The options available for stubble cultivation and cover crop seeding
It used to be simple; following harvest, herbicide was applied to stubble and that stubble was ploughed in the autumn for a winter crop and later for a spring crop.
But today, as Teagasc Research Officer Dermot Forristal explains, different demands in terms of crop establishment machinery being used, regulations, schemes and a desire to protect nutrient and carbon loss, combine to make stubble management more complicated.
Stubble cultivation and cover cropping can be of benefit, but it’s important to have a clear view of what is being targeted in each case and to deploy whatever method is necessary to meet those targets in stubble cultivation or cover crop seeding without incurring excessive costs.
The role of stubble cultivation is to:
- Encourage weed and volunteer germination for subsequent control;
- Prepare for cover crop establishment;
- Prepare for winter cereal establishment in min-till system;
- Reduce slug numbers.
Stubble cultivation can have challenges however:
- Extra cost and operation at a busy time of year;
- Specific cultivator often purchased for this one operation;
- Dries out soil, loses some organic carbon;
- Loosened soil vulnerable to erosion if no cover.
Selecting a suitable cultivator type for your land is important:
- Tine cultivators will penetrate better in dry conditions. Consolidation is essential to conserve moisture and to have an even seeding depth. Tines tend to bring stones to the surface.
- Disc stubble cultivators work well at shallow depth. Penetration in very dry conditions can be limited, depending on machine weight, disc design and angle. They will not bring up stones, but there can be a risk of compaction in wet conditions.
- Tine and disc combinations are flexible, but they are usually heavy, expensive implements.
In the below video, Dermot outlines the topics for discussion at the upcoming Crops and Cover Crop Cultivations event in Teagasc Oak Park, which will be held on June 21st.
Sowing cover crops
Cover crop benefits and challenges, including rotation and weed control constraints, are outlined elsewhere. As cover crops are often small-seeded and sown at harvest, moisture conservation, accurate sowing depth and good soil-to-seed contact are key targets in cultivation and seeding.
There are many seeding possibilities:
- Autocasting: Rarely used, but spreading seed in a standing cereal crop before/during harvest, can work with brassicas if there is moisture available.
- Fertiliser spreader: Many spreaders will have settings for seeds, but bout widths need to be carefully selected and spread checked.
- Simple cultivator-mounted electric spinner: While the simple spreading characteristics of these spinners may not suit all seeds, they can work at the narrow-bout widths used.
- Cultivator-mounted pneumatic seeders: Typically have an accurate metering mechanism, which delivers to 4 to 8 outlets across the cultivators width and are capable of very accurate seeding.
- Direct drill: A direct drill can sow cover crops, while leaving the existing stubble intact.
- Strip-till drills: Will establish cover crops with reduced ground disturbance.
- Conventional drills: Cultivator drills (Vaderstad Rapid or similar type) can establish cover crops with minimal disturbance. Conventional coulter drills will require trash-free conditions and consequently more seedbed preparation than desired for a cover crop.
A range of this equipment is being demonstrated at Crops and Cover Crop Cultivations in conjunction with the Irish Farmers Journal, with commentary by Dermot Forristal and Siobhán Walsh. For more information on the event, click here.