Does extended pasture resting after grazing improve soil microbiology and soil health?

Farmers from three of the trial farms met with coordinator Kate Still and Becky from Farm Carbon Toolkit at Old Burford Farm last week to catch up on the progress of the field lab.

We first looked at the progress of the trial plots over the grazing season, and the experiences on the different farms. It was agreed that the severe drought over the summer had made for a difficult grazing season, though in general the trial plots performed well.

• On one farm the control plot was slightly ahead earlier in the season but now there has been some rain it appears that the trial plot has taken over, and they have pretty much levelled out.
• On one farm the trial plots seemed to run out of steam towards the end of the season, while the control kept growing back, this was potentially due to control being a more diverse sward
• There was no loss of milk from grazing the trial plots at the end of the season for two of the farmers, though a third reported a slight reduction in yields.
• There was a feeling that you can get away with moving the mob less on the higher plants.
• In theory the cows should spend less time grazing the longer grass as they can take larger mouthfuls.
• Some farmers didn’t achieve the trampling effect in the mob paddocks they were hoping for, perhaps need to stock higher

Sward Quality

• One farmer said he was impressed by the quality and quantity of clover on the trial plot compared to the control in the second grazing.  
• Another triallist found that there had been a problem with docks growing in the trial field.  
• He also found that the chicory grew up and shaded out the smaller herbs around it, leading to more bare ground in the field than he would have liked.  “The cows didn’t really like the chicory anyway”.
• One of the triallists had previously found establishing sainfoin more challenging as the large seed size meant it had to be drilled separately. He then found it not to be very persistent
• By the end of the summer two of the triallists found that the trial plot had large amounts of dead grass and chicory stalks lying on the ground which don’t seem to be breaking down – one said “it feels like there is a lack of complex soil biological processes helping it break down”.  This could have been due to the drought and high soil temperature:  Becky explained that the dry season had a massive impact on soil biology, partly because the earthworms were driven so deep underground to find moisture.  As a positive, however, it was thought that this dead matter would have protected the soil during the extreme heat.  Also, one farmer noted lots of mycorrhiza on the surface below the dry grass, because the lignified stems help feed the fungi.  
• One farmer hoped that “Mob grazing will really improve wildlife” and that it would be especially good for nesting birds and bee populations and other pollinators by providing a more steady nectar source.

Soil Test Results
The results from the initial soil tests were then discussed, and we were lucky to have Becky Wilson from Farm Carbon Toolkit with us to guide us through the baseline soil data.

The soils were tested in May/June 22, the full testing will be repeated in Spring 25. The plots have been GPS tagged so the exact same places can be sampled again next year. In general the statistics showed that there was no significant difference between the soil test results, but this was to be expected at this baseline stage of the trial.

There were some differences which were not statistically significant but which are a good indication of soil improvement during the trial:

• There were more earthworms in the trial plots, which might be because the soil of the trial plots was more shaded during the summer heat so they did not have to burrow so deep.
• There is also an improvement in fungi levels in the trial plots which is a good sign, though any increase in fungi levels would usually take longer.

It is expected that a greater statistical difference will be seen in the next samples: hopefully a further shift from bacteria-dominated soil to higher fungi levels in the trial sites. The next round of soil sampling will include infiltration tests, these were not completed in 2022 due to excessively dry conditions.

Next year when the triallists will be looking at doing some soil assessments themselves, including worm counts, infiltration, VESS and also they are looking to include a dung beetle count in the trial as this is usually a good sign of soil health.

All the triallists started with pretty good soils, but because they are so varied the group discussed how to ensure they can produce useful and robust outcomes.

A look at the Trial plots

The group then braved the elements and went to look at the trial plots.  The soil in both control and trial plots was still very dry below the first few inches from the drought, despite the driving rain on the day.  It was felt to be a good sign that three worms were found in the soil in the trial plot and none in the control!
Overall it was a very successful gathering, and reinforced enthusiasm in the group.