Riverine Plains Inc research update

Take home messages

• Riverine Plains Inc conducts a range of research activities to provide local information to its members.
• Large farm scale trials provide farmer-relevant information.
• Understanding in-paddock variability can refine input use.

Background

Riverine Plains Inc is a progressive farmer group dedicated to improving the productivity of broadacre farming systems in north-east Victoria and southern New South Wales (NSW). The group provides relevant and unbiased research and information to its members and acts as a conduit for information flow from credible research sources to its membership.

During 2018, Riverine Plains Inc contributed to a range of research projects. This report will summarise the key information from these projects over the past year, including subsoil acidity, canola nutrition and plant available water (PAW) variation within paddocks. Results and key findings are to be presented at the February 2019 GRDC Grains Research Update at Corowa.

Project information

Optimising sulphur and nutrition in canola – a GRDC investment

The aims of this project were to identify if nitrogen (N) supply is limiting the uptake of sulphur (S) in canola crops of the Riverine Plains and to determine if S uptake and yield are increased when N is non-limiting.

The objectives of this project were to assess the response to N and S in canola crops of the Riverine Plains by determining:

• The influence of N and S application on canola tissue content, yield and oil content.
• The fluctuation in N and S content and N/S ratio in the plant from stem elongation to harvest, and
• The optimum N level of canola in the region at variable levels of S application.

Two trial sites were established at Howlong, NSW, and Yarrawonga, Victoria, in both 2017 and 2018 through a partnership with the Foundation of Arable Research (FAR) Australia, which managed the field research component.

A replicated randomised block design was used with four replicates, with plot sizes of 3m width x 18m length. The trial sites were sown with canola in April 2017 and 2018, after which combinations of the following treatments were applied.

Nitrogen was applied as urea in a split application between 6-8 leaf stage and green bud at five rates (0, 40, 80, 120, 160kg N/ha), with the first 40kg N/ha applied between 6-8 leaf stage, and the remainder applied at green bud.

Sulphur was applied as sulphate of ammonia (SOA) at four rates (0, 10, 20, 30kg S/ha). This was applied with the first application of in-crop N, with urea added to balance the N. These treatments were applied across the suite of N treatments to determine the interaction between N and S (Table 1).

Soil sampling was done across the sites pre-sowing (incremented to depth) to determine existing nutrient levels, and at the end of the season, in the nil and highest S treatments, to determine extraction of S from depth.

The trial site was managed as part of the surrounding commercial crop, except for the S and N applications.

The crop was monitored through the season, with tissue S samples at early flowering, dry matter (DM) sampling at first flower, pod set and harvest, yield and oil content, and % S content of biomass and seed.

Table 1. Treatment list: N applied as urea (46% N) and S applied as ammonium sulphate (21% N and 24% S)

n.b Treatments at 6-leaf stage (GS 1.06) applied as ammonium sulphate with residual N application applied as urea; The first 40kg N/ha of all N treatments applied at 6-leaf stage, remainder applied at green bud; Treatment list excludes monoammonium phosphate (MAP) applied at sowing with the commercial crop.

Results from the 2017 season will be shown. Limited results from one site from 2018 season will be shown. Collection of a full set of data from the second site during 2018 was not possible due to the second site having to be abandoned due to poor and patchy growth and establishment.

Innovative approaches to managing subsoil acidity in the southern grains region – GRDC investment

Aim —To quantify the yield limitation caused by subsoil acidity and evaluate innovative soil amendments which act to ameliorate subsurface acidity.

Riverine Plains Inc is managing two farm-scale trials in the region for this project led by NSW DPI. A site at Rutherglen was established in February 2018, and one is currently being established near Devenish. Both will continue to be monitored for several years.

These trials are evaluating deep placement of lime, lucerne pellets and other products, compared to surface application of lime.

Results from the 2018 season will be shown for the first site.

Understanding subsoil acidity in cropping enterprises of the productive plains – Goulburn Broken Catchment Management Authority (GB CMA)

Aim — To understand the extent to which subsoil acidity may be limiting productivity of cropping systems in the Goulburn Broken cropping region.

Soil acidification is a growing problem in the productive plains, which, if left unchecked, will reduce the productive potential of the region. While surface soil acidity (less than 10cm depth) is an ongoing issue, which some farmers are already aware of, acidification of the subsurface (greater than 10cm depth) is becoming a significant issue in the region, although largely undetected. Even if farmers conduct regular soil testing, most tests are only done in the 0-10cm, with no measurements at depth.

This project is looking for interested farmers across the region to participate in a free soil sampling survey to measure soil pH down to at least 20cm. The results from this sampling survey will be used to understand the extent of subsoil acidity and determine if further research or awareness activities are needed to reduce the incidence and spread of subsoil acidity.

Maintaining profitable farming systems with retained stubble in the Riverine Plains region – GRDC investment

Riverine Plains Inc has recently completed the stubble project titled ‘Maintaining profitable farming systems with retained stubble in the Riverine Plains region’. This was a GRDC investment as part of a National Initiative (RPI0009) and conducted in partnership with FAR Australia.

A side research focus from this work was to understand in-paddock variability, specifically how PAW potential may change across paddocks due to soil type and/or soil constraints. Four focus paddocks were selected for this work — from Howlong, Rutherglen, Telford and Yabba South.

Examples of how potential water storage changes within these paddocks will be shown, corresponding to soil moisture probe data. Such information could assist in supporting decision making in a water-limited season, such as seen in 2018.

Conclusion

Riverine Plains Inc continues to conduct research on behalf of its members. To broaden the delivery of research to members, Riverine Plains Inc also collaborates with other organisations on a range of research projects, from crop nutrition to soil constraints. This supports the ongoing establishment of on-farm trials within the region, ensuring that the results obtained are immediately relevant to local farmers.

Acknowledgements

The research undertaken as part of this project is made possible by the significant contributions of growers through both trial cooperation and the support of the GRDC — the author would like to thank them for their continued support.

Contact details

Cassandra Schefe
Research Officer
Riverine Plains Inc
PO Box 214 Mulwala NSW 2647
(03) 5744 1713
cassandra@riverineplains.org.au