Abstract
Demand for corn ( Zea mays L.) stover as forage or as a cellulosic biofuel has increased the importance of determining the effects of stover removal on biomass production and the soil resource. Our objectives were to evaluate grain yield, soil organic C (SOC), and total soil N (0–150 cm) in a 10‐yr, irrigated, continuous corn study under conventional disk tillage (CT) and no‐till (NT) with variable corn stover removal rates (none, medium, and high). Natural abundance C isotope compositions (δ 13 C) were used to determine C additions by corn (C 4 –C) to the soil profile and to evaluate the retention of residual C 3 –C. After 10 yr of management treatments, mean grain yields were 7.5 to 8.6% higher for NT when stover was removed compared with no stover removal, while grain yields were similar for CT in all stover removal treatments. Turnover of SOC occurred as C 3 –C stocks were replaced by C 4 –C in the 0‐ to 120‐cm soil profile. Total SOC and N stocks changed mainly in surface soils (0–30 cm), with no detectable cumulative changes at 0 to 150 cm. Specifically, SOC declined after 10 yr under CT at 0 to 15 cm and was affected by residue management at 15 to 30 cm. Total soil N was greater when no stover was removed ( P = 0.0073) compared with high stover removal at 0 to 15 cm. Long‐term NT ameliorated medium stover removal effects by maintaining near‐surface SOC levels. Results support the need to evaluate SOC cycling processes below near‐surface soil layers.
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Claims 10
Claim · model-written summary
After 10 years, grain yields were 7.5 to 8.6% higher under no-till when stover was removed compared with no stover removal.
- Taxon
- corn
Zea mays subsp. mayst0 - Treatment
- NT when stover was removede1
- Outcome
- grain yieldse1
- Direction
- highere1
- Value
- 7.5 to 8.6%e1
- Comparator
- no stover removale1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Irrigated Continuous Corn”
e1“mean grain yields were 7.5 to 8.6% higher for NT when stover was removed compared with no stover removal”
Claim · model-written summary
Under conventional disk tillage grain yields were similar across all stover removal treatments.
- Taxon
- cornZea mays subsp. mayst0
- Treatment
- CTe2
- Outcome
- grain yieldse2
- Direction
- similare2
- Comparator
- all stover removal treatmentse2
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Irrigated Continuous Corn”
e2“while grain yields were similar for CT in all stover removal treatments”
Claim · model-written summary
Turnover of soil organic C occurred, with C3-derived carbon replaced by C4-derived carbon in the soil profile.
- Taxon
- cornZea mays subsp. mayst0
- Outcome
- Turnover of SOCe3
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Irrigated Continuous Corn”
e3“Turnover of SOC occurred as”
Claim · model-written summary
Total soil organic C and N stocks changed mainly in surface soils.
- Taxon
- cornZea mays subsp. mayst0
- Outcome
- Total SOC and N stockse4
- Qualifier
- changed mainly in surface soilse4
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Irrigated Continuous Corn”
e4“Total SOC and N stocks changed mainly in surface soils”
Claim · model-written summary
No detectable cumulative changes in total soil organic C and N stocks occurred at 0 to 150 cm.
- Taxon
- cornZea mays subsp. mayst0
- Outcome
- cumulative changese5
- Qualifier
- at 0 to 150 cme5
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Irrigated Continuous Corn”
e5“with no detectable cumulative changes at 0 to 150 cm”
Claim · model-written summary
Soil organic C declined after 10 years under conventional disk tillage at 0 to 15 cm.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Irrigated Continuous Corn”
e6“SOC declined after 10 yr under CT at 0 to 15 cm”
Claim · model-written summary
Soil organic C at 15 to 30 cm was affected by residue management.
- Taxon
- cornZea mays subsp. mayst0
- Treatment
- residue managemente7
- Outcome
- SOCe7
- Qualifier
- at 15 to 30 cme7
Not reportedComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Irrigated Continuous Corn”
e7“SOC declined after 10 yr under CT at 0 to 15 cm and was affected by residue management at 15 to 30 cm”
Claim · model-written summary
Long-term no-till ameliorated medium stover removal effects by maintaining near-surface soil organic C levels.
- Taxon
- cornZea mays subsp. mayst0
- Treatment
- NTe1
- Outcome
- SOC levelse1
- Direction
- maintaininge1
- Comparator
- medium stover removale1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Irrigated Continuous Corn”
e1“Long‐term NT ameliorated medium stover removal effects by maintaining near‐surface SOC levels”
Claim · model-written summary
Total soil N was greater with no stover removal than with high stover removal at 0 to 15 cm.
- Taxon
- cornZea mays subsp. mayst0
- Treatment
- no stover was removede1
- Outcome
- Total soil Ne1
- Direction
- greatere1
- Qualifier
- ( P = 0.0073)e1
- Comparator
- high stover removale1
- Setting
- 0 to 15 cme1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Irrigated Continuous Corn”
e1“Total soil N was greater when no stover was removed ( P = 0.0073) compared with high stover removal at 0 to 15 cm”
Claim · model-written summary
Results support the need to evaluate soil organic C cycling processes below near-surface soil layers.
- Taxon
- cornZea mays subsp. mayst0
- Outcome
- SOC cycling processese1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Irrigated Continuous Corn”
e1“Results support the need to evaluate SOC cycling processes below”
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