Moorepark, Fermoy, Co. Cork
When to Apply Early Nitrogen (N)
Deirdre Hennessy, Teagasc Senior Research Officer, Moorepark, Fermoy, Co. Cork
A lack of nitrogen (N) supply in the soil can limit spring grass growth. The timing and rate of fertiliser N and slurry application are key decisions for every livestock farmer in early spring. Research shows a large range in grass growth response to early spring N (between 5 to 18 kg DM/kg N applied). While the appropriate application of early N is beneficial, the incorrect application of early N is wasteful, costly, pollutes water and increases greenhouse gas emissions. Take the following into consideration when considering applying slurry or fertiliser N:
- Check the weather forecast (met.ie) – do not spread slurry or fertiliser if rain or very cold weather is forecast.
- Only apply fertiliser N when soil temperature is greater than 5°C and rising - grass is growing at these temperatures and will take up the N in the slurry or fertiliser
- Check the soil trafficability before spreading to avoid damage to soil
- Measure farm cover and use the grass growth predictions (available on the Grass10 newsletter, on the PastureBase Ireland website, and on the Farming Forecast on Sunday on RTÉ 1) to inform decision making around slurry and N fertiliser application
- Target areas most likely to respond to early application of N - fields with a high perennial ryegrass content or recently reseeded, drier areas, fields with a grass cover > 400 kg DM/ha (6 cm), fields with optimum soil fertility (index 3 for P and K, pH > 6.2).
Where possible use slurry to replace fertiliser N in spring. Apply slurry to approx. 40% of the farm as soon as permitted, targeting high demand areas where possible, e.g. silage ground and low P and K grazing ground. In February, apply slurry to grazed areas (up to 30% of the farm). Apply all slurry using LESS (low emissions slurry spreading) methods. 2,000 gals/ac applied using LESS will supply ~20 kg/ha (16 units/ac) of available N and 2,500 gals/ac will supply ~25 kg/ha (20 units/ac) of available N. Manage slurry application to ensure that no more than 2,500 gal/ac are applied in each application.
Don’t apply more than 29 kg N/ha (23 units N/ac) chemical N fertiliser in February. The whole farm should receive fertiliser N in March (20-50 kg N/ha; 20-40 units N/ac). No more than 75 kg N/ha (surry N + chemical N) in total up to early April (Table 1 and 2). All chemical N should be applied as protected urea.
Teagasc Moorepark Grass-Clover Research Update 22-11-22
Dr. Deirdre Hennessy and Hannah Irish
The grass-white clover research programme at Teagasc Moorepark is comparing herbage and milk production from three pasture-based systems, all stocked at a whole farm stocking rate of 2.6 cows/ha. The three experimental treatments are grass-only receiving 225 kg N/ha, grass-white clover receiving 150 kg N/ha and grass-white clover receiving 150 kg N/ha in an alternative N application strategy. Paddocks in the grass-white clover treatment receiving 150 kg N/ha in an alternative N application strategy received N fertiliser every second rotation from May to August, while in the other grass-clover treatment N was applied in every rotation.
Current pre-grazing herbage mass is approximately 1,200 kg DM/ha and post-grazing sward height is approx. 4.5 cm. We are using a lot of on-of grazing at the moment. We will be finished grazing around the 28th November. Target closing farm cover is 550 kg DM/ha. Current sward clover content is approximately 30% on both clover treatments. Current average farm cover is 720 kg DM/ha. Current herbage allowance is 11 kg DM/cow, plus 3 kg silage DM and 3 kg concentrate. Milk production is similar across all treatments at 11 kg/cow and 1.05 kg MS/cow. 20-25% of cows in each treatment have been dried in the last 2 weeks.
Herbage production on the Grass225 treatment was 14.5 t DM/ha, on the Clover150 was 14.5 t DM/ha and on the Clover150Alternative was 14.8 t DM/ha. Average sward clover content to early November was 20% on both clover treatments. Cumulative milk solids yield per cow to 20 November was 492 kg on Grass225, 509 kg on Clover150 and 511 kg on Clover150Alternative.
We reseeded 12.5% of the farmlets at the start of May and over-sowed 8% at the end of March.
Update on the Teagasc Moorepark Grass-Clover Research programme
Dr. Deirdre Hennessy and Hannah Irish
The grass-white clover research programme at Teagasc Moorepark is comparing herbage and milk production from three pasture-based systems, all stocked at a whole farm stocking rate of 2.6 cows/ha. The three experimental treatments are grass-only receiving 225 kg N/ha, grass-white clover receiving 150 kg N/ha and grass-white clover receiving 150 kg N/ha in an alternative N application strategy. Paddocks in the grass-white clover treatment receiving 150 kg N/ha in an alternative N application strategy will receive N fertiliser every second rotation from May to August, while in the other grass-clover treatment N is applied in every rotation.
Current pre-grazing herbage mass is approximately 2,250 kg DM/ha and post-grazing sward height is 3.8 cm. Current sward clover content is approximately 10% on both clover treatments. We have 83% of the area grazed and approximately 10 days grass left in the first rotation. The first grazed paddocks have a cover of 900 – 950 kg DM/ha. Average farm cover is 850 kg DM/ha. Current herbage allowance is 15 kg DM/cow plus 2 kg concentrate. To date, 45% of the farmlets have received slurry (2,500 gals/ac) and average fertiliser N application is 56 kg N/ha. Cows are on a 24 hour allocation since early last week. Milk production is similar across all treatments at 23.7 kg/cow and 1.92 kg MS/cow.
We plan to reseed 5-10% of the farmlets this year (April/May), with a small amount of over-sowing in early April in swards with low clover content.