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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

Cumulative difference between the yield of trash blanketed crops less the yield of burnt crops in different N fertilizer ‘treatments’ in the (A,B) Hydrosol, (C,D) Ferrosol, (E,F) HighCN Ferrosol, and (G,H) LowCN Ferrosol soils subjected to the Babinda and Mulgrave climates. The N fertilizer treatment codes in the legend refer to the combination of N fertilizer rates applied to the plant and ratoon crops (e.g., the 60/80 rate refers to the N fertilizer ‘treatment’ with 60 kg N ha–1 applied to the plant crop and 80 kg N ha–1 applied to the ratoon crop). For ease of presentation, three N fertilizer scenarios that span the N rates simulated are displayed: 60/80 (dotted lines), 90/120 (solid lines), and 240/320 (dashed lines). Inverted triangles denote start of scenarios with differing trash management and N fertilizer rates following an initial 24-year period with the same management for all scenarios.
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Figure 9: Cumulative difference between the yield of trash blanketed crops less the yield of burnt crops in different N fertilizer ‘treatments’ in the (A,B) Hydrosol, (C,D) Ferrosol, (E,F) HighCN Ferrosol, and (G,H) LowCN Ferrosol soils subjected to the Babinda and Mulgrave climates. The N fertilizer treatment codes in the legend refer to the combination of N fertilizer rates applied to the plant and ratoon crops (e.g., the 60/80 rate refers to the N fertilizer ‘treatment’ with 60 kg N ha–1 applied to the plant crop and 80 kg N ha–1 applied to the ratoon crop). For ease of presentation, three N fertilizer scenarios that span the N rates simulated are displayed: 60/80 (dotted lines), 90/120 (solid lines), and 240/320 (dashed lines). Inverted triangles denote start of scenarios with differing trash management and N fertilizer rates following an initial 24-year period with the same management for all scenarios.

Mentions: Although trash blanketing had little effect on yield over the last four crop cycles (Figure 8) as total soil N approached equilibrium, it reduced yield in at least the early crop cycles after trash blanketing commenced due to immobilization of SMN in the trash blanket (Figure 9). The average yield of trash blanketed crops was consistently less than that of burnt crops on the Ferrosol soils by 1–6 Mg ha–1 crop–1 with, for example, the 60/80 N rate after scenarios commenced. Differences between the yield of trash blanketed and burnt crops continued to occur in some years after this, but the differences were not as large.


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)

Cumulative difference between the yield of trash blanketed crops less the yield of burnt crops in different N fertilizer ‘treatments’ in the (A,B) Hydrosol, (C,D) Ferrosol, (E,F) HighCN Ferrosol, and (G,H) LowCN Ferrosol soils subjected to the Babinda and Mulgrave climates. The N fertilizer treatment codes in the legend refer to the combination of N fertilizer rates applied to the plant and ratoon crops (e.g., the 60/80 rate refers to the N fertilizer ‘treatment’ with 60 kg N ha–1 applied to the plant crop and 80 kg N ha–1 applied to the ratoon crop). For ease of presentation, three N fertilizer scenarios that span the N rates simulated are displayed: 60/80 (dotted lines), 90/120 (solid lines), and 240/320 (dashed lines). Inverted triangles denote start of scenarios with differing trash management and N fertilizer rates following an initial 24-year period with the same management for all scenarios.
© Copyright Policy
Related In: Results  -  Collection

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

Figure 9: Cumulative difference between the yield of trash blanketed crops less the yield of burnt crops in different N fertilizer ‘treatments’ in the (A,B) Hydrosol, (C,D) Ferrosol, (E,F) HighCN Ferrosol, and (G,H) LowCN Ferrosol soils subjected to the Babinda and Mulgrave climates. The N fertilizer treatment codes in the legend refer to the combination of N fertilizer rates applied to the plant and ratoon crops (e.g., the 60/80 rate refers to the N fertilizer ‘treatment’ with 60 kg N ha–1 applied to the plant crop and 80 kg N ha–1 applied to the ratoon crop). For ease of presentation, three N fertilizer scenarios that span the N rates simulated are displayed: 60/80 (dotted lines), 90/120 (solid lines), and 240/320 (dashed lines). Inverted triangles denote start of scenarios with differing trash management and N fertilizer rates following an initial 24-year period with the same management for all scenarios.
Mentions: Although trash blanketing had little effect on yield over the last four crop cycles (Figure 8) as total soil N approached equilibrium, it reduced yield in at least the early crop cycles after trash blanketing commenced due to immobilization of SMN in the trash blanket (Figure 9). The average yield of trash blanketed crops was consistently less than that of burnt crops on the Ferrosol soils by 1–6 Mg ha–1 crop–1 with, for example, the 60/80 N rate after scenarios commenced. Differences between the yield of trash blanketed and burnt crops continued to occur in some years after this, but the differences were not as large.

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