Carbon sequestration in a long-term conventional versus conservation tillage experiment · Knowledge Library

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Carbon sequestration in a long-term conventional versus conservation tillage experiment · Knowledge Library

SOC concentration

↑ 8↓ 19

increase
Spring MB + secondary tillage vs. Fall CP + secondary tillagesignificant · 20–40 cm · fall before tillage, after25years · Elora Research Station · Table2 actual lettersa/b; prose56percent inconsistent with means, not used.
Numbers
- treatment 15.53 vs. control 6.79 g C kg-1 soil (+128.7 %)
Source · p. 3
“At the 20–40 cm soil depth, the Spring MB+2° tillage treatment had the highest SOC concentration that was significantly higher by 56% compared to Fall CP+2° tillage.”
Source · p. 4
“20–40 | 12.00 (1.91) ab | 12.10 (2.20) ab | 15.53 (3.45) a | 11.16 (3.29) ab | 6.79 (0.99) b”
increase
ZT vs. spring tillagesignificant · 0–5 cm · fall before tillage, after25years · Elora Research Station · Explicit linear contrast against pooled spring treatments; individual all-a letters do not test this pooled contrast.
Source · p. 4
“higher SOC concentration only for the ZT treatment compared to spring and fall tillage for the 0–5 and 40–60 cm soil depth, respectively”
increase
ZT vs. fall tillagesignificant · 40–60 cm · fall before tillage, after25years · Elora Research Station
Source · p. 4
“higher SOC concentration only for the ZT treatment compared to spring and fall tillage for the 0–5 and 40–60 cm soil depth, respectively”
increase
ZT vs. mouldboard tillagesignificant · 0–5 cm · fall before tillage, after25years · Elora Research Station · Explicit linear contrast against pooled three mouldboard treatments.
Source · p. 5
“SOC concentration was significantly higher (P \< 0.05) for ZT versus mouldboard tillage for 0–5 and 40–60 cm”
increase
ZT vs. mouldboard tillagesignificant · 40–60 cm · fall before tillage, after25years · Elora Research Station
Source · p. 5
“SOC concentration was significantly higher (P \< 0.05) for ZT versus mouldboard tillage for 0–5 and 40–60 cm”
decrease
ZT vs. Fall CP + secondary tillagesignificant · 5–10 cm · fall before tillage, after25years · Elora Research Station
Numbers
- treatment 21.38 vs. control 23.46 g C kg-1 soil (-8.866 %)
Source · p. 5
“for ZT versus chisel plow, it was significantly lower (P \< 0.05) for ZT at 5–10 cm”
increase
ZT vs. Fall CP + secondary tillagesignificant · 20–60 cm · fall before tillage, after25years · Elora Research Station · Explicit contrast test as reported differs fromTable2 individual LSD at20-40(ab/b). Preserve this analytical discrepancy forreview.
Numbers
- treatment 12 vs. control 6.79 g C kg-1 soil (+76.73 %) · 20–40 cm
- treatment 11.26 vs. control 5 g C kg-1 soil (+125.2 %) · 40–60 cm
Source · p. 5
“for ZT versus chisel plow, it was significantly lower (P \< 0.05) for ZT at 5–10 cm, and higher at 20–40 and 40–60 cm soil depths”
increase
mouldboard tillage vs. Fall CP + secondary tillagesignificant · 20–40 cm · fall before tillage, after25years · Elora Research Station
Source · p. 5
“SOC concentration was significantly higher (P \< 0.05) for mouldboard compared to chisel plow at 20–40 cm depth”
increase
ZT vs. Fall MB + secondary tillagesignificant · 40–60 cm · fall before tillage, after25years · Elora Research Station · Individual FallMB+secondary (called FallMP in Results) reference, Table2 a/b, LSD.05; different from pooled fall/mouldboard contrasts.
Numbers
- treatment 11.26 vs. control 4.23 g C kg-1 soil (+166.2 %) · 40–60 cm
Source · p. 3
“At 40–60 cm soil depth, the mean SOC concentration for the ZT treatment was 36–62% higher than other tillage treatments”
Source · p. 4
“significant only for the ZT versus Fall MP + 2◦ treatment.”

SOC storage on equivalent soil mass basis

↑ 4↓ 2= 28

increase
Spring MB + secondary tillage vs. Fall CP + secondary tillagesignificant · 0–60 cm · fall before tillage, after25years · Elora Research Station · Equivalent soil mass9249Mg/ha; Table4a/b. Discussion broad null contradicted by Table4 andResults3.4.
Numbers
- treatment 120.9 vs. control 94.84 Mg C ha-1 (+27.44 %) · 9249Mg soil/ha
Source · p. 6
“9249 | 103.72 (4.90) ab | 110.20 (7.89) ab | 120.86 (16.23) a | 99.13 (9.87) ab | 94.84 (12.65) b”
increase
ZT vs. spring tillagesignificant · 0–5 cm · fall before tillage, after25years · Elora Research Station · Equivalent soil mass582Mg/ha; pooled spring contrast.
Source · p. 6
“ZT had a significantly higher (P \< 0.05) SOC storage, but at 5619 Mg C ha−1 equivalent soil mass basis, ZT had a significantly lower (P \< 0.05) SOC storage compared to spring tillage”
decrease
ZT vs. spring tillagesignificant · 0–40 cm · fall before tillage, after25years · Elora Research Station · Equivalent soil mass5619Mg/ha; explicit Results contrast conflicts with generalConclusion null for0-40cm.
Source · p. 6
“at 5619 Mg C ha−1 equivalent soil mass basis, ZT had a significantly lower (P \< 0.05) SOC storage compared to spring tillage”
increase
spring tillage vs. fall tillagesignificant · 0–60 cm · fall before tillage, after25years · Elora Research Station · Equivalent soil mass9249Mg/ha; pooled spring versus pooled fall.
Source · p. 6
“Contrast analysis between spring tillage compared to fall tillage was significant (P \< 0.05) only at 9249 Mg C ha−1 equivalent soil mass.”
Source · p. 1
“SOC storage was significantly higher for spring tillage compared to fall tillage at 0–60 cm depth”
increase
ZT vs. mouldboard tillagesignificant · 0–5 cm · fall before tillage, after25years · Elora Research Station · Equivalent soil mass582Mg/ha; explicitly tested pooled mouldboard reference.
Source · p. 6
“ZT had a significant higher (P \< 0.05) SOC storage at 582 Mg C ha−1, but at 5619 Mg C ha−1 it had a significantly lower (P \< 0.05) SOC storage compared to mouldboard tillage”
decrease
ZT vs. mouldboard tillagesignificant · 0–40 cm · fall before tillage, after25years · Elora Research Station · Equivalent soil mass5619Mg/ha; explicit Results contrast conflicts with Conclusion broad0-40null.
Source · p. 6
“ZT had a significant higher (P \< 0.05) SOC storage at 582 Mg C ha−1, but at 5619 Mg C ha−1 it had a significantly lower (P \< 0.05) SOC storage compared to mouldboard tillage”
no effect
ZT vs. mouldboard and chisel tillage variantsnot significant · 0–60 cm · fall before tillage, after25years · Elora Research Station · Only cumulativewholeprofile9249Mg/ha: ZTvsMB andZTvsCP individual method contrasts nonsignificant (Fig2D/Results3.4). Does not generalize to5619Mg/ha significantZTvsMB loss.
Source · p. 6
“All the remaining contrast analysis were non-significant.”
Source · p. 1
“ZT practices increased SOC concentration and storage compared to conventional tillage operations only for the surface layer but not for the entire soil profile”
no effect
ZT vs. spring and fall tillage variantsnot significant · 0–60 cm · fall before tillage, after25years · Elora Research Station · Equivalent soil mass9249Mg soil/ha, cumulative whole profile only. Both explicit ZT/pooled spring and ZT/pooled fall contrasts nonsignificant; no invented combined test or individual-treatment inference. Level7's two seasonal reference groups reused, coordinator should broaden its surface-depth-stock-only details. Significant ZT/spring loss at5619Mg/ha remains separate.
Source · p. 1
“ZT practices increased SOC concentration and storage compared to conventional tillage operations only for the surface layer but not for the entire soil profile.”
Source · p. 6
“All the remaining contrast analyses for SOC storage on an equivalent soil mass basis were non-significant (Fig. 1D).”

soil bulk density

↑ 55

increase
ZT vs. fall tillagesignificant · 5–10 cm · fall before tillage, after25years · Elora Research Station
Source · p. 3
“higher bulk density (Fig. 1A) only for ZT treatment compared to fall tillage for the 5–10 cm soil depth”
increase
ZT vs. mouldboard tillagesignificant · 5–10 cm · fall before tillage, after25years · Elora Research Station · Explicit pooled mouldboard contrast, not each individual MB pair. Abstract chisel claim conflicts withResults.
Source · p. 3
“Soil bulk density was significantly higher (P \< 0.05) for ZT versus mouldboard tillage for the 5–10 cm soil depth”
increase
Spring MB + secondary tillage vs. Spring MB and Fall MB + secondary tillagesignificant · 5–20 cm · fall before tillage, after25years · Elora Research Station · SpringMB+secondary compared separately withSpringMB withoutsecondary andFallMB+secondary; Table1a/c at5-10, a/c and a/bc at10-20.
Numbers
- treatment 1.45 vs. control 1.29 g cm-3 (+12.4 %) · 5–10 cm · versusSpringMB
- treatment 1.45 vs. control 1.32 g cm-3 (+9.848 %) · 5–10 cm · versusFallMB+secondary
- treatment 1.47 vs. control 1.35 g cm-3 (+8.889 %) · 10–20 cm · versusSpringMB
- treatment 1.47 vs. control 1.38 g cm-3 (+6.522 %) · 10–20 cm · versusFallMB+secondary
Source · p. 3
“At 5–10 cm soil depth, ZT and Spring MB+2”
Source · p. 3
“treatments had significantly higher soil bulk density compared to Spring MB and Fall MB + 2”
Source · p. 3
“this trend generally remained similar for the 10–20 cm soil depth”
increase
ZT vs. Spring MB and Fall MB + secondary tillagesignificant · 5–10 cm · fall before tillage, after25years · Elora Research Station · SpringMB without secondary and FallMB with secondary are agreeing mouldboard reference variants; each c versus ZT ab, LSD.05. No pooled test. Reuses level9's two individual references; its current BD-only details fit this finding.
Numbers
- treatment 1.43 vs. control 1.29 g cm-3 (+10.85 %) · 5–10 cm · versus SpringMB
- treatment 1.43 vs. control 1.32 g cm-3 (+8.333 %) · 5–10 cm · versus FallMB+secondary
Source · p. 3
“At 5–10 cm soil depth, ZT and Spring MB+2”
Source · p. 3
“treatments had significantly higher soil bulk density compared to Spring MB and Fall MB + 2”
increase
ZT vs. Spring MBsignificant · 10–20 cm · fall before tillage, after25years · Elora Research Station · ZT ab versus SpringMB c, LSD.05; FallMB+secondary bc shares b with ZT, excluded from significant scope.
Numbers
- treatment 1.42 vs. control 1.35 g cm-3 (+5.185 %) · 10–20 cm
Source · p. 3
“this trend generally remained similar for the 10–20 cm soil depth”
Source · p. 3
“10–20 1.42 (0.01) ab 1.35 (0.03) c 1.47 (0.01) a 1.38 (0.03) bc 1.41 (0.04) abc”

Sites

Elora Research Station

Location: Elora Research Station of the University of Guelph, southern Ontario, Canada
Soil: Hapludalf (Typic) · USDA
Land use: continuous cornArable land
Management on the whole site: soybean and corn in alternate yearsCrop rotation

Soil layers
Depth	Texture	Clay	pH	Organic C	Bulk density
site soil (depth not stated)	silt loam	–	–	–	–