Diverse forage crops for sustainable livestock wintering

There are some interesting observations on soil structure from one of the farms where a single 8 ha field was used, with a 4 ha x 16 species mix on one side and 4 ha kale on the other. The field has had exactly the same tillage and is on the same soil type. Both sides are doing very well, despite the slow start due to the dry weather.

The most interesting difference was in the soil structure on either side of the field. The diverse mix has beautiful aggregation and was friable and crumbly, the ideal chocolate cake texture. On the kale side the soil was noticeably more compact with obvious layering. Beneath the vigorous top growth you can clearly see bare ground.

Another interesting observation was that this field had a dock problem. Dock persisting on the kale monocrop side, but no sign of docks within the diverse mix.

Pollinators were prolific on the multispecies mix, but cabbage whites prolific across both trial and control.

No doubt the change in soil structure is down to root density and diversity allowing different functional groups to fulfil niche roles. The quantity of total root mass in the soil is far greater in the diverse mix .

We will monitor throughout winter grazing to see how the soil fares on each side, and most importantly animal performance and welfare. It will be interesting to see if one mob decides the 'grass looks greener' on the other side of the electric fence!

• The earliest planted kale was hardest hit by flea beetle; this does not seem to have been much of an issue in the multispecies mix.
• The multispecies mix appears to reduce flea beetle impacts.
• Bolting has been an issue for one farm due to later drilling and very dry and hot weather. Long term impacts of this to be explored. 
• Concern raised over smaller and slower establishing species such as clover and vetch being shaded out by the faster growing species. 
• This may be due to the dry weather and poor establishment conditions. 
• Driest farm has had very low establishment of grasses despite comprising over 50% of the mix.
• Early insect observations showed ladybirds, butterflies and bumblebees were prolific in the multispecies mix.  Insect species preferred the multispecies mix as it matured.  
• Good rhizosheath formation was observed on the multispecies mix, even when seedlings were small (less than 10cm above ground), demonstrating early symbiosis between microbes and plant roots. 
• In some of the control plots there has been regrowth from previous mixes, so the results will not be 100% monocrop vs multispecies mix. However, this would have been business as usual on these fields anyway, and a comparison with the multi species mix is both valid and useful.

At the end of May soil samples were taken from each trial plot which were sent off for a comprehensive chemical, physical and biological overview. The results came back in June and showed that while the microbial biomass was average-good, the microbial activity was less than 1 on a few farms, showing microbial dormancy.

Two of the farms had the same pH but their organic matter (OM) content varied from 3.4% to 9.6%.  The farm with the higher microbial activity had the higher levels of OM which indicates the importance of OM for better microbial activity.

Establishment

• The plots were drilled between 7th May and 20th June 2022. 
• No seed treatment was used.
• Cultivation and drilling methods varied but included subsoiling, discing, ploughing, powerharrow, drilling and rolling.

Unfortunately the extreme dry weather hindered establishment on the sandier soils that received low rainfall, particularly where drilling was towards the end of May. Farmers have reported that the control is struggling more than the multi species mix.  This may be due to a later drilling date for the control.  The earliest drilled crop on the heavier soils near Exmoor have established particularly well.  The first species to get away were the sunflowers and radish, and the radish took the brunt of the flea beetle impacts.  The smaller seed species such as clover and vetch, struggled to get away in the dry weather.  No amount of planning can predict the weather for a field trial! One farmer has put in the same mix a month later and had far better establishment on the later planted section after a bit of rain.