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  • ASHEEP & South Coastal Agencies

2023 Pasture Variety Trials Results

Author: Chad Hall & Tyneal Callus, South Coastal Agencies


2023 marked the fourth year of the ASHEEP & BEEF Pasture Variety Trials, a Meat & Livestock Australia (MLA) Producer Demonstration Site (PDS) project. As a part of this project, South Costal Agencies (SCA) collaborated with sheep and cattle producers to evaluate pasture performance across various management systems, soil types, and rainfall zones. The overarching goal was to scrutinise pasture performance, stocking rate potential, and production costs, facilitating an economic analysis for each scenario. The delineation of areas based on rainfall zones—high (+550mm), medium (350mm), and low (<350mm)—aided in selecting appropriate pasture varieties for each zone.


Method

The trials began in 2020, with years one and two being plot trials to assist producers in determining suitable varieties they would like to grow as if they were being used in a demonstration on the commercial situations in years three, four and five. Producers plant these broadacre demonstrations for the purpose of grazing under normal conditions and stocking rate and, by doing so, test the varieties under pressure.


At each location, three pasture grazing cages were constructed to facilitate livestock (sheep or cattle) grazing in the paddock while enabling continuous monitoring of pasture growth and nutritional value. Soil samples were collected from each paddock to gain insights into each site's specific soil constraints and limitations.


Upon installing the cages, visual observations were recorded, encompassing aspects such as pasture composition, establishment, and the presence of noteworthy pests like mice, diamondback moths and mites.


The break of the season was determined for each site by recording the date of the first opening rain, a rainfall event greater than 10mm in 24 hours. While in 2022, only ten and sixteen-week pasture cuts were taken for analysis, ASHEEP & BEEF and SCA determined that a third cut should be taken at twenty weeks where appropriate biomass was present to represent the entire season better and pinpoint peak biomass production throughout the year.


Pasture samples were extracted from a quadrant and sent for analysis. Each pasture sample underwent weighing to ascertain both wet weight and available biomass, allowing the determination of kilograms of dry matter per hectare (Kg/DM/Ha). The pasture cuts were uniformly trimmed from the same quadrant each time to simulate livestock grazing with subsequent regrowth closely monitored. Observations and notations were made regarding the presence of weeds, insects, diseases, and alterations in pasture composition.

The dry sheep equivalent (DSE) rating is determined by the feed required to maintain a 50kg wether. The calculations in this report allow 20% for fouling and wastage. However, it assumes that all pasture will be consumed thereafter. However, when pasture feed budgeting, it's important to leave residual pasture behind to enable it to remain vegetative throughout the season. This residual pasture serves multiple purposes: it sustains vegetative growth during the season and, by season's end, creates a mulching effect and helps reduce wind and water erosion.


Location of 2023 Pasture Variety Trial Sites

Pastures Trailed by Rainfall Zone

Low Rainfall Zone (LRZ)

<350mm

  • Grass Patch Site 1: Margarita & Cadiz Serradella

  • Grass Patch Site 2: SerraMax Serradella


Medium Rainfall Zone (MRZ)

350-500mm

  • Cascade Site 1: RM4 Vetch

  • Cascade Site 2: RM4 Vetch & Morava Vetch

  • Cascade Site 3: RM4 Vetch & Leafmore Brassica


High Rainfall Zone (HRZ)

>500mm

  • Condingup Site 1: Forester Oats & Abundant Ryegrass Sown into a sub clover base.

  • Dalyup Site 1: Lucerne and South-West Pasture Mix (sown 2021 & 2022 respectively)


An economic analysis compared the number of DSE that a pasture could maintain over the period the samples were taken (ten, sixteen, and twenty weeks post break of season). In 2022, it was determined that the best way to compare pastures in differing rainfall environments and between seasons was to analyse the carrying capacity as DSE per one hundred millimetres of rainfall. The grower inputs were then considered to calculate a cost per ha and a cost per DSE.


The input cost per DSE is relevant as it considers carrying capacity to analyse better the direct cost of feeding a DSE. Finally, the value of nitrogen fixation through legume and rhizobia symbiosis was calculated by assuming twenty units of N is fixed per tonne of biomass produced. The value per unit of N was based on a urea price of $920/t with an analysis of 46% N, equating to $2/unit of N.


NRI Analysis

An NRI analysis measures feed quality to ensure that the feed is adequate for the livestock grazing a pasture. Considerations that are used in this report are that a single DSE requires 8.3 megajoules of metabolizable energy (ME) and at least 9% crude protein (CP) per kilogram of dry matter consumed to maintain condition (pregnant sheep and lambs require 15% CP). All figures used in this report are based on Dry Matter measurements. A description of all measurements has been included below.


  • Moisture and Dry Matter (DM%) – These two figures add up to 100% and are the inverse of each other. They are the percentage of moisture removed to the percentage of DM remaining.

  • Crude Protein (CP%) – The most used measure of proteins available from the feed source. CP% is calculated from the nitrogen content in the plant material.

  • Acid Detergent Fibre (ADF) – ADF measures less digestible fibres, cellulose, and lignin. This can be used to measure digestibility or how much of the DM is useful. The higher the ADF content, the lower the digestibility.

  • Neutral Detergent Fibre (NDF) – NDF is a prediction of all digestible and indigestible fibre contained by the feedstuffs. This encompasses all the ADF but includes the highly digestible fibres, hemicellulose, and pectin. Feeds with NDF levels that are too high will reduce dry matter intake, and too low will reduce roughage and digestibility.

  • Lignin – Lignin is a component of both NDF and ADF that is entirely indigestible. It acts to bind up nutrients that would otherwise be available to the animal. Lignin aids in plant stem rigidity by binding cells to the cell wall; the plant uses this mechanism to strengthen its stem in preparation for reproduction. Abiotic stresses to the plant, such as water, heat, and nutritional stress, will cause lignin biosynthesis, which can prematurely reduce the feed quality.

  • Metabolizable Energy (ME) – This is the measure of ME/kg of DM and is a simple calculation of gross energy minus energy losses in faeces, urine, and gases.

  • Pasture Growth Rates (PGR) – PGR is the amount of feed grown per hectare per day, measured in kilograms of DM/ha/day over a set period.

  • Dry Sheep Equivalent per Hectare (DSE/ha) – This is the amount of DSE that can be stocked per hectare based on the nutritional requirements above.

  • DSE/100mm Rainfall – This is used to roughly compare pastures between differing rainfall conditions by dividing the stocking rate by the rainfall for the period. Note that this method only controls one of many variables.

  • Total DM/Ha – All the dry matter measured over the period.

  • PGR AVE – The average pasture growth rate (kgDM/ha/day) over the period of measurements.

  • DSE/Ha 0- 16 Weeks – The amount of DSE the dry matter could feed over the measurements.

  • DSE/100mm 0-16 Weeks – DSE/ha 0-16 weeks divided by each hundred millimetres of rainfall over the measurement period.


Other Definitions

  • Growing Season Rainfall – The rainfall collected from the 1st of January to the 1st of September; this was when the final pasture samples were taken.

  • Dry Sheep Equivalent (DSE) – One 50kg wether maintaining condition requires 1kg of dry matter containing 8.3 megajoules of metabolisable energy. This model allows for 80% pasture utilisation with 20% wastage due to trampling and fouling.


2023 Project Results

The 2023 season commenced with favourable opening rains across all regions and the break of season was determined to be the 3rd of April across all sites. The month of April was followed by an extended period of dry and hot weather. Pastures were established shortly after the initial April rains, but biomass production was constrained due to a lack of moisture and warm temperatures. The dry period persisted until the end of May, when consistent heavy rainfall and cool temperatures broke the dry spell, leading to waterlogging in some areas. The season concluded abruptly with a significant reduction in rainfall, contributing to premature cessation and compounding the issue with poor biomass production and a restricted period of pasture growth.



CASCADE SITE 1


Grower: Mark & Liv Walter

Variety: RM4 Vetch

Rainfall Zone: MRZ

Annual Rainfall 2023: 211mm

1st Jan – 1st Sept Rainfall: 178mm

Soil PH: 7.6

Organic Carbon: 1.5



The Walter’s Cascade sites were strategically selected to represent the medium rainfall zones within the Esperance district. This specific site faced notable challenges due to drier and warmer-than-normal conditions throughout the season. While the pasture could germinate off the available sub-soil moisture successfully, the subsequent extended dry spell posed difficulties for local growers in managing pasture establishment and performance effectively. RM4 was chosen for its early vigour and establishment, which is said to be 10-14 days earlier than common vetches. Proven to be a preferred variety in the Cascade area, its popularity stems from its significant contributions to mixed cropping and livestock systems, serving as an excellent break in cropping rotations. Furthermore, RM4 plays a vital role in nitrogen production through its symbiotic relationship with Rhizobia. This serves as a valuable nitrogen resource for subsequent cropping phases reducing the costly reliance on applied nitrogen.


The 2023 season posed as a test for any pasture variety, and RM4 showcased resilience under pressure. Early on, the Walters faced a difficult decision – whether to spray out volunteer cereals to preserve limited moisture for the vetch or utilise the cereals as a much-needed feed source.


Ultimately, opting to graze the volunteer cereal proved beneficial, and the vetch survived until the subsequent rain event. The young vetch, with its fine and woody architecture, demonstrated a remarkable ability to cope with drought stress by prioritising root establishment over leaf material during its early growth stages. When rainfall finally arrived in June, the well-prepared plant efficiently utilised the moisture, resulting in a remarkable surge in pasture growth from 3.8 kg DM/ha/day to nearly 60 kg DM/ha/day. Despite the season's continued dryness, the pasture performed well, showcasing its adaptability to challenging conditions. With a total cost of pasture production at $70.80/ha, the biomass generated could sustain a reasonable stocking rate, translating to an input cost per DSE of only $3.09/DSE. Moreover, considering the rainfall factor, the pasture's performance was affirmed by achieving an impressive stocking rate of 12 DSE/100mm of rainfall. Furthermore, it is estimated that this pasture produced eighty-eight units of nitrogen per hectare, to a value of $7.70/DSE. When this is factored into the cost of pasture production, the input cost is -$4.61/DSE.



CASCADE SITE 2


Grower: Mark & Liv Walter

Variety: RM4 Vetch, Morava Vetch

Rainfall Zone: MRZ

Annual Rainfall 2023: 211mm

1st Jan – 1st Sept Rainfall: 178mm

Soil PH: 5.9

Organic Carbon: 1.75



The Cascade 2 site, also situated at the Walter's property in close proximity to the other Cascade sites, encountered similar challenges. The objective of this site was to assess the introduction of Morava to an RM4 pasture, aiming to extend the season length. While RM4 displayed rapid early growth and shorter grazing days, Morava was anticipated to remain vegetative for a longer period. Rust-resistant and Ascochyta-tolerant, Morava is able to remain vegetive and palatable through winter and well into spring.


Although the 2023 season wasn't ideal for testing extended season length, it provided insights into the implications of a long-season strategy under limited rainfall.


The 10-week cuts of the mix show slightly lower biomass and stocking rate potential than the RM4 alone, aligning with expectations due to fewer RM4 plants and less early vigour. However, the 16- and 20-week cuts supported the theory that incorporating Morava vetch increases winter and spring biomass, even in a dry year. Overall, the mix slightly outperformed the RM4 monoculture in biomass, with sufficient energy and protein across all cuts for both varieties. Despite being $8/ha more expensive, the mix only incurred an additional cost of $0.03 per DSE due to the increased stocking rate. When factoring the value of nitrogen fixed, the pasture cost per DSE is -$3.99. We hypothesise that the RM4 Morava mix would likely outperform the RM4 as a monoculture in more favourable seasonal conditions.



CASCADE SITE 3


Grower: Mark & Liv Walter

Variety: RM4 Vetch, Brassica

Rainfall Zone: MRZ

Annual Rainfall 2023: 211mm

1st Jan – 1st Sept Rainfall: 178mm

Soil PH: 7.9

Organic Carbon: 2



Cascade 3, the final site at Walter’s property, shares proximity with the other Cascade sites and faced similar challenges. The objective at this site was to experiment with increasing pasture biomass in an RM4 pasture by introducing a grazing brassica. The chosen brassica, Leafmore, has been selectively bred to achieve maximum biomass and an extended vegetation period, delaying the effects of lignification caused by the plant's preparation for reproduction. Under favourable conditions, Leafmore can produce exceptional biomass and serve as a high-quality feed source with a low leaf-to-stem ratio.


Despite the intended goal, Leafmore establishment fell below expectations, with approximately five plants per square meter. According to the MLA forage brassica management guide, growers should target 30-40 plants per square meter in lower rainfall areas and 50-60 plants per square meter in high rainfall environments. Surprisingly, sheep exhibited selective grazing behaviour, favouring the vetch and avoiding the Leafmore. This observation was intriguing as vetch is generally considered to be of low palatability, especially in its early stages. Typically, growers strategically use this characteristic for weed control, as livestock tend to graze weeds like wild radish before vetch. Unfortunately, in this scenario, vetch struggled to withstand preferential grazing in its early establishment stages due to its relatively high growth point, hindering recovery. Managing vetch carefully, especially in the early stages, is crucial.


As the Leafmore canopy closed, overcrowding occurred, making it challenging for any surviving vetch to compete. Consequently, vetch biomass remained limited, and nitrogen fixation couldn't be accounted for, representing the primary cost in this mix. When comparing the production costs between this system and the straight RM4, the RM4-Leafmore mix incurred a production cost of $3.16/DSE, while RM4 Vetch alone, which additionally produced $7.07 from nitrogen, had a cost of $3.09/DSE. The net result showed a cost difference between RM4 and RM4 with Leafmore of -$4.2/DSE vs. $3.98/DSE respectively, indicating an $8.18/DSE advantage for RM4 Vetch without Leafmore. Additionally, concerns were raised about the brassica's nutrient mining characteristics potentially leading to other nutrient depletions, particularly phosphorus and potassium.



DALYUP SITE


Grower: Scott Wandel

Variety: Lucerne & SW Pasture Mix

Rainfall Zone: HRZ

Annual Rainfall 2023: 570mm

1st Jan – 1st Sept Rainfall: 501mm

Soil PH: 7.2

Organic Carbon: 1.14



The Dalyup site, chosen to represent the high rainfall zone of the Esperance region, received 570mm of annual rainfall in 2023. In 2021, lucerne was sown into this site as a perennial pasture, and in 2022, it was oversewn with Bell’s Seeds South West (SW) Pasture mix to enhance pasture density as the lucerne re-established. The SW pasture mix comprises ryegrass, clover, and oats. While there were no seeding costs in 2023, superphosphate was applied shortly after the break of the season. Lucerne's increased susceptibility to insect damage also resulted in multiple insecticide applications throughout the season.


This trial showcased substantial biomass production. Unlike other varieties trialled, lucerne demonstrated a unique growth pattern, maintaining a consistent trajectory throughout the season, with pasture growth rates increasing at the 20-week cuts. In contrast, annual pastures exhibited a bell curve pattern as they entered the reproductive phase later in the season, with a reduction in pasture growth rates between the 16 and 20-week cuts. The lucerne pasture exhibited greater consistency between cuts, with ME, lignin, and protein levels remaining relatively stable.


While this pasture performed well and aligns with high rainfall programs, the high DSE/hectare contrasts with a low DSE/100mm of rainfall ratio, indicating potential opportunities for improved water use efficiency in high rainfall zones. Challenges may arise from factors such as water holding capacity, runoff, and water repellent soils. Lucerne’s perennial growth pattern and its ability to stay reproductive longer makes it a useful tool for high rainfall growers in the Esperance district.



GRASS PATCH SITE 1


Grower: Dave Vandenberghe

Variety: Cadiz & Margarita Serradella

Rainfall Zone: LRZ

Annual Rainfall 2023: 181mm

1st Jan – 1st Sept Rainfall: 175mm

Soil PH: 6.3

Organic Carbon: 1.09



This site was chosen to represent the low rainfall zone and encountered an exceptionally dry season in 2023, receiving only 181mm of rainfall for the year, with a mere 175mm recorded up until the final pasture cuts at 20 weeks post-break of the season.


Despite 21mm falling before seeding, any potential sub-soil moisture was lost through the deep ripping process before seeding. With this in mind, the paddock only received 154mm until the 20-week observations.


Consequently, Serradella suffered poor establishment, with only 5 plants per square meter and minimal follow-up rain, surviving plants struggled to persist.


During the 10-week observations, the plant population primarily consisted of volunteer barley, with some ryegrass, capeweed, and low numbers of Serradella. The soil was noted to be drying out due to warm, windy conditions. At 16 and 20 weeks, little to no moisture was found to a depth of 100mm, and turnip dominated the plant population. These unforeseen and challenging conditions significantly impacted the feed quality and biomass produced. Despite efforts to control the cost of production, the lack of biomass affecting carrying capacity led to a high cost per DSE.


GRASS PATCH SITE 2


Grower: Michael Ietto Variety: SerraMax Serradella (Ungrazed)

Rainfall Zone: LRZ

Annual Rainfall 2023: 181mm

1st Jan – 1st Sept Rainfall: 174mm

Soil PH: 5.2

Organic Carbon: 1.38



This site was dedicated to SerraMax serradella, sown in 2022 for seed stock production and harvested later that year with a seed yield of 600kg/ha. In 2023, the paddock was allowed to regenerate as a self-seeded pasture, benefiting from evident seed set from the previous year. As the cost of seeding was accounted for in the prior year, only superphosphate application incurred expenses. The paddock remained unstocked due to a lack of fencing, yet the trial cuts were structured to simulate grazing by consistently cutting from the same quadrant in all three cuts (10, 16, and 20 weeks).


At the 10-week observations, SerraMax serradella had established well with robust plant numbers, and the paddock remained weed-free. This cultivar's faster breakdown of hard-seeded dormancy facilitated the reestablishment of self-seeded pastures. Despite the low biomass during these early cuts, the crop experienced rapid growth between the 10 and 16-week cuts, with the 16-week cuts measuring nearly 4 tonne of biomass per hectare. This growth was primarily sustained by sub-soil moisture with a minor top-up from rain.


SerraMax serradella performed well in a drier-than-normal year, showcasing hardiness and persistence once established. It served as a significant protein and energy source for livestock, supporting an impressive carrying capacity of 17 DSE/100mm of rainfall at a cost of production of $2.10/DSE. Furthermore, the nitrogen-fixing capability of SerraMax contributed $7.70 worth of nitrogen for subsequent crops, resulting in a remarkable total cost of production of -$5.60. In this context, SerraMax proved to be an economical feed source able to grow under challenging conditions, fostering synergies between mixed livestock and cropping systems.


CONDINGUP SITE


Grower: Nick Ruddenklau

Variety: Forester Oats, Abundant Ryegrass, Margarita Serradella, Clover

Rainfall Zone: HRZ

Annual Rainfall 2023: 554mm

1st Jan – 1st Sept Rainfall: 513mm

Soil PH: 5



This site was strategically chosen to represent the high rainfall zone, and even amidst dry conditions in other parts of the district, this particular site remained wet. Forester Oats, Abundant Ryegrass, and Margarita Serradella were sown into a sub-clover base, which had been established for two years, providing a robust foundation. Ample to surplus moisture was consistently observed throughout all three cuts, with a significant 206mm falling in June.


Despite the abundant biomass, observations raised concerns about the pasture's high moisture content, posing potential challenges for feed quality and livestock performance. The presence of capeweed later in the season added further complexity to management practices as there is no suitable control for capeweed in serradella. Given the elevated moisture content, livestock must consume 7.69kg of pasture to access one kg of dry matter, presenting a challenge for high-rainfall growers—a common predicament for pasture producers in such environments.


However, strategic grazing approaches, such as strip or rotational grazing, can effectively manage this challenge by encouraging stock to consume more of the plant, including the more fibrous components lower in the canopy. While these strategies aim to enhance feed utilisation and address high moisture content issues, they do incur higher labour costs and potentially pose an opportunity cost in a mixed farming season. It is essential to consider all farm tasks when making decisions. It's worth noting that while attempts were made to simulate grazing by taking cuts from the same quadrant each time, this approach does not replicate daily grazing, and the paddock would likely have measured a higher dry matter percentage under better grazing management.




Summary by Rainfall Zone










Overview

Overall, the 2023 season was filled with challenges right from the start, particularly for the low and medium rainfall zones. In these tight seasons, finding opportunities to defer grazing pastures and allow them to be properly established to achieve maximum vegetation throughout the season is particularly important. Furthermore, the cost of planting pastures can be offset by the value of nitrogen production from legume pastures; however, it is worth noting that this can only be accounted for if the nitrogen is used to increase yield or reduce nitrogen inputs in the subsequent years. It's not worth anything until it's utilised; worse yet, legumes will become lazy, and grasses will dominate if nitrogen is not eventually used up. It’s worth mentioning that the RM4, whether in combination with other cultivars or planted on its own, has performed well in both the 2022 and 2023 seasons in the medium and low rainfall zones. This variety has demonstrated that it can use water efficiently and withstand dry conditions with the correct grazing strategy. RM4 continues to stand out as a great option for mixed farming enterprises in these zones.

High rainfall zones performed well considering a large portion of the growing season; even annual rain fell in one month. The oat, serradella clover and the mix at the Condingup site could grow biomass quickly and utilise this moisture. This site grew the most biomass over the period of observations; however, the season was short-lived with the annual pasture seeding. The lucerne in Dalyup measured a slower growth rate; however, it maintained a strong growth trajectory late in the season when other pastures began to reproduce, locking up valuable energy in lignin and portioning energy to seed production rather than vegetation. These strategies were very successful and could be used strategically in high rainfall situations, although they utilise moisture differently.


Plot Trial Site Regeneration Update

The Cascade and two Grass Patch plot scale trial sites from Year 1 & 2 of the project were monitored for pasture regeneration in 2023. However, there was an insufficient establishment for collection or observation throughout the season. Unfortunately, due to the very dry start and unfavourable seasonal conditions, the three sites did not persist, and we would expect that there would be reduced germination in 2024 due to this false break, particularly in the softer-seeded varieties. These sites will be monitored in 2024 to identify any varieties that were able to persist despite these tough conditions.


Thank You

As always, there are a lot of people to thank when it comes to pulling together a project like this. ASHEEP & BEEF thanks the team at South Coastal Agencies for the data collection and analysis, Theo Oorschot from Esperance Rural Supplies for lending his pasture agronomy expertise to the planning process, all of the site hosts, and Dave Vandenberghe, Mark Walter & Nick Ruddenklau for their role on the steering committee.



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