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LAMMA 2021

LAMMA 2021

Promoting the value of outdoor pigs to future landlords

MORE than 40 per cent of the English pig breeding herd is kept outdoors, but finding sufficient suitable land can be a challenge, so how can producers address this? 


OUTDOOR pigs can benefit both the environment and soil health but making arable farmers and potential landlords aware of this can be an issue.


Andrew Palmer, AHDB knowledge exchange manager says: “Demonstrating good practice and gathering evidence on the value of including outdoor pigs in the rotation can help to sell the positives and builder better relationships with landlords to the benefit of both parties.”


Over the last five years AHDB has held a number of meetings bringing together producers, landlords with key stakeholders including the Environment Agency, Catchment Sensitive Farming, Anglian Water plus other water authorities and local river trusts to look at ways of working more closely together.


Mr Palmer has been running a series of meetings at Swaffham in Norfolk.

He says: “It is about being proactive, rather than reactive. Over the last few years the outdoor sector has become more professional in its approach to site management.
“With a better understanding of the environment and the benefits pigs can bring to the arable rotation, relationships are starting to strengthen between outdoor producers and landowners.

“Looking ahead, including livestock in arable rotations, particularly on large enterprises, may play a role in the new Agriculture Bill linked to public funding for public goods.

“By thinking ahead, not just about the time the pigs will be occupying the land, keys can be put in place to optimise conditions for the pigs, the following crops and the environment.”


Some producers have begun to take land on up to a year before the pigs move on to establish a strong grass sward. Having good ground cover is vital to reduce surface run-off during heavy rain.

Positioning tracks and gateways in sensible locations will also have an impact during wet weather.

Taking land on early can incur additional cost but Mr Palmer suggests working with other partners who may be able to either graze the land or take a forage crop, can help reduce the costs.


Where early access to a site is not possible using a fast growing rye/vetch mix is an option to provide a short term green cover crop which will help to stabilise soil and if left for long enough will provide wildlife friendly pollen and nectar.


Mr Palmer says: “Although outdoor pig producers are confident of the benefits their stock can bring to an enterprise, the sector must work towards providing hard evidence.

“We are hoping to start work on a project with Anglian Water, Norfolk Rivers Trust, the Environment Agency, Natural England and AHDB on crop monitoring to measure yields before and after pigs have been included in the rotation. Other considerations to look at are increased organic soil matter and improved water holding capacity with can help reduce the need for irrigation and the value of muck in terms of reducing fertiliser costs.


“There are also the biodiversity benefits the site can bring with buffer strips and areas of wildflower mixes all providing habitat for wildlife and insects. Birds also thrive around pigs so there is also likely to be increased diversity in the bird population.

“Having the evidence to prove all these benefits can help pig producers in both securing land and the amount of rent paid.”



Choosing a site for outdoor pigs


Outdoor pig units can bring many benefits to both the environment and soil health, but choosing the right site is crucial. However, all sites will need some degree of planned soil management even if the risk are low.


The key risk factors are soil type, the degree of slope across the fields and location of fields.


Minimising soil erosion and surface water run-off to maintain water quality in groundwater, for example, boreholes, and surface water in rivers and streams is essential. This also helps to retain nutrients and good soil structure.


Nitrate Vulnerable Zones (NVZs) need to be taken into account and also Source Protection Zones (SPZs) which are zones around boreholes which show the risk of contamination from activities which might cause ground water pollution in the area.


Maps are available showing the three main zones. Pig producers are encouraged to avoid sites in an SPZ1 and to ensure they apply good land management practice if they are in zones 2 and 3 to minimise pollution.


Soil type


  • Know your top soil, its depth and what lies underneath it
  • Relatively impermeable clay/chalk subsoils have limited short term drainage capacity.
  • Fine silt loams can easily compact
  • First choice would be coarse loamy sands and sandy loams as if deep and over sand or gravel effective infiltration can be achieved.



  • Fields rarely have the same degree of slope across all areas so be sure the area with the greatest slope can be managed, otherwise leave it unstocked.
  • Ideally, the average slope should be less than 3o
  • Take into account slope length as long gentle slopes enable large quantities of surface water to travel along wheelings.


Soil drainage is key, especially with extreme weather patterns becoming increasingly common. It is important that pathways, such as land drains and ditches which take water away from the field, having first been filtered through correctly structured soil, are maintained.


Take into account previous land management as there may be hidden issues such as soil compaction and plough pans. Dig inspection pits with a spade to see soil structure and plan and carry out any remedial measures before stocking.


Options to manage water flow and minimise erosion risk, includes silt traps, which collect nutrients, sediment and phosphates which can then be spread back on the land.


Buffer strips, which often need to be more than six metres wide, can be linked to stewardship agreement, but should be in collaboration with the landlord on rented land.

They might include mixes to benefit biodiversity be left tussocky, which reduces runoff.



Take note

  • Be aware of ground water sources and the proximity to pigs
  • No pigs within a SPZ 1
  • No manure storage in a SPZ 1
  • Where muck is spread in a SPZ 1, it is should not be spread within 50m of a borehole and should be incorporated within 24hours
  • Awareness and prevention of water flow pathways routes towards boreholes.
  • Beware aware of regulations regarding siting of muck heaps


Soil and water management


  • Check whether the site is in or near any restrictive zones
  • Do a risk assessment of the site when managing possible soil erosion risks.
  • Look at how and where water might flow thinking about: ‘Source’, ‘Pathway’ and ‘Receptor’.
  • Sources include fields, manure heaps, yards and stores.
  • Pathways could be roads, tracks, wheelings and field drains.
  • Receptors are watercourses including rivers, lakes, bore holes and SSSIs, SACs, Ancient Woodland or highways
  • It is important in all circumstances to record and demonstrate actions taken. AHDB Pork’s Soil Management plan provides a simple template to help.



For more information and to listen to podcasts on outdoor pigs and order a ‘Keep muck heaps away from water’ cab sticker visit:


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