Direct Seeding Versus Pre-seed Tillage in Red Clover Seed Production

Early weed control and good crop establishment are two of the most important requirements in successful forage seed production. Producers are looking to find the most effective method for planting forage seed crops while controlling early emerging weeds. SFSDC wanted to evaluate the use of direct seeding or pre-seeding tillage combined with pre-seeding herbicide applications to establish crops. This project compared direct seeding with various registered herbicide applications to pre-seeding tillage.

In 2016, wheat stubble in black clay soil was selected at the Agriculture and Agri-Food Canada (AAFC) Research Farm near Melfort, SK. Red clover (variety Altaswede) and faba bean (variety Snowdrop) were planted in alternate rows using a Conserva-Pak airseeder with double-shoot technology and 9 inch row spacing on May 26, 2016. The red clover seed was placed with the seed opener and faba bean through the fertilizer opener to achieve optimum seeding depths for both crops. The ports to alternate rows on the seeder were diverted at the meters, so that when seeded at 18" spacing, the seed from 2 rows was combined into 1 row to target correct seeding rates. A randomized complete block field trial design was used and replicated four times.

Red clover in alternate rows with faba bean stubble at Melfort SK. June 2017. Source: SFSDC

Treatments included pre-seed tillage versus no pre-seed tillage. Pre-seed tillage was done using a rotor tiller at a depth of 7cm. Herbicide treatments included pre-seed herbicide burn-off with either Express SG + Roundup or Roundup alone versus no pre-seed herbicide burn-off. Pre-seed herbicide treatments were applied with a hand-held sprayer. The trial was over-sprayed after emergence with Odyssey herbicide plus Merge using a tractor-mount sprayer. Crops and weeds were evaluated during the 2016 growing season to determine crop tolerance as well as broadleaf and grassy weed control. The faba bean was harvested on November 9, 2016 with a Wintersteiger plot combine.

During 2017, no herbicide was applied for in-crop weed control. All plots were desiccated using Reglone Ion, and the red clover seed crop was harvested September 25, 2017 with a Wintersteiger plot combine. Seed samples were collected and submitted for seed purity analysis.

Very dry conditions in spring 2016 resulted in the pre-seed tillage treatment reducing crop plant counts as well as faba bean yield. Treatments with the herbicide applications appeared to have no impact on red clover or faba bean emergence or faba bean yield. Where tillage was done, red clover density declined sharply compared with where red clover was direct seeded. This was likely due to drying of the seedbed during the tillage operation. May 2016 rainfall was much below normal, so conserving moisture in the seedbed was important to ensure adequate moisture for successful establishment of the shallow-seeded red clover crop.

The results showed that eliminating pre-seed tillage was the most beneficial treatment for increasing red clover establishment, while using Express SG + Roundup without pre-seed tillage was the most beneficial for reducing weed competition.

Red clover seed yields in 2017 were not significantly different, showing the ability of red clover to overcome treatment effects from the year of establishment. Seed purity analysis indicated weed seed contamination was much higher in the pre-seed tillage plots compared to the plots with no pre-seed tillage. Faba bean and red clover appear to be quite compatible and faba bean could be considered as a suitable companion crop for red clover seed production.

This project was supported financially by Saskatchewan Ministry of Agriculture through their ADOPT program. Thank you to DLF Pickseed, DuPont Canada, BASF Canada and Syngenta Canada for supplying seed and herbicide for the project. Thank you to Clayton Myhre, DLF Pickseed as well as Al Foster, Saskatchewan Ministry of Agriculture for their cooperation in planning and carrying out this project. Thank you to the Directors and producers of the Saskatchewan Forage Seed Development Commission for their support. Special thanks to Stewart Brandt, Jessica Pratchler, Stephanie Ginter and the crew at Northeast Agriculture Research Foundation as well as Brett Mollison and the crew at AAFC Melfort for their advice, expertise, time and efforts to carry out this project.

The detailed report for the project can be viewed under RESEARCH - PAST RESEARCH.