theoretical sensor calibrations, (v) understand the basis for local versus global sensor calibrations, (vi) improve signal processing, analysis and reconstruction techniques, (vii) derive and improve methods for sensor data fusion, and (viii) explore the many and varied soil, agricultural, and environmental applications where proximal soil sensors could be used. PSS provides soil scientists with an effective approach to learn more about soils. Proximal soil sensors allow rapid and inexpensive collection of precise, quantitative, fine-resolution data, which can be used to better understand soil spatial and temporal variability. We hope that this review raises awareness about PSS to further its research and development and to encourage the use of proximal soil sensors in different applications. PSS can help provide sustainable solutions to the global issues that we face: food, water, and energy security and climate change. © 2011 Elsevier Inc. Source

Dickinson G.R.,Agri Science Queensland | Dickinson G.R.,University of The Sunshine Coast | Lee D.J.,University of The Sunshine Coast | Wallace H.M.,University of The Sunshine Coast
Annals of Botany

Background and AimsCorymbia species from different sections hybridize readily, with some of increasing economic importance to plantation forestry. This study explores the locations of reproductive barriers between interspecific Corymbia hybrids and investigates the reproductive success of a wide taxonomic range of C. torelliana hybrid crosses. MethodsPollen, pistil and embryo development were investigated for four C. torelliana crosses (×C. torelliana, ×C. citriodora subsp. citriodora, ×C. tessellaris and ×C. intermedia) using fluorescent and standard microscopy to identify the locations of interspecific reproductive isolating barriers. Corymbia torelliana was also crossed with 16 taxa, representing six of the seven Corymbia sections, both Corymbia subgenera and one species each from the related genera, Angophora and Eucalyptus. All crosses were assessed for capsule and seed yields. Key ResultsInterspecific C. torelliana hybridization was controlled by pre-zygotic reproductive isolating barriers inhibiting pollen adhesion to the stigma, pollen germination, pollen tube growth in the style and pollen tube penetration of the micropyle. Corymbia torelliana (subgenus Blakella, sect. Torellianae) was successfully hybridized with Corymbia species from subgenus Blakella, particularly C. citriodora subsp. citriodora, C. citriodora subsp. variegata, C. henryi (sect. Maculatae) and C. tessellaris (sect. Abbreviatae), and subgenus Corymbia, particularly C. clarksoniana and C. erythrophloia (sect. Septentrionales). Attempted intergeneric hybrids between C. torelliana and either Angophora floribunda or Eucalyptus pellita were unsuccessful. ConclusionsCorymbia hybrids were formed between species from different sections and subgenera, but not with species from the related genera Angophora or Eucalyptus. Reproductive isolation between the interspecific Corymbia hybrid crosses was controlled by early- and late-acting pre-zygotic isolating barriers, with reproductive success generally decreasing with increasing taxonomic distance between parent species. These findings support the monophyly of Corymbia and the close relationships of infrageneric clades. The hybridizing propensity of Corymbia species provides opportunities for breeding but suggests risks of environmental gene flow. © The Author 2012. Published by Oxford University Press on behalf of the Annals of Botany Company. All rights reserved. Source

Misra R.K.,University of Southern Queensland | Padhi J.,University of Southern Queensland | Payero J.O.,Agri Science Queensland
Journal of Hydrology

We used twelve load cells (20. kg capacity) in a mini-lysimeter system to measure evapotranspiration simultaneously from twelve plants growing in separate pots in a glasshouse. A data logger combined with a multiplexer was used to connect all load cells with the full-bridge excitation mode to acquire load-cell signal. Each load cell was calibrated using fixed load within the range of 0-0.8 times the full load capacity of load cells. Performance of all load cells was assessed on the basis of signal settling time, excitation compensation, hysteresis and temperature. Final calibration of load cells included statistical consideration of these effects to allow prediction of lysimeter weights and evapotranspiration over short-time intervals for improved accuracy and sustained performance. Analysis of the costs for the mini-lysimeter system indicates that evapotranspiration can be measured economically at a reasonable accuracy and sufficient resolution with robust method of load-cell calibration. © 2011 Elsevier B.V. Source

In the seasonally dry tropics the productivity of grazing cattle is often constrained by nutrition, particularly during the dry season. An experiment during 2 annual cycles estimated the diet selected by grazing Bos indicus heifers, and their growth and growth responses to a non-protein N supplement. Two drafts (groups) of 2 herds (10 heifers per herd) grazed a pasture consisting of buffel grass (Cenchrus ciliaris) with some legume and edible browse, and herds were offered loose mineral mix (LMM) supplements either without (control) or with urea. Near infrared reflectance spectroscopy measurement of faeces (F.NIRS) was used to estimate each 2 weeks the non-grass and crude protein (CP) concentrations, and DM digestibility (DMD) of the diet selected. Rainfall and diet quality generally followed the seasonal pattern expected for the region and for the seasonally dry tropics. Non-grass (i.e. dicotyledonous species) content averaged 0.13 (S.D. 0.053) of the diet and did not appear to be related to season, but during the first dry season and wet season the urea supplemented heifers selected diets lower (P<0.01 and P<0.05, respectively) in non-grass than the control heifers. Diet quality was generally low during the dry seasons, increased sharply after the seasonal break, and later declined gradually through the wet seasons and wet-dry transition seasons. During the dry seasons average diet CP ranged from 33 to 49 g/kg and diet DMD from 0.480 to 0.507. During the 2 wet seasons CP averaged 94 and 100 g/kg, and the DMD 0.591 and 0.601. The control treatment heifers lost 30 and 32 kg LW during the late dry seasons, and gained 143 and 136 kg during the wet, wet-dry transition and early dry seasons of Drafts 1 and 2, respectively. F.NIRS predicted the daily weight gain (DWG) of the heifers with accuracy useful for management purposes except during the early wet season of Draft 2 when intermittent rains increased diet quality but were insufficient for substantial pasture growth. The urea supplement reduced (P<0.01) heifer LW loss during the dry seasons, but much of this benefit subsequently disappeared due to compensatory growth; net benefit of the urea supplement over the annual cycle was 24 and 14 kg in the 2 drafts. This study demonstrated the capacity of F.NIRS to estimate the diet selected, liveweight change and liveweight responses to a N supplement in grazing cattle. Crown Copyright © 2010. Source

Sceliodes cordalis, eggfruit caterpillar, is an important pest of eggplant in Australia but little information was available on its biology. This study was conducted to determine the effect of temperature on the development on eggplant of eggs, larvae and pupae. Insects were reared at five constant temperatures from 20.5°C to 30.5°C with a 12:12 L : D photoperiod and the thermal summation model was fitted to the developmental rate data. Developmental zeroes and thermal constants of 11.22°C and 61.32 day-degrees for eggs, 12.03°C and 179.60 day-degrees for larvae, and 14.43°C and 107.03 day-degrees for pupae were determined. Several larvae reared at 20.5°C entered diapause. © 2010 The Author. Journal compilation © 2010 Australian Entomological Society. Source

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