Department of Agriculture trials

To recommend options to improve;
• soil nutrients and groundcover, and 
• reduce disease levels and chemical use.

Barley grass is becoming an increasingly problematic weed in Western Australia. A GRDC funded project sought to increase adoption of integrated weed management tactics for barley grass, by working with grower groups to develop regionally appropriate rotations for optimal control. A survey indicated that in southwest Australia, many growers thought their barley grass was resistant to grass selective herbicides and may have developed late germination to avoid pre-seeding herbicides. In this area barley grass was a major problem in pastures, and often in break crops too.

A three year trial aimed to investigate pre-emergent herbicides and autumn tickle in wheat in 2019, pre-emergent herbicides and crop density in barley in 2020 and grass selective herbicides and crop topping in pasture in 2021.

To determine if the inclusion of Bentonite clay improves crop yields on non-wetting sandy soils and their ability to store more carbon.

To identify on-farm management strategies to increase soil organic carbon (SOC) and quantify any associated risks and benefits in a grain production system.

In this trial the Facey Group wanted to determine whether:

1. Altering inputs to increase plant biomass would subsequently increase soil carbon and
2. Amending soils with compost would increase soil carbon storage or provide agronomic benefits.

Part 1: Medic cultivars were grown in soil with high boron levels in a glasshouse, leaf damage symptoms recorded and cultivars allocated to different tolerance groups (Howie 2012). 

Part 2: The above identified that all spineless burr medic cultivars are susceptible to high boron levels. Screening wild accessions (supplied by the Australian Pasture Genebank) identified a burr medic accession with boron tolerance and vigorous growth. The boron tolerant accession was crossed with current spineless burr medic cultivars Scimitar and Cavalier. F2 plants with high early vigour were selected and a molecular marker used to identify homozygous boron tolerant plants. A single seed descent breeding method using speed breeding was used to obtain uniform lines. Lines were seed increased at Waite in 2018 and lines with the highest agronomic performance selected for 2019 field evaluation trials. A cohort of 16 boron tolerant lines along with their  parents and barrel medic cultivars that differ in boron tolerance, were sown at Roseworthy and Minnipa. The trials were managed as best practice first year annual medics to maximise dry matter and seed production. Best practice consists of a high sowing rate (10 kg/ha), controlling broadleaf and grass weeds, monitoring and controlling insects and no grazing. Dry matter production was  assessed and pods collected. Seed yield will be determined by April 2020.

Legume pastures have been pivotal to sustainable agricultural development in southern Australia. They provide highly nutritious feed for livestock, act as a disease break for many cereal root pathogens, improve fertility through nitrogen (N) fixation and mixed farming reduces economic risk. Despite these benefits, pasture renovation rates remain low and there is opportunity to improve the quality of the pasture base on many low to medium rainfall mixed farms across southern Australia. A diverse range of pasture legume cultivars are currently available to growers and new material is being developed. Some of these legumes, such as the annual medics, are well adapted to alkaline soils and have high levels of hard seed, which allow them to self-regenerate from
soil seed reserves after cropping (ley farming system). Other legume cultivars and species are available and being developed that
offer improved seed harvestability, are claimed to be better suited to establishment when dry sown and/or provide better nutrition for
livestock. Regional evaluation is being undertaken to determine if they are productive and able to persist in drier areas (<400 mm
annual rainfall) and on Mallee soil types common to the mixed farming zone of southern Australia.

To investigate the potential of organic matter inputs to increase yield and improve soil health.

To measure and demonstrate on-farm strategies that can reduce nitrous oxide by trialling four key practices:

• Use of legumes in the cropping rotation;
• Application of nitrogen fertiliser at key stem elongation growth stages;
• The use of precision farming tools to better measure N mineralisation;
• Use of nitrification inhibitors.

To add normal and higher amounts of nutrients (N, P and S) to different stubble managements (standing, worked and removed) to see if soil humus level would be increased.

To evaluate the effects of mouldboard ploughing and its ability to increase carbon on a poor yellow sand.

To measure N20 emitted by vetch, field peas and wheat stubble over summer and to determine whether top-dressed inhibitor-treated and slow release urea products influence N2O emissions.

Identifying if the increase in soil organic matter content could be beneficial for improving soil water holding capacity, increasing nutrient supply.

Work conducted by Clive Kirkby (CSIRO) has investigated the feasibility of increasing soil carbon levels with the use of balanced amounts of nutrients and incorporation of stubble.

The overall aim of the project was to raise awareness of farmers about how they can reduce green house gas emissions, sequester soil carbon and make improvements in farm productivity.