Pesticide usage in Scotland: Arable Crops and Potato Stores 2024

Data and methodology

Sampling and data collection

Using the June 2024 Agricultural Census [5] data, a sample was drawn representing arable cultivation in Scotland. The country was divided into 11 land-use regions (Figure 11, 2024 Arable survey). Each sample was stratified by these land-use regions and according to holding size. The holding size groups were based on the total area of arable crops grown. The sampling fractions used within both regions and size groups were based on the areas of relevant crops grown rather than number of holdings, so that smaller holdings would not dominate the sample.

Data relating to pesticide use in potato stores were collected from all potato growers encountered in the arable sample, either during an on-farm or telephone interview, or via e-mail. In instances where the potato land was let, and storage was on a separate holding, the potato grower was contacted individually to obtain storage details. Data were collected for all potatoes stored by these growers, not just for those crops grown on the holdings sampled. Therefore, the sample of stored potatoes relates to a greater area of potato cultivation than that for which field pesticide treatments were collected in the 2024 arable pesticide survey report. In total, data were collected from 69 growers. The crops grown by these growers represent 29% of the total 2024 potato crop area.

The data collected included the areas of seed and ware crops grown, quantities of potatoes sold and stored, storage type, storage method and post-harvest pesticide applications at crop lifting and during storage. Fungicidal seed treatments applied prior to planting are included in the arable crop report.

Raising factors

National pesticide use was estimated by ratio raising. This is a standard statistical technique for producing estimates from a sample. It is the same methodology used by the other UK survey teams and has been used for all historical datasets produced by the Pesticide Survey Unit, allowing comparability over time. The sample data were multiplied by raising factors (Table 10). These factors were calculated by comparing the sample area to the areas recorded in the June 2024 Agricultural Census data within each region and size group (please see changes from previous years section for further detail). An adjustment (Table 11) was made to the ware fraction to correct for the potatoes grown as seed that were then designated as ware. A second adjustment (Table 12) was made to align the survey estimates of total tonnes stored with the estimated tonnage of Scottish potato stocks held in store at the end of November provided by SASA Potato section. This represents a change in methodology from previous surveys (see next section).

Due to the low numbers of potatoes grown and sampled in some geographic regions, stored data were amalgamated into three regions to allow more robust estimation of pesticide use: the North & Central (Highlands & Islands, Caithness & Orkney, Moray Firth and Aberdeen, East Fife, Lothian, and Central Lowlands), Angus (the main potato growing area in Scotland) and the South (Tweed Valley, Southern Uplands, and Solway).

Detailed data tables and data used to create the charts in this report are available in Excel format in the supporting document published separately.

Changes from previous years

There are a number of changes which should be noted when comparing the 2024 data with the previous survey.

For all potato store reports (with the exception of 2022), the June Agricultural Census was used to draw a sample of farmers growing the relevant crops to participate in the survey. National pesticide use was then estimated by ratio raising, by comparing the sample area to the areas recorded in the June Agricultural Census data. However, there was no June Agricultural Census in 2022. Instead the May 2022 Single Application Form data was used to draw the sample and estimate national pesticide use (see the 2022 report for full details). This should be taken into account when comparing 2024 data with the previous survey in 2022.

The same raising process was used in 2024 as the previous survey in 2022. However, there was a significant change in the raising process between 2020 and 2022 and prior to that between 2018 and 2020. Please refer to the 2022 report for a full explanation.

Financial burden to farmers

To minimise the burden on farmers, the survey team used non-visit methods of collection such as email, post, or telephone call.

To determine the total burden that the 2024 Potato Storage survey placed on those providing the information, the surveyors recorded the time that 69 respondents spent providing the data during the surveys. This sample represents 100% of growers surveyed. The median time taken to provide the information was 5 minutes.

The following formula was used to estimate the total cost of participating:

Burden (£) = No. surveyed x median time taken (hours) x typical hourly rate*

(* using median “Full Time Gross” hourly pay for Scotland of £19.26) [6]. The total financial burden to all growers resulting from participation in the 2024 Potato Storage survey was calculated to be £110.75.