The world's agricultural system has come under increasing scrutiny recently as an important driver of global climate change, creating a demand for indicators that estimate the climatic impacts of ...agricultural commodities. Such carbon footprints, however, have in most cases excluded emissions from land‐use change and the proposed methodologies for including this significant emissions source suffer from different shortcomings. Here, we propose a new methodology for calculating land‐use change carbon footprints for agricultural commodities and illustrate this methodology by applying it to three of the most prominent agricultural commodities driving tropical deforestation: Brazilian beef and soybeans, and Indonesian palm oil. We estimate land‐use change carbon footprints in 2010 to be 66 tCO2/t meat (carcass weight) for Brazilian beef, 0.89 tCO2/t for Brazilian soybeans, and 7.5 tCO2/t for Indonesian palm oil, using a 10 year amortization period. The main advantage of the proposed methodology is its flexibility: it can be applied in a tiered approach, using detailed data where it is available while still allowing for estimation of footprints for a broad set of countries and agricultural commodities; it can be applied at different scales, estimating both national and subnational footprints; it can be adopted to account both for direct (proximate) and indirect drivers of land‐use change. It is argued that with an increasing commercialization and globalization of the drivers of land‐use change, the proposed carbon footprint methodology could help leverage the power needed to alter environmentally destructive land‐use practices within the global agricultural system by providing a tool for assessing the environmental impacts of production, thereby informing consumers about the impacts of consumption and incentivizing producers to become more environmentally responsible.
► Numerous agricultural practices can alter the soil inorganic carbon (SIC) cycle. ► SIC stocks can increase or decrease at rates as much as 1.0tCha−1yr−1. ► Net sequestration cannot be determined ...from SIC measurements alone. ► The supply and fate of reactants must be tracked well beyond the root zone.
In many important agricultural regions, soil inorganic carbon (SIC) stocks can rival the amount of carbon found in organic form. Land management practices, including irrigation, fertilization and liming, have the potential to greatly alter the soil inorganic carbon cycle thus creating an important feedback to atmospheric CO2 concentrations. However, the current literature is less clear regarding the direction and magnitude of this feedback. Application of irrigation water, for example, can increase the rate of soil carbonate precipitation, but depending on the source of calcium and bicarbonate, the net reaction can be an atmospheric carbon sink, a carbon source or carbon neutral. Similarly, the accelerated dissolution of soil carbonates due to various acidifying processes can act as a net sink or source of atmospheric CO2 depending on the spatial and temporal frame of reference. While SIC stocks in agricultural soils have been found to increase or decrease by as much as 1.0tCha−1yr−1, given the need to account for both the supply and fate of reactants and reaction products, ascribing these stock changes as a net sink or net source activity is difficult. This review paper provides an overview of the major inorganic carbon transformations in soils as affected by agricultural management, including the practice of liming to raise soil pH, and when these transformations should be considered a net atmospheric carbon source or sink.
Agriculture is the main source of terrestrial emissions of N2O, a potent greenhouse gas and the main cause of ozone layer depletion. The reduction of N2O into N2 by microorganisms carrying the ...nitrous oxide reductase gene (nosZ) is the only biological process known to eliminate this greenhouse gas. Recent studies showed that a previously unknown clade of N2O-reducers was related to the capacity of the soil to act as an N2O sink, opening the way for new strategies to mitigate emissions. Here, we investigated whether the agricultural practices could differently influence the two N2O reducer clades with consequences for denitrification end-products. The abundance of N2O-reducers and producers was quantified by real-time PCR, and the diversity of both nosZ clades was determined by 454 pyrosequencing. Potential N2O production and potential denitrification activity were used to calculate the denitrification gaseous end-product ratio. Overall, the results showed limited differences between management practices but there were significant differences between cropping systems in both the abundance and structure of the nosZII community, as well as in the rN2O/r(N2O+N2) ratio. More limited differences were observed in the nosZI community, suggesting that the newly identified nosZII clade is more sensitive than nosZI to environmental changes. Potential denitrification activity and potential N2O production were explained mainly by the soil properties while the diversity of the nosZII clade on its own explained 26% of the denitrification end-product ratio, which highlights the importance of understanding the ecology of this newly identified clade of N2O reducers for mitigation strategies.
Meeting human needs within the ecological limits of our planet calls for continuous reflection on, and redesigning of, agricultural technologies and practices. Such technologies include fertilisers, ...the discovery and use of which have been one of the key factors for increasing crop yield, agricultural productivity and food security. Fertiliser use comes, however, at an environmental cost, and fertilisers have also not been a very economically effective production factor to lift many poor farmers out of poverty, especially in African countries where application on poor soils of unbalanced compositions of nutrients in fertilisers has shown limited impact on yield increase. Agronomic practices to apply existing mineral fertilisers, primarily containing N, P and K, at the right time, the right place, in the right amount, and of the right composition can improve the use efficiency of fertilisers. However, the overall progress to reduce the negative side effects is inadequate for the desired transformation toward sustainable agriculture in poor countries. Globally, there have been no fundamental reflections about the role and functioning of mineral fertilisers over the past 5 decades or more, and compared to other sectors, dismal investments have been made in mineral fertiliser research and development (R&D). In this paper, we reflect on current fertilisers and propose a more deliberate adoption of knowledge of plant physiological processes—including the diversity of mineral nutrient uptake mechanisms, their translocation and metabolism—as an entry point in identifying the physicochemical “packaging” of nutrients, their composition, amount and timing of application to meet plant physiological needs for improved instantaneous uptake. In addition to delivery through the root, we suggest that efforts be redoubled with several other uptake avenues, which as of now are at best haphazard, for the delivery of nutrients to the plant, including above ground parts and seed coating. Furthermore, ecological processes, including nutrient-specific interactions in plant and soil, plant-microorganism symbiosis, and nanotechnology, have to be exploited to enhance nutrient uptake. It is hoped that concerted R&D efforts will be pursued to achieve these strategies.
► The impact of soil management on the humic substances was far less than expected. ► A lower accumulation of humic C was observed in the most disturbed soils. ► Forest soils may have a lower ...resilience to perturbations than grasslands soils. ► Periodical light tillage in the grasslands had a small impact on SOC sink.
The aim of this study was to assess the impact of different long term soil managements on soil organic matter (SOM) quantity and quality in a semi-arid Mediterranean dehesa-like agro-forestry system (North-East of Sardinia, Italy). Seven soil managements were compared: cork oak forest, pasture under oak trees, open pasture, hay crop under oak trees, open hay crop, grass-covered vineyard and tilled vineyard. Analyses include chemical and spectroscopic (FT-IR) characterization of the humic substances (fulvic acids, humic acids and humin) of the A horizons. Lower amounts of total organic C and humic substances were found in the more disturbed soils such as those of the tilled vineyard, while the other soil managements showed a rather similar pattern for many indices of SOM quality (e.g., HA-C/FA-C, fulvic H/C and humic and fulvic C/N ratios) and for spectroscopic characteristics. These results indicated that the impact of soil management on the humic composition was relatively low for these sub-acid (pH ranging from 5.1 to 6.4) sandy soils under Mediterranean type of climate. The relatively small differences between the forest and the grassland land uses also suggested that the periodical light tillage applied to the grassland did not strongly affect SOM accumulation in the topsoil of this land use. In the oak forest soils, a sharp decrease (–77%) of the organic C from the thin A1 to the A2 horizon was observed, which could constrain the resilience of these soils towards disturbance factors, while the grasslands soils, where the organic C sequestration occurred in a thick horizon, may be more resilient.
The compared soil managements revealed to be quite conservative, demonstrating that the traditional agro-silvo-pastoral management practices are effective in maintaining relatively good soil quality traits under semi-arid Mediterranean conditions.
•The Ecosystem Service rendered by trees on infiltration is site-dependent.•Trees’ presence in the pasture improved infiltrability and preferential flow.•Trees’ soil–water improvements were masked in ...the coffee agroforestry system.•Generalization of tree's hydrological services need broader empirical data.
We tested the hypothesis that trees have measurable effects on infiltrability, macroporosity, and preferential flows in agrosilvopastoral systems. Managing agricultural systems for water conservation is a critical component of sustainable systems. We investigated the relationship between infiltrability and the distance to the nearest tree, and whether differences in macroporosity can account for differences in infiltrability.
In both systems, preferential soil water flows were dominant compared to matrix flow. Trees in the pasture landscape improved infiltrability and preferential flow but had no significant effect in the coffee agroforestry system. After comparing rainfall intensity and frequency data to the measured infiltrability values, we conclude that trees in the pasture system reduce surface runoff at the highest observed rainfall intensities (>50mmh−1). The volcanic soils of the coffee plantation are less degraded and their high natural permeability has been maintained. Since the coffee plants at this site are established (40 years) perennial vegetation with substantial residues and extensive root systems like trees, they improve soil physical properties similarly to trees.
Trees increase hydrologic services in pasture lands, a rapidly expanding land use type across Latin America, and therefore may be a viable land management option for mitigating some of the negative environmental impacts associated with land clearing and animal husbandry. However, in land management practices where understorey perennial vegetation makes up a large proportion of the cover, such as for coffee agroforestry systems, the effect of trees on infiltration-related ecosystem services could be less pronounced
Agroecology is in fashion, and now constitutes a territory in dispute between social movements and institutionality. This new conjuncture offers a constellation of opportunities that social movements ...can avail themselves of to promote changes in the food system. Yet there is an enormous risk that agroecology will be co-opted, institutionalized, colonized and stripped of its political content. In this paper, we analyze this quandary in terms of political ecology: will agroecology end up as merely offering a few more tools for the toolbox of industrial agriculture, to fine tune an agribusiness system that is being restructured in the midst of a civilizational crisis or, alternatively, will it be strengthened as a politically mobilizing option for building alternatives to development? We interpret the contemporary dispute over agroecology through the lenses of contested material and immaterial territories, political ecology, and the first and second contradictions of capital.
► We modeled the influence of spatial complexity on relevant ecosystem services (ES). ► Spatial variation in ES other than crop production was complementarily explained by landscape composition and ...configuration. ► Combinations of configuration indices showed higher explanatory value than composition ones. ► Both antagonistic and synergistic availabilities of overall ES were observed at intermediate complexity according to spatial scale.
Despite general agreement on antagonist relationships between ecosystems capacity to simultaneously sustain the availability of regulating services and agricultural production, it is not clear how these tradeoffs operate in response to complexity loss at the rural landscapes level. Here we present a novel evaluation framework of ecosystem services (ES) and pose different response models to landscape complexity. Therefore, we tested the hypothesis that complementarities among different ES types increase and the strength of their apparent tradeoffs diminishes with the spatial complexity of the rural landscapes, using a one million has basin of the Argentine pampas as study case. According to correlation and principal component analysis, main ES tradeoffs among ES availability observed at two spatial scales were represented by crop production vs. the other evaluated ES types (OES), and in contrast with our prediction, their strength was not higher for the fine- than for the coarse-scale (relatively large and internally complex observation units). Landscape composition and configuration indices showed a complementary capacity to explain spatial variation in OES, but combinations of configuration indices showed a higher explanatory value than composition ones. Widely accepted tradeoffs among ecosystem services at local levels, not only were able to explain their antagonistic but also their synergistic availability at intermediate levels of conversion of managed grasslands to croplands, depending on the evaluation scale. Despite intermediate complexity hypothesis was only partly supported by our results, these offer novel evidences about emergent responses in the form of nonlinearities and thresholds of total ES in relation to landscape complexity, which deserve further attention because of their relevance for land use planning.
CONTEXT: In Guadeloupe, the use of a persistent pesticide (chlordecone) contaminated one third of the island’s agricultural soils, causing a major environmental crisis. In the aftermath, banana ...farmers significantly changed their management practices to decrease their pesticide use. With the support of research, farmers have tested and adopted various agroecological practices, such as planting cover crops and using vitroplants and fallow. However, the use of animals to decrease pesticide use on banana plantations has not yet been explored. OBJECTIVE: This study aimed to co-design agroecological cropping systems that integrate animals as an alternative means to manage weeds.METHODS: The study was based on co-design workshops involving farmers, advisors and scientists, a survey of local practices of integrating animals within cropping systems, on-farm experiments with four farmers during which a total of 20 four-month-old male lambs were introduced within their cropping systems, and reflexive monitoring two and six months after the end of the experiments.RESULTS AND CONCLUSIONS: The introduction of sheep into cropping systems was the option deemed the most promising after three co-design workshops. Animals already were integrated into some banana-based farming systems in the study area, but this integration mainly consisted of cattle grazing on fallow land. The on-farm experiments highlighted that sheep made it possible to reduce the herbaceous cover on banana plantations by almost 60%. The growth performance of the lambs allowed by the herbaceous cover was within the range observed for this breed when reared on pastures (50–139 g/day). In this experiment, the lambs were not reared for meat, since the animals were, unsurprisingly, contaminated by chlordecone. The farmers appreciated that the practice enabled them to eliminate a labor-intensive activity (removing by hand the vines around the banana pseudo-stem) and radically reduce brush cutting. Piloted by a technical institution providing farmers technical support, initial changes in the broader socio-technical regime were observed.SIGNIFICANCE: This study highlights a co-design process of agroecological cropping systems involving agronomists, animal scientists, and farmers that led to an innovative, animal-based method of managing weeds within banana cropping systems with positive preliminary adoption outcomes as new farmers start using the practice. Inspired by similar efforts in vineyards, cereal and oil palm plantations, it is one of the first attempts to introduce sheep into banana cropping systems. The challenge is now to support this adoption at the territorial scale through possible cooperation between breeders and farmers, the training of farmers, and finding a means to ensure the safety of sheep.
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