By the time our summer crop butternuts were removed from the Carbon Positive plots, the vines had dried to rope. We disced and direct drilled cover crop seed but couldn’t run an aerator through without massive tangling.
On 26 March, annual ryegrass was sown in both the Conventional and Hybrid plots, and a Triticale/Vetch mix in the Regenerative plots. With very dry, rubbly soil, we irrigated after sowing to help germination.
Because we’ve been disappointed by vetch in recent crops, Olivia ran a germination trial, placing 100 seeds in a tray of plot soil and leaving it outside. This showed 88% germination under field conditions, which we were happy about.
Triticale was first to emerge in drilled plots, with significant numbers by 1 April. Ryegrass and vetch were slower, but well underway by 7 April.
Triticale and Vetch
Annual Ryegrass
By early May, the triticale was well established with roots down at least 20 cm. The vetch roots were also reaching down and had good nodulation.
The ground cover under each cover crop is shown in the chart below. After a lag at initial germination, the ryegrass plots grew at the same rate as the triticale and vetch but did not catch up. The drop at the beginning of June followed an attempt to aerate the soil through a full cover crop once the butternut vine had sufficiently rotted. However, there was some crop damage and the average cover dropped. The regenerative triticale and vetch plots did not return to the previous full ground cover. While the triticale was recovering, around mid-July a leaf rust began spreading through the plots. Even as growth in the Conventional and Hybrid ryegrass plots continued lifting in August, the triticale weakened.
Examples of canopy images taken on 17 August show the ground is well covered, although there are more gaps in the Regenerative image and the presence of rust is apparent.
Conventional Annual Ryegrass
Hybrid Annual Ryegrass
Regenerative Triticale & Vetch
In mid-August we planned to start ground preparation by broadcast spraying the Conventional plots with glyphosate and Torus, and strip-spray the Hybrid and Regenerative plots with glufosinate and Torus. We took above-ground biomass samples on 8 August taking two 0.25 m2 subsamples in each of four sub-plots per plot. The charts below show there is no difference in dry matter percentage between treatments. Despite the lower ground cover in the Regenerative plots as assessed by Canopeo, there is a significant difference in above-ground dry biomass compared to the other two which are the same.
Weather has impacted our plans to spray out the cover crops. Our next summer crop will be food quality maize, and the planting date is flexible so we can delay somewhat. But we do want to get next year’s cover crops in while the autumn is still warm, so we don’t want to wait too long.
We plan a public field walk at the MicroFarm on Carbon Positive Field Walk at 1:00 pm on Wednesday 16 September.