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.


13 Oct 2016

K responses in fodder production

Field experiment at Bessiebelle, 2016

The objectives of this field experiment are:
• To evaluate the growth responses of pasture to combined N, K and Mg
• To assess the effect of N, K and Mg on pasture quality
• To provide a platform for discussion around good pasture and animal nutrition.

Pasture responses to applied K in the dairy industry are reasonably common, but with the increase in the use of bought-in feed, many paddocks are at luxury levels, especially in close proximity to the dairy shed. N use on dairy pastures is common but there is less attention – in general – paid to paddocks that will be grazed then closed for fodder conservation. Those conserved fodder paddocks are often “out-paddocks” or paddocks leased or even from adjacent dry-land mixed farming regions. This experiment aims to assess the impact of N and K – at two rates each on the spring growth of pastures, and then to assess the effect of this nutrition on fodder quality. The magnesium treatment is imposed because of the decline in fodder Mg when K is applied, and low Mg in fodder can lead to hypomagnesia in dairy cows.

Paddock selection
Undertaken in association with farm dairy discussion groups – to propose a paddock that will “most likely” be locked up for hay for the coming spring for either home-grown or sold fodder. I appreciate that selecting paddocks at this time is not definite, so maybe a series of paddocks could be selected as candidates based on possible use, and soil test values.
How important is pasture composition at this stage?

• 3 or 4 K rates – 0, 25, 50. 100? As MOP
• 2 N rates – 0 and 50 N as urea
• 2 Mg rates – 0 and 10 kg Mg as MgCl2
• 4 replicates
Plots are 20 m by 2 m and arranged in a randomised complete block.

1. A pictorial record of the site and selected treatments through the season.
2. An assessment of pasture composition before treatment and near maturity.
3. Pasture biomass at the time of fodder conservation (hand cuts, dried and mass recorded)
4. Samples from each plots provided to submission to appropriate laboratories.
5. Field walk and discussion sessions at the site
6. Nutrient analysis for P, K, S, Mg by ICP-OES or similar (IPNI to arrange).
7. Fodder quality assessments through Feed-Test (IPNI to arrange).