Research Trial Update Clonakilty Agricultural College
James Daunt, Clonakilty Agricultural College Lecturer caught up with Brian McCarthy, Clonakilty Research Officer to get a review of the clover trial at the College which took place from 2019 to 2021. The experiment looked at sward types and nitrogen fertiliser rates.
There has been four grazing treatments N/per hectare per year:
- Grass only swards - 250 kilograms of nitrogen
- Grass only sward - 150 kilograms of nitrogen
- Grass clover sward - 250 kilograms of nitrogen
- Grass Clover sward - 150 kilograms of nitrogen
Clover
The low nitrogen treatment had an average about 17.5% Clover over the three years whereas the high nitrogen treatment had about 13.5%. The clover content has increased over the last three years. In 2021 around 20% clover was achieved in this sward.
Herbage production
- The grass only 150 treatment - 13.8 t/DM/ha
- The grass only 250 treatment - 15.2 t/DM/ha
- Grass/clover - 150 treatment - 14.7 t/DM/ha
- Grass/clover - 250 treatment - 15.6 t/DM/ha
Milk Production
Cows received on average around 600 kilograms of concentrate per cow per year.
- Grass only 150 treatment produced 461 kilograms of milk solids / cow
- Grass only 250 treatments produced 470 kilograms milk solids / cow
- Grass Clover treatments both produced 495 kilograms of milk solids / cow
Research Plan for 2022
It is planned to continue investigating sward type and nitrogen fertilizer rates. The treatment will change slightly in the grass only treatments to have it in line with the new proposed changes in the nitrates derogations. The level of nitrogen in the high nitrogen treatment will be reduced to 225 kilograms per hectare per year. The grass only 150 treatment will be maintained for another couple of years to try and see the efffects of a low level of nitrogen on grass only sward over five or six years
The grass clover 150 treatment will be maintained. Due to pressure to reduce nitrogen fertilizer the nitrogen rate on the remaining grass/clover swards will be reduced from 250 kg/N/ha to 75 kg/N/ha. The nitrogen will be spread in the early part of the year.
Watch the video clip below to find out more about the project