Agronomy · 2026
Cultivation Management Reshapes Soil Profile Configuration and Organic Carbon Sequestration: Evidence from a 45-Year Field Study
Cui, S. Y., Sun, Z. X., Duan, S. Y., Qiu, W. W., Jiang, Y. Y.
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Cultivation Management Reshapes Soil Profile Configuration a…
Abstract
Long-term human cultivation activities are the key factors of the vertical distribution and storage dynamics of soil organic carbon (SOC) in cropland. Based on a 45-year long-term field experiment, this study systematically compared SOC dynamics and carbon storage characteristics in soil profiles (0–200 cm) between cultivated land and adjacent natural forest. The findings reveal the hierarchical regulatory effects of tillage management on the soil carbon pool. The results show that: (1) Under both land use types, SOC content decreased exponentially with depth, but values in cultivated soils were 0.35–1.54% lower than in forest soils at each layer. SOC content in surface soil (0–78 cm) was significantly higher than in the subsoil (78–158 cm) and substratum layers (158–200 cm) (p < 0.01). At equivalent depths, SOC in cultivated land was significantly lower than in forest land (p < 0.01). Over 45 years, the SOC accumulation rate in the surface soil of cropland (0.07 g·kg−1·yr−1) was only half that of forest land (0.14 g·kg−1·yr−1). (2) The controls of soil physicochemical properties on SOC differed with land use: in forest soils, SOC correlated positively with clay content (r = 0.63, p < 0.01), whereas in cultivated soils, SOC was primarily regulated by total nitrogen (r = 0.94, p < 0.01) and sand content (r = 0.60, p < 0.01) and negatively correlated with bulk density (r = −0.55, p < 0.01) and pH value (r = −0.45, p < 0.05). (3) Long-term tillage significantly reshaped soil profile structure, thickening the plough layer from 20 cm to 78 cm. Surface carbon storage reached 20.76 t·ha−2, an increase of 11.13 t·ha−2 compared with forest soil (p < 0.01). However, storage decreased by 4.99 t·ha−2 and 7.60 t·ha−2 in the subsoil and substratum layers, respectively (p < 0.01). The SOC storage increment rate was 50.95 t·ha−2·yr−1 higher than that of forest soil in the surface layer but 46.81 t·ha−2·yr−1 and 11.12 t·ha−2·yr−1 lower in deeper layers. These results confirm that cultivation alters soil structure and material cycling, enhancing carbon enrichment in surface soils while accelerating depletion of deeper carbon pools. This provides new insights into the vertical differentiation mechanisms of SOC under long-term agricultural management.
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Long-term human cultivation activities are the key factors of the vertical distribution and storage dynamics of soil organic carbon (SOC) in cropland. Based on a 45-year long-term field experiment, this study systematically compared SOC dynamics and carbon storage characteristics in soil profiles (0–200 cm) between cultivated land and adjacent natural forest. The findings reveal the hierarchical regulatory effects of tillage management on the soil carbon pool. The results show that: (1) Under both land use types, SOC content decreased exponentially with depth, but values in cultivated soils were 0.35–1.54% lower than in forest soils at each layer. SOC content in surface soil (0–78 cm) was significantly higher than in the subsoil (78–158 cm) and substratum layers (158–200 cm) (p < 0.01). At equivalent depths, SOC in cultivated land was significantly lower than in forest land (p < 0.01). Over 45 years, the SOC accumulation rate in the surface soil of cropland (0.07 g·kg−1·yr−1) was only half that of forest land (0.14 g·kg−1·yr−1). (2) The controls of soil physicochemical properties on SOC differed with land use: in forest soils, SOC correlated positively with clay content (r = 0.63, p < 0.01), whereas in cultivated soils, SOC was primarily regulated by total nitrogen (r = 0.94, p < 0.01) and sand content (r = 0.60, p < 0.01) and negatively correlated with bulk density (r = −0.55, p < 0.01) and pH value (r = −0.45, p < 0.05). (3) Long-term tillage significantly reshaped soil profile structure, thickening the plough layer from 20 cm to 78 cm. Surface carbon storage reached 20.76 t·ha−2, an increase of 11.13 t·ha−2 compared with forest soil (p < 0.01). However, storage decreased by 4.99 t·ha−2 and 7.60 t·ha−2 in the subsoil and substratum layers, respectively (p < 0.01). The SOC storage increment rate was 50.95 t·ha−2·yr−1 higher than that of forest soil in the surface layer but 46.81 t·ha−2·yr−1 and 11.12 t·ha−2·yr−1 lower in deeper layers. These results confirm that cultivation alters soil structure and material cycling, enhancing carbon enrichment in surface soils while accelerating depletion of deeper carbon pools. This provides new insights into the vertical differentiation mechanisms of SOC under long-term agricultural management.
Long-term human cultivation activities are the key factors of the vertical distribution and storage dynamics of soil organic carbon (SOC) in cropland. Based on a 45-year long-term field experiment, this study systematically compared SOC dynamics and carbon storage characteristics in soil profiles (0–200 cm) between cultivated land and adjacent natural forest. The findings reveal the hierarchical regulatory effects of tillage management on the soil carbon pool. The results show that: (1) Under both land use types, SOC content decreased exponentially with depth, but values in cultivated soils were 0.35–1.54% lower than in forest soils at each layer. SOC content in surface soil (0–78 cm) was significantly higher than in the subsoil (78–158 cm) and substratum layers (158–200 cm) (p < 0.01). At equivalent depths, SOC in cultivated land was significantly lower than in forest land (p < 0.01). Over 45 years, the SOC accumulation rate in the surface soil of cropland (0.07 g·kg−1·yr−1) was only half that of forest land (0.14 g·kg−1·yr−1). (2) The controls of soil physicochemical properties on SOC differed with land use: in forest soils, SOC correlated positively with clay content (r = 0.63, p < 0.01), whereas in cultivated soils, SOC was primarily regulated by total nitrogen (r = 0.94, p < 0.01) and sand content (r = 0.60, p < 0.01) and negatively correlated with bulk density (r = −0.55, p < 0.01) and pH value (r = −0.45, p < 0.05). (3) Long-term tillage significantly reshaped soil profile structure, thickening the plough layer from 20 cm to 78 cm. Surface carbon storage reached 20.76 t·ha−2, an increase of 11.13 t·ha−2 compared with forest soil (p < 0.01). However, storage decreased by 4.99 t·ha−2 and 7.60 t·ha−2 in the subsoil and substratum layers, respectively (p < 0.01). The SOC storage increment rate was 50.95 t·ha−2·yr−1 higher than that of forest soil in the surface layer but 46.81 t·ha−2·yr−1 and 11.12 t·ha−2·yr−1 lower in deeper layers. These results confirm that cultivation alters soil structure and material cycling, enhancing carbon enrichment in surface soils while accelerating depletion of deeper carbon pools. This provides new insights into the vertical differentiation mechanisms of SOC under long-term agricultural management.
Findings
What changed what, as the paper reports it. Grouped by the measured property. The largest groups are open; open the others as you need them.
SOC content
↑ 4↓ 48
- decrease
cultivated land vs. adjacent forest landsignificant · 0–200 cm · long-term experimental field of Shenyang Agricultural University · Corresponding genetic surface/subsoil/substratum layers; cultivated0–78/78–158/158–200cm versus forest0–20/20–140/140–200cm (Table1/discussion). These are not equal-depth means. Fig4 b/f/e versus a/c/d, p<.01; mean-of-profile sentence contradicts direction, not used.
Numbers
- treatment 5.41 vs. control 7.38 g kg−1 (-26.69 %) · 0–78 cm · surface; forest reference0–20cm
- treatment 2.3 vs. control 3.06 g kg−1 (-24.84 %) · 78–158 cm · subsoil; forest reference20–140cm
- treatment 2.43 vs. control 2.61 g kg−1 (-6.897 %) · 158–200 cm · substratum; forest reference140–200cm
Source · p. 6 “Furthermore, SOC content across all layers of forest land was significantly higher than that of cultivated land.”
Source · p. 7 “Different lowercase letters indicate significant differences among different land use patterns of the same soil layer (p \< 0.01).”
- increase
with total nitrogensignificant · 0–200 cm · long-term experimental field of Shenyang Agricultural University · Separate Pearson correlations across profile horizons within each land use, not manipulation of N. Actual Table2 labels override misassigned abstract coefficients.
Numbers
- r = 0.94 · forest
- r = 0.96 · cultivated
Source · p. 10 “SOC content showed an extremely significant positive correlation with total nitrogen in both land uses (r = 0.96 for cultivated land; r = 0.94 for forest land).”
- decrease
with bulk densitysignificant · 0–200 cm · long-term experimental field of Shenyang Agricultural University · Within-landuse Pearson correlations across profile horizons; actual Table2 labels.
Numbers
- r = -0.55 · forest
- r = -0.78 · cultivated
Source · p. 10 “SOC was negatively correlated with bulk density (r = −0.78 and −0.55 for cultivated and forest land, respectively)”
- decrease
with pHsignificant · 0–200 cm · long-term experimental field of Shenyang Agricultural University · Forest profile, Pearson; Table2 pH single star p<.05; abstract incorrectly calls it cultivated.
Numbers
- r = -0.45
Source · p. 10 “SOC was also significantly negatively correlated with pH (r = −0.86 and −0.45).”
Source · p. 7 “| Forest land | − 0.55 ** | − 0.45 * | 0.94 ** | 0.63 ** | − 0.75 ** | 0.60 ** |”
- decrease
with pHsignificant · 0–200 cm · long-term experimental field of Shenyang Agricultural University · Cultivated profile, Pearson; actual Table2 double star p<.01.
Numbers
- r = -0.86
Source · p. 10 “SOC was also significantly negatively correlated with pH (r = −0.86 and −0.45).”
Source · p. 7 “| Cultivated land | − 0.78 ** | − 0.86 ** | 0.96 ** | − 0.42 | − 0.62 ** | 0.81 ** |”
- increase
with clay contentsignificant · 0–200 cm · long-term experimental field of Shenyang Agricultural University · Forest profile only, Pearson; Table2 double star p<.01.
Numbers
- r = 0.63
Source · p. 10 “SOC in forest land was positively correlated with clay content (r = 0.63)”
Source · p. 7 “| Forest land | − 0.55 ** | − 0.45 * | 0.94 ** | 0.63 ** | − 0.75 ** | 0.60 ** |”
- increase
with sand contentsignificant · 0–200 cm · long-term experimental field of Shenyang Agricultural University · Forest profile, Pearson; abstract sand coefficient .60 incorrectly assigned to cultivated, corrected from Table2/results. Double star p<.01.
Numbers
- r = 0.6
Source · p. 7 “SOC content in forest land was extremely significantly and positively correlated with total nitrogen, clay content and sand content (p \< 0.01)”
Source · p. 7 “| Forest land | − 0.55 ** | − 0.45 * | 0.94 ** | 0.63 ** | − 0.75 ** | 0.60 ** |”
- increase
with sand contentsignificant · 0–200 cm · long-term experimental field of Shenyang Agricultural University · Cultivated soil profile only; Pearson association across genetic horizons, not a sand manipulation. Abstract names a positive cultivated SOC-sand association but misassigns the forest coefficient; original Table2 cultivated row supplies r=.81 and ** P<.01.
Numbers
- r = 0.81 · Cultivated land
Source · p. 7 “| Cultivated land | − 0.78 ** | − 0.86 ** | 0.96 ** | − 0.42 | − 0.62 ** | 0.81 ** |”
Source · p. 7 “In cultivated land, SOC content was extremely significantly correlated with all physicochemical indicators except clay content”
SOC storage
↑ 1↓ 12
- increase
cultivated land vs. adjacent forest landsignificant · 0–78 cm · long-term experimental field of Shenyang Agricultural University · Cultivated surface0–78cm versus forest surface0–20cm; fixed genetic-horizon stock using measured BD/thickness, not equal mass/equal depth. Fig7 b versus e, p<.01. Printed t ha−2 retained.
Numbers
- treatment 20.76 vs. control 9.63 t ha−2 (as printed) (+115.6 %)
Source · p. 8 “Specifically, the average SOC storage in the topsoil was 9.63 t·ha−2 in forest land and 20.76 t·ha−2 in cultivated land, 11.13 t·ha−2 higher in cultivated land.”
Source · p. 9 “Different lowercase letters indicate significant differences among different land use patterns of the same soil layer (p \< 0.01).”
- decrease
cultivated land vs. adjacent forest landsignificant · 78–200 cm · long-term experimental field of Shenyang Agricultural University · Cultivated subsoil78–158cm versus forest20–140cm; cultivated substratum158–200cm versus forest140–200cm. Fixed genetic-horizon thickness calculation, not equivalent mass/equal depth. Fig7 e/d and c/a, p<.01. Printed t ha−2 retained.
Numbers
- treatment 10.02 vs. control 15.01 t ha−2 (as printed) (-33.24 %) · 78–158 cm · subsoil; forest20–140cm
- treatment 17.52 vs. control 25.12 t ha−2 (as printed) (-30.25 %) · 158–200 cm · substratum; forest140–200cm
Source · p. 8 “In the subsoil layer, SOC storage was 15.01 t·ha−2 in forest land versus 10.02 t·ha−2 in cultivated land, 4.99 t·ha−2 lower in the latter.”
Source · p. 8 “In the substratum layer, forest land storage (25.12 t·ha−2) exceeded that of cultivated land (17.52 t·ha−2) by 7.60 t·ha−2.”
Source · p. 9 “Different lowercase letters indicate significant differences among different land use patterns of the same soil layer (p \< 0.01).”
bulk density
↑ 11
- increase
cultivated land vs. adjacent forest landsignificant · 17–28 cm · long-term experimental field of Shenyang Agricultural University · Text explicitly significant; Fig5 shows profiles without pairwise marks or stated alpha; no chart values inferred.
Source · p. 7 “The bulk density of the 17–28 cm layer in cultivated land was significantly higher than in forest land”
cultivated topsoil thickness
1
- increase
cultivated land vs. adjacent forest landsignificance not stated · long-term experimental field of Shenyang Agricultural University · Morphological topsoil: cultivated Ap1+Ap2+ABr0–78cm versus forest Ahr+ABr0–20cm, Table1 and discussion; land-use comparison, no test given.
Numbers
- treatment 78 vs. control 20 cm (+290 %)
Source · p. 11 “In the first year of reclamation, the topsoil thickness of cultivated land was similar to that of the forest land (about 20 cm).”
Source · p. 11 “the cultivated topsoil expanded vertically, reaching 78 cm in thickness”
Set-up
Treatments
- land use
- cultivated landArable landadjacent forest landBroad-leaved forest
Measured
- SOC contentSoil organic carbon
- Unit
- g kg−1
- Method
- TOC elemental analyzer
- SOC storageSoil organic carbon
- Unit
- t ha−2 (as printed)
- Method
- Stratification, SOC concentration × bulk density × genetic-horizon thickness; gravel ignored. Actual horizon depths differ between land uses; not equivalent soil mass. Dimensionally unusual printed units retained.
- bulk density
- Unit
- g cm−3
- Method
- ring knife
- pH
- Method
- potentiometry; medium unstated
- total nitrogen
- Unit
- g kg−1
- Method
- TOC elemental analyzer
- clay content
- Unit
- %
- Method
- laser particle size analyzer
- sand content
- Unit
- %
- Method
- laser particle size analyzer
- cultivated topsoil thicknessTopsoil / A horizon thickness
- Unit
- cm
Sites
long-term experimental field of Shenyang Agricultural University
- Location
- Shenyang City, Liaoning Province41.83° N, 123.57° E
- Climate
- 7–8.1 °C mean annual temperature574–684 mm annual precipitation
- Soil
- typical brown soil (moist leached soil) · Chinese
- Land use
- cultivated landArable land, forest dominated by perennial oak treesBroad-leaved forest
| Depth | Texture | Clay | pH | Organic C | Bulk density |
|---|---|---|---|---|---|
| 0–17 cm | Silty loam | – | – | – | – |
| 17–28 cm | Silty loam | – | – | – | – |
| 28–78 cm | Silty loam | – | – | – | – |
| 78–111 cm | Silty loam | – | – | – | – |
| 111–133 cm | Silty loam | – | – | – | – |
| 133–158 cm | Silty loam | – | – | – | – |
| 158–200 cm | Silty loam | – | – | – | – |
| 0–7 cm | Silty loam | – | – | – | – |
| 7–20 cm | Silty loam | – | – | – | – |
| 20–62 cm | Silty loam | – | – | – | – |
| 62–85 cm | Silty loam | – | – | – | – |
| 85–110 cm | Silty loam | – | – | – | – |
| 110–140 cm | Silty loam | – | – | – | – |
| 140–200 cm | Silty loam | – | – | – | – |
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