scholarly journals Modeling Nitrous Oxide Emissions From Large-Scale Intensive Cropping Systems in the Southern Amazon

2021 ◽  
Vol 5 ◽  
Author(s):  
Ciniro Costa ◽  
Gillian L. Galford ◽  
Michael T. Coe ◽  
Marcia Macedo ◽  
KathiJo Jankowski ◽  
...  
Keyword(s):  
Nitrous Oxide ◽  
Spatial Data ◽  
Crop Production ◽  
Large Scale ◽  
Cropping Systems ◽  
Field Measurements ◽  
N Fertilization ◽  
Nitrous Oxide Emissions ◽  
Dndc Model ◽  
Mato Grosso

Nitrogen (N) fertilizer use is rapidly intensifying on tropical croplands and has the potential to increase emissions of the greenhouse gas, nitrous oxide (N2O). Since about 2005 Mato Grosso (MT), Brazil has shifted from single-cropped soybeans to double-cropping soybeans with maize, and now produces 1.5% of the world's maize. This production shift required an increase in N fertilization, but the effects on N2O emissions are poorly known. We calibrated the process-oriented biogeochemical DeNitrification-DeComposition (DNDC) model to simulate N2O emissions and crop production from soybean and soybean-maize cropping systems in MT. After model validation with field measurements and adjustments for hydrological properties of tropical soils, regional simulations suggested N2O emissions from soybean-maize cropland increased almost fourfold during 2001–2010, from 1.1 ± 1.1 to 4.1 ± 3.2 Gg 1014 N-N2O. Model sensitivity tests showed that emissions were spatially and seasonably variable and especially sensitive to soil bulk density and carbon content. Meeting future demand for maize using current soybean area in MT might require either (a) intensifying 3.0 million ha of existing single soybean to soybean-maize or (b) increasing N fertilization to ~180 kg N ha−1 on existing 2.3 million ha of soybean-maize area. The latter strategy would release ~35% more N2O than the first. Our modifications of the DNDC model will improve estimates of N2O emissions from agricultural production in MT and other tropical areas, but narrowing model uncertainty will depend on more detailed field measurements and spatial data on soil and cropping management.

scholarly journals Evaluation of the DNDC Model to Estimate Soil Parameters, Crop Yield and Nitrous Oxide Emissions for Alternative Long-Term Multi-Cropping Systems in the North China Plain

Agronomy ◽  
2022 ◽  
Vol 12 (1) ◽  
pp. 109
Author(s):  
Mohamed Abdalla ◽  
Xiaotong Song ◽  
Xiaotang Ju ◽  
Pete Smith
Keyword(s):  
Nitrous Oxide ◽  
Crop Yield ◽  
Crop Yields ◽  
Cropping Systems ◽  
Pore Space ◽  
Nitrous Oxide Emissions ◽  
Soil Parameters ◽  
N2o Emissions ◽  
Dndc Model

Optimizing crop rotations is one of the proposed sustainable management strategies for increasing carbon sequestration. The main aim of this study was to evaluate the DeNitrification-DeComposition (DNDC) model for estimating soil parameters (temperature, moisture and exchangeable NO3− and NH4+), crop yield and nitrous oxide (N2O) emissions for long-term multi-cropping systems in Hebei, China. The model was validated using five years of data of soil parameters, crop yields and N2O emissions. The DNDC model effectively simulated daily soil temperature, cumulative soil nitrogen and crop yields of all crops. It predicted the trends of observed daily N2O emissions and their cumulative values well but overestimated the magnitude of some peaks. However, the model underestimated daily water filled pore space, especially in dry seasons, and had difficulties in correctly estimating daily exchangeable NO3− and NH4+. Both observed and simulated cumulative N2O results showed that optimized and alternative cropping systems used less nitrogen fertiliser, increased grain yield and decreased N2O emissions compared to the conventional cropping system. Our study shows that although the DNDC model (v. 9.5) is not perfect in estimating daily N2O emissions for these long-term multi-cropping systems, it could still be an effective tool for predicting cumulative emissions.

scholarly journals Denitrifying pathways dominate nitrous oxide emissions from managed grassland during drought and rewetting

2021 ◽  
Vol 7 (6) ◽  
pp. eabb7118
Author(s):  
E. Harris ◽  
E. Diaz-Pines ◽  
E. Stoll ◽  
M. Schloter ◽  
S. Schulz ◽  
...  
Keyword(s):  
Growth Rate ◽  
Nitrous Oxide ◽  
N Fertilization ◽  
High Variability ◽  
Nitrous Oxide Emissions ◽  
Severe Drought ◽  
Total N ◽  
The Past ◽  
Precipitation Changes ◽  
Isotopic Measurements

Nitrous oxide is a powerful greenhouse gas whose atmospheric growth rate has accelerated over the past decade. Most anthropogenic N2O emissions result from soil N fertilization, which is converted to N2O via oxic nitrification and anoxic denitrification pathways. Drought-affected soils are expected to be well oxygenated; however, using high-resolution isotopic measurements, we found that denitrifying pathways dominated N2O emissions during a severe drought applied to managed grassland. This was due to a reversible, drought-induced enrichment in nitrogen-bearing organic matter on soil microaggregates and suggested a strong role for chemo- or codenitrification. Throughout rewetting, denitrification dominated emissions, despite high variability in fluxes. Total N2O flux and denitrification contribution were significantly higher during rewetting than for control plots at the same soil moisture range. The observed feedbacks between precipitation changes induced by climate change and N2O emission pathways are sufficient to account for the accelerating N2O growth rate observed over the past decade.

Soil nitrous oxide emissions as affected by long-term tillage, cropping systems and nitrogen fertilization in Southern Brazil

2015 ◽  
Vol 146 ◽  
pp. 213-222 ◽  
Author(s):  
Cimélio Bayer ◽  
Juliana Gomes ◽  
Josiléia Accordi Zanatta ◽  
Frederico Costa Beber Vieira ◽  
Marisa de Cássia Piccolo ◽  
...  
Keyword(s):  
Nitrous Oxide ◽  
Nitrogen Fertilization ◽  
Cropping Systems ◽  
Nitrous Oxide Emissions ◽  
Southern Brazil

scholarly journals Opportunities for mitigating nitrous oxide emissions in subtropical cereal and fiber cropping systems: A simulation study

2016 ◽  
Vol 218 ◽  
pp. 11-27 ◽  
Author(s):  
Henrike Mielenz ◽  
Peter J. Thorburn ◽  
Clemens Scheer ◽  
Massimiliano De Antoni Migliorati ◽  
Peter R. Grace ◽  
...  
Keyword(s):  
Nitrous Oxide ◽  
Simulation Study ◽  
Cropping Systems ◽  
Nitrous Oxide Emissions

scholarly journals Land-use-driven stream warming in southeastern Amazonia

2013 ◽  
Vol 368 (1619) ◽  
pp. 20120153 ◽  
Author(s):  
Marcia N. Macedo ◽  
Michael T. Coe ◽  
Ruth DeFries ◽  
Maria Uriarte ◽  
Paulo M. Brando ◽  
...  
Keyword(s):  
Land Use ◽  
Crop Production ◽  
Large Scale ◽  
Management Practices ◽  
Forest Cover ◽  
Riparian Forest ◽  
Soya Bean ◽  
Nutrient Inputs ◽  
Mato Grosso ◽  
Small Streams

Large-scale cattle and crop production are the primary drivers of deforestation in the Amazon today. Such land-use changes can degrade stream ecosystems by reducing connectivity, changing light and nutrient inputs, and altering the quantity and quality of streamwater. This study integrates field data from 12 catchments with satellite-derived information for the 176 000 km 2 upper Xingu watershed (Mato Grosso, Brazil). We quantify recent land-use transitions and evaluate the influence of land management on streamwater temperature, an important determinant of habitat quality in small streams. By 2010, over 40 per cent of catchments outside protected areas were dominated (greater than 60% of area) by agriculture, with an estimated 10 000 impoundments in the upper Xingu. Streams in pasture and soya bean watersheds were significantly warmer than those in forested watersheds, with average daily maxima over 4°C higher in pasture and 3°C higher in soya bean. The upstream density of impoundments and riparian forest cover accounted for 43 per cent of the variation in temperature. Scaling up, our model suggests that management practices associated with recent agricultural expansion may have already increased headwater stream temperatures across the Xingu. Although increased temperatures could negatively impact stream biota, conserving or restoring riparian buffers could reduce predicted warming by as much as fivefold.

Nitrous oxide emissions from contrasting organic cropping systems

2009 ◽  
Vol 6 (24) ◽  
pp. 242012
Author(s):  
Ngonidzashe Chirinda ◽  
J E Olesen ◽  
S O Petersen ◽  
J R Porter
Keyword(s):  
Nitrous Oxide ◽  
Cropping Systems ◽  
Nitrous Oxide Emissions
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