Table 1 Critical appraisal criteria for agricultural experiments with time series data on soil organic carbon (SOC)

Spatial (true) replication

2 replicates

0

3–4 replicates

1

>4 replicates

2

Temporal replication

≤3 replicates

0

4–6 replicates

1

>6 replicates

2

Treatment allocation (as described for the full experimental design)

Purposive (selective)

0

split-/strip-plot/Latin square/blocked/randomised/exhaustive

2

Duration of experiment

10–19 years

0

20–29 years

1

≥30 years

2

Soil sampling depth

Shallow (<15 cm) single or multiple sampling

0

Plough layer (0–25 cm) single or multiple sampling, or deep (>25 cm) single sampling

1

Multiple deep sampling (>25 cm)

2