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Soil Regenerative Agriculture Group - updates

Terminating cover crops

One of areas Ross Mitchell at Castleton has been looking into is the various ways to terminate cover crops, writes Zach Reilly, Senior Consultant and Soil RegeneratA field of flailed cover crop - the crop stalks are left as a brown stubble.ive Agriculture Group Facilitator.

Ross has set up an on-farm trial in several fields where some cover crops are grazed; some are flailed; and some are left to be sprayed off with glyphosate. Ross is also planning to use a crimper roller to terminate covers if the weather permits (-4°C or colder is required).  The flailed cover crop (first photo right) had little surface residue remaining as the small particle size has allowed the biomass to break down quickly. However, it was noted that the roots of the cover crop are still intact. Ross is planning to leave the flailed areas to see if there is any regrowth before deciding if this area needs desiccated prior to sowing.

Several areas have been left untouched (second photo); this is to provide a comparison to the grazed and flailed areas. Ross plans to use glyphosate to terminate these areas, however, he is concerned that the high amount of biomass will cause nitrogen lock up in following crops if it has not broken down prior to sowing.

Standing, weathered covercrop that was neither flailed or eaten by the sheep this winter.

The cover crops have also provided significant grazing between grazing cereals. The third photo on the right shows what is left after grazing, with only straw  from the previous crop left on the soil surface. Surprisingly, there is little manure left on the soil surface, instead this has been washed in or incorporated by worms. The soil felt a little wetter on the top, potentially due to some surface capping.

Ross dug soil pits in each of the three treatment areas to see if the grazing or flailing were showing any signs of soil compaction. Although there was not a large difference between each soil block, the grazed soil was more easily broken up and had a higher worm count, even though this area is in a heavier part of the field. There was little difference noted between the flailed and the intact cover crop. All three soil blocks had roots present to the full spade depth and were abundant in worms; there's more information, including photos of the soil blocks, on this and other activities in Ross’s update for
A field of grazed cover crop - or what is left of what was the cover crop!
January 2022 at Case Study: Ross Mitchell - Farming for a Better Climate.



Crop establishment methods at Backboath

Winter can be a quiet time for field work on an arable unit, but there are always jobs to be done, writes SAC Consultant Zach Reilly.

On the left-hand side, a field of wheat at Backboath established after potatoes, potatoes are visible on the soil surface. On the right-hand side is a picture of wheat seedlings and their roots.

Soil Regen group farmer Hugh Black at Backboath has looked at crop establishment methods following potatoes and has used his modified subsoiler drill to break up compaction and sow the subsequent crop of wheat. Hugh has been adapting this system for several years now and has added a third coulter behind each cultivation leg to reduce his row spacing. Using non-inversion tillage after potatoes can help to keep ground keepers on the soil surface to increase the destruction of tubers, preventing volunteer potatoes in future crops. The photo shows a field of wheat at Backboath established after potatoes; potatoes are visible on the soil surface, on the right hand side of the photo we can see the established wheat seedlings and their roots.  Read more about Hugh’s experience with the modified subsoiler drill and establishing his winter oilseed rape over on our webpages in his December 2021 update Case Study: Hugh Black - Backboath near Forfar - Farming for a Better Climate.

Could soil structure be holding back yields?

Although the soils are a little wet due to recent weather, Hugh has taken some time to investigate his soil structure in the fields planned for spring crops. Through better soil management, Hugh has seen a large increase in the number of worms he is finding and is also noticing less compaction in his fields.  The photos below highlight the difference between a trafficked area of the field and an area which has not been driven on. The left-hand block is angular and has a clear fracture line at a 5cm depth. Additionally, there were fewer worm holes in this block. On the right hand side, the soil from the field has a crumb structure and was easy to break apart.

Angular aggregates on the left indicating compaction, rounded crumbly aggregates on the right indicating a healthy soil.

There is more information on assessing your soils in the Valuing Your Soils brochure, available on the Farming for a Better Climate webpages.


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