Environmental impacts of pasture improvement

Results:

Calculations show that emissions from permanent pasture using the chosen levels of N fertiliser are significantly higher than from reseeded pastures, despite the emissions generated by soil disturbance and machinery when reseeding by whichever method chosen. The increased animal performance achieved on improved pastures (with clover) further outweighs the emissions from reseeding giving consistently lower emissions per kg of live-weight gain for all reseeded pastures.

Emissions per hectare of land are highly dependent on nitrogen fertiliser input, grass yield, nutritional value of the sward, utilisation and animal stocking rate and will vary very considerably from site to site.

Planned activity:

These findings will feed into relevant knowledge transfer activity.

The Problem:

EBLEX has been organising grazing events that have looked at the benefit of reseeding in terms of improved animal performance and forage yield. For example, a permanent pasture that has been reseeded with good varieties can produce grass over five years worth an extra £2,000/ha (£800/acre). Questions have arisen about the benefit of re-seeding in relation to the release of greenhouse gases (GHG) during cultivation, both from the machinery and from the land. Different methods of cultivation need to be taken into consideration, eg direct drilling, over-seeding, broadcasting and ploughing. Consideration also needs to be given to the benefit in terms of liveweight gain and days on farm for animals grazing better quality pasture in relation to GHG emissions.

Project Aims:

1. To review literature on the advantage of reseeding on animal performance and forage yield that can be realised at a farm level, especially in relation to different species and mixtures
2. To calculate the emissions generated from the various forms of reseeding in terms of energy used by machinery and land disturbance
3. To produce information on the benefits in relation to GHG emissions from improved animal performance from better quality pasture

Approach:

ADAS will look at the performance at grass of spring calving suckled calves, finishing cattle and lambs pre and post weaning on permanent pastures and medium term leys. Calculations will be produced for different establishment methods (ploughing, discing, direct drilling and broadcasting) on the emissions generated from the machinery and the land. The performance benefits will be combined with the emission figures to understand which establishment methods provides a balance between good establishment, low emissions and good animal performance.

Deliverables:

The data produced by this project will be used as part of the beef and sheep roadmap, and will also be used in technical information for pasture improvement.