Persistence of annual and perennial legumes 12 years after sowing in the Monaro region of New South Wales

Belinda Hackney1, 2, Jo Powells3, Susan Orgill1, 2

1 NSW Department of Primary Industries, PMB, Pine Gully Rd, Wagga Wagga, NSW 2650

2 Graham Centre for Agricultural Innovation, Charles Sturt University and NSW Department of Primary Industries, Pugsley Place, Wagga Wagga, NSW, 2650

3South East Local Land Services, Cooma, NSW 2630

Abstract:

The productivity of introduced and native-based pastures across the Monaro region of NSW is often constrained by a low legume content. Full pasture renovation is frequently precluded by landscape, soil or economic constraints with producers often spreading legume seed with fertiliser in an attempt to increase the legume content of pastures. Four methods of legume introduction into an existing pastures (surface broadcasting and direct drilling with and without a pre-sowing glyphosate knockdown) at two landscape positions (north and south facing aspect) for four legume species, subterranean clover (Trifolium subterraneum), Caucasian clover (T. ambiguum), Talish clover  (T. tumens) and lucerne (Medicago sativa), were investigated. Direct drilling after a glyphosate knockdown was the most successful method of introduction with subterranean clover achieving the highest seedling density. However, after 12 years, few legumes could be found on the north-facing aspect and subterranean clover had not survived on the south facing aspect. Legumes were found only in the direct drilled-glyphosate knockdown treatment; lucerne having the highest plant density and herbage availability. Where legume treatments had failed, populations of tall speargrass (Austrostipa scabra), a native perennial grass, had returned to their original density. A. scabra density was significantly lower on the south facing aspect in the lucerne and Caucasian clover treatments. There is capacity to introduce legumes into existing pastures but seed-soil contact and reduction in competition from existing pasture species at establishment is crucial to long-term persistence

Paddock scale modelling and mapping of dry matter yield using UAV derived datasets: A case from dairy farming systems in Victoria

Senani Karunaratne, Elizabeth Morse-McNabb, Anna Thomson, Dani Stayches, Joe Jacobs

Agriculture Victoria Research, Ellinbank VIC 3821, website: www.agriculture.vic.gov.au; E: senani.karunaratne@ecodev.vic.gov.au

Abstract:

Traditionally, quantification of dry matter (DM) yield at a paddock or farm scale is undertaken using a rising plate meter (RPM) which provides paddock scale estimates via calibrated equations to predict pasture DM yield. This approach ignores the inherent spatial variability within a paddock which may limit optimum utilisation. In this study, unmanned aerial vehicle (UAV) datasets were coupled with modern machine learning data analytical methods to model and map pasture DM yield variability across individual paddocks at 1 m spatial resolution. The results revealed that the near infrared spectral band had the highest influence in predicting the pasture DM yield. However, the use of additional UAV-derived data sources, such as digital surface and digital terrain models as proxies for pasture height, further improved the prediction. Height derived from the UAV datasets was identified as the second most important variable in prediction of the pasture DM yield. Derived models were cross-validated and also independently validated through data splitting which resulted in concordance values of 0.90 and 0.40 respectively.  Model comparison with the calibration equation derived using a RPM revealed that both methods reported equal validation of the results based on the cross-validation. However, the RPM model surpassed the independent validation results of the UAV-machine learning modelling approach. There is potential to explore a wider spectral range and other ancillary datasets for model improvement, in order to improve these machine learning models for prediction of DM yield across the paddock scale.

Liming changes more than the pH – A field study on wheat and pasture species

Daniel Kidd1,

1 University of Western Australia, 35 Stirling Hwy, Perth, W.A, 6009, daniel.kidd@uwa.edu.au

Abstract:

This experiment was conducted to investigate the enduring effects of prior liming of an acidic duplex soil. In 2018, the response of cereal crops (wheat and cereal rye) and pasture legumes (serradella, subterranean clover and lucerne) spanning a range of susceptibility to acid soil was assessed. Despite the site having uniform nutrient additions and crop management over a number of years, nutrient availability (particularly nitrogen, phosphorus and potassium) was still significantly lower in the unlimed strips compared with the limed strips. Of the root diseases assessed, most were more prevalent under cereals and had a greater disease risk rating in limed plots. There was no effect of lime on shoot and root DM of acid soil tolerant varieties (i.e yellow serradella and cereal rye). Acid soil tolerant varieties are a good option in these soil types but the potential use of higher yielding, acid soil sensitive varieties combined with the longevity of the liming effects in low rainfall environments should be taken into account when considering the economics of soil amelioration by liming.

The potential of forage brassicas to produce herbage for mixed farming systems

Lucy Watt1, 4, Lindsay Bell1, Brett Cocks1, Tony Swan2, Andrew Toovey3

1 Agriculture & Food, CSIRO, 203 Tor Street, TOOWOOMBA, QLD, 4350

2 Agriculture & Food, CSIRO, Black Mountain, 2-40 Clunies Ross Street, ACTON, ACT, 2601

3 Agriculture & Food, CSIRO, 147 Underwood Avenue, FLOREAT, WA, 6014

4lucy.watt@csiro.au

Abstract:

Forage brassicas are not commonly utilised in Australian mixed farming systems. Integrating forage brassicas into these systems may improve crop rotations and livestock productivity, but their adoption is limited mostly due to a lack of knowledge of the most suitable species and the potential systems benefits from their use. In seven field experiments carried out in 2011-2013 (Phase 1) and 2018 (Phase 2) across a range of environments, including Eastern and Western Darling Downs QLD, North West and Central West NSW, and Avon Wheatbelt WA, the biomass production of a range of forage brassica species were compared with other annual forage benchmark species. In Phase 1, forage rape cultivars were able to produce 80-90% of the biomass of forage cereal controls, but there were some differences between the diverse forage brassica types across growing environments. In Phase 2, Experiments 4, 5 and 7, several of the forage brassicas produced similar (P > 0.05) maximum biomass as forage oats. Conversely, in Experiment 6, maximum biomass of forage oats was higher (P < 0.001) than all other species. Maximum biomass of raphanobrassica cv. Pallaton and forage rape cv. HT-R24 were similar (P > 0.05) to forage oats at three of the four sites, whilst performance of the other forage brassicas was variable between sites.

 

Neptune’, the world’s first messina (Melilotus siculus) cultivar: an annual pasture legume for saline soils prone to winter waterlogging

Phillip G.H. Nichols1,2, Ross A. Ballard3, Amanda L. Pearce4, Bradley J. Wintle1,2, Andrew D. Craig5

1School of Agriculture and Environment, University of Western Australia, 35 Stirling Highway, Perth WA 6009, www.uwa.edu.au,phillip.nichols@uwa.edu.au
2Formerly Department of Primary Industries and Regional Development,
3 Baron-Hay Court, South Perth WA 6151, 3South Australian Research and Development Institute, GPO Box 397, Adelaide SA 5001,
4South Australian Research and Development Institute, Struan Research Centre, PO Box 618, Naracoorte SA 5271,
5Formerly South Australian Research and Development Institute, current address: PO Box 1196, Naracoorte SA 5271

Abstract:

Saline soils are widespread across southern Australia. Such areas tend to be waterlogged in winter with traditional pasture legumes highly sensitive to the combined stresses, resulting in poor pasture productivity. A search for pasture legumes adapted to saline, waterlogged soils, has resulted in release of the annual pasture legume, ‘Neptune’, as the world’s first cultivar of messina (Melilotus siculus). This paper reports on the field performance of Neptune compared with balansa clover (Trifolium michelianum) cv. Frontier, burr medic (Medicago polymorpha) cv. Scimitar, and white melilot (Melilotus albus) cv. Jota over three years at five sites in South Australia and Western Australia. At the three most saline sites, Neptune had a dry matter yield that was 2.5, 4.2 and 57.2 times higher than Frontier, Scimitar and Jota, respectively. A salt-tolerant Rhizobium strain, SRDI554, has been released to facilitate nodulation of regenerating messina in saline soils

Host

The Australian Society of Agronomy is the professional body for agronomists in Australia. It has approximately 500 active members drawn from government, universities, research organisations and the private sector.

Photo Credits

David Marland Photography david_marland@hotmail.com Graham Centre for Agricultural Innovation, Charles Sturt University

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