GRASSING BARE PATCHES

Variation 4 (V4) was treated in the same way as the Control Plot except that it was burned in April 2021 using practices learned from Den Barber in a Cultural Burning workshop. This variation may need to be monitored over a longer period to see if there are obvious differences from the Control Plot.

January 2021 before burning the long grass in April 2021.

July 2021 when herbage mass was measured as 858 kgDM/ha which was the lowest measurement of all the trial plots. A diverse range of plant species were observed.

November 2021 when soil test samples and herbage mass were taken.

Variation 3 (V3) was selected as a demonstration of a more conventional agricultural approach to improving soil. It turned out that the initial soil tests showed that Phosphorus was unlikely to be a limiting factor on the site so application of superphosphate is unlikely to have had much impact.

Lime (Aglime250 Superfine) was applied to the surface at rate of 150g/m2 (equivalent to 1.5 tonne/ha).

Superphosphate (SuPerfect) was applied at rate of 12.5gm2 (equivalent to 125kg/ha).

September 2020 after application of lime and superphosphate.

January 2021 after the dry grass was mown with the flail mower.

February 2021 when herbage mass was measured as 703 kgDM/ha which was quite similar to the Control Plot.

July 2021 when herbage mass was measured as 1361 kgDM/ha. Again this was similar to the Control Plot.

November 2021 when soil test samples and herbage mass were taken. There is little fodder value in this plot.

Variation 2 (V2) was based on observations that on other parts of the farm, the grass grew better in drought along riplines along contour used for establishing shelter belts.

For the trial, the riplines were only approximately 200mm deep and space approximately 1m apart since the ground was extremely hard when they were installed.

The lime was installed at the same rate as for other plots but applied mainly along the riplines.

Crimson Clover and Ryecorn was broadcast on the surface as a green manure in Spring 2020. Cowpeas and millet were broadcast as a green manure in Summer 2021 just before mowing.

September 2020 with riplines, lime and green manure applied.

January 2021 after mowing with the flail mower.

February 2021 when herbage mass was measured as 1041 kgDm/ha across the plot.

July 2021 when herbage mass was measured as 1296 kgDm/ha. Greener plant material was clearly visible along the riplines.

November 2021 when soil test samples and herbage mass were taken. The Crimson Clover has reseeded along the riplines.

This variation (V1) was the same as the Common Plot except that there was no jute mesh used. It has produced the highest herbage mass figures of all the trial plots.

September 2020 - the Common Plot is in the front and V1 is at the back.

January 2021 after mowing green manure with flail mower.

February 2021 when herbage mass on V1 measured 1408 kg Dm/ha.

July 2021 when herbage mass measured 1573 kgDM/ha.

November 2021 when soil test samples and herbage mass were taken.

The Crimson Clover has reseeded and proved to be a good coloniser species in the wet conditions with plenty of root activity in what was bare soil.

On this plot lime (Aglime250 Superfine) was applied at a rate of 150g/m2 (equivalent to 1.5 tonne/ha) to the surface.

Ryecorn Crimson Clover and Ryecorn green manure seed was broadcast on the surface at a rate of 20g/m2 in Spring 2020. Cowpeas and millet seed was broadcast as a Summer green manure on the surface in January 2021 immediately before the grass was scythed (since jute mesh prevented use of flail mower).

QPRC soil conditioner compost was applied over the surface in an approximately 1cm deep layer in Spring 2020 after seed was broadcast.

Jute mesh was applied over the compost.

September 2020 after lime was applied.

October 2020 after jute mesh was applied over green manure seed and compost.

November 2020 after a surprising flush of growth compared to the control plot.

January 2021 when the grass and green manure in the Common Plot was scythed. This left a significant amount of dry litter on the surface which was slow to break down compared to V1.

February 2021 when herbage mass was measured as 1301 kgDM/ha.

July 2021 when herbage mass measured 1477 kgDm/has and groundcover reached 100%.

A comparison in July 2021 of the Control Plot (front) with V1 (back) which had the same treatment as the Control Plot without the jute mesh. V1 was able to be mown with the flail mower in January which cuts the grass into smaller pieces.

November 2021 when herbage mass and soil test samples were taken. The herbage mass and fodder value was clearly superior to the Control Plot.

The Control plot gave a good basis for comparing different treatments. The year of the trial turned out to be exceedingly wet so more grass grew on the Control plot (but not as much on some of the treatment plots).

In October 2020 the herbage mass on the Control plot averaged 875kg DM/ha (kilograms of dry matter per hectare). At the same time, a good patch nearby measured 3500kg DM/ha.

The photos show what happened.

October 2020 - Control plot  pegged out ready to start trial. 

The good patch in September 2020 for comparison.

January 2021 after mowing the dry grass with the flail mower. This was the only intervention for this plot during the trial.

Here is the good patch after mowing in January 2021 for comparison.

February 2021 when we measured herbage mass (580-824 kgDM/ha).

July 2021 when herbage mass measured 1350 kg DM/ha even though the longer grass was very dry and the green grass was super short.

November 2021 when we measured herbage mass and took soil test samples. Even though the grass looks long and green, there is very little forage value here for our sheep.

The good patch in November 2021 for comparison with more forage value despite being outside stock exclusion fence.

The Farm 1 bare patch demonstration site in Bywong NSW is near the top of a north facing slope that is moderately steep and rocky. 22 years ago the area had a huge amount of Serrated Tussock and had a history of heavy grazing by sheep. After years of removal of the tussocks, in many places the most obvious ground cover was a sparse scattering of native Austrostipa scabra plants (Corkscrew Grass) with mostly bare ground between.

Many areas were completely bare during the last drought. Even though conservative grazing techniques have been used for 22 years including no grazing in the first 10 years and removal of stock during the droughts, this poor groundcover has shown little sign of improvement.

Our question was how to increase the amount of grassy groundcover on the site to reduce erosion and improve feed quality when the site has a light, acidic soil and is too steep to cultivate?

Soil samples were taken from the bare patch trial plots in 5cm increments down to 20cm in October 2020. These soil cores provide visual clues about the soil structure (the soil surface is at the bottom of the photo). There is a coarse gravel layer not far below the surface.

We also did slaking tests to observe what happens to the soil when it gets wet. There is a surprising amount of organic carbon in the top layer of the soil which helps to stabilise the soil. The soil 10cm down from the surface is much less stable.

The soil test results showed that the pH in the top 5cm of soil in the bare patches was more acidic than lower in the profile.

We compared the bare patch with a nearby good patch.

What has happened so far .... the story continues with Allan

49 Weeks Later

There has been plenty of continuing rain in June and July. My understanding is this is likely to continue until the beginning of summer due to a negative Indian Ocean dipole. The waters in the eastern Indian Ocean (near Indonesia) are warmer than normal, and the western Indian Ocean (near Africa) are cooler than normal. This causes more moisture-filled air to flow towards Australia that promotes more rainfall to southern parts of Australia including parts of Western Australia, South Australia, Victoria, NSW and the ACT. I believe this has also contributed to a milder winter so far.

Read the full report here

Allan Spencer has documented the changes to his demonstration plots over the past 40 weeks. In this blog post Allan describes the grasses he has sown and what he is observing from the different treatments.  Below is a summary of one of the treatment plots and photos over time.  

The Common Improved plot had lime added to the surface and was to be incorporated to a depth of 5cm by hand.  My compact soil did not allow for the lime to be incorporated to that depth and was “scratched” into a maximum depth of 2cm.  The green manure crop consisting of 90% ryecorn and 10% crimson clover was broadcast across the plot at a rate of 40 grams per m².  The Common Improved plot was then covered with jute mesh.  The jute mesh as covered with compost obtained from the Queanbeyan Palerang Regional Council waste minimisation centre.

Figure 1 Common Control Plot – No Treatment September 2020

Figure 2 Common Control Plot A May 2021 – Slashed and seeded

Figure 3 Common Control Plot B May 2021– No Treatment

Read Allan's full report here.

In this update Allan Spencer tells us what is happening at his demonstration plot. With sequential photos of each of the trial plots. Allan's update shows the changes that have occurred over the seasons.

The story continues .......

Some rain falls have continued over summer but it has definitely reduced.  April has been well below average.  All the plots browned off during summer and there were only a few hints of green.  I have noticed as we moved into autumn growth of some grasses on the plots which I assume are the mostly C4 type grasses. The ryecorn and crimson clover has sprung to life within the Common Improved and Variation 2 plots.  Variation 1 had very good germination originally in September / October and there is no evidence of any ryecorn or crimson clover germination in that plot.  Examination of the active crimson clover root system did show some nitrogen nodules.

With plenty of feed around the farm, the temporary fence seems to continue restricting native grazing and I have still not seen any Kangaroos or Wallabies etc on the demonstration plots.

Read more here.