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. 2018 Feb 28;24(6):2563–2584. doi: 10.1111/gcb.14066

Table 8.

Changes in amount of organic C in continuous arable or ley‐arable rotations. Woburn Ley‐arable experiment (14)a

Crop rotationb Treatment Sampling period No. of years Amount of organic Cc Rate of increase (t C ha−1 year−1) Annual increase (‰ /yr) Notes
At start (t/ha) At endd (t/ha)
Ar Arable with root crops 1938–1965/74 30.5 36.95 35.25 −0.06 −1.5 Arable after long‐term arable
AF Arable with 2‐year fallows 1965/74–2000/09 35 35.25 30.91 −0.12 −3.5
Ah Arable with 1‐year hay 1938–1965/74 30.5 36.95 38.64 0.06 1.5 ”
AB Arable 1965/74–2000/09 35 38.64 35.63 −0.09 −2.2
Lu3 3‐year lucerne ley + 2‐year arable 1938–1965/74 30.5 36.95 40.34 0.11 3.0 Ley‐arable rotations after long‐term arable
LC3 3‐year grass/clover ley + 2‐year arable 1965/74–2000/09 35 40.34 46.24 0.17 4.2
L3 3‐year grazed ley + 2‐year arable 1938–1965/74 30.5 36.95 47.18 0.34 9.1 ”
LN3 3‐year grass ley with N + 2‐year arable 1965/74–2000/09 35 44.24 44.76 0.01 0.3
LC8 8‐year grass/clover ley + 2‐year arable 1965/74–2000/09 35 41.28 51.69 0.30 7.2 ”
LN8 8‐year grass ley with N + 2‐year arable 1965/74–2000/09 35 39.77 52.61 0.37 9.2 ”
Rotation X year group F‐ratio(10 302) = 35.40, p < 0.001
SED for all amounts of organic C = 1.84 
a

Adapted from Tables 2 and 4, Johnston et al. (2017). Data are the mean of plots without FYM and with FYM once every 5th year from 1938 to the mid‐1960s.

b

Ar: 5‐year arable crops including root crops; becomes AF: 5‐year arable including 2‐year bare fallow. Ah: 5‐year arable including 1‐year hay; becomes AB: 5‐year arable. Lu3: 3‐year lucerne ley followed by 2‐year arable; becomes LC3: 3‐year grass/clover ley followed by 2‐year arable. L3: 3‐year grazed grass/clover ley followed by 2‐year arable; becomes LN3: 3‐year grass+N ley followed by 2‐year arable. LC8: 8‐year grass/clover ley followed by 2‐year arable. LN8: 8‐year grass+N ley followed by 2‐year arable.

c

% OC determined by Tinsley or combustion.

d

Includes any additional C present in the soil to an “equivalent” depth; i.e. so that the same mass of mineral soil was being considered at both the start and the end of each period.