2020
Development of new pasture systems in NW Victoria Authors: Roy Latta1, Michael Moodie1 Research Team: Todd McDonald1, Chris Davies1, Michael Case1 1Frontier
Farming Systems
Funded By: The Australian Government Department of Agriculture as part of its Rural R&D for Profit program, the Grains Research and Development Corporation, Meat and Livestock Australia and Australian Wool Innovation. Project Title: Dryland Legume Pasture Systems (DLPS) Key Words: Pasture establishment, novel pasture species, pasture wheat rotation, serradella, vetch, Rose clover, Bladder clover, trigonella, astragalus, medic,
Key Messages ● ● ● ● ●
Year 3 of the 4-year pasture development project has measured a 1 t/ha wheat yield increase and almost 2% grain protein improvement following a legume pasture break crop as opposed to a continuous cereal. Having approximately 100 kg N/ha in the 100 cm soil profile following a legume pasture break crop compared to 20 following a cereal was a major driver of the benefit from the legume break crop. This work has identified serradella as an option on Mallee soils where lupins are grown successfully. The serradella established successfully from the seed pod sown 1 year and 3 months prior to and at the season break. Serradella has been at least as productive as vetch on the deep sands and where the seed pod has been harvested at commercial rates with a plot header.
● We plan 2021 broad acre assessments to help form and support a confident commercial package. Background This article reports year 3 of the project “Dryland Legume Pasture Systems” (DLPS) which aims to discover resilient low-cost pasture legumes with appropriate management packages to provide livestock and cropping benefits to the low-medium rainfall mixed farming regions of Australia. The components of the novel pasture systems studied through this project include: 1. In 2019 new legume pasture species/cultivars that have not traditionally been grown in the target region. Each species may provide benefits such as alternative pasture establishment systems aimed at reducing the cost of pasture establishment and increased production on certain soils types. 2. In 2020 the response in the cropping phase of the rotation to the new legume pasture species and in a separate trial the ability for their seed to be machine harvested and retained. 3. In 2021 their hard seed characteristics that may provide a viable pasture after a cropping phase.
About the trial Trials 1 and 2 are on farm trial site near Piangil and the soil type is characterised as having a red loamy sand texture and a pH (CaCl2) which graduates from 7.4 at 0-10 cm to 8.4 at 70-100 cm. Trial 1 was sown to wheat on 28 April 2020 by direct drilling into existing plots which were established in 2018. In 2019 the plots were either one of seven pasture legumes that were established through twin, summer or autumn sowing, autumn sown vetch or barley. The trial design and 2019 results were fully described in the MSF 2019
Page 2 compendium article “Development of new pasture systems in NW Victoria” (https://msfp.org.au/development-ofnew-pasture-systems-in-nw-victoria/). Measurements of the trial in 2020 included pre-seeding total soil nitrogen (0 – 100 cm) and water content (mm H2O, 0 – 100 cm), plant establishment (plants/m 2), root disease (visual assessment ratings 0 to 5), pre-harvest crop biomass (t/ha) and harvest index (% grain to biomass), grain yield (t/ha) and protein content (%), and post-harvest soil water content (mm H2O, 0 – 100 cm). In 2019 the novel pasture legumes were maintained through to maturity in late October with total biomass yields 1.2 to 2 tDM/ha. The vetch was chemically fallowed on 5 September 2019 with 2.5 tDM/ha. The barley went through to harvest yielding 2.7 t/ha. Two further trials were established in 2020, Trial 2 at Piangil (11 entries x 3 replicates, 18 m x 1.68 m plots) and trial 3 at Speed (7 entries x 3 replicates, 8 m x 1.68 m plots) with the site located on a deep yellow sand. The establishment (plants/m2), productivity (tDM/ha), harvested seed yields (plot header) and seed left behind postharvest of forage varieties were measured at both sites. The trial entries are presented in Tables 2 and 3. Seeding rates were based on germination tests and seed size to try to achieve similar early biomass production. Trials were sown with 50 kg of Granulock Z MAP fertiliser. All seed was inoculated with the specific rhizobia group required. Both sites received a grass selective herbicide with an insecticide included in July. Trial 2 had flumetsulam herbicide applied to all but the vetch and astragalus entries, which were hand weeded as required as well as all the Speed entries. Piangil had glyphosate applied to increase rate of senescence on 12 November in preparation for machine harvest on 9 December. At Speed machine harvest took place on 11 December. In 2020 the Piangil Trials had 187 mm growing season rainfall, 235 mm total on the sandy loam over clay. Speed had 276 mm growing season and 416 mm total annual rainfall, on a deep sand over a sandy clay loam at 60 -70 cm. Soil pH, (0-10 cm) 6.4 CaCl2 , SOC 0.37%, EC 0.075 dS/m, Colwell P 20 mg/kg and pH 8.2 CaCl2 (70-100 cm). Where measurement comparisons were applicable ANOVA’s were completed as fully randomised blocks using Genstat 5.
Results & Discussion The Piangil trials received more than 80% of their average growing season and annual rainfall but a dry 27 mm May June and July period. The Speed trial approximately 125% with 70 mm over that ‘dry’ winter period. Table 1. 2019 pasture biomass (tDM/ha) from the novel legume pasture species, vetch and barley and the subsequent 2020 total soil N (kg 0 -100 cm), grain yields (t/ha) and grain protein contents (%) of Trial 1 at Piangil. 2019 Treatments
2019 Biomass
2020 Total soil N
(tDM/ha Biserrula 1.1cd Bladder clover 1.6b Barley na Gland clover 0.8d Annual medic 2a Rose clover 1.9ab Serradella 1.6b Trigonella 1.2c Vetch 2.5* Lsd P=0.05 0.38** *Green manured August 2019 **Applicable only to the 7 pasture legumes
(kgs) 110ab 116ab 22c 135a 103b 118ab 91b 107ab 102b 30.7
2020 Wheat Grain Yield (t/ha) 2.8ab 2.7ab 1.8c 2.9a 2.5b 2.7ab 2.7ab 2.7ab 2.6b 0.3
2020 Wheat Grain Protein (%) 11.9b 12.4a 10.7c 12.3ab 12.3ab 12.5a 12.4a 12.3ab 12.7a 0.42
Page 2 The 2020 wheat grain yield and protein contents were increased following all legume treatments relative to the wheat following barley. Irrespective of 20 units of N spread in-crop plus 10 units of N included at sowing the protein content of the wheat following barley coupled with a low grain yield reflect the 2020 benefit of the legume break crop in plant available N. The 2020 total soil N trial mean of 100 kg/ha was an increase from approximately 55 kg/ha at the commencement of the trial, an addition of approximately 45 kg N/ha over the pasture phase. Wheat grain yield and total soil N were negatively correlated with 2019 pasture biomass production (r2=-0.82 and 0.50 respectively). Therefore, the higher 2019 annual medic biomass resulted in similar or lower soil N and wheat yield than the other legume treatments. Means of all treatments showed a 5 mm soil water reduction over growing season, a seminal root rating of 1 out of 5 and a harvest index of 44%. Statistically all three sets of results were similar between species at the 5% level. The 2019 pasture establishment methods had no effect on wheat grain yields or protein contents. 2018/19 twin sowing, summer sowing and autumn sowing treatments yielded similar wheat yields and protein contents in 2020, 2.5, 2.7 and 2.6 t/ha of wheat and 12.2, 11.8 and 12.2% protein contents respectively. The negative correlation was repeated over all legume establishment methods with annual medic having generally higher 2019 biomass production but generally lower following 2020 grain yield.
Table 2 Trial entries, establishment (plants/m2) total biomass (tDM/ha) machine harvested and post-harvest plot retained seed (kg/ha) Trial 2 at Piangil Entries
Variety
Vetch Strand medic Strand medic Barrel medic Barrel medic Burr medic Serradella Bladder clover Trigonella Astragalus Clover Lsd (P=0.05)
Volga PM 250 Jaguar Sultan Cheetah Scimitar Margurita Bartolo SA 5045 Loman Sardi Rose
(plants/m2) 10 May 21 135 201 130 131 140 153 90 384 146 143
(tDM/ha) 8 September 3.1 4.2 3.6 3.3 4.7 3.9 2.7 1.5 2.5 3.2 2.5 1.46
Seed yield (kg/ha) Harvest Retained 1200 260 0 680 30 620 0 640 20 640 0 690 220 440 10 860 120 220 0 860 10 390
In trial 2 the small seeded trigonella, bladder and rose clover were sown at rates to achieve 300 plants/m2. The trigonella exceeded the aim, and the other two reached only 30 to 50%. The other entries reached at least 65% of the projected densities, medics, serradella and astragalus 200 plants/m2 and vetch 30 plants/m2. The annual medics were well adapted to the alkaline sandy loam soil type with similar or higher total biomass production than other entries. Compared to vetch only the bladder clover had less total September biomass. Irrespective of the observed pod retaining characteristics of Jaguar and Cheetah they did not produce the height and/or amount of biomass required for successful header pod collection. The bladder clover and astragalus produced high seed yields but the seed was not available to the header due to lack of biomass and/or height. The Rose clover seed heads were collected by the header but due to low unit weight were lost straight over the straw walkers. A different method or machine would be required to achieve successful harvest. 30% of the total seed production of the more erect serradella and trigonella were collected by the plot harvester. The plot header with crop lifters attached collected more than 80% of the total vetch seed yield.
Page 2 Table 3 Trial entries sown as seed or seedpod, establishment numbers (plants/m2) total biomass (tDM/ha) machine harvested, and post-harvest plot retained seed (kg/ha) at Speed
Volga PM 250 seed
(plants/m2) 4 May 45 165
(tDM/ha) 16 October 7.1 4
PM 250 pod
77
4.9
0
1690
Margurita seed Margurita and Eliza pod Sardi Rose seed Sardi Rose pod
199 154 193 83
7.5 7.6 3.5 3.1 2.43
1030 990 0 0
800 800 600 700
Entries
Variety
Vetch Strand medic Strand medic Serradella Serradella Clover Clover Lsd (P=0.05)
Seed yield (t/ha) Harvest Retained 2200 820 0 1500
In the Speed trial the Rose clover sown as unprocessed seed reached less than 30% of the projected 300 plants/m 2. However, that was not a disadvantage in biomass or seed production. Sowing as pod was as successful as sowing as seed. The medic sown as seed and pod reached more than 75% of their projected densities, 200 and 100 plants/m2 respectively, as did the serradella seed and pod, 200 plants/m2, and vetch 50 plants/m2. The serradella produced more biomass than the annual medic or Rose clover and similar to the vetch. More than 50% of the serradella seed was collected by the harvester as opposed to more than 70% of the vetch.
Implications for commercial practice The project aims to identify the application and system benefits of novel legume pasture species that have not traditionally been grown in the target region (Victorian Mallee). Vetch is the most commonly grown legume in the region. However, there are alternative pasture legumes which have the potential to increase production on certain soil types that are not suited to vetch. The commercial uptake of any of these forages will be based on their capability to: 1. establish successfully, Trial 2 at Piangil and at Speed all entries apart from the bladder clover established satisfactorily, from seed and seedpod. However, this did not restrict the bladder clover seed production. 2. produce more biomass than vetch. Serradella was the only entry which produced comparable biomass and flowering dates to the “early season” vetch variety Volga at both Trial 2 and Speed. 3. benefit subsequent cereals, Trial 1 partly met the subsequent cereal productivity benefit of the novel legumes with wheat yield and quality following all entries like the green manured vetch. Similar or lower pre-seeding total soil N and soil water content following vetch than other legumes was interesting as vetch had the perceived advantage of higher 2019 biomass and an August 2019 plant senescence. 4. provide a regular machine harvestable on-farm seed supply. Serradella and trigonella, along with vetch, produced machine harvested seed yields. Based on 1000 grain weights, vetch 60 grams, serradella 3 grams, trigonella 1.5 grams approximately 10 times more seed numbers of serradella and trigonella were harvested than the vetch. At Speed the vetch produced seedpod for potentially sowing 100 hectares at 10 kg/ha from each hectare harvested, as did the vetch, sowing 100 hectares at 22 kg/ha from the deep sand Trial 2. This study supports serradella as a multi-purpose (forage, hay, seed) option for deep Mallee sands. However, this and previous local studies have shown no clear benefit over vetch in productivity, only in the flexibility in the timing of seeding. Alternatively, as an option to the annual medic self-regenerating ley farming system serradella provides the opportunity for on-farm seed supply and possibly improved productivity on the deep sands. The areas where it falls short in the annual medic comparison are in a later maturity, of the current cultivar Margurita, and possibly
Page 2 adequate hard seed available to regenerate following a cropping phase. 2021, when regeneration of the pasture species following the wheat phase will be assessed may provide some answers.
Acknowledgements This project is supported by funding from the Australian Government Department of Agriculture, Water & Environment as part of its Rural R&D for Profit program, the Grains Research and Development Corporation, Meat and Livestock Australia and Australian Wool Innovation. The research partners include the South Australian Research and Development Institute, Murdoch University, the Commonwealth Scientific and Industrial Research Organisation, the WA Department of Primary Industries and Regional Development, the NSW Department of Primary Industries and Charles Sturt University, as well as grower groups.