How do selected crop rotations affect soil organic carbon in boreo-temperate systems? A systematic review protocol

Table 2 Critical appraisal criteria

Variable	Value	Score
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^a)	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 (maximum depth ≤15 cm) single or multiple sampling	0
	Plough layer (maximum depth 15–25 cm) single or multiple sampling, or deep (maximum depth >25 cm) single sampling	1
	Multiple deep sampling (maximum depth >25 cm)	2

ISSN: 2047-2382