“It's worth remembering that all drills come factory set” Dick Neale, Hutchinsons.
At a recent Farmacy open day at Redhouse Farm, Waddingworth, Lincolnshire, Dick Neale spent some time explaining the subtleties of direct drilling. Andy Newbold went along to find out more.
Dick explained how the topsoil changes from the first year of direct drilling through subsequent seasons and how the grower's approach should reflect these changes.
He mentioned that although it's possible to laboratory test for soil texture, that lab texturing may not be very accurate, its best to get out in the field and check the texture for yourself. For instance, a soil with 21% clay and another soil with 40% clay content may both be described as clay loam, in practice they will behave very differently.
“As a rule of thumb, you produce about an inch of extra topsoil per year, so after 5 or six years you have 5 or 6 inches of lovely friable topsoil, and you will need to adjust the drill for this”, Dick Neale
Changing Soil Structures with Direct Drilling
The drill needs to be adjusted to aggressively cut a slot through the compacted, closed soil structure. Often soils like this are damaged and need at least on cultivation pass to open up the structure before the drill.
The soils need less aggressive cutting as it becomes more friable, the slot will open easily as the soils are softer, so the leading disc or tine needs to be set much less aggressively, which in turn will make the drill easier to pull. The open soil structure will also start to extend down further through the profile. The surface will be more open.
Now the root mass is quite substantial, the soil behaves very differently, the drill has to tear the root mass apart, so it's not cutting a slot anymore, its tearing one.
Drill coulters drop the seed into the slot cut by the drill, the slot needs to close on the seed. If the slot doesn't close properly and there's a decent amount of clay in the soil, as the land dries out particularly in the spring or late summer the slot will open back up and expose the seed.
Open seed slots will cause problems with herbicides, as growing seedlings need good contact with the soils, the slot needs to stay closed. The closing wheel or paddle boards will need to be set to ensure a well closed seed slot. Be prepared to check how the closing wheel adjusts.
Factory Drill Settings
It's worth remembering that all drills come factory set with a middle of the road' setting for paddle boards, disc angles, press wheel pressures etc.. This may not necessarily be appropriate for all soil types and not only is each season different, but as the soil structure changes the drill settings need to reflect this.
“Be prepared to adjust your machine as the soil changes from year to year” Dick says “Usually when we find direct drilling is failing, in the early stages of transition, the drill has been set by the book, and not to the field in question, obvious things have been missed”
Press wheels are a case in point as growers progress into direct drilling. Most press wheels are smooth, which are great for closings a nice clean open slot. However, as the root mass in the soil increases, there is less need for a pressed close, due to the increasingly ragged nature of the slot, so the press wheel needs to 'stitch' this back together. You will see on many direct drills either a standard fit, or a retro fit (in certain cases) 'guttler' type press wheels.