Impact of future nitrogen and phosphorus legislation on feed formulation and pig performance.


By Nigel Penlington, CEnv, MSc, MIAgrE and Emma Slater BSc (Hons), Agriculture and Horticulture Development Board


Summary Livestock feed ingredients especially nitrogen and phosphorus compounds have the potential to cause pollution of water, soil and air. UK legislation for manure handling and spreading has focused on preventing nitrogen pollution of water. Air pollution controls have been implemented on pig and poultry farms by regulations aimed at reducing ammonia impacts on habitats. This is set to change with a greater emphasis on air quality, and new rules limiting excretion of nitrogen and phosphorus to be applied to permitted farms and ammonia gas emissions to both permitted and non-permitted sites. Pig feed is the largest single contributor to four key measures


of environmental impact associated with pig production, especially greenhouse gases. Changes to regulation and other pressures mean that feed technologists will have to be ever more mindful of legislation when decision making and work closely with their clients to ensure not just compliance but provide the industry with a long-term sustainable future.


Introduction In the United Kingdom legislation to control agricultural pollution associated with farm livestock production has not changed much in recent years. In comparison to some other European countries with much higher densities of livestock it has also been relatively light touch. Systems of taxing farmers who produce more manure than they have land to spread on in countries such as the Netherlands, or the regions of Britany and Flanders have been reported in the past. In these instances, livestock nutrition has been very much part of farmers strategy to manage their business. In the UK we do not nationally have a high density of livestock so


farmers have been able to manage the spreading and utilisation of their manures and slurries within constraints of for example “The Protection of Water Against Agricultural Nitrate Pollution (England and Wales) Regulations 1996”1


(SI 1996 No.888) and successor regulations, known


as the Nitrate Vulnerable Zone (NVZ) Regulations. Thus the animal feed industry has been free to improve utilisation


efficiency and provide cost competitive diets for their customers without having to be mindful of legislative constraints arising from products of livestock excretion, that is not to say it has not been a consideration. Recent and anticipated changes to legislation are going to start having a bigger impact on pig, and other livestock producers with


respect to their housing feeding strategies. This paper tries to outline these changes to prepare the feed industry so that they will better understand external factors which may influence their client’s decision making.


Pollution routes and legislation Nitrogen and phosphorous dominate thinking when considering key potential pollutants excreted by livestock. Generally, when in solid or liquid form these are actually capable of controlled management whether deposited directly to land by the animal, or within housing. Strategies have developed for handling, storage and land spreading to implement scientific knowledge enabling maximum recovery as plant nutrients. Farmers have invested in storage and spreading equipment, sometimes costing in excess of £50k, to enable this. Where this is the case, perhaps, a holistic approach is best where feed ingredients arise as co-products from other processes, and assimilation and redistribution through an animal’s digestion system actually could provide the best environmental outcome. Unfortunately legislative controls struggle with this as a concept and constraints are placed either at the feeding or excreting end of the animal, rather than lifecycle of the ingredient. Pollution of water has dominated most thinking and action to date


with nitrates receiving most attention on many farms. NVZ legislation has been implemented to improve the quality of water abstracted for public consumption in areas where the EU standard of 50mg/l is, or predicted to be exceeded (EU Nitrates Directive1


). The tackles soluble


nitrogen compounds, nitrates and ammonium-nitrogen which are carried either to surface waters such as ponds, rivers and the sea, or below ground aquifers which supply what is referred to as “ground water”. Phosphorous may also exist in soluble forms and be leached


into surface or ground waters. This is most likely to occur when the levels in soil are higher than required, but still below those harmful for commercial crops. Control of soil nutrients through soil testing, planned fertiliser and manure applications based on crop yield and off take means in most situations, it has escaped legislative control. Both nitrogen (N) and phosphorus (P) compounds can be carried


on soil particles removed either by water or wind erosion. Control of this is predominately through farm management practice rather than feeding of animals. Farmers are rapidly becoming, or being made aware of Drinking


FEED COMPOUNDER JANUARY/FEBRUARY 2018 PAGE 27


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