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An experiment to test sustainable management systems for unimproved neutral grassland - BD1460

Previous research (Defra project BD1440) has shown that the use of continuous grazing over the growing season to manage agriculturally unimproved species-rich grasslands can compromise botanical quality, irrespective of grazing intensity, and if grazing occurs over more than three years. Periodic hay cutting with aftermath grazing may, therefore, be a necessary management tool with which to maintain or enhance botanical quality of unimproved grassland. This project will examine the effectiveness of periodic hay cutting rotated with grazing to provide long-term maintenance or enhancement of grassland botanical richness and quality which has, to date, not been evaluated against either grazing only or hay-cutting only managements. The results from this experimental work will inform the management of species-rich neutral grassland entered into agri-environment agreements helping to deliver scheme biodiversity objectives. The research though, should also inform the management of such grasslands more widely throughout the UK.

No clear sward management recommendations for setting HLS agreements that will meet the Indicators of Success for maintenance and restoration of species-rich grassland are currently available. This means that delivery of PSA and BAP targets for this habitat may not be met despite the fact that in HLS these options are two of the most popular and are likely to require a major spend over at least 10 years.

The proposed project is designed to directly build on the research platform that was developed in the Defra project BD1440, which sought to determine the appropriate severity of grazing, by cattle, to maintain species rich grassland, and to quantify the impact of grazing on invertebrates, and on the growth rate of the cattle. BD1440 showed that over 5 years grazing to mean sward heights of > 8cm resulted in very good cattle performance (c.0.8 kg/day) and swards with a wide diversity and abundance of invertebrates. Grazing to < 8cm reduced cattle growth rate, and invertebrates.

However, on all of the grazing treatments imposed in BD1440 there were changes in botanical composition in the last 2 years that were consistent with increased nutrient availability, including increased ryegrass and white clover abundance, raising doubts over sustainability of prolonged continuous grazing management for maintaining this important grassland community. There was also a large increase in abundance of creeping thistle which would be unacceptable in an HLS agreement. These issues, therefore, did not allow clear recommendations for sward management that would maintain desirable species, whilst controlling undesirable species, to be made from BD1440.

On the basis of the Defra project BD1440 results it was contended that re-introduction of hay-cutting, either indefinitely or for 2-3 years, might be required to control or reverse grazing induced botanical changes in pastures. This will be tested in the proposed project. Stimulation of N availability by early onset of continuous grazing could have been a factor behind the observed botanical changes in BD1440. In the proposed project we will examine this by measuring change in the potential net nitrogen mineralization in the unimproved grassland under either continuous grazing or when closed for hay cutting. Dispersal limitations and lack of micro-sites for germination/seedling recruitment have been identified as major factors limiting restoration of botanical diversity in grasslands. The proposed project will explore whether constraints on species recruitment into the pasture is dispersal or germination niche limited through the use of green hay spreading and scarification of the ground.
Overall: to identify management systems that will maintain or enhance the abundance of positive indicator plant species of high nature conservation value and control pernicious weed abundance on agriculturally unimproved species-rich lowland grassland.

Specific objectives
On unimproved lowland grassland:
1. Identify the consequences for the cover of positive and negative indicator species, and for cattle performance, of applying moderate – lenient continuous grazing pressure over more than 5 successive years.

2. Identify whether a prolonged period of hay cutting is required to restore botanical diversity, increase positive indicator species abundance and control negative indicator species.

3. Identify whether periodic hay cutting of a pasture can provide a practical method for maintaining/restoring botanical diversity, positive indicator species abundance and control negative indicator species.

4. Examine effects of green hay addition and scarification on botanical composition.

5. Provide sustainable management system(s) for lowland neutral pastures for use in Environmental Stewardship agreements.
Project Documents
• FRP - Final Report : BD1460 final report   (2314k)
• TPS - Two Page Summary : BD1460 TWO PG SUM   (377k)
Time-Scale and Cost
From: 2007

To: 2012

Cost: £887,407
Contractor / Funded Organisations
North Wyke Research, Institute of Grassland and Environment Research (IGER)
Agricultural Land              
Environmental Protection