Abstract
Intensively cropped dryland systems in the central Great Plains require adequate N fertilization for optimum residue and grain production. However, this N fertilization could be slowly changing the chemistry of the surface soil because of a decrease in soil pH and an increase in soil organic matter (SOM) and basic cations, even in previously well buffered calcareous soil systems. We investigated the effects of five increasing ammonium-N fertilizer rates in a Platner loam, on physical and chemical changes at the 0 to 5, and 0 to 15-cm depths after three cycles of no-till wheat (Triticum aestivum L.)-corn (Zea mays L.)-fallow rotation. We measured soil pH, texture, bulk density, cation exchange capacity (CEC), total P, soluble and total soil organic carbon (SOC), nitrate-N to a depth of 60 cm, and grain yields. No significant changes were found with soil texture, bulk densities, CEC, and total P. The data showed a significant reduction in surface (0-5 cm) soil pH (6.5 to 5.1) with the highest N rate (112 kg/ha), but this was accompanied by a 40% increase in SOC. Although there were significant increases in Al and Mn and decreases in Ca concentrations in the surface 0 to 5 cm at the highest N rate, no reduction in grain yields occurred relative to lower N levels with near neutral pHs. Because only a shallow depth of the soil was affected, residue, SOM, and rapid root growth could be compensating for surface acidity. Over the longer term, we need to monitor the effects of ammoniacal-N on downward soil acidity and yield trends under these new intensive cropping systems.
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Claims 8
Claim · model-written summary
Five ammonium-N rates caused no significant changes in soil texture or bulk density in the wheat-corn-fallow rotation.
- Taxon
- wheat
Triticum aestivume0 - Treatment
- five increasing ammonium-N fertilizer ratese1
- Outcome
- soil texture, bulk densitiese2
- Direction
- No significant changese2
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“wheat (Triticum aestivum L.)”
e1“five increasing ammonium-N fertilizer rates”
e2“No significant changes were found with soil texture, bulk densities”
Claim · model-written summary
Five ammonium-N rates caused no significant changes in cation exchange capacity or total P.
- Taxon
- wheatTriticum aestivume0
- Treatment
- five increasing ammonium-N fertilizer ratese1
- Outcome
- CEC, and total Pe2
- Direction
- No significant changese2
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“wheat (Triticum aestivum L.)”
e1“five increasing ammonium-N fertilizer rates”
e2“No significant changes were found with soil texture, bulk densities, CEC, and total P”
Claim · model-written summary
The highest N rate (112 kg/ha) significantly reduced surface (0-5 cm) soil pH from 6.5 to 5.1.
- Taxon
- wheatTriticum aestivume0
- Treatment
- highest N rate (112 kg/ha)e1
- Outcome
- surface (0-5 cm) soil pHe1
- Direction
- reductione1
- Value
- 6.5 to 5.1e1
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“wheat (Triticum aestivum L.)”
e1“a significant reduction in surface (0-5 cm) soil pH (6.5 to 5.1) with the highest N rate (112 kg/ha)”
Claim · model-written summary
The pH reduction at the highest N rate was accompanied by a 40% increase in soil organic carbon.
- Taxon
- wheatTriticum aestivume0
- Treatment
- highest N rate (112 kg/ha)e1
- Outcome
- SOCe2
- Direction
- increasee2
- Value
- 40%e2
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“wheat (Triticum aestivum L.)”
e1“highest N rate (112 kg/ha)”
e2“a 40% increase in SOC”
Claim · model-written summary
At the highest N rate, Al and Mn concentrations in the surface 0 to 5 cm increased significantly.
- Taxon
- wheatTriticum aestivume0
- Treatment
- highest N ratee1
- Outcome
- Al and Mne1
- Direction
- increasese1
Not reportedOrgan / stageComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“wheat (Triticum aestivum L.)”
e1“significant increases in Al and Mn and decreases in Ca concentrations in the surface 0 to 5 cm at the highest N rate”
Claim · model-written summary
At the highest N rate, Ca concentration in the surface 0 to 5 cm decreased significantly.
- Taxon
- wheatTriticum aestivume0
- Treatment
- highest N ratee1
- Outcome
- Ca concentrationse1
- Direction
- decreasese1
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“wheat (Triticum aestivum L.)”
e1“significant increases in Al and Mn and decreases in Ca concentrations in the surface 0 to 5 cm at the highest N rate”
Claim · model-written summary
Grain yields at the highest N rate were not reduced relative to lower N levels with near neutral pHs.
- Taxon
- wheatTriticum aestivume0
- Treatment
- highest N ratee1
- Outcome
- grain yieldse1
- Direction
- no reductione1
- Comparator
- lower N levelse1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“wheat (Triticum aestivum L.)”
e1“at the highest N rate, no reduction in grain yields occurred relative to lower N levels”
Claim · model-written summary
The authors suggest that residue, SOM and rapid root growth could be compensating for surface acidity because only a shallow soil depth was affected.
- Taxon
- wheatTriticum aestivume0
- Outcome
- surface aciditye1
- Qualifier
- residue, SOM, and rapid root growth could be compensatinge1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“wheat (Triticum aestivum L.)”
e1“residue, SOM, and rapid root growth could be compensating for surface acidity”
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