LEGUMES IN KIKUYU
PRODUCER DEMONSTRATION SITE
Please note, the purpose of this project was to demonstrate proven technology and systems. It is not an in depth, replicated trial so the findings should not be taken as agronomic advice. Please contact one of our many knowledgeable local agronomists to discuss your own situation.
In 2014 ASHEEP received funding from MLA to run a Producer Demonstration Site project to sow alternative legumes into permanent Kikuyu pastures to improve grazing productivity. The project has now ended, and the final report has been submitted to MLA. This is a summary of the findings, see here for the full report
The trial was hosted by the Hoggart family on their property “The Duke” on Orleans Bay Rd, Condingup WA. The site was on deep sand and the initial pasture was a long term stand of Kikuyu with some background sub clover that hadn’t been seen for some years.
Within the site the following treatments were applied:
Summer Sown Plots- paddock was grazed heavily and 2L/ha Glyphosate was applied 1st March 2014 and sown on 10th March 2014 to Margurita Serradella enhanced pod 25kg/ha , Avilla Serradella enhanced pod and Bartolo bladder clover unscarified seed 20kg/ha. Kikuyu was suppressed again with glyphosate on 30th May 2014.
Autumn Sown Plots- paddock was grazed heavily up until March, 2L/ha glyphosate applied 13th May 2014 and 30th May 2014 and on 17th June 2014 sown to Margurita Serradella scarified seed 10kg/ha, Santorini Serradella scarified seed 10kg/ha, Dalkeith sub-clover seed 20kg/ha and Bartolo bladder clover scarified seed 20kg/ha was sown.
A control plot was left unsprayed and unsown, a second control was sprayed but unsown.
The Legumes in Kikuyu trial design:
The project objectives were to:
Compare summer sowing and conventional autumn sowing as an establishment method when sowing legumes into Kikuyu.
Asses the feed production of kikuyu to determine the benefits over time of incorporation of legumes to increase the paddock’s stocking rate.
Demonstrate management techniques to maintain the legume seed bank for continued legume regeneration.
Summer vs. Autumn sowing legumes into Kikuyu
In this project the best performing plots were the Autumn sown Margurita and Santorini serradellas and the summer sown Avilla (Avilla was not Autumn sown). The summer sowing did occur later than preferred due to seed availability and Angelo Loi has advised this may be the cause of the poorer performance of these plots as the hard seed wouldn’t have had time to break down as it should. As well as this, Kikuyu is a summer active plant and will utilise the rain that falls in the summer months. This means we had germinating legumes trying to compete with actively growing kikuyu for water & nutrients which is not an ideal situation. The summer sown plots were re-sown in 2015 but still did not perform compared to the 2014 Autumn sown plots. In this scenario summer sowing does not seem to suit the system, however it has been used to great success in many other scenarios around the district.
Of the varieties Bartolo Bladder Clover was the worst performing, it was included in the trial due to it being a new variety however we have learned that it is not suited to coastal soil types and climates as it is susceptible to powdery mildew, as well as K and P deficiency. When in the right environment Bartolo is suited to summer sowing (with unscarified seed) and is a prolific seed producer, we have seen it go well in other areas[AaRC1] . Both Autumn sown serradellas and the summer sown Avilla persisted to the final year. The Avilla was only found in significant numbers in 2017, the final year. It was not apparent in significant numbers in 2015 or 2016. So, while it was a good performer in the end, it took a few years to get there which is not ideal. The Autumn sown Margarita and Santorini Serradella both performed well in each year of the trial. The host of the trial, Alan Hoggart was particularly impressed with the performance of Santorini and has established it successfully in several other paddocks on the property using Autumn sowing.
Alan had some left over commercial pasture mix which was sown next to the trial in 2014, out of interest. It was not measured but it was visually observed that some varieties in this mix persisted when it was thought they wouldn’t due to not being suited to the environment. The varieties that persisted were Gland, Arrowleaf, Balansa and Crimson clover. This was not explored further due to time and budget constraints of the project however it was an interesting observation.
Pasture composition in April 2014, the beginning of the project. 100% Kikuyu
Pasture composition end of 2017, the end of the project. A mix of Kikuyu, clover & serradella
Kikuyu recovery after suppression
As most people know Kikuyu can survive almost anything and after a couple high doses of glyphosate it came back very well. The glyphosate had a greater effect during active growth of the kikuyu so we saw a better rate of suppression of the summer sprayed plots compared to a lower rate of suppression on the Autumn sprayed plots. Ron Master from Albany DPIRD has shown in other work that a winter application of clethodim to kikuyu can be beneficial for legume establishment.
One important observation was the band of organic matter in the top 10 cm of soil (initially seen in 2015) created by the thatch of the kikuyu had extended to the top 15-20 cm by 2017. In 2015 it was observed that roots of the legumes were predominately restricted to this 10cm band, with tap roots growing sideways rather than down into the sand below. We were not able to find a reason for this at the time other than to speculate that the white sand below was potentially inhospitable due to soil acidity, aluminium toxicity and compaction. This shallow root depth is not ideal as it makes the legumes susceptible to moisture stress during dry spells when the top 10cm dries out. In the plots where the kikuyu was suppressed it was observed that this band of organic matter had become gradational and reached a depth of 15-20cm by 2017. This could be due to the decay of the dead kikuyu plants and the freeing up of the top soil. This was supported by the soil tests which showed a higher level of organic carbon in the 2017 results compared to the 2014 results.
Kikuyu roots where found at a depth of 70cm when deep core soil samples where taken. This shows what a valuable plant it can be by taking advantage of moisture and nutrients at depths that other pasture plants will not reach.
Changes in grazing patterns of the stock on the trial were observed but there was no significant difference in feed quality of the kikuyu between plots.
Frequency of Occurrence- this shows the level kikuyu ground cover in each plot over time. All suppressed plots (blue & purple) recover to their level of Kikuyu cover over time compared to the unsuppressed control plot (green)
Frequency of ocurrence measurements were carried out to measure the groundcover percentage of kikuyu in each plot. Because kikuyu it is a stoloniferous grass with multiple growth points sprouting from runners, standard plant counts are not applicable. On a 1m x 1m pasture square, a grid is created with 10cm x 10cm squares. Counts are then done of how often kikuyu is present on the intersections of the gridlines representing a percentage of total groundcover.
The efficiency of kikuyu as a weed suppressant was demonstrated during the trial. Once the Kikuyu was suppressed this gave the weeds (mainly silver grass in this situation) a great opportunity to come through. The learning was that it is important to manage the seed bank, to get a good seed set of your legumes in the first year (keep sheep off it when flowering and setting seed) to compete with both the kikuyu and other grass weeds. This is where the hard seeded varieties have an advantage as their seed break down pattern will mean you should have a good seed bank for many years if managed correctly.
Native budworm will badly effect seed production of serradella, particularly Margurita, if not controlled. During key periods (when the plants began to pod) the trial was swept for native budworm and a pesticide was applied if numbers were above recommended thresholds.
Native Budworm damage to serradella pods
Native Budworm eating serradella pods
We would like to give a huge thanks to Alan & Bec Hoggart for allowing ASHEEP to use their property for this trial and for their time to get it established and maintained.
Thanks also to MLA for supporting our group and this project.