ORCID Profile
0000-0001-6060-3290
Current Organisation
CSIRO
Does something not look right? The information on this page has been harvested from data sources that may not be up to date. We continue to work with information providers to improve coverage and quality. To report an issue, use the Feedback Form.
Publisher: CSIRO Publishing
Date: 2006
DOI: 10.1071/SR05138
Abstract: Most of the nitrogen (N) used by Australian crops is mineralised from the residues of previous crops and pastures. Net N mineralisation was studied in 2 field experiments in southern NSW, one comparing different residue-management and tillage systems during continuous cropping and the other comparing residues of annual and perennial pastures in a pasture–crop system. After 14 years of continuous cropping, soil total N concentration had decreased by 50%. Neither stubble retention nor direct drilling affected potential N mineralisation or the decrease in total N. However, soil mineral N in the field was greater after direct drilling than cultivation and greater after stubble retention than stubble burning. There were 2 reasons for the discrepancy. One was because retained stubble conserved soil water, leading to periods of increased mineralisation. The other was that direct drilling and stubble retention reduced growth and N uptake by crops. In contrast to the similar rates of potential mineralisation under different tillage and stubble systems, there were significant differences following different pasture species. In a 5-year study of a pasture–crop system we measured net mineralisation following annual pasture based on subterranean clover and perennial pasture based on lucerne and/or the grasses phalaris and cocksfoot. Mineralisation generally decreased with number of years after pasture removal. Previous lucerne pastures led to slow net mineralisation in the first year after removal, apparently because of immobilisation by high C : N residues. Mineralisation in soil containing perennial grass residues was the highest measured. This high rate may be due to redistribution of N to the topsoil by roots of perennial grasses. The comparison of continuous crop and pasture–crop systems showed that the decline in soil N supply was not prevented by direct drilling and stubble conservation, but N mineralisation was increased by pastures, particularly those containing perennial grasses.
Publisher: Wiley
Date: 12-03-2022
DOI: 10.1111/JAC.12588
Abstract: Prospects for improving the productivity of species mixtures in transitions between phases by changing row configuration at sowing were examined in two series of field experiments in rain‐fed, semi‐arid environments in south‐eastern Australia. The first series explored how the choice of cover crop and use of alternate drill row configurations affected establishment and yields of sward components in the transition from a cropping into a pasture phase. Cover‐crop species included wheat ( Triticum aestivum L.), barley ( Hordeum vulgare L.), canola ( Brassica napus L.) and lupins ( Lupinus augustifolius L.), each sown in mixed or alternate drill rows with lucerne ( Medicago sativa L.) and subterranean clover ( Trifolium subterraneum L.). The second series of experiments examined the productivity implications when returning from the pasture phase back into cropping following 10 contrasting pastures sown to various combinations of lucerne, subterranean clover or phalaris ( Phalaris aquatica L.) sown in mixed, alternate (1:1) or double skip (1:2) row configurations in the absence of cover crops. All experiments were sown on a 0.25‐m row spacing. In the transition into the pasture phase, grain yields of cover crops in the mixed drill row treatment were similar to those achieved by crops grown in the absence of pasture species but were reduced by an average of 24% in the alternate drill row configuration. Canola and lupin crop biomass were lower, compared with wheat and barley, leading to increased pasture yields in year 1, highlighting an opportunity for increased use of these species as cover/companion crops in semi‐arid environments. Pasture yields beyond year 1 were reduced by ~20% in the alternate drill row treatments compared with where species were sown in mixed drill rows, with greater yield differences under more favourable growing conditions. This response largely reflected yield reductions in lucerne where it was concentrated in fewer drill rows. The alternate drill row configuration increased the abundance of subterranean clover in year 1, but this species remained a minor component of all swards beyond the establishment year. In the transition into the cropping phase, effects on grain quality could only be attributed to row configuration of the previous pasture to the extent that row configuration changed pasture composition. Grain size was smallest and protein concentration highest where previous pastures contained both lucerne and subterranean clover without phalaris. Taken together, there was little advantage in total productivity attributable to spatially separating species in drill rows at sowing.
Publisher: Elsevier BV
Date: 09-2018
Publisher: CSIRO Publishing
Date: 2001
DOI: 10.1071/EA99139
Abstract: Experimental estimates of amounts of foliage nitrogen (N) fixed in Australian pastures range from 2 to 284 kg N/ha.year for annual and perennial legumes growing in temperate and tropical environments. Differences in the amounts of N2 fixed relate primarily to the legume content and net productivity of pastures. On average, close to 20–25 kg of shoot N are fixed for every tonne of legume herbage dry matter produced across a wide range of environments. Strategies likely to improve the potential for N2 fixation include: (i) rhizobial inoculation at time of first sowing a new legume species (ii) amelioration of nutritional problems (applications of superphosphate or lime) (iii) manipulation of pasture composition (herbicide applications to remove grasses in annual pastures in the year prior to cropping) and (iv) including lucerne to offset the year-to-year variability in N2 fixation inputs from annual legumes. However, pasture response to such management treatments and the subsequent availability of soil mineral N may be modified by livestock effects on nutrient cycling, pasture productivity and botanical composition. Conclusions about the relative size of the contributions of fixed N to the N economies of Australian farming systems depend on whether or not estimates of fixed N are included for nodulated roots. Thus residual net inputs of fixed N after each year of a legume-based pasture are generally rated sufficient to balance the N removed by at least 1 subsequent wheat crop provided estimates of below-ground N are included in calculations. Pasture type influences the duration of subsequent rotational benefits and while residual effects on mineral N are commonly exhausted within 2 years after an annual legume-based pasture phase, N carry-over following lucerne generally lasts considerably longer.
Publisher: CSIRO Publishing
Date: 2004
DOI: 10.1071/EA03076
Abstract: Biopores left in the soil by perennial and annual pastures and their effects on macroporosity, water infiltration and the water use and productivity of subsequent wheat and canola crops were investigated in a field experiment on a Sodosol in southern New South Wales. Phases of both lucerne (4 years) and phalaris (10 years) improved the macroporosity and water infiltration into the dense B horizon compared with continuous annual crops and pastures. After removal of lucerne and phalaris, the subsoil ( 12 cm depth) contained similar numbers of pores 2 mm diameter (228 and 190/m2, respectively) compared with a mean of 68/m2 after annual crops. However water infiltration rate after lucerne was greater than after phalaris, apparently because of more numerous pores 4 mm, rather than a change in total porosity. The subsoil after phalaris on the other hand contained more pores 0.3 mm in diameter and a higher total porosity, possibly because of more roots around this diameter, and a longer period without traffic or cultivation. The number of lucerne biopores in the subsoil remained unchanged (170–180/m2) for at least 2 crops after the lucerne was removed although the average size decreased. The volume of water extracted from the subsoil by crops following lucerne was similar to that following annual crop asture for 10 of the 12 crop comparisons made. For 2 of the crops, more subsoil water (22 and 24 mm) was used after lucerne than after annuals, and in 1 season this was associated with higher yield of canola. During the 3-year study there was no winter waterlogging or post-anthesis water stress, so there was little opportunity for yield responses to improved subsoil structure. The results confirm speculation that the unfavourable structure of dense subsoils can be improved by the biological action of perennial pasture roots, although reduced wheel traffic and cultivation during the pasture phases may also play a role. Further studies will be necessary to demonstrate associated yield improvements.
Publisher: Wiley
Date: 13-03-2021
Abstract: Accurately quantifying rates and patterns of biological nitrogen fixation (BNF) in terrestrial ecosystems is essential to characterize ecological and biogeochemical interactions, identify mechanistic controls, improve BNF representation in conceptual and numerical modelling, and forecast nitrogen limitation constraints on future carbon (C) cycling. While many resources address the technical advantages and limitations of different methods for measuring BNF, less systematic consideration has been given to the broader decisions involved in planning studies, interpreting data, and extrapolating results. Here, we present a conceptual and practical road map to study design, study execution, data analysis and scaling, outlining key considerations at each step. We address issues including defining N‐fixing niches of interest, identifying important sources of temporal and spatial heterogeneity, designing a s ling scheme (including method selection, measurement conditions, replication, and consideration of hotspots and hot moments), and approaches to analysing, scaling and reporting BNF. We also review the comparability of estimates derived using different approaches in the literature, and provide s le R code for simulating symbiotic BNF data frames and upscaling. Improving and standardizing study design at each of these stages will improve the accuracy and interpretability of data, define limits of extrapolation, and facilitate broader use of BNF data for downstream applications. We highlight aspects—such as quantifying scales of heterogeneity, statistical approaches for dealing with non‐normality, and consideration of rates versus ecological significance—that are ripe for further development.
Publisher: Oxford University Press (OUP)
Date: 24-03-2021
DOI: 10.1093/BJS/ZNAB101
Abstract: Preoperative SARS-CoV-2 vaccination could support safer elective surgery. Vaccine numbers are limited so this study aimed to inform their prioritization by modelling. The primary outcome was the number needed to vaccinate (NNV) to prevent one COVID-19-related death in 1 year. NNVs were based on postoperative SARS-CoV-2 rates and mortality in an international cohort study (surgical patients), and community SARS-CoV-2 incidence and case fatality data (general population). NNV estimates were stratified by age (18–49, 50–69, 70 or more years) and type of surgery. Best- and worst-case scenarios were used to describe uncertainty. NNVs were more favourable in surgical patients than the general population. The most favourable NNVs were in patients aged 70 years or more needing cancer surgery (351 best case 196, worst case 816) or non-cancer surgery (733 best case 407, worst case 1664). Both exceeded the NNV in the general population (1840 best case 1196, worst case 3066). NNVs for surgical patients remained favourable at a range of SARS-CoV-2 incidence rates in sensitivity analysis modelling. Globally, prioritizing preoperative vaccination of patients needing elective surgery ahead of the general population could prevent an additional 58 687 (best case 115 007, worst case 20 177) COVID-19-related deaths in 1 year. As global roll out of SARS-CoV-2 vaccination proceeds, patients needing elective surgery should be prioritized ahead of the general population.
Publisher: Springer Science and Business Media LLC
Date: 19-10-2011
Publisher: Elsevier BV
Date: 06-2014
Publisher: CSIRO Publishing
Date: 25-03-2021
DOI: 10.1071/CP20270
Abstract: Spatial separation of species at sowing has been proposed as a means of managing interspecific competition in mixed swards. This study examined the effect of row configuration on persistence of lucerne (Medicago sativa L.) in pastures and pasture–cover crop mixtures at three sites in the Central West, and in pasture mixtures at three sites in the Riverina, New South Wales, Australia. Lucerne density, taproot diameter, groundcover, and spatial distribution relative to the original drill row were measured at all sites, and plant-available soil water and light interception during spring were assessed at some sites. Row configuration (alternate or mixed drill rows) did not affect lucerne persistence however, where lucerne seed was concentrated in every third drill row, intraspecific competition led to increased lucerne mortality. This was estimated to occur at densities plants/m drill row. A lucerne density of ~55 plants/m2 in every or alternate drill rows (at row spacings of 250 mm) would likely achieve maximum lucerne production in the semi-arid environments tested, subject to the chance event of favourable conditions in the period after sowing that would maintain that density (e.g. cumulative summer rainfall mm and summer day degrees °C in 2 years at Cowra). The presence of a cover crop in the establishment year reduced lucerne density by 39% compared with pasture only, regardless of row configuration. Changed row configuration did not reduce competition for light under a cover crop, but there was a small increase in available soil water of up to 4.9 mm in the 0–1.15 m depth, mainly during the first summer, where pasture was sown in alternate compared with mixed drill rows with a cover crop. Soil was drier in pasture-only treatments than those with a cover crop, attributable to increased lucerne density and lower levels of litter cover on the soil surface. Pasture species remained largely confined to the original drill row, especially in drier environments, highlighting the importance of narrower row spacings for pasture establishment. In addition, we determined a mathematical relationship between lucerne density and the non-destructive measure of basal frequency this relationship could be applied in mature lucerne stands with densities ≤80 plants/m2.
Publisher: CSIRO Publishing
Date: 28-02-2023
DOI: 10.1071/CP22370
Abstract: Context Herbicide-resistant annual ryegrass (Lolium rigidum ARG) is a major weed of commercial significance globally, including no-till wheat-based production systems in south-eastern Australia. Aims To compare the cost-effectiveness of different crop sequences and intensities of weed management to control ARG in rainfed grain production. Methods Two on-farm studies in southern New South Wales, Australia, compared the effect of combinations of 3-year crop-sequence options (continuous wheat, 1- or 2-years of break crops), conservative or aggressive weed-control measures, hay cuts, legume brown manure (BM), and/or weed-free winter fallow on in-crop ARG infestations and soil seedbanks. Gross margins were calculated for each combination of treatments to compare system economic performance. Key results Double-breaks consisting of two consecutive broadleaf crops, or canola–cereal hay, were frequently the most profitable and effective ARG control strategies. Single canola or lupin crops, BM, cereal hay, and fallow all significantly reduced subsequent in-crop ARG and seedbank numbers compared with continuous wheat. Aggressive in-crop control measures in wheat were more expensive than those applied to break crops. Gains in ARG control could be lost by a single year of poor weed control. Conclusions High levels of control ( %) over three consecutive seasons are required to reduce ARG seedbanks, and this is most cost-effectively achieved with erse crop sequences. Implications Farmers with high populations of ARG can reduce seedbanks by growing three crops sequentially that achieve complete weed seed control. This must be followed with ongoing high levels of control in subsequent years to keep ARG seedbanks low.
Publisher: CSIRO Publishing
Date: 2016
DOI: 10.1071/CP16211
Abstract: Despite the potential productivity benefits, intercrops are not widely used in modern, mechanised grain cropping systems such as those practised in Australia, due to the additional labour required and the added complexity of management (e.g. harvesting and handling of mixed grain). In this review we investigate this dilemma using a two-dimensional matrix to categorise and evaluate intercropping systems. The first dimension describes the acquisition and use of resources in complementary or facilitative interactions that can improve resource use efficiency. The outcome of this resource use is often quantified using the land equivalent ratio (LER). This is a measure of the relative land area required as monocultures to produce the same yields as achieved by an intercrop. Thus, an LER greater than 1 indicates a benefit of the intercrop mixture. The second dimension describes the benefits to a farming system arising not only from the productivity benefits relating to increased LER, but from other often unaccounted benefits related to improved product quality, rotational benefits within the cropping system, or to reduced business risks. We contend that a successful intercrop must have elements in both dimensions. To date most intercropping research has considered only one of these two possible dimensions. Intercrops in large, mechanised, rain-fed farming systems can comprise those of annual legumes with non-legume crops to improve N nutrition, or other species combinations that improve water use through hydraulic redistribution (the process whereby a deep-rooted plant extracts water from deep in the soil profile and releases a small proportion of this into the upper layers of the soil at night), or alter disease, pest or weed interactions. Combinations of varieties within cereal varieties were also considered. For our focus region in the southern Australian wheatbelt, we found few investigations that adequately dealt with the systems implications of intercrops on weeds, diseases and risk mitigation. The three main intercrop groups to date were (1) ‘peaola’ (canola-field pea intercrops) where 70% of intercrops (n = 34) had a 50% productivity increase over the monocultures, (2) cereal-grain legume intercrops (n = 22) where 64% showed increases in crop productivity compared with monocultures and (3) mixtures of cereal varieties (n = 113) where there was no evidence of a productivity increase compared with the single varieties. Our review suggests that intercropping may have a role in large rain-fed grain cropping systems, based on the biophysical benefits revealed in the studies to date. However, future research to develop viable intercrop options should identify and quantify the genotypic differences within crop species for adaptation to intercropping, the long-term rotational benefits associated with intercrops, and the yield variability and complexity-productivity trade-offs in order to provide more confidence for grower adoption. Farming systems models will be central to many of these investigations but are likely to require significant improvement to capture important processes in intercrops (e.g. competition for water, nutrients and light).
Publisher: CSIRO Publishing
Date: 2015
DOI: 10.1071/CP14252
Abstract: Wheat crops usually yield more when grown after another species than when grown after wheat. Quantifying the yield increase and explaining the factors that affect the increase will assist farmers to decide on crop sequences. This review quantifies the yield increase, based on comparisons of wheat growing after a break crop with wheat after wheat. The mean increase in wheat yield varied with species of break crop, ranging from 0.5 t ha–1 after oats to 1.2 t ha–1 after grain legumes. Based on overlapping experiments, the observed ranking of break-crop species in terms of mean yield response of the following wheat crop was: oats canola ≈ mustard ≈ flax field peas ≈ faba beans ≈ chickpeas ≈ lentils ≈ lupins. The mean additional wheat yield after oats or oilseed break crops was independent of the yield level of the following wheat crop. The wheat yield response to legume break crops was not clearly independent of yield level and was relatively greater at high yields. The yield of wheat after two successive break crops was 0.1–0.3 t ha–1 greater than after a single break crop. The additional yield of a second wheat crop after a single break crop ranged from 20% of the effect on a first wheat crop after canola, to 60% after legumes. The mean yield effect on a third wheat crop was negligible, except in persistently dry conditions. The variability of the break-crop effect on the yield of a second wheat crop was larger than of a first wheat crop, particularly following canola. We discuss the responses in relation to mechanisms by which break crops affect soil and following crops. By quantifying the magnitude and persistence of break-crop effects, we aim to provide a basis for the decision to grow continuous cereal crops, strategic rotations or tactically selected break crops. In many wheat-growing areas, the large potential yield increases due to break crops are not fully exploited. Research into quantifying the net benefits of break crops, determining the situations where the benefits are greatest, and improving the benefits of break crops promises to improve the efficiency of wheat-based cropping systems.
Publisher: CSIRO Publishing
Date: 2012
DOI: 10.1071/CP11320
Abstract: Broadleaf break crops improve cereal yield through disease and weed control, increased nitrogen (N) availability and other mechanisms. In the rainfed farming systems of Australia the magnitude of the yield benefit is highly variable, yet is a major driver for adoption of break crops which are often less profitable and more risky than cereals. Declining area of break crops throughout Australia has re-ignited interest in better understanding the circumstances in which break-crop benefits can be maximised from a farming systems perspective. We compiled and analysed a database of 167 crop sequence experiments conducted throughout Western Australia in the period 1974–2007 to evaluate the impact on wheat (Triticum aestivum L.) grain yield from the use of narrow-leafed lupin (Lupinus angustifolius L.), field pea (Pisum sativum L.), canola (Brassica napus L.) or oats (Avena sativa L.), or following a long fallow where no crop had been sown the previous year. Adjusted for the years in which each was represented the average yield benefit to wheat compared with wheat after wheat was 0.60, 0.45, 0.40, 0.35 and 0.30 t/ha following lupin, field pea, canola, oats or fallow, though direct comparisons between break crops could not be made as few experiments (3) included all species. For all break crops, the mean wheat yield increase was independent of the level of wheat yield, representing a step-change rather than a proportional improvement in yield. Analysis of the larger number and spread of lupin experiments revealed that break-crop benefits increased in higher rainfall areas, following higher yielding lupin crops ( .5 t/ha), and that the break-crop benefit in terms of yield and water-use efficiency increased significantly after 1991. These observations were often related to the level and/or effectiveness of diseases or grass weed control in the break crop however, increased contribution of fixed N was also likely with better legume crops. For both lupin and field pea, the magnitude of the break-crop response declined as rate of N fertiliser applied to subsequent wheat crop increased, although non-N related benefits (disease and weed control) tended to dominate wheat response to lupin after 1989. Significant break-crop benefits from lupins (+0.40 t/ha) persisted to a third wheat crop (n = 29) but effects were inconsistent beyond that point. The magnitude, persistence and reliability of the break-crop benefits revealed in this study provide a more accurate framework to assess their likely benefit within the farming system. Further information is required to define the key ‘trigger points’ for the major drivers of the response – water, N, weeds and disease – at which the benefits outweigh the higher risk of these crops and would influence the decision to include them within the system.
Publisher: Springer Science and Business Media LLC
Date: 06-10-2021
Publisher: Springer Science and Business Media LLC
Date: 25-03-2022
Publisher: Elsevier BV
Date: 05-2016
Publisher: Cambridge University Press (CUP)
Date: 26-07-2016
DOI: 10.1017/S1742170516000260
Abstract: A field experiment was established to test the impact on crop yield, total productivity and biological di-nitrogen (N 2 ) fixation of a self-regenerating annual legume, subterranean clover ( Trifolium subterraneum L.), grown in mixtures with experimental perennial wheat lines. Legume content was altered in one intermediate wheatgrass ( Thinopyrum intermedium (Host) Barkworth & Dewey) and two wheat ( Triticum aestivum L.) × wheatgrass ( Th . spp.) hybrid-based stands by sowing the legume in the same drill row as the perennial crop, or in every second or third row, spatially separated from the perennial crop. The hybrid perennial crops were more vigorous than intermediate wheatgrass in year 1, competing strongly and reducing legume biomass over the 2 yr period leading to reduced inputs of fixed nitrogen (N). However, both hybrid crops declined to negligible levels following the first summer with only the intermediate wheatgrass persisting in adequate densities in year 2. Spatially separating the perennial crop from the legume in alternate drill rows increased legume biomass by 32–128% and clover regeneration by 31–195%, and reduced weed incursion by up to 47% compared with where it was sown in mixed rows. However, spatial separation more than halved grain yields in year 2 compared with where the perennial crop was grown in every drill row. This likely reflected changed competition dynamics where the modified spatial configurations at sowing limited the perennial crops’ access to resources. When estimates of the total inputs of fixed N from the clover (5–165 kg N ha −1 in year 2) were compared with the amounts of N removed in grain by the different perennial wheat treatments (10–55 kg N ha −1 in year 1), it appears feasible that a companion legume could fix sufficient N to maintain the N balance of a cropping system producing 1.5–2.0 t grain ha −1 each year. The inclusion of a legume increased total above-ground biomass by up to 142%, particularly in year 2, but this did not translate into increased grain yields. It seems unlikely that a self-regenerating annual legume will be able to effectively coexist among a dense perennial wheat canopy where both species are sown in the same drill row. Further research is required to develop strategies to channel more of the additional resources apparently accessed by the companion legume into grain production.
Publisher: Cambridge University Press (CUP)
Date: 03-06-2020
DOI: 10.1017/S1742170520000174
Abstract: Changed spatial configurations at sowing have been investigated as a strategy to minimize interspecific competition and improve the establishment and persistence of multi-species plantings in pastures, but the impact of this practice on the soil microbiome has received almost no previous research attention. Differences in populations of bacteria and fungi in the surface 10 cm of soil in the third year following pasture establishment were quantified using quantitative polymerase chain reaction and terminal restriction fragment length polymorphism methods. Populations were compared on, and between, drill rows sown to either the perennial grass phalaris ( Phalaris aquatica L.), perennial legume lucerne (alfalfa Medicago sativa L.) or the annual legume subterranean clover ( Trifolium subterraneum L.). Results showed that soil microbial abundance and ersity were related to plant distribution across the field at the time of s ling and to soil chemical parameters including total carbon (C), mineral nitrogen (N), pH, and available phosphorus (P), potassium (K) and sulfur (S). Despite the 27-month lag since sowing, pasture species remained concentrated around the original drill row with very little colonization of the inter-row area. The abundance and ersity of bacterial and fungal populations were consistently greater under drill rows associated with higher total C concentrations in the surface soil compared with the inter-row areas. Our results showed that the pH and available nutrients were similar between the subterranean clover drill row and the inter-row, suggesting that soil microbial populations were not impacted directly by these soil fertility parameters, but rather were related to the presence or absence of plants. The abundance of bacteria and fungi were numerically lower under phalaris rows compared to rows sown to legumes. The richness and ersity of fungal populations were lowest between rows where lucerne was planted. Possible explanations for this observation include a lower C:N ratio of lucerne roots and/or a lack of fibrous roots at the soil surface compared to the other species, illustrating the influence of contrasting plant types on the soil microflora community. This study highlights the enduring legacy of the drill row on the spatial distribution of plants well into the pasture phase of a cropping rotation and discusses the opportunity to enhance the microbiome of cropping soils on a large scale during the pasture phase by increasing plant distribution across the landscape.
Publisher: Elsevier BV
Date: 07-2012
Publisher: Elsevier
Date: 2019
Publisher: CSIRO Publishing
Date: 2017
DOI: 10.1071/CP16395
Abstract: This study examined whether the productivity and persistence of mixed pastures that included subterranean clover (Trifolium subterraneum L.), lucerne (Medicago sativa L.), and/or phalaris (Phalaris aquatica L.) were improved if species were spatially separated rather than being sown together in each drill row. The study also compared the productivity and persistence of subterranean clover with alternative annual legume species biserrula (Biserrula pelecinus L.) and strand medic (Medicago littoralis Rhode ex Loisel). Twelve pasture treatments were sown in replicated field experiments at five locations across the medium-rainfall region of south-western New South Wales in 2012 and monitored for 3 years. Pastures that included lucerne, phalaris and subterranean clover were generally more productive than pastures with only one or two of those species, regardless of sowing configuration. Averaged across sites, subterranean clover regeneration in year 3 was 29% higher and total cumulative biomass 13% higher where subterranean clover was sown in a 1 : 1 configuration with lucerne than where the species were mixed together in every drill row. There were fewer consistent benefits of alternative spatial configurations on swards containing phalaris with subterranean clover or with lucerne. Results of the present study appeared to be highly site-specific, or season-dependent, and therefore alternative spatial configurations cannot be recommended as a universal strategy at this time. More research is required to understand the factors driving the responses to alternative spatial configurations observed in the present study. Neither biserrula nor strand medic was superior to subterranean clover in a 3-year pasture phase with lucerne, despite abundant rhizobia compatible with all species at all sites. The density of subterranean clover in year 3 was 29% and 41% higher than of biserrula and strand medic, respectively. A narrow choice of adapted cultivars as well as excessive levels of hard seed for the legumes used in phased pastures with lucerne are suggested as contributing to the inferior performance of the alternative legumes species tested in the study.
Publisher: Springer Netherlands
Date: 2012
Publisher: CSIRO Publishing
Date: 2007
DOI: 10.1071/SR07105
Publisher: Springer Science and Business Media LLC
Date: 14-07-2020
Publisher: Elsevier BV
Date: 09-2016
Publisher: Springer Science and Business Media LLC
Date: 19-05-2020
Publisher: Wiley
Date: 09-03-2021
DOI: 10.1111/ANAE.15458
Abstract: Peri‐operative SARS‐CoV‐2 infection increases postoperative mortality. The aim of this study was to determine the optimal duration of planned delay before surgery in patients who have had SARS‐CoV‐2 infection. This international, multicentre, prospective cohort study included patients undergoing elective or emergency surgery during October 2020. Surgical patients with pre‐operative SARS‐CoV‐2 infection were compared with those without previous SARS‐CoV‐2 infection. The primary outcome measure was 30‐day postoperative mortality. Logistic regression models were used to calculate adjusted 30‐day mortality rates stratified by time from diagnosis of SARS‐CoV‐2 infection to surgery. Among 140,231 patients (116 countries), 3127 patients (2.2%) had a pre‐operative SARS‐CoV‐2 diagnosis. Adjusted 30‐day mortality in patients without SARS‐CoV‐2 infection was 1.5% (95%CI 1.4–1.5). In patients with a pre‐operative SARS‐CoV‐2 diagnosis, mortality was increased in patients having surgery within 0–2 weeks, 3–4 weeks and 5–6 weeks of the diagnosis (odds ratio (95%CI) 4.1 (3.3–4.8), 3.9 (2.6–5.1) and 3.6 (2.0–5.2), respectively). Surgery performed ≥ 7 weeks after SARS‐CoV‐2 diagnosis was associated with a similar mortality risk to baseline (odds ratio (95%CI) 1.5 (0.9–2.1)). After a ≥ 7 week delay in undertaking surgery following SARS‐CoV‐2 infection, patients with ongoing symptoms had a higher mortality than patients whose symptoms had resolved or who had been asymptomatic (6.0% (95%CI 3.2–8.7) vs. 2.4% (95%CI 1.4–3.4) vs. 1.3% (95%CI 0.6–2.0), respectively). Where possible, surgery should be delayed for at least 7 weeks following SARS‐CoV‐2 infection. Patients with ongoing symptoms ≥ 7 weeks from diagnosis may benefit from further delay.
Publisher: CSIRO Publishing
Date: 2023
DOI: 10.1071/CP23009
Publisher: CSIRO Publishing
Date: 2012
DOI: 10.1071/CP12123
Abstract: The amounts of foliage nitrogen (N) fixed by various annual and perennial legumes growing in Australian pastures range from to kg N/ha.year. Differences in N2 fixation result from variations in the proportion of the legume-N derived from atmospheric N2 (%Ndfa) and/or the amount of legume-N accumulated during growth. On-farm surveys of %Ndfa achieved by legumes growing in farmers’ paddocks in Australia indicated that N2 fixation contributed % of the legume’s N requirements in three-quarters of the annual legumes examined, but this decreased to two-thirds of lucerne (Medicago sativa also known as alfalfa), and half of white clover (Trifolium repens) s les. Factors such as low numbers or the poor effectiveness of rhizobial strains in the soil, water stress, high soil concentrations of N, and nutrient disorders contribute to poor nodulation and %Ndfa values %, but there is also evidence that the observed %Ndfa can be dependent on the legume species present, and whether the legume is grown in a pure stand or in a mixed sward. The accumulation of legume-N relates primarily to the legume content and net productivity of the pasture. For many legume species, ~20 kg of shoot-N is fixed on average for every tonne of herbage dry matter produced. Legume productivity can be influenced by (i) sowing and establishment techniques and other strategies that enhance the legume content in pasture swards (ii) the amelioration of soil constraints (iii) the use of new legume species (and host–rhizobial strain combinations) that are more tolerant of hostile soil environments than subterranean clover (T. subterraneum) or annual medics (Medicago spp) and (iv) the inclusion of perennials such as lucerne to offset the year-to-year variability in productivity and N2 fixation that is a common occurrence with annual legumes.
Publisher: CSIRO Publishing
Date: 2017
DOI: 10.1071/CP16248
Abstract: Several new and existing short-term forage legumes could be used to provide nitrogen (N) inputs for grain crops in subtropical farming systems. The fixed-N inputs from summer-growing forage legumes lablab (Lablab purpureus), burgundy bean (Macroptilium bracteatum) and lucerne (Medicago sativa) and winter-growing legume species snail medic (Medicago scutellata), sulla (Hedysarum coronarium) and purple vetch (Vicia benghalensis) were compared over several growing seasons at four locations in southern Queensland, Australia. Available soil mineral N and grain yield of a following cereal crop were compared among summer-growing legumes and forage sorghum (Sorghum spp. hybrid) and among winter-growing legumes and forage oats (Avena sativa). In the first year at all sites, legumes utilised the high initial soil mineral N, with % of the legume N estimated to have been derived from atmospheric N2 (%Ndfa) and legume-fixed N kg/ha. In subsequent years, once soil mineral N had been depleted, %Ndfa increased to 50–70% in the summer-growing legumes and to 60–80% in winter-growing legumes. However, because forage shoot N was removed, rarely did fixed N provide a positive N balance. Both lablab and burgundy bean fixed up to 150 kg N/ha, which was more than lucerne in all seasons. Prior to sowing cereal grain crops, soil nitrate was 30–50 kg/ha higher after summer legumes than after forage sorghum. At one site, lablab and lucerne increased the growth and yield of a subsequent grain sorghum crop by 1.4 t/ha compared with growth after forage sorghum or burgundy bean. Of the winter-growing legumes, sulla had the highest total N2 fixation (up to 150 kg N/ha.year) and inputs of fixed N (up to 75 kg N/ha), and resulted in the highest concentrations of soil N (80–100 kg N/ha more than oats) before sowing of the following crop. Wheat protein was increased after winter legumes, but there was no observed yield benefit for wheat or grain sorghum crops. New forage legume options, lablab, burgundy bean and sulla, showed potential to increase N supply in crop rotations in subtropical farming systems, contributing significant fixed N (75–150 kg/ha) and increasing available soil N for subsequent crops compared to non-legume forage crops. However, high soil mineral N ( kg N/ha) greatly reduced N2 fixation by forage legumes, and significant N2 fixation only occurred once legume shoot N uptake exceeded soil mineral N at the start of the growing season. Further work is required to explore the impact of different management strategies, such as livestock grazing rather than harvesting for hay, on the long-term implications for nutrient supply for subsequent crops.
Publisher: Springer Science and Business Media LLC
Date: 09-08-2012
Publisher: Springer Science and Business Media LLC
Date: 20-04-2010
Publisher: CSIRO Publishing
Date: 2017
DOI: 10.1071/SR16330
Abstract: Nitrogen (N) contributed by legumes is an important component of N supply to subsequent cereal crops, yet few Australian grain-growers routinely monitor soil mineral N before applying N fertiliser. Soil and crop N data from 16 dryland experiments conducted in eastern Australia from 1989–2016 were examined to explore the possibility of developing simple predictive relationships to assist farmer decision-making. In each experiment, legume crops were harvested for grain or brown-manured (BM, terminated before maturity with herbicide), and wheat, barley or canola were grown. Soil mineral N measured immediately before sowing wheat in the following year was significantly higher (P 0.05) after 31 of the 33 legume pre-cropping treatments than adjacent non-legume controls. The average improvements in soil mineral N were greater for legume BM (60 ± 16 kg N/ha n = 5) than grain crops (35 ± 20 kg N/ha n = 26), but soil N benefits were similar when expressed on the basis of summer fallow rainfall (0.15 ± 0.09 kg N/ha per mm), residual legume shoot dry matter (9 ± 5 kg N/ha per t/ha), or total legume residue N (28 ± 11%). Legume grain crops increased soil mineral N by 18 ± 9 kg N/ha per t/ha grain harvested. Apparent recovery of legume residue N by wheat averaged 30 ± 10% for 20 legume treatments in a subset of eight experiments. Apparent recovery of fertiliser N in the absence of legumes in two of these experiments was 64 ± 16% of the 51–75 kg fertiliser-N/ha supplied. The 25 year dataset provided new insights into the expected availability of soil mineral N after legumes and the relative value of legume N to a following wheat crop, which can guide farmer decisions regarding N fertiliser use.
Publisher: Springer Science and Business Media LLC
Date: 05-07-2017
Publisher: CSIRO Publishing
Date: 2012
DOI: 10.1071/CP12161
Abstract: Legume-based pastures, particularly those containing a large proportion of lucerne (alfalfa, Medicago sativa), have a prodigious capacity to fix atmospheric N2. Budgets of N show that permanent pastures in south-eastern Australia, when growing with no management limitations, can supply more N than is removed in animal products and can eventually lead to excess soil N. For a mixed crop–livestock farm, legume-dominant ley pastures occupying ~40% of the land area can maintain a stable N balance. The actual performance of pastures on farms normally falls below the potential. Pastures are being replaced by crops in the wheat-sheep zone and, to a lesser extent, in the high-rainfall zone. Pasture productivity, as indicated by the area topdressed, the mean stocking rate, input of superphosphate and sale of pasture legume seed has decreased in the period 1990–2010. It is therefore likely that N2 fixation by pastures is falling sharply in the wheat–sheep zone and is static or falling slightly in the high-rainfall zone. Reversing the decrease in N2 fixation by pastures will become important if the real price of N fertilisers increases, as seems likely because the efficiency of fertiliser synthesis is approaching a maximum and the reserves of natural gas feedstock will eventually be depleted. Increased N2 fixation by pastures will depend on more profitable grazing industries, improved management methods and genotypes, and re-adoption of ley pastures by farmers. There is evidence that profitability of grazing enterprises is approaching that of crops so investment in pasture science is likely to lead to increased N2 fixation.
Location: Australia
No related grants have been discovered for Mark Peoples.