Abstract
Switchgrass (Panicum virgatum L.) production for biofuels has potential economic values. It can also improve soil properties and perform better under marginal lands than the other major biomass crops. However, little is known about its potential ecological impacts assessed in terms of soils, water, and air quality in the northern Great Plains region of United States of America. The objectives of this study were to (i) evaluate the impacts of nitrogen fertilization rate (N rate) and landscape position on soil pH, soil organic carbon (SOC), total nitrogen (TN), bulk density (ρb), and phosphorus (P) in switchgrass field; (ii) assess the impacts of the N rate and landscape position on dissolved organic carbon (DOC) leaching in switchgrass land; (iii) evaluate the effects of the N rate and landscape position on N-dynamics that includes soil nitrate (NO3 -), NO3 - leaching, and soil nitrous oxide (N2O) fluxes from switchgrass field; (iv) simulate the long-term impacts of future temperature and precipitation changes using DAYCENT model on soil carbon dioxide (CO2) fluxes from switchgrass land; and (v) predict the long-term impacts of switchgrass production on the SOC, NO3 -, water-filled pore space (WFPS), CO2 and N2O fluxes for switchgrass fields under changing climatic scenarios using the DAYCENT models. The experiment was a split-plot design with 4 replications, 3 N rates (low, 0 kg N ha-1; medium, 56 kg N ha-1; and high, 112 kg N ha-1), and 3 landscape positions (shoulder, backslope, and footslope) in South Dakota, USA. This study showed that N rate did not impact soil pH, SOC, TN, ρb, SOC stock, and P, however, landscape position significantly impacted the soil properties. The SOC, TN, and Pb at the footslope were significantly higher than that of the shoulder and backslope. The ρb at the footslope was significantly lower than the shoulder and backslope. The SOC and TN values at the 0- to 5-cm depth increased from 2009 to 2013. The SOC was significantly influenced by year under the high and medium N rates at the 0- to 5-cm depth. The average daily DOC contents at the backslope (6.45 mg L-1) were significantly lower than that at the shoulder (8.38 mg L-1) and footslope (8.95 mg L-1). The N rate significantly impacted the soil NO3 -. At the 0- to 5-cm depth, the mean soil NO3 - contents under the high N rate (0.72 mg kg-1) were significantly lower than those of the medium (2.28 mg kg-1) and the low N (3.16 mg kg-1) rates in 2010. The NO3 - contents under the low N rate were 68% higher than that of the high N rate in 2013. The N rate significantly impacted the soil surface N2O fluxes. The annual mean soil N2O fluxes under the high N rate were 30% higher than those under the low N rate for 2014. However, the N rate did not impact NO3 - leaching. The soil NO3 -, NO3 - leaching and N2O fluxes at the footslope position were significantly higher than the other positions in some observed years. The N rate significantly impacted the switchgrass biomass yield. The yield from 2009 to 2015 under the high and medium N rates (high N rate > medium N rate) was significantly higher than that of the low N rate. The DAYCENT modeling results provided satisfactory calibration and validation by using the measured high-frequency soil CO2 fluxes from the switchgrass field from 2010 to 2013. The simulated CO2 fluxes from the switchgrass land under the different changing climate scenarios were not significantly different. To further compare the soils and environmental parameters among different N rates and positions, another 12 DAYCENT models under the high, medium, and low N rates at shoulder and footslope positions were developed using the measured CO2 and N2O fluxes for 2010 through 2015. The predicted SOC, soil NO3 -, CO2 and N2O fluxes at the footslope were significantly higher than that of the shoulder. Generally, the predicted SOC, soil NO3 -, CO2 and N2O fluxes under the higher N rates were higher than that under the low N rate. Results from this study concluded that the switchgrass seeded on marginally yielding croplands can act as a sustainable bioenergy crop through improving and maintaining soil properties, storing N nutrient, and reducing NO3 - leaching. Furthermore, the medium N fertilization rate (56 kg N ha-1) was the optimal rate for the switchgrass fields to increase the biomass yield, improve soil properties, and reduce the soil N2O emissions and NO3 - leaching.
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Claims 20
Claim · model-written summary
N rate did not affect soil pH, SOC or TN.
- Taxon
- Switchgrass (Panicum virgatum L.)
Panicum virgatume0 - Treatment
- N ratee1
- Outcome
- soil pH, SOC, TNe1
- Direction
- no_changeinferrede1
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Switchgrass (Panicum virgatum L.)”
e1“This study showed that N rate did not impact soil pH, SOC, TN, ρb, SOC stock, and P, however, landscape position significantly impacted the soil properties”
Claim · model-written summary
N rate did not affect soil bulk density, SOC stock or P.
- Taxon
- Switchgrass (Panicum virgatum L.)Panicum virgatume0
- Treatment
- N ratee1
- Outcome
- ρb, SOC stock, and Pe1
- Direction
- no_changeinferrede1
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Switchgrass (Panicum virgatum L.)”
e1“This study showed that N rate did not impact soil pH, SOC, TN, ρb, SOC stock, and P, however, landscape position significantly impacted the soil properties”
Claim · model-written summary
SOC, TN and P were significantly higher at the footslope than at the shoulder and backslope.
- Taxon
- Switchgrass (Panicum virgatum L.)Panicum virgatume0
- Treatment
- footslopee1
- Outcome
- SOC, TN, and Pbe1
- Direction
- highere1
- Comparator
- shoulder and backslopee1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Switchgrass (Panicum virgatum L.)”
e1“The SOC, TN, and Pb at the footslope were significantly higher than that of the shoulder and backslope”
Claim · model-written summary
Bulk density (ρb) at the footslope was significantly lower than at the shoulder and backslope.
- Taxon
- Switchgrass (Panicum virgatum L.)Panicum virgatume0
- Treatment
- footslopee1
- Outcome
- ρbe1
- Direction
- lowere1
- Comparator
- shoulder and backslopee1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Switchgrass (Panicum virgatum L.)”
e1“The ρb at the footslope was significantly lower than the shoulder and backslope”
Claim · model-written summary
SOC and TN values at 0- to 5-cm depth increased from 2009 to 2013.
- Taxon
- Switchgrass (Panicum virgatum L.)Panicum virgatume0
- Organ / stage
- 0- to 5-cm depthe1
- Outcome
- SOC and TN valuese1
- Direction
- increasede1
- Qualifier
- from 2009 to 2013e1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Switchgrass (Panicum virgatum L.)”
e1“The SOC and TN values at the 0- to 5-cm depth increased from 2009 to 2013”
Claim · model-written summary
SOC at 0- to 5-cm depth was significantly influenced by year under the high and medium N rates.
- Taxon
- Switchgrass (Panicum virgatum L.)Panicum virgatume0
- Organ / stage
- 0- to 5-cm depthe1
- Treatment
- yeare1
- Outcome
- SOCe1
- Qualifier
- under the high and medium N ratese1
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Switchgrass (Panicum virgatum L.)”
e1“The SOC was significantly influenced by year under the high and medium N rates at the 0- to 5-cm depth”
Claim · model-written summary
Average daily DOC at the backslope (6.45 mg L-1) was significantly lower than at the shoulder (8.38 mg L-1).
- Taxon
- Switchgrass (Panicum virgatum L.)Panicum virgatume0
- Treatment
- backslopee1
- Outcome
- average daily DOC contentse1
- Direction
- lowere1
- Value
- 6.45 mg L-1e1
- Qualifier
- 8.38 mg L-1e1
- Comparator
- shouldere1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Switchgrass (Panicum virgatum L.)”
e1“The average daily DOC contents at the backslope (6.45 mg L-1) were significantly lower than that at the shoulder (8.38 mg L-1) and footslope (8.95 mg L-1)”
Claim · model-written summary
Average daily DOC at the backslope (6.45 mg L-1) was significantly lower than at the footslope (8.95 mg L-1).
- Taxon
- Switchgrass (Panicum virgatum L.)Panicum virgatume0
- Treatment
- backslopee1
- Outcome
- average daily DOC contentse1
- Direction
- lowere1
- Value
- 6.45 mg L-1e1
- Qualifier
- 8.95 mg L-1e1
- Comparator
- footslopee1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Switchgrass (Panicum virgatum L.)”
e1“The average daily DOC contents at the backslope (6.45 mg L-1) were significantly lower than that at the shoulder (8.38 mg L-1) and footslope (8.95 mg L-1)”
Claim · model-written summary
Mean soil NO3 - under the high N rate (0.72 mg kg-1) was significantly lower than under the medium N rate in 2010.
- Taxon
- Switchgrass (Panicum virgatum L.)Panicum virgatume0
- Organ / stage
- 0- to 5-cm depthe1
- Treatment
- high N ratee1
- Outcome
- mean soil NO3 - contentse1
- Direction
- lowere1
- Value
- 0.72 mg kg-1e1
- Qualifier
- in 2010e1
- Comparator
- mediume1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Switchgrass (Panicum virgatum L.)”
e1“At the 0- to 5-cm depth, the mean soil NO3 - contents under the high N rate (0.72 mg kg-1) were significantly lower than those of the medium (2.28 mg kg-1) and the low N (3.16 mg kg-1) rates in 2010”
Claim · model-written summary
Mean soil NO3 - under the high N rate (0.72 mg kg-1) was significantly lower than under the low N rate in 2010.
- Taxon
- Switchgrass (Panicum virgatum L.)Panicum virgatume0
- Organ / stage
- 0- to 5-cm depthe1
- Treatment
- high N ratee1
- Outcome
- mean soil NO3 - contentse1
- Direction
- lowere1
- Value
- 0.72 mg kg-1e1
- Qualifier
- 3.16 mg kg-1e1
- Comparator
- low Ne1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Switchgrass (Panicum virgatum L.)”
e1“At the 0- to 5-cm depth, the mean soil NO3 - contents under the high N rate (0.72 mg kg-1) were significantly lower than those of the medium (2.28 mg kg-1) and the low N (3.16 mg kg-1) rates in 2010”
Claim · model-written summary
NO3 - contents under the low N rate were 68% higher than under the high N rate in 2013.
- Taxon
- Switchgrass (Panicum virgatum L.)Panicum virgatume0
- Treatment
- low N ratee1
- Outcome
- NO3 - contentse1
- Direction
- highere1
- Value
- 68%e1
- Qualifier
- in 2013e1
- Comparator
- high N ratee1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Switchgrass (Panicum virgatum L.)”
e1“The NO3 - contents under the low N rate were 68% higher than that of the high N rate in 2013”
Claim · model-written summary
Annual mean soil N2O fluxes under the high N rate were 30% higher than under the low N rate in 2014.
- Taxon
- Switchgrass (Panicum virgatum L.)Panicum virgatume0
- Treatment
- high N ratee1
- Outcome
- annual mean soil N2O fluxese1
- Direction
- highere1
- Value
- 30%e1
- Qualifier
- for 2014e1
- Comparator
- low N ratee1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Switchgrass (Panicum virgatum L.)”
e1“The annual mean soil N2O fluxes under the high N rate were 30% higher than those under the low N rate for 2014”
Claim · model-written summary
Soil NO3 -, NO3 - leaching and N2O fluxes at the footslope were significantly higher than at other positions in some observed years.
- Taxon
- Switchgrass (Panicum virgatum L.)Panicum virgatume0
- Treatment
- footslope positione1
- Outcome
- soil NO3 -, NO3 - leaching and N2O fluxese1
- Direction
- highere1
- Qualifier
- in some observed yearse1
- Comparator
- other positionse1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Switchgrass (Panicum virgatum L.)”
e1“The soil NO3 -, NO3 - leaching and N2O fluxes at the footslope position were significantly higher than the other positions in some observed years”
Claim · model-written summary
The medium and high N rates gave significantly higher switchgrass biomass yield than the low N rate.
- Taxon
- Switchgrass (Panicum virgatum L.)Panicum virgatume0
- Treatment
- high and medium N ratese2
- Outcome
- switchgrass biomass yielde1
- Direction
- highere2
- Comparator
- low N ratee2
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Switchgrass (Panicum virgatum L.)”
e1“The N rate significantly impacted the switchgrass biomass yield”
e2“The yield from 2009 to 2015 under the high and medium N rates (high N rate > medium N rate) was significantly higher than that of the low N rate”
Claim · model-written summary
The DAYCENT model gave satisfactory calibration and validation against measured high-frequency soil CO2 fluxes.
- Taxon
- Switchgrass (Panicum virgatum L.)Panicum virgatume0
- Outcome
- calibration and validatione1
- Qualifier
- satisfactorye1
- Comparator
- measured high-frequency soil CO2 fluxese1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Switchgrass (Panicum virgatum L.)”
e1“The DAYCENT modeling results provided satisfactory calibration and validation by using the measured high-frequency soil CO2 fluxes from the switchgrass field from 2010 to 2013”
Claim · model-written summary
Simulated CO2 fluxes from switchgrass land did not differ significantly among changing climate scenarios.
- Taxon
- Switchgrass (Panicum virgatum L.)Panicum virgatume0
- Treatment
- changing climate scenariose1
- Outcome
- simulated CO2 fluxese1
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Switchgrass (Panicum virgatum L.)”
e1“The simulated CO2 fluxes from the switchgrass land under the different changing climate scenarios were not significantly different”
Claim · model-written summary
Predicted SOC, NO3 -, CO2 and N2O fluxes at the footslope were significantly higher than at the shoulder.
- Taxon
- Switchgrass (Panicum virgatum L.)Panicum virgatume0
- Treatment
- footslopee1
- Outcome
- predicted SOC, soil NO3 -, CO2 and N2O fluxese1
- Direction
- highere1
- Comparator
- shouldere1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Switchgrass (Panicum virgatum L.)”
e1“The predicted SOC, soil NO3 -, CO2 and N2O fluxes at the footslope were significantly higher than that of the shoulder”
Claim · model-written summary
Predicted SOC, NO3 -, CO2 and N2O fluxes under higher N rates were higher than under the low N rate.
- Taxon
- Switchgrass (Panicum virgatum L.)Panicum virgatume0
- Treatment
- higher N ratese1
- Outcome
- predicted SOC, soil NO3 -, CO2 and N2O fluxese1
- Direction
- highere1
- Comparator
- low N ratee1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Switchgrass (Panicum virgatum L.)”
e1“Generally, the predicted SOC, soil NO3 -, CO2 and N2O fluxes under the higher N rates were higher than that under the low N rate”
Claim · model-written summary
The medium N rate (56 kg N ha-1) is the optimal rate for switchgrass fields to increase biomass yield.
- Taxon
- Switchgrass (Panicum virgatum L.)Panicum virgatume0
- Treatment
- medium N fertilization ratee1
- Outcome
- optimal ratee1
- Value
- 56 kg N ha-1e1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Switchgrass (Panicum virgatum L.)”
e1“the medium N fertilization rate (56 kg N ha-1) was the optimal rate for the switchgrass fields to increase the biomass yield”
Claim · model-written summary
N rate did not affect NO3 - leaching.
- Taxon
- Switchgrass (Panicum virgatum L.)Panicum virgatume0
- Treatment
- N ratee1
- Outcome
- NO3 - leachinge1
- Direction
- no_changeinferrede1
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Switchgrass (Panicum virgatum L.)”
e1“However, the N rate did not impact NO3 - leaching”
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See all 6 papers →Claims are grouped by organism, treatment and what was measured or targeted. A paper counts as positive when any of its claims in the group is positive.