Loam sampling is carried out throughout the year. Fields larger than 10 ha (25ac) need to be split and more than one sample taken.
Fields should also be split into separate sampling units if the :-
- Area has been split cropped in the past
- Soil types vary significantly
- Area was recently several small fields
- Area incorporates old cottage gardens or allotments, etc
- A poor patch was identified and mapped in the last crop
Remove any surface plant debris prior to sampling. Avoid sampling within three months of fertilser application or twelve months of lime application. Take care to avoid areas where previously there have been manure heaps, feeding rings, water bowsers, areas where animals congregated or within the proximity of trees. If it is felt necessary sample these separately.
Sample at regular intervals, walking in an extended ‘W’ pattern across the whole sampling unit area. Adjust the angle of the ‘W’ to suit the shape of the field.
At least 25 cores are needed however small the area to be sampled.
Sample with a narrow diameter corer to a depth of approx. 15 cm (6inch). On stubble, sample to plough depth for maximum accuracy. Put all the cores from one sample area into a polythene bag and secure it to prevent cross contamination from other samples. Each sample bag of soil should weigh a minimum of 0.5kg and ideally about 1kg. Too large a sample requires sub sampling in the laboratory for analytical analysis which can then introduce an unnecessary error especially on wet heavy sample.