Information on machinery is only collected through the December Survey (of larger holdings only, generally greater than one hectare) and not the June Census. This means that we have been unable to scale figures up for smaller holdings, as we do not have a proxy measure to use from the June Census. The results published here relate therefore only to the larger holdings.
In the past, and with the exception of tractors and transport vehicles, machinery data were divided into two sets of categories, so that different categories were collected in odd and even years. From December 2015, all categories of data are now collected, but are not collected in as much detail as previously. Figures on milking parlours are also added for the first time in 2015.
These changes have been made with the aim of producing more consistent annual data, however it appears to have affected comparison with previous years' data for all machinery and transport categories. This is possibly because in previous years, in the absence of all categories, respondents may have put some of their machinery in the category that best fitted.
Changes in the number of holdings classified as large enough to be covered by the December Survey will also have affected the amount of machinery included in the survey.
In December 2017, on the 26,300 larger holdings in Scotland, there were 40,500 wheeled tractors and 21,500 transport vehicles.
When considering trends in machinery, it is also worth noting that there has been a real terms increase in the value of agricultural contract work being carried out over the past ten years (about 27 per cent, unpublished background data used in ' Total Income from Farming Estimates for Scotland, 2015 to 2017'  ). If it is the case that there are more holdings using contractors and their machinery to carry out certain work, it is possible that this may have led to a decrease in some of the machinery categories observed in the survey results.