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Long Term Sugarcane Crop Residue Retention Offers Limited Potential to Reduce Nitrogen Fertilizer Rates in Australian Wet Tropical Environments.

Meier EA, Thorburn PJ - Front Plant Sci (2016)

Bottom Line: Soil carbon increased in trash blanketed soils relative to SOC in soils with burnt trash.Simulated N fertilizer rates were able to be reduced from conventional rates regardless of trash management, because of low yield potential in the wet tropics.While these savings in N fertilizer use were modest at the field scale, they were potentially important when aggregated at the regional level.

View Article: PubMed Central - PubMed

Affiliation: Agriculture & Food Unit, Commonwealth Scientific and Industrial Research Organisation (CSIRO), St. Lucia QLD, Australia.

ABSTRACT
The warming of world climate systems is driving interest in the mitigation of greenhouse gas (GHG) emissions. In the agricultural sector, practices that mitigate GHG emissions include those that (1) reduce emissions [e.g., those that reduce nitrous oxide (N2O) emissions by avoiding excess nitrogen (N) fertilizer application], and (2) increase soil organic carbon (SOC) stocks (e.g., by retaining instead of burning crop residues). Sugarcane is a globally important crop that can have substantial inputs of N fertilizer and which produces large amounts of crop residues ('trash'). Management of N fertilizer and trash affects soil carbon and nitrogen cycling, and hence GHG emissions. Trash has historically been burned at harvest, but increasingly is being retained on the soil surface as a 'trash blanket' in many countries. The potential for trash retention to alter N fertilizer requirements and sequester SOC was investigated in this study. The APSIM model was calibrated with data from field and laboratory studies of trash decomposition in the wet tropics of northern Australia. APSIM was then validated against four independent data sets, before simulating location × soil × fertilizer × trash management scenarios. Soil carbon increased in trash blanketed soils relative to SOC in soils with burnt trash. However, further increases in SOC for the study region may be limited because the SOC in trash blanketed soils could be approaching equilibrium; future GHG mitigation efforts in this region should therefore focus on N fertilizer management. Simulated N fertilizer rates were able to be reduced from conventional rates regardless of trash management, because of low yield potential in the wet tropics. For crops subjected to continuous trash blanketing, there was substantial immobilization of N in decomposing trash so conventional N fertilizer rates were required for up to 24 years after trash blanketing commenced. After this period, there was potential to reduce N fertilizer rates for crops when trash was retained (≤20 kg N ha(-1) per plant or ratoon crop) while maintaining ≥95% of maximum yields. While these savings in N fertilizer use were modest at the field scale, they were potentially important when aggregated at the regional level.

No MeSH data available.


Related in: MedlinePlus

Measured and simulated commercial yields for each crop during 1990–2003 for the small plot field experiments at the Hydrosol Site (HS) and Ferrosol Site (FS) used to parameterize the model. Root mean square error (RMSE), index of agreement (d), and model efficiency (ME) are included.
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Figure 2: Measured and simulated commercial yields for each crop during 1990–2003 for the small plot field experiments at the Hydrosol Site (HS) and Ferrosol Site (FS) used to parameterize the model. Root mean square error (RMSE), index of agreement (d), and model efficiency (ME) are included.

Mentions: Sugarcane yields ranged from 46 to 110 Mg ha–1 at HS and from 36 to 132 Mg ha–1 at FS during the period 1990–2003 (Figure 2). The crops were subjected to five and seven tropical cyclones during this period at HS and FS, respectively, and the highest commercial yields at each site occurred in years where crops experienced the lowest rainfall (< ∼3,000 mm crop–1). After parameterization, the model captured the general response of yield to these conditions (e.g., ME = 0.53 at HS and 0.30 at FS, Figure 2). RMSE values for the parameterization were greater than in other studies (e.g., 2 and 5 Mg ha–1 in Keating et al., 1999 and Thorburn et al., 2011, respectively), likely because more accurate management information and yield data were available to parameterize simulations of the shorter-term field experiments in those studies than from the mill records for HS and FS.


Long Term Sugarcane Crop Residue Retention Offers Limited Potential to Reduce Nitrogen Fertilizer Rates in Australian Wet Tropical Environments.

Meier EA, Thorburn PJ - Front Plant Sci (2016)

Measured and simulated commercial yields for each crop during 1990–2003 for the small plot field experiments at the Hydrosol Site (HS) and Ferrosol Site (FS) used to parameterize the model. Root mean square error (RMSE), index of agreement (d), and model efficiency (ME) are included.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4940410&req=5

Figure 2: Measured and simulated commercial yields for each crop during 1990–2003 for the small plot field experiments at the Hydrosol Site (HS) and Ferrosol Site (FS) used to parameterize the model. Root mean square error (RMSE), index of agreement (d), and model efficiency (ME) are included.
Mentions: Sugarcane yields ranged from 46 to 110 Mg ha–1 at HS and from 36 to 132 Mg ha–1 at FS during the period 1990–2003 (Figure 2). The crops were subjected to five and seven tropical cyclones during this period at HS and FS, respectively, and the highest commercial yields at each site occurred in years where crops experienced the lowest rainfall (< ∼3,000 mm crop–1). After parameterization, the model captured the general response of yield to these conditions (e.g., ME = 0.53 at HS and 0.30 at FS, Figure 2). RMSE values for the parameterization were greater than in other studies (e.g., 2 and 5 Mg ha–1 in Keating et al., 1999 and Thorburn et al., 2011, respectively), likely because more accurate management information and yield data were available to parameterize simulations of the shorter-term field experiments in those studies than from the mill records for HS and FS.

Bottom Line: Soil carbon increased in trash blanketed soils relative to SOC in soils with burnt trash.Simulated N fertilizer rates were able to be reduced from conventional rates regardless of trash management, because of low yield potential in the wet tropics.While these savings in N fertilizer use were modest at the field scale, they were potentially important when aggregated at the regional level.

View Article: PubMed Central - PubMed

Affiliation: Agriculture & Food Unit, Commonwealth Scientific and Industrial Research Organisation (CSIRO), St. Lucia QLD, Australia.

ABSTRACT
The warming of world climate systems is driving interest in the mitigation of greenhouse gas (GHG) emissions. In the agricultural sector, practices that mitigate GHG emissions include those that (1) reduce emissions [e.g., those that reduce nitrous oxide (N2O) emissions by avoiding excess nitrogen (N) fertilizer application], and (2) increase soil organic carbon (SOC) stocks (e.g., by retaining instead of burning crop residues). Sugarcane is a globally important crop that can have substantial inputs of N fertilizer and which produces large amounts of crop residues ('trash'). Management of N fertilizer and trash affects soil carbon and nitrogen cycling, and hence GHG emissions. Trash has historically been burned at harvest, but increasingly is being retained on the soil surface as a 'trash blanket' in many countries. The potential for trash retention to alter N fertilizer requirements and sequester SOC was investigated in this study. The APSIM model was calibrated with data from field and laboratory studies of trash decomposition in the wet tropics of northern Australia. APSIM was then validated against four independent data sets, before simulating location × soil × fertilizer × trash management scenarios. Soil carbon increased in trash blanketed soils relative to SOC in soils with burnt trash. However, further increases in SOC for the study region may be limited because the SOC in trash blanketed soils could be approaching equilibrium; future GHG mitigation efforts in this region should therefore focus on N fertilizer management. Simulated N fertilizer rates were able to be reduced from conventional rates regardless of trash management, because of low yield potential in the wet tropics. For crops subjected to continuous trash blanketing, there was substantial immobilization of N in decomposing trash so conventional N fertilizer rates were required for up to 24 years after trash blanketing commenced. After this period, there was potential to reduce N fertilizer rates for crops when trash was retained (≤20 kg N ha(-1) per plant or ratoon crop) while maintaining ≥95% of maximum yields. While these savings in N fertilizer use were modest at the field scale, they were potentially important when aggregated at the regional level.

No MeSH data available.


Related in: MedlinePlus