Methane in Australian agriculture: current emissions, sources and sinks, and potential mitigation strategies

Methane is a potent greenhouse gas with a global warming potential ∼28 times that of carbon dioxide. Consequently, sources and sinks that influence the concentration of methane in the atmosphere are of great interest. In Australia, agriculture is the primary source of anthropogenic methane emissions (60.4% of national emissions, or 3260kt-1methaneyear-1, between 1990 and 2011), and cropping and grazing soils represent Australia's largest potential terrestrial methane sink. As of 2011, the expansion of agricultural soils, which are ∼70% less efficient at consuming methane than undisturbed soils, to 59% of Australia's land mass (456Mha) and increasing livestock densities in northern Australia suggest negative implications for national methane flux. Plant biomass burning does not appear to have long-term negative effects on methane flux unless soils are converted for agricultural purposes. Rice cultivation contributes marginally to national methane emissions and this fluctuates depending on water availability. Significant available research into biological, geochemical and agronomic factors has been pertinent for developing effective methane mitigation strategies. We discuss methane-flux feedback mechanisms in relation to climate change drivers such as temperature, atmospheric carbon dioxide and methane concentrations, precipitation and extreme weather events. Future research should focus on quantifying the role of Australian cropping and grazing soils as methane sinks in the national methane budget, linking biodiversity and activity of methane-cycling microbes to environmental factors, and quantifying how a combination of climate change drivers will affect total methane flux in these systems.

Improved understanding of the damage, ecology, and management of mirids and stinkbugs in Bollgard II

In recent years mirids and stinkbugs have emerged as important sucking pests in cotton. While stinkbugs are causing damage to bolls, mirids are causing damage to seedlings, squares and bolls. With the increasing adoption of Bollgard II and IPM approaches the use of broad-spectrum chemicals to kill Helicoverpa has been reduced and as a result mirids and stinkbugs are building to levels causing damage to bolls later in crop growth stages. Studies on stinkbugs by Dr Moazzem Khan revealed that green vegetable bug (GVB) caused significant boll damage and yield loss. A preliminary study by Dr Khan on mirids revealed that high mirid numbers at later growth stages also caused significant boll damage and that damage caused by mirids and GVB were similar. Mirids and stinkbugs therefore demand greater attention in order to minimise losses caused by these pests and to develop IPM strategies against these pests to enhance gains in IPM that have been made with Bt-transgenic cotton. Progress in this area of research will maintain sustainability and profitability of the Australian cotton industry. Mirid damage at early growth stages of cotton (up to squaring stage) has been studied in detail by Dr Khan. He found that all ages of mirids cause damage to young plants and damage by mirid nymphs is cumulative. Maximum damage occurs when the insect reaches the 4th and 5th nymphal stages. He also found that mirid feeding causes shedding of small and medium squares, and damaged large squares develop as ‘parrot beak’ bolls. Detailed studies at the boll stage, such as which stage of mirids is most damaging or which age boll is most vulnerable to feeding, is lacking. This information is a prerequisite to developing an IPM strategy for the pest in later crop growth stages. Understanding population change of the pest over time in relation to crop development is an important aspect for developing management strategies for the pest which is lacking for mirids in BollgardII. Predators and parasitoids are integral components of any IPM system and play an important part in regulating pest populations. Some generalist predators such as ants, spiders, damsel bugs and assassin bugs are known to predate on mirids. Nothing is known about parasitoids of mirids. Since green mirid (GM), Creontiades dilutus, is indigenous to Australia it is likely that we have one or more parasitoids of this mirid in Australia, but that possibility has not been investigated yet. The impact of the GVB adult parasitoid, Trichopoda giacomelli, has been studied by Dr Khan who found that the fly is established in the released areas and continues to spread. However, to get wider and greater impact, the fly should be released in new locations across the valleys. The insecticides registered for mirids and stinkbugs are mostly non-selective and are extremely disruptive to a wide range of beneficial insects. Use of these insecticides at stage I and II will minimise the impact of existing IPM programs. Therefore less disruptive control tactics including soft chemicals for mirids and stinkbugs are necessary. As with soft chemicals, salt mixtures, biopesticides based on fungal pathogens and attractants based on plant volatiles may be useful tools in managing mirids and stinkbugs with less or no disruption. Dr Khan has investigated salt mixture against mirids and GVB. While salt mixtures are quite effective and less disruptive, they are quite chemical specific. Not all chemicals mixed with salt will give the desired benefit. Therefore further investigation is needed to identify those chemicals that are effective with salt mixture against mirids and 3 of 37 GVB. Dr Caroline Hauxwell of DPI&F is working on fungal pathogen-based biopesticides against mirids and GVB and Drs Peter Gregg and Alice Del Socorro of Australian Cotton CRC are working on plant volatile-based attractants against mirids. Depending on their findings, inclusion of fungal-based biopestcides and plant volatile-based attractants in developing a management system against mirids and stinkbugs in cotton could be an important component of an IPM approach.

Connecting people and ideas from around the world: global innovation platforms for next-generation ecology and beyond

We present a case for using Global Community Innovation Platforms (GCIPs), an approach to improve innovation and knowledge exchange in international scientific communities through a common and open online infrastructure. We highlight the value of GCIPs by focusing on recent efforts targeting the ecological sciences, where GCIPs are of high relevance given the urgent need for interdisciplinary, geographical, and cross-sector collaboration to cope with growing challenges to the environment as well as the scientific community itself. Amidst the emergence of new international institutions, organizations, and meetings, GCIPs provide a stable international infrastructure for rapid and long-term coordination that can be accessed by any individual. This accessibility can be especially important for researchers early in their careers. Recent examples of early-career GCIPs complement an array of existing options for early-career scientists to improve skill sets, increase academic and social impact, and broaden career opportunities. We provide a number of examples of existing early-career initiatives that incorporate elements from the GCIPs approach, and highlight an in-depth case study from the ecological sciences: the International Network of Next-Generation Ecologists (INNGE), initiated in 2010 with support from the International Association for Ecology and 20 member institutions from six continents.

Mile-a-minute (Mikania micrantha): its distribution, growth and physical and socio-economic impacts in Papua New Guinea

Mikania micrantha, Kunth. H.B.K (Asteraceae) or mile-a-minute is a weed of Neotropical origin in 17 Pacific Island countries. It is becoming increasingly regarded as an invasive weed in Papua New Guinea and is now the focus of an Australian Government-funded biological control program. As part of the program, growth rates, distribution and physical and socia-economic impacts were studied to obtain baseline data and to assist with the field release of biological control agents. Through public awareness campaigns and dedicated surveys, mikania has been reported in most lowland provinces. It is particularly widespread in East New Britain and West New Britain Province. In field trials, mikania grew more than 1 metre per month in open sunny areas but slightly slower when growing under cocoa. The weed invades a wide range of land types, impacting on plantations and food gardens, smothering pawpaw, young cocoa, banana, taro, young oil palms and ornamental plants. In socia-economic surveys, mikania was found to have severe impacts on crop production and income generated through reduced yields and high weeding costs. These studies suggest that there would be substantial benefits to the community if biological control of mikania is successful.

Insect pests in tropical forestry

The layout of this second edition follows that of the first, though the content has been substantially rewritten to reflect 10 years of research and development, as well as the emergence of new pest species. Chapter 1 presents an overview, from a somewhat entomological perspective, of tropical forestry in its many guises. Chapters 2, 3 and 4 then discuss the 'pure' biology and ecology of tropical insects and their co-evolved relationships with the trees and forests in which they live. Chapter 5 is necessarily the largest chapter in the book, looking in detail at a selection of major pest species from all over the tropical world. Chapters 6, 7, 8 and 9 then discuss the theory and practice of insect pest management, starting at the fundamental planning stage, before any seeds hit the soil. Nursery management and stand management were considered in Chapters 7 and 8. Chapter 9 covers the topics of forest health surveillance, quarantine and forest invasive species, topics which again have significance at all stages of forestry but for convenience are presented after nursery and forest management. This, in fact, we attempt to do in the final chapter, Chapter 10, which combines most of the previous nine chapters in examples illustrating the concept of integrated pest management. ©CABI Publishing CABI Publishing

Understanding the barriers to the implementation of precision agriculture in the central region

There is an increasing requirement for more astute land resource management through efficiencies in agricultural inputs in a sugar cane production system. A precision agriculture (PA) approach can provide a pathway for a sustainable sugarcane production system. One of the impediments to the adoption of PA practices is access to paddock-scale mapping layers displaying variability in soil properties, crop growth and surface drainage. Variable rate application (VRA) of nutrients is an important component of PA. However, agronomic expertise within PA systems has fallen well behind significant advances in PA technologies. Generally, advisers in the sugar industry have a poor comprehension of the complex interaction of variables that contribute to within-paddock variations in crop growth. This is regarded as a significant impediment to the progression of PA in sugarcane and is one of the reasons for the poor adoption of VRA of nutrients in a PA approach to improved sugar cane production. This project therefore has established a number of key objectives which will contribute to the adoption of PA and the staged progression of VRA supported by relevant and practical agronomic expertise. These objectives include provision of base soils attribute mapping that can be determined using Veris 3100 Electrical Conductivity (EC) and digital elevation datasets using GPS mapping technology for a large sector of the central cane growing region using analysis of archived satellite imagery to determine the location and stability of yield patterns over time and in varying seasonal conditions on selected project study sites. They also include the stablishment of experiments to determine appropriate VRA nitrogen rates on various soil types subjected to extended anaerobic conditions, and the establishment of trials to determine nitrogen rates applicable to a declining yield potential associated with the aging of ratoons in the crop cycle. Preliminary analysis of archived yield estimation data indicates that yield patterns remain relatively stable overtime. Results also indicate the where there is considerable variability in EC values there is also significant variation in yield.

Conversion of sub-tropical native vegetation to introduced conifer forest: Impacts on below-ground and above-ground carbon pools

Land-use change can have a major influence on soil organic carbon (SOC) and above-ground C pools. We assessed a change from native vegetation to introduced Pinus species plantations on C pools using eight paired sites. At each site we determined the impacts on 0–50 cm below-ground (SOC, charcoal C, organic matter C, particulate organic C, humic organic C, resistant organic C) and above-ground (litter, coarse woody debris, standing trees and woody understorey plants) C pools. In an analysis across the different study sites there was no significant difference (P > 0.05) in SOC or above-ground tree C stocks between paired native vegetation and pine plantations, although significant differences did exist at specific sites. SOC (calculated based on an equivalent soil mass basis) was higher in the pine plantations at two sites, higher in the native vegetation at two sites and did not differ for the other four sites. The site to site variation in SOC across the landscape was far greater than the variation observed with a change from native vegetation to introduced Pinus plantation. Differences between sites were not explained by soil type, although tree basal area was positively correlated with 0–50 cm SOC. In fact, in the native vegetation there was a significant linear relationship between above-ground biomass and SOC that explained 88.8% of the variation in the data. Fine litter C (0–25 mm diameter) tended to be higher in the pine forest than in the adjacent native vegetation and was significantly higher in the pine forest at five of the eight paired sites. Total litter C (0–100 mm diameter) increased significantly with plantation age (R2 = 0.64). Carbon stored in understorey woody plants (2.5–10 cm DBH) was higher in the native vegetation than in the adjacent pine forest. Total site C varied greatly across the study area from 58.8 Mg ha−1 at a native heathland site to 497.8 Mg ha−1 at a native eucalypt forest site. Our findings suggest that the effects of change from native vegetation to introduced Pinus sp. forest are highly site-specific and may be positive, negative, or have no influence on various C pools, depending on local site characteristics (e.g. plantation age and type of native vegetation).

An Investigation of the Impacts of Ponded Pastures on Barramundi and Other Finfish Populations in Tropical Coastal Wetlands

Objectives: 1) To document the extent of ponded pastures and other pondage systems in and adjacent to coastal wetlands on the central coast of Queensland. 2) To assess the movement, growth and survival of barramundi in ponded pastures. 3) To assess the utilisation by barramundi of ponded pastures and wetlands dominated by exotic grass species. 4) To identify appropriate wetland management strategies for facilitating barramundi movement and survival in ponded pastures and other pondage systems. 5) To document the species composition of finfish populations and their relative abundance in ponded pastures.

A field investigation of solubility and food chain accumulation of biosolid-cadmium across diverse soil types

One of the pathways for transfer of cadmium (Cd) through the food chain is addition of urban wastewater solids (biosolids) to soil, and many countries have restrictions on biosolid use to minimize crop Cd contamination. The basis of these restrictions often lies in laboratory or glasshouse experimentation of soil-plant transfer of Cd, but these studies are confounded by artefacts from growing crops in controlled laboratory conditions. This study examined soil to plant (wheat grain) transfer of Cd under a wide range of field environments under typical agronomic conditions, and compared the solubility and bioavailability of Cd in biosolids to soluble Cd salts. Solubility of biosolid Cd (measured by examining Cd partitioning between soil and soil solution) was found to be equal to or greater than that of soluble Cd salts, possibly due to competing ions added with the biosolids. Conversely, bioavailability of Cd to wheat and transfer to grain was less than that of soluble Cd salts, possibly due to addition of Zn with the biosolids, causing reduced plant uptake or grain loading, or due to complexation of soluble Cd2+ by dissolved organic matter.

No-tillage and nitrogen application affects the decomposition of 15N-labelled wheat straw and the levels of mineral nitrogen and organic carbon in a Vertisol

No-tillage (NT) practice, where straw is retained on the soil surface, is increasingly being used in cereal cropping systems in Australia and elsewhere. Compared to conventional tillage (CT), where straw is mixed with the ploughed soil, NT practice may reduce straw decomposition, increase nitrogen immobilisation and increase organic carbon in the soil. This study examined 15N-labelled wheat straw (stubble) decomposition in four treatments (NT v. CT, with N rates of 0 and 75 kg/ha.year) and assessed the tillage and fertiliser N effects on mineral N and organic C and N levels over a 10-year period in a field experiment. NT practice decreased the rate of straw decomposition while fertiliser N application increased it. However, there was no tillage practice x N interaction. The mean residence time of the straw N in soil was more than twice as long under the NT (1.2 years) as compared to the CT practice (0.5 years). In comparison, differences in mean residence time due to N fertiliser treatment were small. However, tillage had generally very little effect on either the amounts of mineral N at sowing or soil organic C (and N) over the study period. While application of N fertiliser increased mineral N, it had very little effect on organic C over a 10-year period. Relatively rapid decomposition of straw and short mean residence time of straw N in a Vertisol is likely to have very little long-term effect on N immobilisation and organic C level in an annual cereal cropping system in a subtropical, semiarid environment. Thus, changing the tillage practice from CT to NT may not necessitate additional N requirement unless use is made of additional stored water in the soil or mineral N loss due to increased leaching is compensated for in N supply to crops.

Assessing the sustainability of wheat-based cropping systems using APSIM: Model parameterisation and evaluation

Assessing the sustainability of crop and soil management practices in wheat-based rotations requires a well-tested model with the demonstrated ability to sensibly predict crop productivity and changes in the soil resource. The Agricultural Production Systems Simulator (APSIM) suite of models was parameterised and subsequently used to predict biomass production, yield, crop water and nitrogen (N) use, as well as long-term soil water and organic matter dynamics in wheat/chickpea systems at Tel Hadya, north-western Syria. The model satisfactorily simulated the productivity and water and N use of wheat and chickpea crops grown under different N and/or water supply levels in the 1998-99 and 1999-2000 experimental seasons. Analysis of soil-water dynamics showed that the 2-stage soil evaporation model in APSIM's cascading water-balance module did not sufficiently explain the actual soil drying following crop harvest under conditions where unused water remained in the soil profile. This might have been related to evaporation from soil cracks in the montmorillonitic clay soil, a process not explicitly simulated by APSIM. Soil-water dynamics in wheat-fallow and wheat-chickpea rotations (1987-98) were nevertheless well simulated when the soil water content in 0-0.45 m soil depth was set to 'air dry' at the end of the growing season each year. The model satisfactorily simulated the amounts of NO3-N in the soil, whereas it underestimated the amounts of NH 4-N. Ammonium fixation might be part of the soil mineral-N dynamics at the study site because montmorillonite is the major clay mineral. This process is not simulated by APSIM's nitrogen module. APSIM was capable of predicting long-term trends (1985-98) in soil organic matter in wheat-fallow and wheat-chickpea rotations at Tel Hadya as reported in literature. Overall, results showed that the model is generic and mature enough to be extended to this set of environmental conditions and can therefore be applied to assess the sustainability of wheat-chickpea rotations at Tel Hadya.

Development and testing of an evaluation procedure for commercial manure additive products.

Manure additive products can be used to reduce odour emissions (OE) from livestock farms. The standardised evaluation of these manure additive products under specific farm conditions is important. In this study, the efficacy of a manure additive (WonderTreat(TM), CKLS, Inc., Hong-Kong) was assessed under Australian conditions utilising a combination of laboratory and field-scale evaluation techniques. As a first step, the efficacy of the manure additive was assessed in a laboratory-scale trial using a series of uniformly managed digesters and standard odour, liquor ammonia and hydrogen sulphide concentration measurement procedures. This showed that the addition of WonderTreat(TM) at the 'low dose rate' (LDR) (102.6 g m-2) used during the trial significantly, but only marginally (30%; P = 0.02) reduced the OE rate (mean 13.9 OU m-2 s-1) of anaerobic pig liquor relative to an untreated control (UC) (19.9 OU m-2 s-1). However, the 'high dose rate' (HDR) (205.3 g m-2) also assessed during the trial preformed similarly (19.7 OU m-2 s-1) to the UC. No statistically significant difference in the concentrations of a range of measured water quality variables at the 5% level was observed between the treatments or controls digesters. As a second step, a field-scale assessment of the manure additive was undertaken at a commercial piggery. Two piggery manure lagoons (each with approximately 2500 m2 surface area) were included in the study; one was treated with WonderTreat(TM) while the other was used as control. The efficacy of the treatment was assessed using olfactometric evaluation of odour samples collected from the surface of the pond using a dynamic wind tunnel and ancillary equipment. No statistically significant reduction in OE rate could be demonstrated (P = 0.35), partially due to the limited number of samples taken during the assessment. However, there was a numerical reduction in the average OE rate of the treatment pond (29 OU m-2 s-1 at 1 m s-1) compared to the control lagoon (38 OU m-2 s-1 at 1 m s-1).

Bats and Emerging Zoonoses: Henipaviruses and SARS.

Nearly 75% of all emerging infectious diseases (EIDs) that impact or threaten human health are zoonotic. The majority have spilled from wildlife reservoirs, either directly to humans or via domestic animals. The emergence of many can be attributed to predisposing factors such as global travel, trade, agricultural expansion, deforestation habitat fragmentation, and urbanization; such factors increase the interface and or the rate of contact between human, domestic animal, and wildlife populations, thereby creating increased opportunities for spillover events to occur. Infectious disease emergence can be regarded as primarily an ecological process. The epidemiological investigation of EIDs associated with wildlife requires a trans-disciplinary approach that includes an understanding of the ecology of the wildlife species, and an understanding of human behaviours that increase risk of exposure. Investigations of the emergence of Nipah virus in Malaysia in 1999 and severe acute respiratory syndrome (SARS) in China in 2003 provide useful case studies. The emergence of Nipah virus was associated with the increased size and density of commercial pig farms and their encroachment into forested areas. The movement of pigs for sale and slaughter in turn led to the rapid spread of infection to southern peninsular Malaysia, where the high-density, largely urban pig populations facilitated transmission to humans. Identifying the factors associated with the emergence of SARS in southern China requires an understanding of the ecology of infection both in the natural reservoir and in secondary market reservoir species. A necessary extension of understanding the ecology of the reservoir is an understanding of the trade, and of the social and cultural context of wildlife consumption. Emerging infectious diseases originating from wildlife populations will continue to threaten public health. Mitigating and managing the risk requires an appreciation of the connectedness between human, livestock and wildlife health, and of the factors and processes that disrupt the balance.

Nutrient mass balance for Lockyer vegetable production

The potential for fertiliser use in Lockyer Valleys intensive vegetable production to impact on the Moreton Bay Waterways (MBW) is not well defined. Notwithstanding nutrient runoff through soil erosion of agricultural lands has been identified as a process that significantly contributes artificial fertiliser to the MBW (SEQ Healthy Waterways Draft Strategy 2006). In order to better understand this issue the present study undertakes a nutrient mass balance to evaluate nitrogen use efficiency in the intensive horticultural industry of the Lockyer Valley.

GRDC Improving crop and farm water use efficiency in Australia

Project Objectives: 1. Improving yield and water use efficiency of the wheat crop, the backbone of the Australia grains industry, by better matching management, variety, soil and climate. The aim is thus increasing kg grain/ha per mm evapotranspiration and kg grain/ha per mm rain. 2. Improving land and water productivity and profit by better arrangement of the components of the cropping system. This involves better allocation of farm resources (land, water, machinery, labour) and identifying strategies that account for trade-offs between profit and risk. The aim is thus improving $/ha per year and mm rain in a risk framework.