N2O emissions from decomposing crop residues are strongly linked to their initial soluble fraction and early C mineralization

Soil C-CO2 emissions are sensitive indicators of management system impacts on soil organic matter (SOM). The main soil C-CO2 sources at the soil-plant interface are the decomposition of crop residues, SOM turnover, and respiration of roots and soil biota. The objectives of this study were to evaluate the impacts of tillage and cropping systems on long-term soil C-CO2 emissions and their relationship with carbon (C) mineralization of crop residues. A long-term experiment was conducted in a Red Oxisol in Cruz Alta, RS, Brazil, with subtropical climate Cfa (Köppen classification), mean annual precipitation of 1,774 mm and mean annual temperature of 19.2 ºC. Treatments consisted of two tillage systems: (a) conventional tillage (CT) and (b) no tillage (NT) in combination with three cropping systems: (a) R0- monoculture system (soybean/wheat), (b) R1- winter crop rotation (soybean/wheat/soybean/black oat), and (c) R2- intensive crop rotation (soybean/ black oat/soybean/black oat + common vetch/maize/oilseed radish/wheat). The soil C-CO2 efflux was measured every 14 days for two years (48 measurements), by trapping the CO2 in an alkaline solution. The soil gravimetric moisture in the 0-0.05 m layer was determined concomitantly with the C-CO2 efflux measurements. The crop residue C mineralization was evaluated with the mesh-bag method, with sampling 14, 28, 56, 84, 112, and 140 days after the beginning of the evaluation period for C measurements. Four C conservation indexes were used to assess the relation between C-CO2 efflux and soil C stock and its compartments. The crop residue C mineralization fit an exponential model in time. For black oat, wheat and maize residues, C mineralization was higher in CT than NT, while for soybean it was similar. Soil moisture was higher in NT than CT, mainly in the second year of evaluation. There was no difference in tillage systems for annual average C-CO2 emissions, but in some individual evaluations, differences between tillage systems were noticed for C-CO2 evolution. Soil C-CO2 effluxes followed a bi-modal pattern, with peaks in October/November and February/March. The highest emission was recorded in the summer and the lowest in the winter. The C-CO2 effluxes were weakly correlated to air temperature and not correlated to soil moisture. Based on the soil C conservation indexes investigated, NT associated to intensive crop rotation was more C conserving than CT with monoculture.

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Soil N2O emissions following cover-crop residues application under two soil moisture conditions

Journal of Plant Nutrition and Soil Science ◽

10.1002/jpln.201400392 ◽

2015 ◽

Vol 178 (4) ◽

pp. 631-640 ◽

Cited By ~ 27

Author(s):

Laisa Gouveia Pimentel ◽

Douglas Adams Weiler ◽

Gabriel Munhoz Pedroso ◽

Cimélio Bayer

Keyword(s):

Soil Moisture ◽

Cover Crop ◽

Crop Residues ◽

N2o Emissions ◽

Moisture Conditions

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Estimation of N2O emissions from agricultural soils in Canada. II. 1990–2005 inventory

Canadian Journal of Soil Science ◽

10.4141/cjss07026 ◽

2008 ◽

Vol 88 (5) ◽

pp. 655-669 ◽

Cited By ~ 35

Author(s):

P. Rochette ◽

D E Worth ◽

E C Huffman ◽

J A Brierley ◽

B G McConkey ◽

...

Keyword(s):

Climate Change ◽

Crop Residues ◽

Agricultural Soils ◽

Primary Objective ◽

N2o Emissions ◽

Soil N ◽

Intergovernmental Panel ◽

Total N ◽

Tier Ii ◽

Tier I

International initiatives such as the United Nations Framework Convention on Climate Change and the Kyoto Protocol require that countries conduct national inventories of their greenhouse gas emissions. The primary objective of the present study was to apply a country-specific (Tier II) methodology at the regional (≈150 000 ha) scale to estimate direct N2O emissions from agricultural soils in Canada for the period 1990–2005. Other N2O sources such as manure management and indirect emissions were estimated using the Tier I Intergovernmental Panel on Climate Change (IPCC) methodology and were included to provide a complete assessment of agricultural N2O emissions. Total N2O emissions from agricultural sources averaged 58.1 Gg N2O-N yr-1 between 1990 and 2005 (from 48.9 in 1990 to 71.6 Gg N2O-N yr-1 in 2004). Of these mean emissions, 39.3 Gg N2O-N yr-1 or 68% were direct emissions from soils, 8.7 Gg N2O-N yr-1 or 15% were direct emissions from animal waste management systems and 10.1 Gg N2O-N yr-1 or 17% were from indirect emissions. Application of synthetic N fertilizers was the largest direct source of soil N2O with average emissions during the inventory period of 13.7 Gg N2O-N yr-1 or 35% of direct emissions. Crop residues (9.3 Gg N2O-N yr-1; 24%), grazing animals (6.8 Gg N2O-N yr-1; 17%) and manure applied to soils (4.1 Gg N2O-N yr-1; 10%) were the other major direct soil N2O sources. New non-IPCC N2O sources/offsets included in the Tier II methodology accounted for 10% of total direct soil emissions. Emissions occurring during summerfallow (2.2 Gg N2O-N yr-1; 6%), in lower portions of the landscape (2.2 Gg N2O-N yr-1; 6%), and following irrigation (0.7 Gg N2O-N yr-1; 2%) were partially offset by changes in tillage practices (-1.2 Gg N2O-N yr-1; -3%) and in coarse-textured soils (-0.2 Gg N2O-N yr-1; -1%). Differences in N2O estimates between Tier I and Tier II approaches mainly arise from the use of lower fertilizer-induced emission factors in the dry Prairie region and the addition of several new N2O sources/offsets in the Tier II methodology. Key words: Nitrous oxide, soils, greenhouse gases, inventory

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High-Resolution Denitrification Kinetics in Pasture Soils Link N2O Emissions to pH, and Denitrification to C Mineralization

PLoS ONE ◽

10.1371/journal.pone.0151713 ◽

2016 ◽

Vol 11 (3) ◽

pp. e0151713 ◽

Cited By ~ 34

Author(s):

Md Sainur Samad ◽

Lars R. Bakken ◽

Shahid Nadeem ◽

Timothy J. Clough ◽

Cecile A. M. de Klein ◽

...

Keyword(s):

High Resolution ◽

N2o Emissions ◽

C Mineralization ◽

Denitrification Kinetics

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Catch Crop Residues Stimulate N2O Emissions During Spring, Without Affecting the Genetic Potential for Nitrite and N2O Reduction

Frontiers in Microbiology ◽

10.3389/fmicb.2018.02629 ◽

2018 ◽

Vol 9 ◽

Cited By ~ 6

Author(s):

Yun-Feng Duan ◽

Sara Hallin ◽

Christopher M. Jones ◽

Anders Priemé ◽

Rodrigo Labouriau ◽

...

Keyword(s):

Crop Residues ◽

N2o Emissions ◽

Catch Crop ◽

N2o Reduction ◽

Genetic Potential

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Reviews and syntheses: Review of causes and sources of N<sub>2</sub>O emissions and NO<sub>3</sub> leaching from organic arable crop rotations

Biogeosciences ◽

10.5194/bg-16-2795-2019 ◽

2019 ◽

Vol 16 (14) ◽

pp. 2795-2819 ◽

Cited By ~ 7

Author(s):

Sissel Hansen ◽

Randi Berland Frøseth ◽

Maria Stenberg ◽

Jarosław Stalenga ◽

Jørgen E. Olesen ◽

...

Keyword(s):

Organic Matter ◽

Soil Organic Matter ◽

Cover Crops ◽

Crop Residues ◽

Cropping Systems ◽

Crop Rotations ◽

N2o Emissions ◽

Arable Crop ◽

Organic Fertilisers ◽

N2o Fluxes

Abstract. The emissions of nitrous oxide (N2O) and leaching of nitrate (NO3) from agricultural cropping systems have considerable negative impacts on climate and the environment. Although these environmental burdens are less per unit area in organic than in non-organic production on average, they are roughly similar per unit of product. If organic farming is to maintain its goal of being environmentally friendly, these loadings must be addressed. We discuss the impact of possible drivers of N2O emissions and NO3 leaching within organic arable farming practice under European climatic conditions, and potential strategies to reduce these. Organic arable crop rotations are generally diverse with the frequent use of legumes, intercropping and organic fertilisers. The soil organic matter content and the share of active organic matter, soil structure, microbial and faunal activity are higher in such diverse rotations, and the yields are lower, than in non-organic arable cropping systems based on less diverse systems and inorganic fertilisers. Soil mineral nitrogen (SMN), N2O emissions and NO3 leaching are low under growing crops, but there is the potential for SMN accumulation and losses after crop termination, harvest or senescence. The risk of high N2O fluxes increases when large amounts of herbage or organic fertilisers with readily available nitrogen (N) and degradable carbon are incorporated into the soil or left on the surface. Freezing/thawing, drying/rewetting, compacted and/or wet soil and mechanical mixing of crop residues into the soil further enhance the risk of high N2O fluxes. N derived from soil organic matter (background emissions) does, however, seem to be the most important driver for N2O emission from organic arable crop rotations, and the correlation between yearly total N-input and N2O emissions is weak. Incorporation of N-rich plant residues or mechanical weeding followed by bare fallow conditions increases the risk of NO3 leaching. In contrast, strategic use of deep-rooted crops with long growing seasons or effective cover crops in the rotation reduces NO3 leaching risk. Enhanced recycling of herbage from green manures, crop residues and cover crops through biogas or composting may increase N efficiency and reduce N2O emissions and NO3 leaching. Mixtures of legumes (e.g. clover or vetch) and non-legumes (e.g. grasses or Brassica species) are as efficient cover crops for reducing NO3 leaching as monocultures of non-legume species. Continued regular use of cover crops has the potential to reduce NO3 leaching and enhance soil organic matter but may enhance N2O emissions. There is a need to optimise the use of crops and cover crops to enhance the synchrony of mineralisation with crop N uptake to enhance crop productivity, and this will concurrently reduce the long-term risks of NO3 leaching and N2O emissions.

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Changes in chemical composition of cover crops residue during decomposition

Ciência Rural ◽

10.1590/0103-8478cr20210357 ◽

2022 ◽

Vol 52 (4) ◽

Author(s):

Douglas Adams Weiler ◽

Leonardo Mendes Bastos ◽

Janquieli Schirmann ◽

Celso Aita ◽

Sandro José Giacomini

Keyword(s):

Chemical Composition ◽

Cover Crops ◽

Plant Tissue ◽

Cover Crop ◽

Lignin Degradation ◽

Crop Residue ◽

Crop Residues ◽

Soluble Fraction ◽

Structural Composition ◽

Main Components

ABSTRACT: Crop residues decomposition are controlled by chemical tissue components. This study evaluated changes on plant tissue components, separated by the Van Soest partitioning method, during cover crop decomposition. The Van Soest soluble fraction was the first to be released from the crop residues, followed by cellulose and hemicellulose. Lignin was the crop residue component that suffered the least degradation, and for certain crop residue types, lignin degradation was not detected. The degradation of the main components of crop residues (soluble fraction, cellulose, hemicellulose and lignin) is determined by the chemical and structural composition of each fraction.

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Soil N2O emissions after perennial legume termination in an alfalfa-wheat crop rotation system under Mediterranean conditions

Italian Journal of Agronomy ◽

10.4081/ija.2020.1613 ◽

2020 ◽

Vol 15 (3) ◽

Author(s):

Laura Trozzo ◽

Matteo Francioni ◽

Ayaka Wenhong Kishimoto-Mo ◽

Lucia Foresi ◽

Michele Bianchelli ◽

...

Keyword(s):

Crop Rotation ◽

Crop Residues ◽

Block Design ◽

N Uptake ◽

Ghg Emissions ◽

N2o Emission ◽

Wheat Crop ◽

N2o Emissions ◽

Alfalfa Field ◽

Perennial Legume

Agricultural activities are potential sources of greenhouse gas (GHG) emissions, and nitrous oxide (N2O) is one of the most important non-carbon-dioxide GHGs. Perennial legumes such as alfalfa (Medicago sativa L.) have potential roles for reduction of soil GHG emissions as part of crop rotation systems. However, the implications of perennial legume termination by tillage and subsequent soil incorporation of the residues for reduced GHG emissions have been poorly examined in Mediterranean environments. With the aim to assess the magnitude of soil N2O emissions (important for the definition of mitigation strategies) after perennial legume termination in alfalfa-wheat crop rotation systems in a Mediterranean environment, we defined the hypothesis that alfalfa termination by tillage with incorporation of the crop residues will increase soil N2O emissions during the subsequent wheat season. To test this hypothesis, closed static chambers were used in a field–plot experiment, using a complete randomised block design with three replicates. Soil N2O emissions were monitored across 33 sampling dates from October 2017 to July 2018, as a comparison between an original 6-year-old alfalfa field (‘continuous alfalfa’) and alfalfa termination followed by wheat (‘alfalfa+ wheat’). The soil N2O emission fluxes varied markedly across the treatments and throughout the monitoring period (from – 0.02±0.01 to 0.53±0.14 g N-N2O ha–1 h–1, and from 0.02±0.07 to 0.37±0.11 g N-N2O ha–1 h–1 for continuous alfalfa and alfalfa+wheat, respectively), generally following the changes in soil temperature. Several soil N2O emission peaks were recorded for both treatments, which mainly coincided with rainfall and with increased soil water content. In the 2 months following alfalfa termination, alfalfa+wheat showed higher cumulative weekly soil N2O emissions compared to continuous alfalfa. Following alfalfa termination for alfalfa+wheat, the increased cumulative weekly soil N2O emissions appeared to be due to asynchrony between nitrogen (N) released into the soil from mineralisation of the alfalfa residues and N uptake by the wheat. Despite these initial high soil N2O emissions for alfalfa+wheat, the seasonal cumulative soil N2O emissions were not significantly different (0.77±0.09 vs 0.85±0.18 kg N-N2O ha–1 for continuous alfalfa and alfalfa+wheat, respectively). These data suggest that legume perennial crop termination in alfalfa–wheat rotation systems does not lead to significant loss of N2O from the soil. The alfalfa termination by tillage performed in autumn might, on the one hand, have slowed the mineralisation process, and might, on the other hand, have synchronised the N release by the mineralised crop residues, with the N uptake by the wheat reducing the soil N2O emissions.

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Earthworm-induced N2O emissions in a sandy soil with surface-applied crop residues

Pedobiologia ◽

10.1016/j.pedobi.2011.09.005 ◽

2011 ◽

Vol 54 ◽

pp. S103-S111 ◽

Cited By ~ 9

Author(s):

Georgios Giannopoulos ◽

Jan Willem van Groenigen ◽

Mirjam M. Pulleman

Keyword(s):

Sandy Soil ◽

Crop Residues ◽

N2o Emissions

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