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GRASSING BARE PATCHES


Grassing Bare Patches was a citizen science demonstration on three small farms in the Capital Region. It aimed to test and demonstrate methods for improving grassy groundcover on persistent bare patches in acidic and low fertility soils through soil improvement, green manures and erosion management. The strategies for tackling bare patches were chosen to be practical, effective and easily applied on small farms in our region. See our project protocol for details of the strategies.

The demonstration ran from September 2020 to May 2022. Updates have been posted on this page.

The Small Farms Network Capital Region received funding from the Australian Government's National Landcare Program for this demonstration. 

 

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  • 29 Jun 2022 2:46 PM | Alex James (Administrator)

    This field day was an opportunity to meet Dr Jason Condon, Associate Professor in  Soil Science from Charles Sturt University and Helen Burns Development Officer – Pastures from the NSW Department of Primary Industries. We visited two farms just outside Canberra to talk about the major findings of the Grassing the Bare Patches Demonstration and learn about soils from Jason. Farmers Jennie Curtis, Harjinder Dhindsa and Allan Spencer shared their experiences from the Grassing the Bare Patches project.

    It was interesting to look at the differences in the soils between the properties and see the factors limiting pasture growth. At Jennie’s farm, Jason showed us how to test for dispersive soils, soil pH and soil structure. We looked at the soil profile and the soil test results together. We could see the effect that soil acidity was having on root growth below 10cm, where low pH and high aluminium were stunting root growth and causing roots to grow sideways. Jason explained that high aluminium in the soil stops the uptake of nutrients by plants because the ion spaces on the plant roots are filled with the Al ion. The application of liming materials to increase the pH will inactivate the aluminium, thus increasing the level of plant available nutrients. Jason explained that soil pH closer to neutral favours conditions for soil microbes to replicate and flourish. The dispersion test showed that soils lower in the soil profile are vulnerable to erosion. Ripping or cultivating the soil at these depths could be risky.


    Jason discussed the methodology for addressing low soil pH, suggesting the initial application of lime for the project could be  2.5 tonnes per hectare. The removal of agricultural products acidifies the soil, therefore agricultural soils will become more acidic over time. Selecting pastures with low pH tolerance is one strategy to help combat acid soils but over time the species of plants you can grow will be narrowed. Jason suggested that is it better to address the soil factors limiting pasture growth through liming, correct fertiliser application and increasing soil carbon.

    At Harjinder’s farm, Jason dug another series of soil profiles, it was interesting to see the effect that the physical soil characteristics were having on the pasture. At this farm the demonstration plot had been cultivated to 15cm over a number of years. Harjinder explained how his crops would grow to a certain height and then wilt and die. Jason showed us the effect that a cultivation hardpan was having on root growth. The hard pan was causing J rooting and had formed a barrier preventing the roots growing below 15cm. Helen told us that once off deep ripping could be a remedy, as well as planting an annual cover crop of rye grass that is renowned for helping breaking down hard pans. A reference for using rye grass and clover in citrus orchards is included in the resources section below, look for the heading ‘Permanent Sod Culture’.


    We learnt that the usual soil testing approach where samples from the 0-10cm range are combined is not always useful in a pasture management context because soil and physical factors can vary significantly though the soil profile. In this case, physical factors lower in the soil profile were preventing root growth. One simple way for landholders to look at soil acidity and texture below 10cm is to use a dig stick to take deeper soil samples and then use a home pH test kit to see the variation in pH at different depths. The home test kits show pH (water) which is different from lab tests for pH (CaCl).


    When we compared soil profiles from the control plots with soil profiles from the common treatment plots, growing green manure crops with minimal tillage appears to have been a useful strategy for increasing soil biology and improving soil texture on previously bare patches. One of the major observations from farmers hosting the demonstration plots is that green manure crops need to be managed by mowing or grazing to keep them short during the growing season. This allows other shorter species including sub clover to germinate and not be out competed. When the green manure was left to grow high in the trial plots, the biomass made it hard to sow the permanent grass seed since there was a lot of thatch covering the bare soil.


    The farmers also found that using jute mesh in a pasture setting was limiting because the cover crop could not be slashed or mowed without machinery becoming entangled in the mesh. Jute mesh still has useful applications in more inaccessible erosion sites that would not be slashed or mown.

    Further details about the final monitoring can be found here.

    What will the farmers do next?

    Jason asked us to think about what we had learned and what we would do next in the paddocks where the trial plots are.

    Jennie is planning to apply lime at a rate of 2.5kg/ha over the surface of the paddock and elsewhere on the property to raise the pH of the soil. This will be a slow process but Jason told us that the lime will travel down through the soil profile if the surface pH(CaCl) is 5.5. She is also intending to surface broadcast Crimson Clover on bare patches as an early coloniser and green manure and manage the height using strategic grazing. She observed that her sheep preferentially grazed the plots that had been limed and then grew green manure.

    Allan found that deep ripping inhibited the growth of seed in one of his plots, on his property he will be using harrows to scratch in grass seed and lime on the surface of the soil. He will use green manure crops but only to get the soil processes going and he won’t allow them to grow higher than 600cm. He observed that excluding kangaroos had a big impact on the diversity of his control plot and that the kangaroos preferentially grazed the areas that had been limed. Allan also observed that increasing soil pH had a direct impact on Sifton bush (Cassinia sifton) germinating, there was no Sifton bush in the plots treated with lime or in the paddocks he has applied lime for growing oak trees for truffles.

    Harjinder is keen to use organic methods to improve the fertility on his property and was surprised to see the impact that repeated cultivation had on the soil profile. He believes that doing something, whether that be applying lime, compost of fertiliser is better than leaving the bare patches of ground on your property. He could see definite improvement in the areas that the compost was applied to the ground, the grass seed germinated better and there was less space for weeds to colonise. He is investigating what to do next in the cultivation paddock to treat the soil compaction layer, future strategies may include deep ripping or growing cover crops to break up the compaction.  


    Resources

    NSW DPI - Soil Acidity and Liming 4th Edition

    Northern Rivers Soil Health Card 

    Sodic Soils 

    Soil test interpretation 

    Protect your soils from compaction

    How to manage soil for citrus (using rye grass for compaction)

    This project received funding from the National Landcare Program. South East Local Land Services provided funding for soil testing and provided technical support. Thank you to the demonstration plot farmers Jennie Curtis, Allan Spencer and Harjinder Dhindsa for their support and hosting the trials. 

  • 30 Apr 2022 8:12 PM | Alex James (Administrator)

    Grassing the Bare Patches is a citizen science project that has been running in Bywong and Sutton over the past eighteen months. It has been looking at bare patches of ground on three small farms and simple things that might be done to repair them. 


    Photo: Farm 2 in Sutton Common Treatment March 2022

    We have tested the soil before and after so we can compare the controls with the plots where we applied treatments. We have measured the herbage mass each season and recorded the plant species that we observed growing on each plot.

    This blog post contains a summary of the project findings and a comparison of the soil test results from the beginning and end of the project.

    Project Summary

    Soil Test Comparison 

  • 28 Nov 2021 3:21 AM | Jennie Curtis (Administrator)

    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.


  • 28 Nov 2021 3:05 AM | Jennie Curtis (Administrator)

    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.


  • 28 Nov 2021 2:51 AM | Jennie Curtis (Administrator)

    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.


  • 28 Nov 2021 2:37 AM | Jennie Curtis (Administrator)

    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.


  • 28 Nov 2021 2:12 AM | Jennie Curtis (Administrator)

    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.


  • 28 Nov 2021 1:47 AM | Jennie Curtis (Administrator)

    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.


  • 28 Nov 2021 1:11 AM | Jennie Curtis (Administrator)

    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.


  • 3 Sep 2021 11:39 AM | Alex James (Administrator)

    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

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