a. List FIVE hazards that could be encountered when handling soil using a mini digger.
b. State FIVE measures taken to maintain biosecurity when handling soil prior to it being stored on a site.
The RHS note that “the first part of this question was to assess the candidate’s understanding of safe soil handling on a large site using typical machinery. The second part requires knowledge of how existing soil on a site is maintained in a healthy state during the initial handling processes… most candidates were able to identify appropriate hazards but there is still confusion as to what a hazard is with some candidates’ quoting problems causing damage to the soil and the environment.” This is a clear indication that the examiners’ were looking for a discussion of hazards to people involved in the work.
- Bystanders being struck/run over by a machine
- falling into open excavations
- Wet and muddy ground conditions (causing machinery to slip)
- Working on a slope(machine toppling)
- striking underground services.
Appropriate measures include:
- Employment of personnel, e.g. machine operators and personnel should be able to test and accurately identify pests, diseases and weeds, and trained in how to keep accurate records.
- Removal of vegetation – soil should be free of organic material, such as roots and stumps, turf and topsoil.
- Segregation of soil types and isolation from deleterious materials (Topsoil and subsoil should be removed, handled and stored separately. Waste materials such as wood trash or foreign material should be removed from the soil and disposed of safely and hygienically.)
- Vehicles should be confined to designated haul routes and the number of vehicles allowed on site minimised to essential vehicles only.
- Exclusion zones should be clearly signed and fenced.
- Use of appropriate tools and machines – this helps to ensure that jobs are carried out safely and efficiently, with minimal damage to plants and production of plant waste.
- Appropriate conditions, e.g. not waterlogged. Boot and machine washes both on site and between sites.
The examiners note that this question relates only to soil handling but some students also discussed soil storage issues which could not be awarded marks (examples of issues that should not have been included were temporary crops, length of storage time and dimensions of storage piles.) This is a good example of the importance of reading the original question carefully, it reads: “… when handling soil prior to it being stored on a site.”
For more on identifying hazards and the steps that should be taken to help protect those working on a site download the HSE Landscape Gardening Booklet (PDF)
Plant Biosecurity can be defined as the prevention of disease-causing agents entering or leaving any place where crops are present (or have been present recently). It involves a number of measures and protocols designed to prevent disease-causing agents from entering or leaving a property and being spread (based on a definition by Defra, 2003). Biosecurity measures may also be employed to prevent the spread of pests and non-native invasive species. This exam question covers all three of these areas. For more information on non-native species visit the
non-native species secretariat.
Soil deserves special mention because it can readily act as a medium for transporting many plant pests including invertebrates in their various stages of development, fungal sclerotes, bacterial spores, nematodes in a resting state and weed seeds of phytosanitary importance. For example, cysts of the Potato Cyst Nematode (Globodera rostochiensis (Wollenweber) Behrens, and G. pallida (Stone) Behrens) nay remain viable in soil for 30+ years.
The Handbook of Plant Biosecurity, Gordon Gordh and Simon McKirdy, editors, 2013
In order to take effective biosecurity measures we first need to understand how plant diseases spread. Although this varies with each disease, mechanisms that are typically considered include:
- Rain splashing on infected plants and leaves
- wind, wind borne mists and water courses
- movement of infected plants
- plant debris carrying infection
- movement of contaminated soil or plant material stuck to footwear, clothing, timber, vehicles and equipment.
Precautions that can help to prevent the spread of disease from one site to another include:
- Ensure footwear is cleaned of all soil and plant debris and then disinfected before entering or leaving a control site. The use of wellington boots can assist with this.
- Footwear must be washed off on a hard standing near the entrance to the site using a stiff brush and water. It is essential that all traces of soil and debris are removed.
The brush should be kept on site in a bucket of disinfectant.
- After cleaning, footwear should be sprayed with disinfectant and left until it has evaporated.
- The site for cleaning should be carefully chosen so that water run-off does not enter water courses such as streams.
- Clothing should be carefully checked for plant debris before leaving a control site. Any debris should be shaken out or brushed off before leaving the site or getting into a vehicle.
- Visitors to the site should be asked to check inside footwear, hoods, outer pockets and collars. They should also be reminded to check any protective equipment such as helmets and ear-defenders.
- Wet clothing must be bagged and laundered before reuse. It should be changed before moving between sites.
- Hand tools and motorised tools used on infected sites for cutting and digging may become contaminated. They should be thoroughly cleaned and disinfected before being moved to another site.
- Vehicle tyres and lorry beds should be checked to ensure that they are free of loose soil and debris before leaving an infected site.
- Minimise the number of vehicles entering an infected site by allowing only essential vehicles to enter.
- When on site, road vehicles should stay on stone roads wherever possible and be parked in areas that are as free of plant debris as possible.
- Machines, plant and any road vehicles that have been driven off hard surfaced roads onto an infected site must be cleaned on a hard standing before moving from the site. Ideally, a pressure washer should be used, preferably one that uses hot water or steam. The cleaning area should be chosen carefully to ensure that water run-off does not enter water courses. Remember to clean inside vehicles in the footwell and on seats as well as obvious areas such as tyre treads.
You can download a full guide to biosecurity policy here: