A Short-Term Assessment of Carbon Dioxide Fluxes under Contrasting Agricultural and Soil Management Practices in Zimbabwe

O'Dell, Deb; Hicks, B. B.; Thierfelder, Christian; Lambert, Dayton M.; Logan, Joanne; Eash, Neal S.

doi:10.5539/jas.v7n3p32

Cited by 9 publications

(10 citation statements)

References 43 publications

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“…Conventional tillage breaks down aggregates and exposes organic matter to microbial decomposition with release of CO 2 (Six et al 2002). In a study done on chromic Lixisols in Zimbabwe, O'Dell et al (2015) found out that a winter wheat cover crop produced a net accumulation of 257 g CO 2 -C m −2 under no-tillage, while tilled plot with no cover crop produced a net emission of 197 g CO 2 -C m −2 and the untilled plot with no cover emitted even higher rates of 235 g CO 2 -C m −2 . Additionally, growing a cover crop during winter or even weeds led to a positive sequestration balance.…”

Section: Greenhouse Gas Emissionsmentioning

confidence: 99%

How climate-smart is conservation agriculture (CA)? – its potential to deliver on adaptation, mitigation and productivity on smallholder farms in southern Africa

et al. 2017

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Climate resilient cropping systems are required to adapt to the increasing threats of climate change projected for Southern Africa and to better manage current climate variability. Conservation agriculture (CA) has been proposed among technologies that are climate-smart. For a cropping system to be labelled Bclimate-smart^it has to deliver three benefits: a) adapt to the effects of climate and be of increased resilience; b) mitigate climate effects by sequestering carbon (C) and reducing greenhouse gas emissions (GHG); and c) sustainably increase productivity and income. Research on smallholder farms from Southern Africa was analysed to assess if CA can deliver on the three principles of climate-smart agriculture. Results from Southern Africa showed that CA systems have a positive effect on adaptation and productivity, but its mitigation potential lags far behind expectations. CA systems maintain higher infiltration rates and conserve soil moisture, which helps to overcome seasonal dry-spells. Increased productivity and profitability were recorded although a lag period of 2-5 cropping seasons is common until yield benefits become significant. Immediate economic benefits such as reduced labour requirements in some systems will make CA more attractive in the short term to farmers who cannot afford to wait for several seasons until yield benefits accrue. The available data summarizing the effects of CA on soil organic C (SOC) and reductions in greenhouse gases, are often contradictory and depend a great deal on the agro-ecological environment and the available biomass for surface residue retention. There is an urgent need for more research to better quantify the mitigation effects, as the current data are scanty. Possible co-interventions such as improved intercropping/ relay cropping systems, agroforestry and other tree-based systems may improve delivery of mitigation benefits and need further exploration.

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Section: Greenhouse Gas Emissionsmentioning

confidence: 99%

How climate-smart is conservation agriculture (CA)? – its potential to deliver on adaptation, mitigation and productivity on smallholder farms in southern Africa

et al. 2017

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“…For example, the relationship between wind speed and the surface stress is usually quantified by a correlation coefficient of the order of 0.4, so that less than 20% of the variance in stress is accounted for by changes in the wind speed. In this light, the values plotted in Figure 4 in Zimbabwe, starting in (O'Dell et al, 2015. Identical BREB 284 instrumentation was set up centrally in four neighboring experimental areas, of which two will 285 be considered here (identified as #1 and #2 in the site depiction in Figure 5).…”

Section: The Ohio Study Of Tillingmentioning

confidence: 99%

On surface fluxes at night – the virtual chamber approach

Hicks

Lichiheb

O'Dell

et al. 2019

Preprint

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Abstract. Quantification of the emission rates of various gases from soils at night remains a challenge, confronting climate science (in the case of CO2 and CH4) and agriculture science (for NH3 and N2O, among others). In the stable conditions prevailing at night, concentrations of such emitted gases build up at the surface during the night, with intermittent interruptions commonly attributed to the passage of packets of turbulence. The utility of conventional micrometeorological experimental methods in such circumstances is questionable, and chamber methods have been developed to meet the challenge. Here, a statistical approach is proposed, in which micrometeorological field data are used to replicate the likely characteristics of a chamber experiment, yielding estimates of surface fluxes at the surface itself and not at some height above it. The methodology proposed is developmental at this time, with details intended to correspond to the use of both closed and vented chambers. Its application to three recent field studies is explored: (1) a study of nocturnal CO2 emission from two test areas (one previously tilled and the other not) in Ohio in 2015; (2) a similar experiment conducted in Zimbabwe in 2013 (one area previously tilled and a second left fallow), and (3) an investigation of NH3 effluxes from a crop previously treated with urea ammonium nitrate (UAN), in Illinois in 2014. There are few measurements with which to compare the results presented here, however the values obtained are within the range of available field data.

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“…Five-second micrometeorological measurements were averaged to calculate 30-min CO 2 fluxes according to BREB system theory (Bowen, 1926;Kanemasu et al, 1979;Webb et al, 1980;Held et al, 1990;McGinn & King, 1990;Dugas, 1993;Perez et al, 1999, Rosenberg et al, 1983 using the following equations as reported by O'Dell et al (2015). Values of the Bowen ratio () were derived as:…”

Section: Micrometeorological Measurements and Data Analysismentioning

confidence: 99%

“…Similarly, recent work found greater C sequestration with no-till during the crop growing season using BREB in Lesotho and greater no-till sequestration when comparing fallow treatments with cover crops in Zimbabwe (O'Dell et al, 2014;O'Dell et al, 2015). Baker and Griffis (2005) compared the net ecosystem exchange (NEE) of contrasting tillage regimes and cover crops in a maize (Zea mays L.)-soybean (Glycine max L.) rotation using eddy covariance (EC) but found no significant differences in the NEE of strip tillage with a cover crop compared to conventional tillage with no cover crop.…”

Section: Introductionmentioning

confidence: 99%

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Reducing CO2 Flux by Decreasing Tillage in Ohio: Overcoming Conjecture with Data

O'Dell¹,

Eash²,

Hicks³

et al. 2018

JAS

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While the literature is clear about excessive tillage decreasing soil carbon (C) content, there are few experimental studies that document the comparative effects of soil and crop management on C sequestration. Using micrometeorology we measured CO 2 flux from a maize crop grown on both no-till and tilled soils in north-central Ohio. We used Bowen Ratio Energy Balance (BREB) systems to quantify the flux between the atmosphere and either the soil surface (at crop planting) or 0.2 m above the canopy once the crop was established and growing. The no-till plot sequestered 263 g CO 2 m -2 (90% confidence interval -432.1 to -99.9) while the tilled plot emitted 146 g CO 2 m -2 (90% confidence interval -53.3 to 332.2) during 104 days of the 2015 growing season; a net difference of 410 g CO 2 m -2 . The difference is statistically significant at the 90% confidence level (based on a bootstrap analysis). The results indicate that no-tillage practices can sequester C, maintain soil productivity, and ensure landscape sustainability.

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A Short-Term Assessment of Carbon Dioxide Fluxes under Contrasting Agricultural and Soil Management Practices in Zimbabwe

Cited by 9 publications

References 43 publications

How climate-smart is conservation agriculture (CA)? – its potential to deliver on adaptation, mitigation and productivity on smallholder farms in southern Africa

How climate-smart is conservation agriculture (CA)? – its potential to deliver on adaptation, mitigation and productivity on smallholder farms in southern Africa

On surface fluxes at night – the virtual chamber approach

Reducing CO2 Flux by Decreasing Tillage in Ohio: Overcoming Conjecture with Data

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