scholarly journals Strategies to mitigate greenhouse gas emissions in intensively managed vegetable cropping systems in subtropical Australia

Soil Research ◽  
2015 ◽  
Vol 53 (5) ◽  
pp. 475 ◽  
Author(s):  
M. Rezaei Rashti ◽  
W. J. Wang ◽  
S. M. Harper ◽  
P. W. Moody ◽  
C. R. Chen ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Greenhouse Gas ◽  
Cropping Systems ◽  
Pore Space ◽  
Cropping System ◽  
Mitigation Strategies ◽  
Control Treatment ◽  
N2o Emissions ◽  
Application Rates ◽  
Intensively Managed

The greenhouse gas fluxes and effective mitigation strategies in subtropical vegetable cropping systems remain unclear. In this field experiment, nitrous oxide (N2O) and methane (CH4) fluxes from an irrigated lettuce cropping system in subtropical Queensland, Australia, were measured using manual sampling chambers. Four treatments were included: Control (no fertiliser), U100 (100 kg N ha–1 as urea), U200 (200 kg N ha–1 as urea) and N100 (100 kg N ha–1 as nitrate-based fertilisers). The N fertilisers were applied in three splits and irrigation was delivered sparingly and frequently to keep soil moisture around the field capacity. The cumulative N2O emissions from the control, U100, U200 and N100 treatments over the 68-day cropping season were 30, 151, 206 and 68 g N2O-N ha–1, respectively. Methane emission and uptake were negligible. Using N2O emission from the Control treatment as the background emission, direct emission factors for U100, U200 and N100 treatments were 0.12%, 0.09% and 0.04% of applied fertiliser N, respectively. Soil ammonium (NH4+) concentration, instead of nitrate (NO3–) concentration, exhibited a significant correlation with N2O emissions at the site where the soil moisture was controlled within 50%–64% water-filled pore space. Furthermore, soil temperature rather than water content was the main regulating factor of N2O fluxes in the fertilised treatments. Fertiliser type and application rates had no significant effects on yield parameters. Partial N balance analysis indicated that approximately 80% and 52% of fertiliser N was recovered in plants and soil in the treatments receiving 100 kg N ha–1 and 200 kg N ha–1, respectively. Therefore, in combination with frequent and low-intensity irrigation and split application of fertiliser N, substitution of NO3–-based fertilisers for urea and reduction in fertiliser N application rates were considered promising mitigation strategies to maintain yield and minimise N2O emissions during the low rainfall season.

scholarly journals Revisiting the relationship between soil moisture and N<sub>2</sub>O production pathways by measuring <sup>15</sup>N<sub>2</sub>O isotopomers

2019 ◽  
Author(s):  
Kate A. Congreves ◽  
Trang Phan ◽  
Richard E. Farrell
Keyword(s):  
Soil Moisture ◽  
Pore Space ◽  
Mitigation Strategies ◽  
Soil Conditions ◽  
Site Preference ◽  
N2o Emissions ◽  
Spectroscopic Techniques ◽  
N2o Production ◽  
Nitrification And Denitrification ◽  
The Relationship

Abstract. Understanding the production pathways of potent greenhouse gases, such as nitrous oxide (N2O), is essential for accurate flux prediction and for developing effective adaptation and mitigation strategies in response to climate change. Yet, there remain surprising gaps in our understanding and precise quantification of the underlying production pathways – such as the relationship between soil moisture and N2O production pathways. A powerful, but arguably underutilized, approach for quantifying the relative contribution of nitrification and denitrification to N2O production involves determining 15N2O isotopomers and 15N site preference (SP) via spectroscopic techniques. Using one such technique we conducted a short-term incubation to precisely quantify the relationship between soil moisture and N2O production pathways. For each of three soils, microcosms were arranged in a complete random design with four replicates; each microcosm consisted of air-dried soil packed into plastic petri dishes wherein moisture treatments were established for water contents equivalent to 45 to 105 % water-filled pore space (WFPS). The microcosms were placed in 1-L jars and sealed; headspace samples were collected after 24-h and analyzed for total N2O concentrations using gas chromatography, and for 15N2O isotopomers using cavity ring-down spectroscopy. Relatively low N2O fluxes and high SP values indicted nitrification during dry soil conditions, whereas at higher soil moisture, peak N2O emissions coincided with a sharp decline in SP indicating denitrification. This pattern supports the classic N2O production curves from nitrification and denitrification as inferred by earlier research; however, our isotopomer data enabled the quantification of source partitioning for either pathway thereby providing clarity on N2O sources during the transition from nitrification to denitrification. At soil moisture levels  78 %, denitrification completely dominated. Clearly, the soil moisture levels during transition is a key regulation of N2O production pathways.

scholarly journals Effect of Biochar on Soil Greenhouse Gas Emissions at the Laboratory and Field Scales

Soil Systems ◽  
2019 ◽  
Vol 3 (1) ◽  
pp. 8 ◽  
Author(s):  
Rivka Fidel ◽  
David Laird ◽  
Timothy Parkin
Keyword(s):  
Field Study ◽  
Greenhouse Gas Emissions ◽  
Greenhouse Gas ◽  
Cropping Systems ◽  
Cropping System ◽  
N2o Emission ◽  
N2o Emissions ◽  
Gas Emissions ◽  
Continuous Corn ◽  
The Impact

Biochar application to soil has been proposed as a means for reducing soil greenhouse gas emissions and mitigating climate change. The effects, however, of interactions between biochar, moisture and temperature on soil CO2 and N2O emissions, remain poorly understood. Furthermore, the applicability of lab-scale observations to field conditions in diverse agroecosystems remains uncertain. Here we investigate the impact of a mixed wood gasification biochar on CO2 and N2O emissions from loess-derived soils using: (1) controlled laboratory incubations at three moisture (27, 31 and 35%) and three temperature (10, 20 and 30 °C) levels and (2) a field study with four cropping systems (continuous corn, switchgrass, low diversity grass mix and high diversity grass-forb mix). Biochar reduced N2O emissions under specific temperatures and moistures in the laboratory and in the continuous corn cropping system in the field. However, the effect of biochar on N2O emissions was only significant in the field and no effect on cumulative CO2 emissions was observed. Cropping system also had a significant effect in the field study, with soils in grass and grass-forb cropping systems emitting more CO2 and less N2O than corn cropping systems. Observed biochar effects were consistent with previous studies showing that biochar amendments can reduce soil N2O emissions under specific but not all, conditions. The disparity in N2O emission responses at the lab and field scales suggests that laboratory incubation experiments may not reliably predict the impact of biochar at the field scale.

scholarly journals Effect of Biochar on Soil Greenhouse Gas Emissions at the Laboratory and Field Scales

2018 ◽  
Author(s):  
Rivka B. Fidel ◽  
David A. Laird ◽  
Timothy B. Parkin
Keyword(s):  
Field Study ◽  
Greenhouse Gas Emissions ◽  
Greenhouse Gas ◽  
Cropping Systems ◽  
Cropping System ◽  
N2o Emission ◽  
N2o Emissions ◽  
Gas Emissions ◽  
Continuous Corn ◽  
The Impact

Biochar application to soil has been proposed as a means for reducing soil greenhouse gas emissions and mitigating climate change. The effects, however, of interactions between biochar, moisture and temperature on soil CO2 and N2O emissions, remain poorly understood.&nbsp; Furthermore, the applicability of lab-scale observations to field conditions in diverse agroecosystems remains uncertain. Here we investigate the impact of a mixed wood gasification biochar on CO2 and N2O emissions from loess-derived soils using: (1) controlled laboratory incubations at three moisture (27, 31 and 35%) and three temperature (10, 20 and 30&deg;C) levels, and (2) a field study with four cropping systems (continuous corn, switchgrass, low diversity grass mix, and high diversity grass-forb mix). Biochar reduced N2O emissions under specific temperatures and moistures in the laboratory and in the continuous corn cropping system in the field. However, the effect of biochar on N2O emissions was only significant in the field, and no effect on cumulative CO2 emissions was observed. Cropping system also had a significant effect in the field study, with soils in grass and grass-forb cropping systems emitting more CO2 and less N2O than corn cropping systems. Observed biochar effects were consistent with previous studies showing that biochar amendments can reduce soil N2O emissions under specific, but not all, conditions. The disparity in N2O emission responses at the lab and field scales suggests that laboratory incubation experiments are not reliable for predicting the impact of biochar at the field scale.

scholarly journals Exploring Suitable Biochar Application Rates with Compost to Improve Upland Field Environment

Agronomy ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 1136
Author(s):  
Se-Won Kang ◽  
Jin-Ju Yun ◽  
Jae-Hyuk Park ◽  
Ju-Sik Cho
Keyword(s):  
Soil Quality ◽  
Chinese Cabbage ◽  
Early Period ◽  
Crop Productivity ◽  
Application Rate ◽  
Control Treatment ◽  
N2o Emissions ◽  
Treatment Area ◽  
Application Rates ◽  
Upland Field

A field experiment was carried out to investigate crop productivity, emissions of carbon dioxide (CO2) and nitrous oxide (N2O), and soil quality of an upland field treated with compost and varying rates of biochar (BC) derived from soybean stalks during crop growing periods in a corn and Chinese cabbage rotation system. Compost was supplemented with BC derived from soybean stalks at varying rates of 5, 10, 15, and 20 t ha−1 (BC5, BC10, BC15, and BC20, respectively); the control (BC0) area was untreated. Our results reveal that crop productivity and emissions of CO2 and N2O varied significantly with the biochar application rate. Moreover, irrespective of the biochar application rate, crop productivity was improved after BC application as compared to the control treatment area, by 11.2–29.3% (average 17.0 ± 8.3%) for corn cultivation and 10.3–39.7% (average 27.8 ± 12.7%) for Chinese cabbage cultivation. Peak emissions of CO2 and N2O were mainly observed in the early period of crop cultivation, whereas low CO2 and N2O emissions were determined during the fallow period. Compared to the control area, significant differences were obtained for CO2 emissions produced by the different biochar application rates for both crops. During the two cropping periods, the overall N2O emission was significantly decreased with BC5, BC10, BC15, and BC20 applications as compared to the control, ranging from 11.1 to 13.6%, 8.7 to 15.4%, 23.1 to 26.0%, and 15.0 to 19.6%, respectively (average 16.9% decrease in the corn crop period and 16.3% in the Chinese cabbage crop period). Soil quality results after the final crop harvest show that bulk density, soil organic carbon (SOC), pH, and cation exchange capacity (CEC) were significantly improved by biochar application, as compared to the control. Taken together, our results indicate that compost application supplemented with biochar is potentially an appropriate strategy for achieving high crop productivity and improving soil quality in upland field conditions. In conclusion, appropriate application of biochar with compost has the concomitant advantages of enriching soil quality for long-term sustainable agriculture and reducing the use of inorganic fertilizers.

scholarly journals Long-Term Green Manure Rotations Improve Soil Biochemical Properties, Yield Sustainability and Nutrient Balances in Acidic Paddy Soil under a Rice-Based Cropping System

Agronomy ◽  
2019 ◽  
Vol 9 (12) ◽  
pp. 780
Author(s):  
Muhammad Qaswar ◽  
Jing Huang ◽  
Waqas Ahmed ◽  
Dongchu Li ◽  
Shujun Liu ◽  
...  
Keyword(s):  
Grain Yield ◽  
Green Manure ◽  
Cropping Systems ◽  
Cropping System ◽  
Biochemical Properties ◽  
Control Treatment ◽  
Yield Sustainability ◽  
Double Rice ◽  
Winter Fallow

Cultivation of green manure (GM) crops in intensive cropping systems is important for enhancing crop productivity through soil quality improvement. We investigated yield sustainability, nutrient stocks, nutrient balances and enzyme activities affected by different long-term (1982–2016) green manure rotations in acidic paddy soil in a double-rice cropping system. We selected four treatments from a long-term experiment, including (1) rice-rice-winter fallow as a control treatment (R-R-F), (2) rice-rice-milkvetch (R-R-M), (3) rice-rice-rapeseed (R-R-R), and (4) rice-rice-ryegrass (R-R-G). The results showed that different GM rotations increased grain yield and the sustainable yield index compared with those of the R-R-F treatment. Compared with those of R-R-F, the average grain yield of early rice in R-R-M, R-R-R, and R-R-G increased by 45%, 29%, and 27%, respectively and that of late rice increased by 46%, 28%, and 26%, respectively. Over the years, grain yield increased in all treatments except R-R-F. Green manure also improved the soil chemical properties (SOM and total and available N and P), except soil pH, compared to those of the control treatment. During the 1983–1990 cultivation period, the soil pH of the R-R-M treatment was lower than that of the R-R-F treatment. The addition of green manure did not mitigate the soil acidification caused by the use of inorganic fertilizers. The soil organic matter (SOM), total nitrogen (TN) and total phosphorus (TP) contents and stocks of C, N and P increased over the years. Furthermore, GM significantly increased phosphatase and urease activities and decreased the apparent N and P balances compared with those in the winter fallow treatment. Variance partitioning analysis revealed that soil properties, cropping systems, and climatic factors significantly influenced annual grain yield. Aggregated boosted tree (ABT) analysis quantified the relative influences of the different soil properties on annual grain yield and showed that the relative influences of TN content, SOM, pH, and TP content on annual crop yield were 27.8%, 25.7%, 22.9%, and 20.7%, respectively. In conclusion, GM rotation is beneficial for sustaining high crop yields by improving soil biochemical properties and reducing N and P balances in acidic soil under double- rice cropping systems.

scholarly journals Simulating Long-Term Development of Greenhouse Gas Emissions, Plant Biomass, and Soil Moisture of a Temperate Grassland Ecosystem under Elevated Atmospheric CO2

Agronomy ◽  
2019 ◽  
Vol 10 (1) ◽  
pp. 50
Author(s):  
Ralf Liebermann ◽  
Lutz Breuer ◽  
Tobias Houska ◽  
David Kraus ◽  
Gerald Moser ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Greenhouse Gas Emissions ◽  
Greenhouse Gas ◽  
Elevated Co2 ◽  
Biomass Production ◽  
Atmospheric Co2 ◽  
N2o Emissions ◽  
Gas Emissions ◽  
Co2 Concentrations

The rising atmospheric CO2 concentrations have effects on the worldwide ecosystems such as an increase in biomass production as well as changing soil processes and conditions. Since this affects the ecosystem’s net balance of greenhouse gas emissions, reliable projections about the CO2 impact are required. Deterministic models can capture the interrelated biological, hydrological, and biogeochemical processes under changing CO2 concentrations if long-term observations for model testing are provided. We used 13 years of data on above-ground biomass production, soil moisture, and emissions of CO2 and N2O from the Free Air Carbon dioxide Enrichment (FACE) grassland experiment in Giessen, Germany. Then, the LandscapeDNDC ecosystem model was calibrated with data measured under current CO2 concentrations and validated under elevated CO2. Depending on the hydrological conditions, different CO2 effects were observed and captured well for all ecosystem variables but N2O emissions. Confidence intervals of ensemble simulations covered up to 96% of measured biomass and CO2 emission values, while soil water content was well simulated in terms of annual cycle and location-specific CO2 effects. N2O emissions under elevated CO2 could not be reproduced, presumably due to a rarely considered mineralization process of organic nitrogen, which is not yet included in LandscapeDNDC.

scholarly journals A new look at an old concept: using <sup>15</sup>N<sub>2</sub>O isotopomers to understand the relationship between soil moisture and N<sub>2</sub>O production pathways

SOIL ◽  
2019 ◽  
Vol 5 (2) ◽  
pp. 265-274 ◽  
Author(s):  
Katelyn A. Congreves ◽  
Trang Phan ◽  
Richard E. Farrell
Keyword(s):  
Soil Moisture ◽  
Mitigation Strategies ◽  
Soil Conditions ◽  
Site Preference ◽  
N2o Emissions ◽  
Spectroscopic Techniques ◽  
N2o Production ◽  
Nitrification And Denitrification ◽  
The Relationship ◽  
Source Partitioning

Abstract. Understanding the production pathways of potent greenhouse gases, such as nitrous oxide (N2O), is essential for accurate flux prediction and for developing effective adaptation and mitigation strategies in response to climate change. Yet there remain surprising gaps in our understanding and precise quantification of the underlying production pathways – such as the relationship between soil moisture and N2O production pathways. A powerful, but arguably underutilized, approach for quantifying the relative contribution of nitrification and denitrification to N2O production involves determining 15N2O isotopomers and 15N site preference (SP) via spectroscopic techniques. Using one such technique, we conducted a short-term incubation where N2O production and 15N2O isotopomers were measured 24 h after soil moisture treatments of 40 % to 105 % water-filled pore space (WFPS) were established for each of three soils that differed in nutrient levels, organic matter, and texture. Relatively low N2O fluxes and high SP values indicted nitrification during dry soil conditions, whereas at higher soil moisture, peak N2O emissions coincided with a sharp decline in SP, indicating denitrification. This pattern supports the classic N2O production curves from nitrification and denitrification as inferred by earlier research; however, our isotopomer data enabled the quantification of source partitioning for either pathway. At soil moisture levels < 53 % WFPS, the fraction of N2O attributed to nitrification (FN) predominated but thereafter decreased rapidly with increasing soil moisture (x), according to FN=3.19-0.041x, until a WFPS of 78 % was reached. Simultaneously, from WFPS of 53 % to 78 %, the fraction of N2O that was attributed to denitrification (FD) was modelled as FD=-2.19+0.041x; at moisture levels of > 78 %, denitrification completely dominated. Clearly, the soil moisture level during transition is a key regulator of N2O production pathways. The presented equations may be helpful for other researchers in estimating N2O source partitioning when soil moisture falls within the transition from nitrification to denitrification.

Emissions of nitrous oxide, ammonia and methane from Australian layer-hen manure storage with a mitigation strategy applied

2016 ◽  
Vol 56 (9) ◽  
pp. 1367 ◽  
Author(s):  
T. A. Naylor ◽  
S. G. Wiedemann ◽  
F. A. Phillips ◽  
B. Warren ◽  
E. J. McGahan ◽  
...  
Keyword(s):  
Nitrous Oxide ◽  
Greenhouse Gas ◽  
Emission Factors ◽  
Control Treatment ◽  
N2o Emissions ◽  
Gaseous Emissions ◽  
Total N ◽  
Volatile Solids ◽  
Manure Storage ◽  
The Relationship

Greenhouse gas and ammonia emissions are important environmental impacts from manure management in the layer-hen industry. The present study aimed to quantify emissions of nitrous oxide (N2O), methane (CH4) and ammonia (NH3) from layer-hen manure stockpiles, and assess the use of an impermeable cover as an option to mitigate emissions. Gaseous emissions of N2O, CH4 and NH3 were measured using open-path FTIR spectroscopy and the emission strengths were inferred using a backward Lagrangian stochastic model. Emission factors were calculated from the relationship between gaseous emissions and stockpile inputs over a 32-day measurement period. Total NH3 emissions were 5.97 ± 0.399 kg/t (control) and 0.732 ± 0.116 kg/t (mitigation), representing an 88% reduction due to mitigation. Total CH4 emissions from the mitigation stockpile were 0.0832 ± 0.0198 kg/t. Methane emissions from the control and N2O emissions (control and mitigation) were below detection. The mass of each stockpile was 27 820 kg (control) and 25 120 kg (mitigation), with a surface area of ~68 m2 and a volume of ~19 m3. Total manure nitrogen (N) and volatile solids (VS) were 25.2 and 25.8 kg/t N, and 139 and 106 kg/t VS for the control and mitigation stockpiles respectively. Emission factors for NH3 were 24% and 3% of total N for the control and mitigation respectively. Methane from the mitigation stockpile had a CH4 conversion factor of 0.3%. The stockpile cover was found to reduce greenhouse gas emissions by 74% compared with the control treatment, primarily via reduced NH3 and associated indirect N2O emissions.

scholarly journals The nitrogen, carbon and greenhouse gas budget of a grazed, cut and fertilised temperate grassland

2017 ◽  
Vol 14 (8) ◽  
pp. 2069-2088 ◽  
Author(s):  
Stephanie K. Jones ◽  
Carole Helfter ◽  
Margaret Anderson ◽  
Mhairi Coyle ◽  
Claire Campbell ◽  
...  
Keyword(s):  
Greenhouse Gas ◽  
Soil Layer ◽  
The Body ◽  
Sink Strength ◽  
N2o Emissions ◽  
N Budget ◽  
Enteric Fermentation ◽  
Total N ◽  
Intensively Managed ◽  
Ch4 And N2o

Abstract. Intensively managed grazed grasslands in temperate climates are globally important environments for the exchange of the greenhouse gases (GHGs) carbon dioxide (CO2), nitrous oxide (N2O) and methane (CH4). We assessed the N and C budget of a mostly grazed and occasionally cut and fertilised grassland in SE Scotland by measuring or modelling all relevant imports and exports to the field as well as changes in soil C and N stocks over time. The N budget was dominated by import from inorganic and organic fertilisers (21.9 g N m−2 a−1) and losses from leaching (5.3 g N m−2 a−1), N2 emissions (2.9 g N m−2 a−1), and NOx and NH3 volatilisation (3.9 g N m−2 a−1), while N2O emission was only 0.6 g N m−2 a−1. The efficiency of N use by animal products (meat and wool) averaged 9.9 % of total N input over only-grazed years (2004–2010). On average over 9 years (2002–2010), the balance of N fluxes suggested that 6.0 ± 5.9 g N m−2 a−1 (mean ± confidence interval at p > 0.95) were stored in the soil. The largest component of the C budget was the net ecosystem exchange of CO2 (NEE), at an average uptake rate of 218 ± 155 g C m−2 a−1 over the 9 years. This sink strength was offset by carbon export from the field mainly as grass offtake for silage (48.9 g C m−2 a−1) and leaching (16.4 g C m−2 a−1). The other export terms, CH4 emissions from the soil, manure applications and enteric fermentation, were negligible and only contributed to 0.02–4.2 % of the total C losses. Only a small fraction of C was incorporated into the body of the grazing animals. Inclusion of these C losses in the budget resulted in a C sink strength of 163 ± 140 g C m−2 a−1. By contrast, soil stock measurements taken in May 2004 and May 2011 indicated that the grassland sequestered N in the 0–60 cm soil layer at 4.51 ± 2.64 g N m−2 a−1 and lost C at a rate of 29.08 ± 38.19 g C m−2 a−1. Potential reasons for the discrepancy between these estimates are probably an underestimation of C losses, especially from leaching fluxes as well as from animal respiration. The average greenhouse gas (GHG) balance of the grassland was −366 ± 601 g CO2 eq. m−2 yr−1 and was strongly affected by CH4 and N2O emissions. The GHG sink strength of the NEE was reduced by 54 % by CH4 and N2O emissions. Estimated enteric fermentation from ruminating sheep proved to be an important CH4 source, exceeding the contribution of N2O to the GHG budget in some years.

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