Millthorpe RTC

April 2016 Update

Spring wheat and barley has now been drilled at different seed rates in the varying cultivation and cover crop plots. The site should be able to demonstrate to growers on medium to heavy soils:

• The effects of cultivation regimes on management of black grass.

• Field impacts of commercial and home saved cover crop mixtures, prior to establishing spring cereals.

• Identify when the most appropriate timing for cover crop destruction should be and managing soil moisture.

• Determine the viability of commercially growing spring wheat and barley.

• Seed rate work looking at 350, 450 and 550 seeds/m2 in both spring wheat and barley plots.

The primary aim of this site has been to manage black grass, which has been an ever increasingly common situation on many farms in Lincolnshire. Variables such as cover crops therefore have had to fit around black grass management practices. All findings listed below are from the work carried out in the current season so far. More data will be collected over spring and summer to add to existing findings.

Ploughed land – Left bare after 2015 WOSR harvest, the rain we received in August and early September was enough to stimulate an average of 285 plants/m2 of black grass to grow.

For the August and September period it was interesting to note that similar numbers of black grass plants had germinated in the bare soil (pre-ploughing) as the plots with two shallow cultivation passes. In future cases, I shall trial not disturbing the surface until late September for spring sown crops as the benefit from early surface cultivations compared to leaving bare have been negligible.

The bare land was then ploughed on the 26th September before soil moisture rose too high. Since ploughing, the next door plot with the same seed burden had over 900 seedlings/m2 germinate. It will be interesting to see how this flush effects germination this spring, or whether we’re just scratching the surface of the fields BG seedbank.

Surface cultivations– Following on from Brampton findings looking at maximising autumn BG germination, we trialled shallow legs and ridged roll packer alongside a shallow discs and DD packer. Germination was marginally better in the shallow legs and ridged roll packer plots, attributed to a more even depth and spaced topsoil cultivation, in combination with a roll packer; opposed to two rows off DD rings. Cultivated in early august, we achieved an average of 132 BG plants/m2 for the August period. Cultivated shallow once more at the beginning of September, the preceding dry three weeks after resulted in average germination figures of 87 BG plants/m2.

Subsoiling – Interestingly, the sub-soiled plot cultivated in mid-September had next to no black grass germinate at all over winter. Soil had been lifted dry and not consolidated which inhibited BG germination, an interesting point to discuss with visiting growers. We shall see the impact of having no surface BG germinate throughout the autumn and winter period within spring wheat and barley plots in the upcoming months.

Rolling – Work looking at multiple roll passes, in all plots found an average of 50-60% increase in BG germination from rolling twice compared to once. Three passes had little benefit over two passes.

Soil Moisture – In the spring, leading up to drilling we found lowest soil moisture in the shallow cultivated plots. Both the ploughed land and subsoiled land remained noticeably wetter in early spring. Cover crop density prevented airflow to the soil surface, combined with a lack of transpiration during the February period meant the cover crop plots held back drilling the most.

Cover crops – With a high CEC and organic matter content of 6%, the field itself is not lacking in fertility. Having the field in as spring cropping has allowed us to follow ‘best practice’ and trial different green cover mixtures (commercial and home-saved) to see their soil conditioning effects. Commercial mixes of egyptian & persian clover, niger, lupin, common vetch, buckwheat and sunflower generally established poorly when drilled in clay soils in September, with the exception of deep-till raddish, bristle oat, peas and phacelia. The farm commercially grows winter oats and spring beans so we trialled the green cover effects of these two species mixed with a low common vetch seed rate for EFA compliance.

In this late drilled clay soil, a large mix of foreign species has not been the best option. Winter oats have worked well, although a prostrate growth pattern from a spring oat would benefit soil drying in the spring. Beans have also nodulated well with the mild winter experienced, but are rotation specific. My current thoughts for next season are to trial a spring oat, phacelia and raddish mix at a low enough rate to allow sufficient airflow to the soil surface.

Destruction timings – The largest drilling issues have been in areas of higher soil moisture and matting of root skeletons, causing soil binding and open channels. Drier soils with loose topsoil aggregates filled in coulter channels. Spraying off on the 11th and 26th of February enabled sufficient soil drying, whereas leaving until 11th March, in this case was too late for drilling on 08/04/16.

Spring drilling - Which direct drill make should growers buy?? From looking at various setups of direct drills for heavy soils, my preference is favored towards disc coulter type drills which cause less topsoil heave and more consistent seed depth placement. The issues we’ve faced at Millthorpe trial site is applying enough pressure both on the coulter for seed depth and the press setup in order to close up the channel. There are drills available where pressure placement settings between coulter and press wheels can be adjusted. To overcome the open slots we have crossed rolled the field twice which has done a good job. More open coulter slots were left in the dense cover cropped areas where root binding and higher soil moisture prevented any loose soil from filling in the channels. Seed rates of 350, 450 and 550 seeds/m2 have been sown in both the spring wheat and barley. We can assume 350 is too low, however should act as an interesting visual for growers visiting the site.