Harvesting potato crops

Minimising damage

Damaged crops cost the UK potato industry over £200/ha and care needs to be taken at every stage of the production system to minimise this cost. Planning ahead, routine maintenance and adapting machinery settings to the conditions are key areas to reducing the risk of damaging crops.

There are many damage points through the harvesting and grading process where tuber damage could occur. Some components, when badly set or operated, will only result in small changes in damage, while others could show a massive reduction in damage if carefully set and operated. 

Minimising damage guide

The Minimising damage guide aims to highlight settings and operations for minimising damage without compromising field or crop conditions. When damage is referred to, it includes both bruising and shatter cracking, both of which are caused by impacts.

Download: The minimising damage guide


The videos below highlight areas of high risk to help reduce damage to your crops. 

Examples and checking

Claire Hodge, Senior Knowledge Exchange Manager - Arable, explains how to spot areas of damage such as bruising, scuffing, mechanical and splitting.

Your harvester and potato damage

This video discusses the importance of maintaining your harvesting equiptment and looking at areas of damage caused by the harvester.

Potato grader settings

This video looks at damage assessment and awareness in potato grading lines. 

Assessing your risk

Fourteen risk assessment advice sheets are available covering the agronomic factors that can influence a crop's susceptibility to bruising.  The advice sheets contain the latest findings from research, practical actions to take and give information on how to assess a crop's bruising susceptibility risk.


Varieties differ in their susceptibility to bruising. AHDB Potatoes Independent Variety Trials score varieties for their susceptibility to bruising on a 1 to 9 scale (1 = susceptible, 9 = resistant).

Site selection

Site selection can influence tuber bruising at harvest. Potatoes should only be grown on suitable land.

Download advice sheet 2: Site selection

Soil type

Soil type is a major factor in influencing tuber susceptibility to bruising.

Download advice sheet 3: Soil type

Field layout

The shape, size and slope(s) of a field will influence layout. Careful planning of field layout can help minimise bruising levels.

Download advice sheet 4: Field layout

Soil preparation

Soil preparation should produce a seedbed free of large clods and stone, without creating too fine a tilth and avoiding compaction or smearing. An ideal seedbed has at least 20 cm of fine tilth free from large clods and stones.

Download advice sheet 5: Soil preparation


Season, site location, soil type and soil preparation will all influence planting conditions, rate of crop development and maturity. Whilst the season cannot be influenced, time operations to reduce the incidence of a cold and wet, cloddy seed bed.

Download advice sheet 6: Planting

Crop nutrition

Nitrogen (N) can affect maturity and dry matter (DM) content (see advice sheet No. 9). N applications should be tailored to variety and length of growing season. BPC funded research shows bruising can be significantly lowered in crops receiving a 240 kg/ha N application. However, N application at this level is excessive for most crops and other factors for managing bruising should be progressed.

Download advice sheet 7: Crop nutrition


Crops suffering from water-stress are more likely to be susceptible to bruising, therefore, availability of irrigation can help minimise bruising

Download advice sheet 8: Irrigation

Crop maturity and dry matter

Bruising has been reported to increase with crop maturity, some trials have supported this but not for all varieties. However, there is no clear definition or measure of crop maturity.

Download advice sheet 9: Crop maturity and dry matter

In the majority of harvesting operations the less haulm that needs to be removed by the harvester the lower the tuber damage. Bruising can often occur when haulm is separated from the crop by the haulm rollers/separators, especially if the tubers are firmly attached to the stolons.

Soil moisture at burn-off

In the BPC funded BRUCE study, soil moisture at burn-off showed a consistent correlation with tuber susceptibility to bruising. Dry soils were also associated with greater susceptibility. These results support speculation about the water status of tubers around the time of haulm destruction having an influence over bruising levels. Tubers in dry soils could be dehydrated and hence more susceptible to bruising.

Download advice sheet 11: Soil moisture at burn-off

Soil moisture at harvest

Soil moisture at harvest is a well known, key factor in relation to the levels of bruising. Extremes of soil moisture, such as very wet or very dry, will challenge the harvester operator. In very dry conditions there is difficulty in achieving adequate soil cushioning for tubers on the webs or at transfer points.

Download advice sheet 12: Soil moisture at harvest


Lower tuber and soil temperatures experienced when harvesting early in the morning or late in the season increase bruising susceptibility.

Download advice sheet 13: Temperature


Storage length and temperature influences tuber physiological age.

Download advice sheet 14: Grading

Best practice

Everyone involved in the production and handling of potatoes has a part to play in minimising bruising. To act as reminders of the actions that will help to contribute to reduce bruising, a trailer driver's advice card and series of harvest checklists are available by clicking on the relevant flags below:

Grading checklist

Harvesting checklist

Manager's checklist 

Picking checklist 

Trailer driving checklist 

Information on the Safe Use of Potato Harvesters AIS 13

How to complete a damage and bruising assessment