Options for control of 'Nassella trichotoma' on the Northern Tablelands of New South Wales
Extensive work has been carried out to determine the management strategies that best control 'Nassella trichotoma' (serrated tussock) throughout the south eastern regions of Australia and New Zealand. 'N. trichotoma' infested areas on the Northern Tablelands of New South Wales (NSW) in the early 1960s and it went unnoticed and uncontrolled for many decades. Since the recognition of 'N. trichotoma' on the Northern Tablelands as a weed of significance, measures have been taken for its control and management. Many of the ideas for control have been taken from the practices that are used on current infestations in the south eastern areas of Australia and in New Zealand. The variation in the environmental conditions and characteristics of infestations between these southern areas and the Northern Tablelands are the motive for development of more specific management options.
Spatial variability in pH and key soil nutrients: is this an opportunity to increase fertiliser and lime-use efficiency in grazing systems?
Nutrient-use efficiency is a key issue for grazing systems in Australia. Spatial variability in soil pH and nutrients at the sub-paddock scale may affect the efficiency of utilisation of, and provide an opportunity for, site-specific management (SSM) of fertiliser and soil ameliorants. However, there has been little research exploring the potential for SSM in grazing systems. This study examines the spatial variability of soil test pH, phosphorus (P), potassium (K) and sulfur(S) in two typical pasture fields (a native and an improved) on the Northern Tablelands of New South Wales and evaluates the potential for SSM based on a comparison with critical values. In both fields, the overall paddock mean from a grid survey containing >80 samples for pH, P, K and S (0-10 cm) exceeded the critical values, suggesting that the addition of fertiliser or lime was not required. However, considerable sub-paddock-scale variability was observed, with CV ranging from 35% to 66% for the key nutrients (P, K and S). The Sprengel-Liebig Law of the Minimum was applied to evaluate the proportion of each field constrained by one or more soil characteristics. Up to 55% of the improved paddock and 78% of the native pasture was potentially responsive to amendments. The results of this study suggest that SSM of fertilisers and ameliorants could provide substantial improvements in productivity and possibly reductions in fertiliser use. The development and application of appropriate systems and tools to effectively quantify this spatial variability remain a challenge, coupled with management strategies that optimise the placement of amendments and account for the variability in other production limiting factors.
Monitoring and managing landscape variability in grazing systems
Precision agriculture (PA) technologies and applications have largely been targeted at the cropping and horticultural industries. Little research has been undertaken exploring the potential for PA in grazing systems. This paper reports on the results of five studies examining PA technologies and techniques in grazing systems including: spatial variability in soil nutrients and fertiliser response across the grazing landscape; spatial landscape utilisation in relationship to individual animal productivity and health; spatial variability in pasture pests; and the development of a sensor network for monitoring spatial soil moisture, soil temperature and ambient temperature across a grazing landscape. The large variability exhibited in our trials suggests there is an enormous opportunity for precision agriculture in grazing systems. Sensing and responding to this variability will require careful application of modern PA technology and a substantial investment in research to better understand spatial variability in our grazing landscapes.
Objective biomass assessment using an active plant sensor (Crop Circle™) - preliminary experiences on a variety of agricultural landscapes
Quantifying spatial variation in pasture and crop biomass can help to direct management practices and improve farm productivity, through accurate and informed movements of grazing rotations, crop and pasture nutrient management and yield production. Visual pasture assessments are often subjective, and require a degree of expert knowledge/experience. Quadrat-based plant harvesting determinations of biomass is labour intensive and costly when accurate quantification of pasture and crop variability over large areas is required. Furthermore, quadrats of 1m² or less are not easy to relate to remotely sensed images with spatial resolutions ranging from 4 to 400m². Active optical plant sensors that measure the red and near-infrared radiation reflected from the vegetation canopy offer the potential of deriving objective estimates of the photosynthetically-active plant biomass and may also hold the key to quantifying biomass over large areas with high spatial resolution. Crop Circle™ (Holland Scientific) is one example of an active plant sensor that measures red and near infrared light reflected from the canopy/soil matrix. In this paper we present the results of a project to assess the accuracy of Crop Circle™ for biomass assessment in a variety of agricultural environments including: native, improved and irrigated pasture; and forage and cereal crops.
Proceedings of the 1st Australian and New Zealand Spatially Enabled Livestock Management Symposium
Spatial monitoring of livestock and their environment has been a rapidly expanding area of research in Australia, New Zealand and around the world over the past few years. Furthermore, systems for commercial deployment are currently being developed to enable producers to make use of this technology. It's an exciting time to be a researcher; however we need to be aware of the many challenges we face if these technologies are to be successfully adopted by industry. Communication between technology developers, researchers, funding bodies and producers is fundamental to ensuring a coordinated approach to research and to ensure practical outcomes for industry. This is one of the primary functions of this symposium, bringing together all these parties to share knowledge and build working relationships! This symposium has a diverse range of speakers and, as a direct consequence of discussions from last year's GPS Livestock Tracking Forum, keynote speaker Toby Patterson will provide insights into animal movement and behavioural modelling in ecology, an allied research area from which the livestock industry can learn a great deal. So whether you are a researcher intent on using the technology to understand the mysteries of plant and animal interactions, or a producer just wanting to know where your cows are, we hope you will glean something useful from the event!
The effect of longwall mine subsidence on native vegetation and agricultural environments
Longwall mining generally results in subsidence of the land surface. While the extent and nature of subsidence on surface topography is reasonably well understood the effects on surface environments (agricultural and native vegetation) arc less well known. In this paper we will describe the initial stage of a three year ACARP project to develop scientific protocols to quantify changes to above-ground environments. Specifically, the project objectives are to: quantify the effects of longwall mine subsidence on agricultural and terrestrial native vegetation; develop industry-standard methods for monitoring these effects; optimise monitoring quality, quantity, safety aspects, timeliness and cost effectiveness through the integration of high resolution remote sensing and ground-based sampling.
Effects of shade on seed production of 'Nassella trichotoma' in northern New South Wales
Serrated tussock ('Nassella trichotoma' (Nees) Arechav.) is a perennial grass weed of pastures. It is a widespread problem on the Southern Tablelands of New South Wales (NSW) that have a Mediterranean climate and is now invading the Northern Tablelands of NSW where rainfall is summer dominant. Isolated infestations are found under trees and in open areas. Due to the importance of wind-borne seeds to the invasive capability of serrated tussock and the suppression of seeding in effective management, it is necessary to understand when plants set seed and the factors that affect the level of seed production. In particular a reduction in the intensity or amount of light received by a plant can have implications on physiological responses such as changes in seed production. The aim of this study was to assess the effect of shade on the timing and amount of seed production.