Carbon Sequestration In Agricultural Soils Research Articles

How critical is the baseline to assess carbon sequestration in agricultural soils?

How critical is the baseline to assess carbon sequestration in agricultural soils?

The Twin Failures of the CDM: Recommendations for the "Copenhagen Protocol"

The Kyoto Protocol's Clean Development Mechanism (CDM) was intended to reduce greenhouse gas emissions while facilitating sustainable development in developing countries. However, most CDM projects contribute little to sustainable development and are inequitably distributed. The 15th Conference of the Parties to the United Nations Framework Convention on Climate Change, which will take place in Copenhagen in December 2009, is an opportunity to create a more effective version of the CDM. This paper argues that the CDM should be modified to include formal sustainable development requirements and to extend eligibility to additional land use, land-use change and forestry projects. In particular, the CDM should include credit for deforestation prevention, provide more scope for afforestation and reforestation projects, and encourage further study of agricultural soil carbon sequestration.

Carbon sequestration in agricultural soils in the Cerrado region of the Brazilian Amazon

The introduction of crop management practices after conversion of Amazon Cerrado into cropland influences soil C stocks and has direct and indirect consequences on greenhouse gases (GHG) emissions. The aim of this study was to quantify soil C sequestration, through the evaluation of the changes in C stocks, as well as the GHG fluxes (N 2O and CH 4) during the process of conversion of Cerrado into agricultural land in the southwestern Amazon region, comparing no-tillage (NT) and conventional tillage (CT) systems. We collected samples from soils and made gas flux measurements in July 2004 (the dry season) and in January 2005 (the wet season) at six areas: Cerrado, CT cultivated with rice for 1 year (1CT) and 2 years (2CT), and NT cultivated with soybean for 1 year (1NT), 2 years (2NT) and 3 years (3NT), in each case after a 2-year period of rice under CT. Soil samples were analyzed in both seasons for total organic C and bulk density. The soil C stocks, corrected for a mass of soil equivalent to the 0–30-cm layer under Cerrado, indicated that soils under NT had generally higher C storage compared to native Cerrado and CT soils. The annual C accumulation rate in the conversion of rice under CT into soybean under NT was 0.38 Mg ha −1 year −1. Although CO 2 emissions were not used in the C sequestration estimates to avoid double counting, we did include the fluxes of this gas in our discussion. In the wet season, CO 2 emissions were twice as high as in the dry season and the highest N 2O emissions occurred under the NT system. There were no CH 4 emissions to the atmosphere (negative fluxes) and there were no significant seasonal variations. When N 2O and CH 4 emissions in C-equivalent were subtracted (assuming that the measurements made on 4 days were representative of the whole year), the soil C sequestration rate of the conversion of rice under CT into soybean under NT was 0.23 Mg ha −1 year −1. Although there were positive soil C sequestration rates, our results do not present data regarding the full C balance in soil management changes in the Amazon Cerrado.

La politique optimale de séquestration du carbone par les sols agricoles en France

The Kyoto Protocol, which came in force in February 2005, allows countries to resort to supplementary activities consisting, in particular, in the sequestration of carbon in agricultural soils. Considering the importance of its agricultural land and its weak possibilities of low-cost reduction in GHG emissions (given the high nuclear share in electricity generation), France can exploit this opportunity. This paper analyzes the optimal path of carbon sequestration in French agricultural soils. Our model takes into account one of the essential characteristics of the dynamics of carbon storage in agricultural soils: the asymmetry of the sequestration/de-sequestration process. The calibration of the model on French data gives a clear-cut result: the adoption of sequestration practices must be permanent. A temporary sequestration is never optimal. Numerical simulations also show the sensitivity of the optimal policy to sequestration costs and to the bounded number of units of land on which a change of practice can take place at each date. The numerical results demonstrate that a permanent sequestration policy leads to temporary emission reductions. These annual reductions are very limited as compared to the Kyoto objectives for France.

Agricultural carbon sequestration, poverty, and sustainability

ABSTRACTThis paper explores the potential impacts of payments for agricultural soil carbon sequestration on poverty of farm households and on the sustainability of agricultural systems, using economic theory combined with evidence from three case studies in Kenya, Peru, and Senegal. The case studies indicate that the likely impact of carbon contracts will be to raise rural incomes and reduce the rate of soil carbon loss. In some cases, carbon contracts may be able to stabilize soil carbon stocks at a higher level than would otherwise be economically feasible. These findings suggest that carbon payments could have a positive impact on the sustainability of production systems while also reducing poverty. The analysis indicates that payments for environmental services are most likely to have a positive impact when they are implemented in an enabling economic and institutional environment.

The optimal carbon sequestration in agricultural soils: Do the dynamics of the physical process matter?

The Kyoto Protocol, which came into force in February 2005, allows countries to resort to ‘supplementary activities’, consisting particularly in carbon sequestration in agricultural soils. Existing papers studying the optimal carbon sequestration recognize the importance of the temporality of sequestration, but overlook the fact that it is an asymmetric dynamic process. This paper takes explicitly into account the temporality of sequestration. Its first contribution lies in the modelling of the asymmetry of the sequestration/de-sequestration process at a micro level, and of its consequences at a macro level. Its second contribution is empirical. We compute numerically the optimal path of sequestration/de-sequestration for specific damage and cost functions, and a calibration that mimics roughly the world conditions. We show that with these assumptions sequestration must be permanent, and that the error made when sequestration is supposed immediate can be very significant.

Review of literature on economics and policy of carbon sequestration in agricultural soils

PurposeThe purpose of this paper is to identify and describe key economic and policy‐related issues with regard to terrestrial C sequestration and provide an overview of the economics of C sequestration on agricultural soils in the USA.Design/methodology/approachRecent economic literature on carbon sequestration was reviewed to gather insights on the role of agriculture in greenhouse gas emissions mitigation. Results from the most salient studies were presented in an attempt to highlight the general consensus on producer‐level responses to C sequestration incentives and the likely mechanisms used to facilitate C sequestration activities on agricultural soils.FindingsThe likely economic potential of agriculture to store soil C appears to be considerably less than the technical potential. Terrestrial C sequestration is a readily implementable option for mitigating greenhouse gas emissions and can provide mitigation comparable in cost to current abatement options in other industries. Despite considerable research to date, many aspects of terrestrial C sequestration in the USA are not well understood.Originality/valueThe paper provides a useful synopsis of the terms and issues associated with C sequestration, and serves as an informative reference on the economics of C sequestration that will be useful as the USA debates future greenhouse gas emissions mitigation policies.

A diagnostic test for autocorrelation in increment-averaged data with application to soil sampling

Motivated by the problem of detecting spatial autocorrelation in increment- averaged data from soil core samples, we use the Cholesky decomposition of the inverse of an autocovariance matrix to derive a parametric linear regression model for autocovariances. In the absence of autocorrelation, the off-diagonal terms in the lower triangular matrix from the Cholesky decomposition should be identically zero, and so the regression coefficients should be identically zero. The standard F-test of this hypothesis and two bootstrapped versions of the test are evaluated as autocorrelation diagnostics via simulation. Size is assessed for a variety of heteroskedastic null hypotheses. Power is evaluated against autocorrelated alternatives, including increment-averaged Ornstein-Uhlenbeck and Matern processes. The bootstrapped tests maintain approximately the correct size and have good power against moderately autocorrelated alternatives. The methods are applied to data from a study of carbon sequestration in agricultural soils.

Semiparametric Mixed Models for Increment-Averaged Data With Application to Carbon Sequestration in Agricultural Soils

Adoption of conservation tillage practice in agriculture offers the potential to mitigate greenhouse gas emissions. Studies comparing conservation tillage methods to traditional tillage pair fields under the two management systems and obtain soil core samples from each treatment. Cores are divided into multiple increments, and matching increments from one or more cores are aggregated and analyzed for carbon stock. These data represent not the actual value at a specific depth, but rather the total or average over a depth increment. A semiparametric mixed model is developed for such increment-averaged data. The model uses parametric fixed effects to represent covariate effects, random effects to capture correlation within studies, and an integrated smooth function to describe effects of depth. The depth function is specified as an additive model, estimated with penalized splines using standard mixed model software. Smoothing parameters are automatically selected using restricted maximum likelihood. The methodology is applied to the problem of estimating a change in carbon stock due to a change in tillage practice.

Earthworm activity affects soil aggregation and organic matter dynamics according to the quality and localization of crop residues—An experimental study (Madagascar)

Soil organic matter (SOM) plays a central role in the functioning of ecosystems, and is beneficial from agronomic and from environmental point of view. Alternative cultural systems, like direct seeding mulch-based cropping (DMC) systems, enhance carbon (C) sequestration in agricultural soils and lead to an increase in soil macrofauna. This study aimed at evaluating in field mesocosms the effects of earthworms on SOM dynamics and aggregation, as influenced by residue quality and management. In the highlands of Madagascar, buckets were filled with 2 mm-sieved clayey Inceptisol. The effects of earthworm addition ( Pontoscolex corethrurus), residue addition (rice, soybean, and no addition), and localization of the residues (mulched or buried) were studied. After 5 months, soil from mesocosms with earthworms had significantly lower C concentration and higher proportion of large water-stable macroaggregates (>2000 μm) than those without earthworms, because of the production of large macroaggregates by earthworms. Earthworm effect on soil aggregation was greater with rice than with soybean residues. Casts (extracted from mesocosms with earthworms) were slightly enriched in C and showed significantly higher mineralization than the non-ingested soil (NIS), showing that at the time scale of our study, the carbon contained in the casts was not protected against mineralization. No difference in microbial biomass was found between casts and NIS. Complementary investigations are necessary to assess long-term effects of earthworm addition on SOM dynamics, the conditions of occurrence of physical protection, and the impact of earthworms on the structure of the microbial community.

Transfers and environmental co-benefits of carbon sequestration in agricultural soils: retiring agricultural land in the Upper Mississippi River Basin

This study investigates the carbon sequestration potential and co-benefits from policies aimed at retiring agricultural land in the Upper Mississippi River Basin, a large, heavily agricultural area. In addition to empirically measuring environmental co-benefits, we also compute economic transfers, which have sometimes been referred to as a co-benefit. Very little empirical work measuring the potential magnitude of these transfers has previously been undertaken. We compare and contrast alternative targeting schemes. We find that there are considerable amount of co-benefits and transfers and that the geographic distribution of co-benefits and transfers varies significantly with the specific benefit targeted. This implies that policy design related to targeting can have very important implications for both environmental conditions and income distributions in sub-regions. Issues related to policy design in the presence of co-benefits are considered.

Economic consequences of consideration of permanence, leakage and additionality for soil carbon sequestration projects

This paper introduces, explains, and describes methods for addressing the issues of permanence, leakage, and additionality (PLA) of agricultural soil carbon sequestration (ASCS) activities at the project level. It is important to cast these as project-level issues, because they relate to the integrity and consistency of using location-specific ASCS projects as an offset against GHG emissions generated in other sectors (e.g., energy). The underlying objective is to understand and quantify what the net carbon benefits of an ASCS project are once we account for the fact that (1) the sequestered carbon may be stored impermanently, (2) the project may displace emissions outside the project boundaries (leakage), and (3) the project’s carbon sequestration may not be entirely additional to what would have occurred anyway under business-as-usual (no project) conditions. This article evaluates methods for identifying and estimating PLA and gauges the potential magnitude of these effects on the economic returns to a project.

Estimating the economic potential for agricultural soil carbon sequestration in the Central United States using an aggregate econometric-process simulation model

The purpose of this paper is to develop and apply a new method to assess economic potential for agricultural greenhouse gas mitigation. This method uses secondary economic data and conventional econometric production models, combined with estimates of soil carbon stocks derived from biophysical simulation models such as Century, to construct economic simulation models that estimate economic potential for carbon sequestration. Using this method, simulations for the central United States show that reduction in fallow and conservation tillage adoption in the wheat-pasture system could generate up to about 1.7 million MgC/yr, whereas increased adoption of conservation tillage in the corn–soy–feed system could generate up to about 6.2 million MgC/yr at a price of $200/MgC. About half of this potential could be achieved at relatively low carbon prices (in the range of $50 per ton). The model used in this analysis produced estimates of economic potential for soil carbon sequestration potential similar to results produced by much more data-intensive, field-scale models, suggesting that this simpler, aggregate modeling approach can produce credible estimates of soil carbon sequestration potential. Carbon rates were found to vary substantially over the region. Using average carbon rates for the region, the model produced carbon sequestration estimates within about 10% of those based on county-specific carbon rates, suggesting that effects of spatial heterogeneity in carbon rates may average out over a large region such as the central United States. However, the average carbon rates produced large prediction errors for individual counties, showing that estimates of carbon rates do need to be matched to the spatial scale of analysis. Transaction costs were found to have a potentially important impact on soil carbon supply at low carbon prices, particularly when carbon rates are low, but this effect diminishes as carbon prices increase.

Modeling Soil Organic Matter Dynamics Under Intensive Cropping Systems on the Huang-Huai-Hai Plain of China

ABSTRACT A modified CQESTR model, a simple yet useful model frequently used for estimating carbon sequestration in agricultural soils, was developed and applied to evaluate the effects of intensive cropping on soil organic matter (SOM) dynamics and mineralization as well as to estimate carbon dioxide emission from agricultural soils at seven sites on the Huang-Huai-Hai Plain of China. The model was modified using site-specific parameters from short- and mid-term buried organic material experiments at four stages of biomass decomposition. The predicted SOM results were validated using independent data from seven long-term (10- to 20-year) soil fertility experiments in this region. Regression analysis on 1151 pairs of predicted and measured SOM data had an r2 of 0.91 (P ≤ 0.01). Therefore, the modified model was able to predict the mineralization of crop residues, organic amendments, and native SOM. Linear regression also showed that SOM mineralization rate (MR) in the plow layer increased by 0.22% when annual crop yield increased by 1 t ha−1 (P ≤ 0.01), suggesting an improvement in SOM quality. Apparently, not only did the annual soil respiration efflux merely reflect the intensity of soil organism and plant metabolism, but also the SOM MR in the plow layer. These results suggested that the modified model was simple yet valuable in predicting SOM trends at a single agricultural field and could be a powerful tool for estimating C-storage potential and reconstructing C storage on the Huang-Huai-Hai Plain of China.

Carbon Sequestration in Agricultural Soils: Discounting for Uncertainty

The study presents a conceptual model of an aggregator who selectively pays farmers for altering farming practices in exchange for carbon offsets that the change in practices generates. Under the assumption that the offsets are stochastic and that the aggregator maximizes the sum of the offsets from the purchase that he/she can rightfully claim with a specified level of confidence subject to a budget constraint, we investigate the optimal discounting of expected carbon offsets. We use the model to empirically estimate of the optimal discounting levels and costs for a hypothetical carbon purchasing project in the Upper Iowa River basin.

The Consequences of Cobenefits for the Efficient Design of Carbon Sequestration Programs

In this paper, we study the social efficiency of private carbon markets that include trading in agricultural soil carbon sequestration when there are significant cobenefits (positive environmental externalities) associated with the practices that sequester carbon. Likewise, we investigate the efficiency of government run conservation programs that are designed to promote a broad array of environmental attributes (both carbon sequestration and its cobenefits) for the supply of carbon. Finally, policy design and efficiency issues associated with the potential interplay between a private carbon market and a government conservation program are studied. Empirical analyses for an area that represents a significant potential source of carbon sequestration and its associated cobenefits illustrate the magnitude and complexity of these issues in real world policy design.

Assessing the impact of changes in climate and CO2 on potential carbon sequestration in agricultural soils

Changes in soil management can potentially increase the accumulation of soil organic carbon (SOC), thereby sequestering CO2 from the atmosphere. However, the amount of carbon sequestered in soils can be augmented or lessened due to changes in climate and atmospheric CO2 concentration. The purpose of this paper is to study the influence of climate and CO2 feedbacks on soil carbon sequestration using a terrestrial carbon cycle model. Model simulations consist of observed adoption rates of no‐tillage practices on croplands in the U.S. and Canada between 1981–2000. Model results indicate potential sequestration rates between 0.4–0.6 MgC/ha/yr in the Midwestern U.S. with decreasing rates towards the western, dryer regions of the U.S. It is estimated here that changes in climate and CO2 between 1981–2000 could be responsible for an additional soil carbon sequestration of 42 Tg. This is 5% of the soil carbon estimated to be potentially sequestered as the result of conversion to no‐tillage in the U.S. and Canada.

Management Strategies to Sequester Carbon in Agricultural Soils and to Mitigate Greenhouse Gas Emissions

Carbon sequestration in agricultural soils is frequently promoted as a practical solution for slowing down the rate of increase of CO2 in the atmosphere. Consequently, there is a need to improve our understanding of how land management practices may affect the net removal of greenhouse gases (GHG) from the atmosphere. In this paper we examine the role of agriculture in influencing the GHG budget and briefly discuss the potential for carbon mitigation by agriculture. We also examine the opportunities that exist for increasing soil C sequestration using management practices such as reduced tillage, reduced frequency of summer fallowing, introduction of forage crops into crop rotations, conversion of cropland to grassland and nutrient addition via fertilization. In order to provide information on the impact of such management practices on the net GHG budget we ran simulations using CENTURY (a C model) and DNDC (a N model) for five locations across Canada, for a 30-yr time period. These simulations provide information on the potential trade-off between C sequestration and increased N2O emissions. Our model output suggests that conversion of cropland to grassland will result in the largest reduction in net GHG emissions, while nutrient additions via fertilizers will result in a small increase in GHG emissions. Simulations with the CENTURY model also indicated that favorable growing conditions during the last 15 yr could account for an increase of 6% in the soil C at a site in Lethbridge, Alberta.

Nitrogen pools and fluxes in grassland soils sequestering carbon

Carbon sequestration in agricultural, forest, and grassland soils has been promoted as a means by which substantial amounts of CO2 may be removed from the atmosphere, but few studies have evaluated the associated impacts on changes in soil N or net global warming potential (GWP). The purpose of this research was to (1) review the literature to examine how changes in grassland management that affect soil C also impact soil N, (2) assess the impact of different types of grassland management on changes in soil N and rates of change, and (3) evaluate changes in N2O fluxes from differently managed grassland ecosystems to assess net impacts on GWP. Soil C and N stocks either both increased or both decreased for most studies. Soil C and N sequestration were tightly linked, resulting in little change in C:N ratios with changes in management. Within grazing treatments N2O made a minor contribution to GWP (0.1–4%), but increases in N2O fluxes offset significant portions of C sequestration gains due to fertilization (10–125%) and conversion (average = 27%). Results from this work demonstrate that even when improved management practices result in considerable rates of C and N sequestration, changes in N2O fluxes can offset a substantial portion of gains by C sequestration. Even for cases in which C sequestration rates are not entirely offset by increases in N2O fluxes, small increases in N2O fluxes can substantially reduce C sequestration benefits. Conversely, reduction of N2O fluxes in grassland soils brought about by changes in management represents an opportunity to reduce the contribution of grasslands to net greenhouse gas forcing.

The issues of energy and carbon cycle: new perspectives for assessing the environmental impact of animal waste utilization

This paper focuses on the benefits of an efficient use of animal waste from the standpoint of curbing the rise of anthropogenic carbon dioxide (CO 2) in the atmosphere. An effective use of animal waste resources might provide a partial, but still important, contribution in reducing net CO 2 emissions. In particular: the fulfilment of nutrient requirements of crop plants growing in non-limiting conditions and thus sequestering CO 2 at their potential level; the chance of diminishing the use of fossil energy, and related CO 2 emissions, required for manufacturing industrial fertilizers; the possibility of enhancing carbon sequestration in agricultural soils by the application of farmyard manure. The future success of agriculture in providing these ecosystem services can only be achieved with a changed social awareness of the links between sustainable land use and global environmental change.