Regulation of soil CO2 and N2O emissions by cover crops: A meta-analysis

Abstract. Deforestation and forest degradation in the tropics may substantially alter soil N-oxide emissions. It is particularly relevant to accurately quantify those changes to properly account for them in a REDD+ climate change mitigation scheme that provides financial incentives to reduce the emissions. With this study we provide updated land use (LU)-based emission rates (104 studies, 392 N2O and 111 NO case studies), we determine the trend and magnitude of flux changes with land-use change (LUC) using a meta-analysis approach (44 studies, 135 N2O and 37 NO cases) and evaluate biophysical drivers of N2O and NO emissions and emission changes for the tropics. The average N2O and NO emissions in intact upland tropical forest amounted to 2.0 ± 0.2 (n = 90) and 1.7 ± 0.5 (n = 36) kg N ha−1 yr−1, respectively. In agricultural soils annual N2O emissions were exponentially related to N fertilization rates and average water-filled pore space (WFPS) whereas in non-agricultural sites a Gaussian response to WFPS fit better with the observed NO and N2O emissions. The sum of soil N2O and NO fluxes and the ratio of N2O to NO increased exponentially and significantly with increasing nitrogen availability (expressed as NO3− / [NO3−+NH4+]) and WFPS, respectively; following the conceptual Hole-In-the-Pipe model. Nitrous and nitric oxide fluxes did not increase significantly overall as a result of LUC (Hedges's d of 0.11 ± 0.11 and 0.16 ± 0.19, respectively), however individual LUC trajectories or practices did. Nitrous oxide fluxes increased significantly after intact upland forest conversion to croplands (Hedges's d = 0.78 ± 0.24) and NO increased significantly following the conversion of low forest cover (secondary forest younger than 30 years, woodlands, shrublands) (Hedges's d of 0.44 ± 0.13). Forest conversion to fertilized systems significantly and highly raised both N2O and NO emission rates (Hedges's d of 1.03 ± 0.23 and 0.52 ± 0.09, respectively). Changes in nitrogen availability and WFPS were the main factors explaining changes in N2O emissions following LUC, therefore it is important that experimental designs monitor their spatio-temporal variation. Gaps in the literature on N oxide fluxes included geographical gaps (Africa, Oceania) and LU gaps (degraded forest, wetland (notably peat) forest, oil palm plantation and soy cultivation).

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Development of Urea Coated with Neem (Azadirachta indica) to Increase Fertilizer Efficiency and Reduce Greenhouse Gases Emission

Jurnal Teknologi ◽

10.11113/jt.v69.3195 ◽

2014 ◽

Vol 69 (5) ◽

Author(s):

Yusminah Hala ◽

Oslan Jumadi ◽

Abd. Muis ◽

Hartati Hartati ◽

Kazuyuki Inubushi

Keyword(s):

Greenhouse Gases ◽

Azadirachta Indica ◽

Leaf Length ◽

Fertilizer Efficiency ◽

Nitrification Rate ◽

N2o Emissions ◽

Nitrification Inhibition ◽

Soil Co2 ◽

Coated Urea ◽

Urea Granules

Urea coated with neem fertilizer is one of the solutions to increase the efficiency of nitrogen fertilizer and reduce greenhouse gases emission. Inhibition of the nitrification rate of urea can reduce NO3‒ and N2O gas, and at the same time urea can be efficiently absorbed by the plants. Neem (Azadirachta indica) can suppress nitrification rate of 20-50%, which is slightly lower than that of dyciandiamide (DCD) (56-80%). Coating of urea granules was done by dipping urea granules in 1% neem oil, exposed it to 2.5% and 5% neem cake and then homogenized by rotation. The results were compared to urea coated with 5% DCD. The efficiency of fertilizer and nitrification inhibition were measured by nitrate and ammonium changes and fluxes of N2O gas. The results showed that application of urea coated with 5% neem on cabbage plants yielded the highest plant height. However, the leaf length and width were not significantly different with other urea treatments. Application of urea coated neem reduced nitrification rate and N2O emissions in the soil. Soil CO2’s levels treated either with 2.5% or 5% neem coated urea showed the lowest levels of CO2 soil. This suggests that neem can reduce N2O and CO2 emissions from urea fertilizer as well as the capacity to reduce nitrification rate.

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Global Meta-Analysis of Cotton Yield and Weed Suppression from Cover Crops

Crop Science ◽

10.2135/cropsci2018.10.0603 ◽

2019 ◽

Vol 59 (3) ◽

pp. 1248-1261 ◽

Cited By ~ 6

Author(s):

Heather D. Toler ◽

Robert M. Augé ◽

Victoria Benelli ◽

Fred L. Allen ◽

Amanda J. Ashworth

Keyword(s):

Cover Crops ◽

Meta Analysis ◽

Weed Suppression ◽

Cotton Yield

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Management of cover crops in temperate climates influences soil organic carbon stocks: a meta‐analysis

Ecological Applications ◽

10.1002/eap.2278 ◽

2020 ◽

Author(s):

Shelby C. McClelland ◽

Keith Paustian ◽

Meagan E. Schipanski

Keyword(s):

Organic Carbon ◽

Soil Organic Carbon ◽

Cover Crops ◽

Meta Analysis ◽

Carbon Stocks ◽

Soil Organic Carbon Stocks ◽

Temperate Climates

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Emission factors for estimating fertiliser-induced nitrous oxide emissions from clay soils in Australia’s irrigated cotton industry

Soil Research ◽

10.1071/sr16091 ◽

2016 ◽

Vol 54 (5) ◽

pp. 598 ◽

Cited By ~ 12

Author(s):

Peter Grace ◽

Iurii Shcherbak ◽

Ben Macdonald ◽

Clemens Scheer ◽

David Rowlings

Keyword(s):

Nitrous Oxide ◽

Meta Analysis ◽

Exponential Model ◽

N2o Emission ◽

Nitrous Oxide Emissions ◽

N2o Emissions ◽

Tier 2 ◽

Cotton Industry ◽

Greenhouse Gas Inventories ◽

N Rates

As a significant user of nitrogen (N) fertilisers, the Australian cotton industry is a major source of soil-derived nitrous oxide (N2O) emissions. A country-specific (Tier 2) fertiliser-induced emission factor (EF) can be used in national greenhouse gas inventories or in the development of N2O emissions offset methodologies provided the EFs are evidence based. A meta-analysis was performed using eight individual N2O emission studies from Australian cotton studies to estimate EFs. Annual N2O emissions from cotton grown on Vertosols ranged from 0.59kgNha–1 in a 0N control to 1.94kgNha–1 in a treatment receiving 270kgNha–1. Seasonal N2O estimates ranged from 0.51kgNha–1 in a 0N control to 10.64kgNha–1 in response to the addition of 320kgNha–1. A two-component (linear+exponential) statistical model, namely EF (%)=0.29+0.007(e0.037N – 1)/N, capped at 300kgNha–1 describes the N2O emissions from lower N rates better than an exponential model and aligns with an EF of 0.55% using a traditional linear regression model.

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Do cover crops increase or decrease nitrous oxide emissions? A meta-analysis

Journal of Soil and Water Conservation ◽

10.2489/jswc.69.6.471 ◽

2014 ◽

Vol 69 (6) ◽

pp. 471-482 ◽

Cited By ~ 115

Author(s):

A. D. Basche ◽

F. E. Miguez ◽

T. C. Kaspar ◽

M. J. Castellano

Keyword(s):

Nitrous Oxide ◽

Cover Crops ◽

Meta Analysis ◽

Nitrous Oxide Emissions

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Impact of agronomy practices on the effects of reduced tillage systems on CH4 and N2O emissions from agricultural fields: A global meta-analysis

PLoS ONE ◽

10.1371/journal.pone.0196703 ◽

2018 ◽

Vol 13 (5) ◽

pp. e0196703 ◽

Cited By ~ 15

Author(s):

Jinfei Feng ◽

Fengbo Li ◽

Xiyue Zhou ◽

Chunchun Xu ◽

Long Ji ◽

...

Keyword(s):

Meta Analysis ◽

Agricultural Fields ◽

Reduced Tillage ◽

N2o Emissions ◽

Tillage Systems ◽

Ch4 And N2o

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Opportunities to reduce nitrous oxide emissions from horticultural production systems in Canada

Canadian Journal of Plant Science ◽

10.1139/cjps-2021-0107 ◽

2021 ◽

Author(s):

Inderjot Chahal ◽

Khagendra R. Baral ◽

Kate A. Congreves ◽

Laura L. Van Eerd ◽

C. Wagner-Riddle

Keyword(s):

Cover Crops ◽

Production Systems ◽

Current Knowledge ◽

N Fertilizer ◽

Mitigation Strategies ◽

Nitrous Oxide Emissions ◽

N2o Emissions ◽

N Losses ◽

N2o Production ◽

Fertilizer Application Rate

Horticultural systems, specifically vegetable production systems, are considered intensive agricultural systems as they are characterized by high nitrogen (N) fertilizer application rate, frequent tillage and irrigation operations. Accordingly, horticultural production in temperate climates is prone to N losses—mainly during post-harvest (during fall and winter) or pre-plant (spring) periods—such as N2O emissions and nitrate leaching. The risk for N losses is linked to low crop N use efficiency (NUE) combined with a narrow C:N and high N content of crop residues. Here we reviewed the studies conducted in Canada and similar climates to better understand the risk of N2O emission and potential agronomic management strategies to reduce N2O emissions from horticultural systems. Current knowledge on N2O emissions from horticultural systems indicate that increasing crop NUE, modifying the amount, type, time, and rate of N fertilizer inputs, and adopting cover crops in crop rotations are some of the effective approaches to decrease N2O emissions. However, there is uncertainty related to the efficiency of the existing N2O mitigation strategies due to the complex interactions between the factors (soil characteristics, type of plant species, climatic conditions, and soil microbial activity) responsible for N2O production from soil. Little research on N2O emissions from Canadian horticultural systems limits our ability to understand and manage the soil N2O production processes to mitigate the risk of N2O emissions. Thus, continuing to expand this line of research will help to advance the sustainability of Canadian horticultural cropping systems.

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