Integrated Crop Management (CPA Book)

Waste and Pollution Management


Waste is something for which there is no practical use. Out ancestors were experts at minimising waste. They had little problem with disposing of the waste that they produced, because they had still concern with pollution control. Combustible materials, if they could not be used on the home fire were burnt in the open air and the smoke allowed to disperse freely.  The ash would then be recycled by spreading on the land or the garden vegetable patch. Liquid wastes were simply poured away and solid materials burnt.

Organic waste from the farm was recycled on the land and so, too, was human organic waste, as night-soil. Sewage disposal only became fully organised and mechanised in the middle of the nineteenth century.

The industrial revolution bought the dawn of a massive waste disposal and pollution problem. Machines running on fossil fuels produced vast, unsightly heaps of waste from the fires and furnaces, and dense black emissions into the air that subsequently deposited onto buildings and the land. From the factories came new man-made chemicals and materials for use in our clothes, in our homes and, most importantly, as packaging.

Beautiful buildings became blackened with soot, and people died from respiratory illnesses in the smog. But at the same time, knowledge of toxicology and the impact of some chemicals in everyday use, such as lead, on human health advanced rapidly. Gradually the march of progress brought with it an awareness that something had to be done. Waste disposal and pollution control thus became one of the major challenges facing modern society.

What are the particular waste disposal challenges that face agriculture?

Agriculture and horticulture have their own special problems in handling waste because many of the activities are not confined to a building or a purpose-built factory; much of it is done in the open air in areas to which the public often have free access. Furthermore, as an industry, agriculture produces significant quantities of organic waste which is not only unsightly but also often, by its very nature smelly.

In most industrial processes, for example in factories, production and waste disposal can be managed as discrete operations. Much of the disposal of waste in agriculture and horticulture has to take place on the production site - the land. It follows that precautions need to be taken not only to protect the environment, but also to protect the soil as the fundamental natural resource for future generations.

Finally, both agriculture and horticulture have responded to the challenge of meeting an increasing demand for high quality affordable food by the adoption of a wide range of new technologies. At the forefront of these are fertilisers and pesticides, both of which are potential pollutants of water and soil. Because of this, farmers and growers have a duty to adopt safe and responsible practices to manage their disposal.

Waste on the farm

Every manufacturing process - even the production of waste - consumes energy. Therefore waste products on the farm should be regarded, first and foremost, as a resource to be reused or recycled if possible, and minimised if not. Farm wastes come from a variety of sources: natural or organic waste, inorganic wastes and chemical wastes which require specialised handling because they present particular toxicological or contamination hazards.

Organic wastes include the obvious animal wastes like farm yard manure, poultry manure and slurry. Less apparent waste materials from animals are feathers, carcasses and unwanted milk. Anaerobic digestion is one means of handling slurry, especially where other means of disposal might create a nitrate pollution hazard. The process produces methane which can then be used as an energy source.

Crop organic waste again includes obvious plant residues like cereal straw, sugar beet tops, and potato haulm but also materials like the green waste from packing houses, hedge trimming and prunings.

Inorganic farm waste is derived mainly from packaging materials such as glass, metal drums, pesticide containers, plastic fertiliser bags, polythene sheeting, cardboard and paper. Also in this category one might include general litter, rubble and even stones.

Chemical wastes that require specialised handling are generally those concerned with pesticides, both concentrated and dilute, and spent sheep dip, bulb dip or fruit dip. However, also included here are washings from sprayers and pesticide containers, parlours, dairies and packing houses. Slurry and silage effluents are potent pollutants, especially of water, and are some of the most difficult wastes to handle because they are liquids and not 'contained' in the same way as pesticides, for example.

Principles of waste management

The fundamental principles of waste management are:

  • reduction and minimisation of wastes with no practical value
  • re-using or recycling those wastes where suitable opportunities exist
  • safe and efficient disposal using licensed waste disposal contractors where necessary

The plan should cover both anticipated waste disposal (crop residues, packaging etc.) and accidental waste disposal problems. Thus, contingency plans for spillages and contaminated materials should all be included.

An example of how waste can be reduced is by taking steps on the farm to keep 'clean' and 'dirty' water separate. For instance, there is little point in allowing a slurry lagoon - itself a considerable investment - to be filled with rainwater when, at a little extra cost for guttering and down pipes, this water could be collected and used.

Practical steps to manage waste and pollution

Any waste that cannot be reused or recycled is a potential pollutant, as are wastes pending their re-use. Not only is the whole farm (soil, water, air, crops and non-cropped areas) at risk, but so too is the wider environment where water and air is concerned. Therefore there is a duty of care not just within the confines of the farm, but to the community at large. waste management plan

Creation of a farm waste management plan is an essential component of an ICM system. The plan should include the identification of high pollution risk, low risk and no risk area on the farm together with contingency plans for emergencies. To assist in this, DEFRA has produced three Codes of Good Agricultural Practice covering soil, water and air. These are written as practical guides for farmers and growers to avoid causing long-term damage to the environment in which they operate. Except for the water Code, they are not statutory documents, but in each case they describe the main causes of pollution and the risks involved. Ensuring that all staff are familiar with the guidelines offered in these Codes, as well as the farm contingency plans for emergencies, is an essential part of the forward planning for waste disposal.

...provision for handling waste and avoiding public nuisance

Making adequate provision for handling wastes in such areas as slurry and silage storage, sheep dip handling, carcass disposal and fuel storage are obvious practical measures to take. Also included here would be systems for handling organic manure which achieve rapid incorporation or injection into the soil to ensure efficient nutrient uptake and to minimise air pollution which might otherwise antagonise neighbours. Compliance with legislation, for example in handling sewage, is obviously important.

An unfortunate, but very real, problem that many farmers face, especially those close to population centres, is fly-tipping. Under present legislation, land-owners are responsible for the disposal of dumped waste, unless the culprit can be found and convicted. Burning is the most convenient option but not always the most practical. There are strict regulations governing burning materials, especially plastics or rubber, in the open air. The creation of dense smoke is an infringement of the Clean Air Acts and any fumes or smoke can be a health risk and a safety risk if created near a public highway. The introduction, in 1996, of a new tax of 7 per tonne for waste disposed of in designated landfill sites is likely to result in an increase in fly-tipping and a consequently increased cost for farmers faced with its disposal.

Handling pesticides and fertilisers

Pesticides present special problems because of statutory constraints concerning their use, the disposal of their containers and their presence in water and produce. The EC Drinking Water Directive imposes maximum admissible concentrations for all pesticides (irrespective of their toxicity) and nitrogen and it is therefore important to avoid contaminating surface or groundwaters with these chemicals. Furthermore their presence on the wrong crop, or in hedgerows and other non-target areas are forms of pollution. Finally, gross contamination of land can place severe constraints on what may be grown subsequently.

For all these reasons, pesticides and fertilisers require specialist management from the moment they arrive on farm to the time when any surplus material, together with the containers, are disposed of. Various steps can be taken long before they are actually applied in the field. Accurate application of these materials in the field contributes a lot to the minimisation of waste and therefore risk.

It is inevitable that, for a lot of the time, some pesticides have to be stored on the farm. They are not only valuable - theft is not uncommon - but they are potentially hazardous to users, other people and the environment. Storage of pesticides places heavy responsibility on everyone concerned who must take all reasonable precautions to protect the health of human beings, creatures and plants, and to safeguard the environment. Avoiding pollution of water, whether in day-to-day management or following accident or spillage, is of particular importance.

In general, chemical stores must meet specified minimum standards in such matters as security, fire resistance, weather proofing and containment of spillage's and leakage. Detailed guidance on the legal requirements of pesticide storage, together with information about the construction and siting of pesticide stores is available from the Health and Safety Executive.

...getting ready to use pesticides

Accurate applications makes sense from both economical and environmental viewpoints. Underdosing or overdosing, or merely failing to ensure even application across the delivery width of the machine, are inefficient uses of these chemicals. At the very least these mistakes make the crop look unsightly, while more often damage to the crop or failure to control the pest reduce its yield or its quality. Yet, in spite of al this, over half of all pesticide sprayers in the UK are never calibrated, and a similar proportion of fertiliser spreader operators have never read the machine manual. Providing training for operators and, where appropriate, ensuring that they have the necessary Certificate of Competence, is the vital first step. This needs to be followed up by checking that the lessons learnt are actually applied in practice.

...turning the legal approval into practical safety

In the UK, government approval for a pesticide is obligatory before it is sold or used. Approval is an assurance that the product can achieve effective pest control without unacceptable risk to humans or the environment, provided it is used correctly. The product label stipulates legally binding limitations about how it should be used. The crops that may be sprayed, the maximum dose that should be applied and the interval that should elapse before harvest are listed.

Once in the field, the onus clearly rests with the operator. In-field checks of spillages, spray or spread patterns, together with an awareness of the need to protect watercourses and hedgerows, are all practical measures to ensure that the safety indicated by the product approval is achieved in practice. Accurate records must be kept.

...disposing of the surplus

Mixing only as much as you need is a prerequisite for efficient pesticide use. Nevertheless some surplus dilute pesticide is unavoidable and its disposal is a challenge that requires careful management. It is certainly not good practice to leave it in the sprayer. The legally binding conditions of the pesticide approval will normally prevent disposal of any surplus in the sprayer onto another, different, crop. Even using it up on the crop just treated is not possible unless it (or part of it) has been deliberately underdosed. The same constraints apply to any contaminated water resulting from washing out the sprayer or pesticide containers.  Here again there are guidelines in the Code of Practice and forward planning can help to minimise the scale of the problem in the first place, by careful calculation of the amount needed for the job.

...disposing of plastic containers, bags and sheeting

The pesticide containers themselves will often have guidance for safe disposal on the label. Where this is not the case, the normal correct procedure is to rinse three times followed by burial, or burning where this is permitted. Plastic sheeting and fertiliser bags are also often burnt, but there should be few circumstances where other practical methods of disposal can not be found. Ideally materials should be burnt only if there is no other practical method of disposal and then they should be handled in an incinerator rather than in the open. When an incinerator is used, the installation may require authorisation by the local authority under Part 1 of the Environmental Protection Act 1990.

Recycling plastic materials

Suitable polythene materials for recycling include:

  • Silage bags and sheets;
  • Polythene inners from fertiliser 'big bags';
  • 50 kg fertiliser bags;
  • Pallet covers;
  • Polythene covers from greenhouses.

Apart from pesticide containers, many plastic materials can be reused or recycled, and the possibilities of this should always be addressed on the farm waste disposal plan. If an item can be used several times before it becomes unserviceable, the volume of plastics for disposal is greatly reduced. If re-use or recycling is not practicable then biodegradable plastic materials should be chosen when ever possible. Guidance on the re-use and recycling of plastics, as well as the disposal of those items for which there is no alternative, is given in the DEFRA Code of Good Agricultural Practice for the Protection of Air. This is an area of rapidly changing legislation and awareness of any changes is part of managing an ICM system.

...bulk supply and returnable containers

Some fertilisers are already delivered in bulk thereby reducing the amount of packaging involved but possibly increasing storage difficulties. Storage areas should be on level, well-drained ground without projections or snags which could cause puncturing or tearing of packages. Ideally they should be sited away from population centres, but if this is unavoidable, the bulk storage should be surveyed frequently if there is a risk of vandalism.

The pesticide industry is taking the first steps towards the supply of chemicals in returnable containers, with some suppliers setting voluntary targets for the reduction of plastic waste by the end of the century. This is in response to a European Directive that requires 58% of all pesticide packaging to be recovered by the year 2001, of which 25% must be recycled for other uses such as fence posts. Already farmers in Belgium and Austria have to pay for the disposal of empty chemical containers.

Returnable containers bring the added benefit of closed filling systems, in which the chances of spillage and operator or environmental contamination during filling and rinsing are dramatically reduced. In the meantime the industry is playing an important part in helping to alleviate the problems by formulating pesticide effervescent tables or water soluble granules. these can be packaged in water-soluble sachets where users can safely burn the outer cardboard packaging in areas where this is permitted. Increasing the concentration of the pesticide itself also reduces the amount of packaging required.

...unused pesticide

Unused pesticide concentrate should be kept in the original container, tightly closed in a safe place - under lock and key if the label so directs. It might be possible to dispose of unopened containers to a neighbour, or even back to the original supplier. If not, it will be necessary to use a reputable licensed waste disposal contractor who will also handle opened containers if there is no foreseeable use on the farm. It is not good practice to keep opened pesticide containers for any length of time, and those that are kept must be sound and securely closed with the original label firmly attached.

The benefits of managing farm waste

A farm waste management policy demands attention to detail and ensures better use of resources. The result is a more profitable business. To this is added the benefit of a reduced risk of prosecution and consequent heavy fines for pollution. There are also benefits in public relations terms. A well-managed farm that is kept tidy and clear of litter, rusting pesticide containers and plastic fertiliser bags is a visible and reassuring sign to the public of an efficient and conscientiously run business.   Obviously they will need the same reassurance in other aspects, such as quality of produce, but much of that stems from proper controls of waste and pollution in the first place.

Finally, the employees themselves have the assurance of working in an environment that not only seeks to minimise pollution of soil, water and air, but also has clear emergency procedures and an emergency plan to cater for unforeseen circumstances.


Careless waste disposal procedures are potentially damaging to the environment, to the public perception  about farming and to the economy of the business. A carefully written farm waste management plan is an essential component of an ICM system.

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© University of Hertfordshire, 2011