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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

Mean yield of burnt and trash blanketed crops in the last four crop cycles fertilized with two N fertilizer ‘treatments.’ The codes for these N fertilizer rates are shown in the legend as the combination of N fertilizer rates applied to the plant and ratoon crops: the 60/80 rate (i.e., 60 kg N ha–1 applied to the plant crop and 80 kg N ha–1 applied to the ratoon crop) and the 90/120 rate. For each location-soil combination, the value for 95% of maximum average yield is shown with a horizontal line. Error bars represent the standard deviation of the mean.
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Figure 7: Mean yield of burnt and trash blanketed crops in the last four crop cycles fertilized with two N fertilizer ‘treatments.’ The codes for these N fertilizer rates are shown in the legend as the combination of N fertilizer rates applied to the plant and ratoon crops: the 60/80 rate (i.e., 60 kg N ha–1 applied to the plant crop and 80 kg N ha–1 applied to the ratoon crop) and the 90/120 rate. For each location-soil combination, the value for 95% of maximum average yield is shown with a horizontal line. Error bars represent the standard deviation of the mean.

Mentions: The average yield of crops across all N rates from the last four crop cycles in simulated scenarios ranged from 57 to 93 Mg ha–1 for the Babinda climate, and 62 to 103 Mg ha–1 for the Mulgrave climate (Figure 7). Differences between climates at the two locations tended to have a stronger effect on yield than trash management or N rates equal to or greater than the 60/80 rate. For example, for the Babinda-Ferrosol soil at the 60/80 N rate, yield was 6–7 Mg ha–1 higher with the drier Mulgrave climate than the Babinda climate. By comparison, yields for this soil increased by only 2 Mg ha–1 if trash was retained instead of burnt, and increased by only 3–5 Mg ha–1 if the N rate was increased from 60/80 to 90/120.


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)

Mean yield of burnt and trash blanketed crops in the last four crop cycles fertilized with two N fertilizer ‘treatments.’ The codes for these N fertilizer rates are shown in the legend as the combination of N fertilizer rates applied to the plant and ratoon crops: the 60/80 rate (i.e., 60 kg N ha–1 applied to the plant crop and 80 kg N ha–1 applied to the ratoon crop) and the 90/120 rate. For each location-soil combination, the value for 95% of maximum average yield is shown with a horizontal line. Error bars represent the standard deviation of the mean.
© Copyright Policy
Related In: Results  -  Collection

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

Figure 7: Mean yield of burnt and trash blanketed crops in the last four crop cycles fertilized with two N fertilizer ‘treatments.’ The codes for these N fertilizer rates are shown in the legend as the combination of N fertilizer rates applied to the plant and ratoon crops: the 60/80 rate (i.e., 60 kg N ha–1 applied to the plant crop and 80 kg N ha–1 applied to the ratoon crop) and the 90/120 rate. For each location-soil combination, the value for 95% of maximum average yield is shown with a horizontal line. Error bars represent the standard deviation of the mean.
Mentions: The average yield of crops across all N rates from the last four crop cycles in simulated scenarios ranged from 57 to 93 Mg ha–1 for the Babinda climate, and 62 to 103 Mg ha–1 for the Mulgrave climate (Figure 7). Differences between climates at the two locations tended to have a stronger effect on yield than trash management or N rates equal to or greater than the 60/80 rate. For example, for the Babinda-Ferrosol soil at the 60/80 N rate, yield was 6–7 Mg ha–1 higher with the drier Mulgrave climate than the Babinda climate. By comparison, yields for this soil increased by only 2 Mg ha–1 if trash was retained instead of burnt, and increased by only 3–5 Mg ha–1 if the N rate was increased from 60/80 to 90/120.

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