Potassium responses in winter crops and pastures

In collaboration with NSW DPI and the GRDC, the response of wheat and barley (Warndoo 2015) and wheat, triticale and canola (Breadalbane 2015) are being investigated. Responses of wheat and canola to K are assessed at Glenthompson (2016) with Southern Farming Systems and the reponse of pasture yield and quality to N, K and Mg is being addressed at Bessiebelle. Additional demonstrations have been undertaken on pastures in coilaboration with Meridian Ag P/L. Support of these trials is provided by Canpotex P/L and IPNI ANZ.


26 Feb 2016

K responses at Breadalbane 2015.

Through the contacts with NSW DPI, a relationship was developed to access and participate in the field experiments on K in the New South Wales southern Tablelands. Dr Jonathan Holland undertook this experiment which was funded by GRDC and New South Wales DPI. Collaborators were Delta Ag and the Southern Tablelands Farming Systems group. The original plan was to develop strip trials for visual assessment, in comparison to a replicated field experiment in the same paddock. However, it was considered a better option to provide support to Dr Holland to take some added measurements that could then provide Canpotex access to some of the data. This report provides a summary of the 2015 experiment at Breadalbane, situated half way between Canberra and Goulburn in southern New South Wales.
The field K experiment was established in 2014 and a second experiment undertaken in 2015 in the same paddock but at a different site. The results from the experiment in 2014 showed statistically significant responses to K and liming in wheat and triticale, which encouraged that another K experiment be undertaken at this site.
The 2015 experiment is comparing the response of 6 K rates (0, 12.5, 25, 50, 100, 150 kg K/ ha) for 3 crops (canola - Hyola CL970, triticale – Endeavour and wheat – Revenue). The site soil K test values and depths are exchangeable K concentrations 34 mg/kg (0-10 cm), 16 mg/kg (10-20 cm) and 13 mg/kg (20-30 cm). Top 10 cm exchangeable K or Colwell K critical K values for wheat are around 40-45 mg/kg.
All crops were sown on the same day on the 30th of March. The K was applied by top-dressing (as muriate of potash) shortly after the plants were well established in May. The crops were managed using commercial best practice including supplementary N and B during the season/
The crops were hand harvested in January and the yields are shown in Figure 3.1. The cereal grown at this site were very responsive to added K. Wheat yields increased by 113% with 100 kg K/ha and the triticale crop showed a 54% yield increase to 100 kg K/ha. It appears that wheat is more responsive than triticale on this site. Canola yield responses were more modest, with a 28% increase with 100 kg K/ha.

Figure 3.1 Yield responses of wheat, triticale and canola to added K at Breadalbane, 2015 (preliminary results only).

Dr Holland took additional measurements and these include some data on forage quality during the winter, when these crops can be grazed. Dr Holland advised that there were small improvements in energy content and digestibility with added K, but little response in growth over the very cold winter period. The results (above) are preliminary with no statistical analyses, and as those results become available, they will be made available through the IPNI website.

• The crop responses seen at this site were consistent with the soil test values recorded.
• Yield responses of 113% for wheat, 54% for triticale and 28% were recorded to 100 kg K/ha topdressed during early growth.