► Field measurements show that soil erosion in olive orchards eroded nearly 30% of the soil profile over a 250-year time period. ► Models calibrated with historical data on soil management reflect ...the large temporal variation in soil erosion rates. ► Soil erosion rates are above critical thresholds for sustainability, even during historical periods with less intensive management. ► Agronomic practices resulted in continuously increasing yields since 1752.
Olive orchards are an important agro-ecosystem in the Mediterranean. Soil erosion is a widely recognized threat to their sustainability. However, the variability of short-term soil erosion measurements and the limited understanding of driving processes result in a considerable uncertainty over the long-term effects of soil erosion. This study aims at measuring and modelling soil erosion rates in olive orchards over a 250-year period, and relating these to changes in management practices and yield, as documented from historical sources. In three study areas in S-Spain, the height of relic tree mounds was measured in olive orchards dated between 153 and 291 years old to determine soil profile truncation. Measured average soil erosion rates were between 29 and 47
t
ha
−1
year
−1. Historical documents allowed characterizing land management since 1752 in eight distinct periods. This information was then used to calibrate a soil erosion model, combining water and tillage erosion. The model reproduced the temporal patterns in soil erosion rates and showed considerable historical variation: between 8 and 124
t
ha
−1
year
−1 for water and between 3 and 42
t
ha
−1
year
−1 for tillage. Mainly due to improved agronomic practices, yield was not affected by soil erosion and has continuously increased over time.
This article aims to situate a national case study of the global periphery at the core of the debate on the socio-ecological transition by drawing on new data of biomass flows in twentieth-century ...Colombia. We draw up a century-long annual series converting a wide set of indicators from Net Primary Production (NPP) into the final socioeconomic uses of biomass, distinguishing around 200 different categories of crops, forests, and pastures. Our calculations draw on FAOSTAT and several corpuses of national statistics. The results show a fall of 10% in total NPP related to land-use changes involving forest conversion. Throughout the twentieth century, pasture was the most relevant among domestic extraction. Allocations of cash crops to industrial processing rose while the figure for staple crops for primary food consumption stagnated. The critical role of cattle throughout all periods and the higher yields of the industrial cash crops are behind this profile. This might also mean the start of a new trend of using pasture land for more profitable export crops, which establishes a new inner frontier of land-use intensification. Lastly, the article points out the phases of the socio-metabolic transition of biomass, explores the changes in biomass flows by looking at the history of the main drivers, and identifies the socio-ecological impacts of deforestation and industrial agribusiness.
Summary
The aim of this work is to reconstruct the main economy‐wide/material flow accounting indicators for the Spanish economy between 1860 and 2010. The main results indicate that from 1960 ...onward, the country saw a very rapid industrial transition based on the domestic extraction of quarry products and the import of fossil fuels and manufactured goods. Direct material consumption rose from 58.7 million tonnes (Mt) in 1860 to 570.2 Mt in 2010. In per capita terms, it rose from 2.76 tonnes per capita per year (t/cap/yr) to 11.61 t/cap/year. Of the decennial years studied in this article, a peak of 15.23 t/cap/yr occurs in the year 2000; the subsequent fall is explained by the crisis of 2008. Until 1930, Spain was a net exporter of resources, but since that year, and especially since 1960, it began to depend heavily on overseas resources. The physical trade balance per inhabitant in Spain was –0.01 t/cap/year in 1860 and today it is 2.45 t/cap/year. This process also reveals the change in consumption patterns, which became increasingly dependent on abiotic resources. In 1860, 98.1% of resources consumed was biomass, whereas today the figure is 16.2%. In all events, this article shows how, although the great transformation did not occur until 1960, before that date the country saw significant qualitative transformation, which did not involve relevant changes in the mobilization of resources.
The role of trade in global environmental change is receiving increasing attention and there is a lively debate about Ecologically Unequal Exchange (EUE). Little is known, however, about the role of ...colonial legacy for the evolution of physical trade patterns. This study provides empirical evidence on the basis of a systematic evaluation of global trade data. We quantify, in physical and monetary terms, the development of trade relations between France, its former colonies and the rest the world from the immediate post-colonial period until 2015. We use a set of physical trade indicators including physical trade balance and terms of trade to analyse differences in trade patterns and EUE. The results indicate that colonial ties were very strong in the 1960s, but thereafter quickly diminished. We find strong evidence for EUE between France and its former colonies in the post-colonial period and that the colonial factor explains EUE between centre and peripheries better than income differences until the 1970s. In recent decades colonial legacy increasingly vanished. Our findings corroborate that socio-political factors, and in particular colonial legacy, play an important role for EUE relations and that they deserve more attention in quantitative empirical research on trade.
•Quantitative assessment of the significance of colonial legacy for Ecologically Unequal Exchange•Physical trade flows indicate strong colonial ties between France and its former colonies in the immediate post-colonial period.•Physical trade indicators provide evidence for Ecologically Unequal Exchange between France and its former colonies.•Terms of trade between France, its former colonies and the rest of the world converge over time•The colonial factor explains unequal trade relations better than income differences in the post-colonial years.
•We examine decoupling between augmented human development index and greenhouse gas emissions since 1870.•Wellbeing-growth decoupling is more common in low-income countries, while growth-impact ...decoupling is more common in higher income countries.•Growth-impact decoupling, i.e., ‘green growth’, is not new nor exclusively Western, and has proved reversible.•No world region has reached a ‘safe and just operating space’ at any point in the last 150 years.
Since the Industrial Revolution, modern economic growth has made the world increasingly (if unevenly) rich. This trajectory led to unprecedented improvements in human wellbeing but, at the same time, produced environmental impacts which threaten material prosperity itself. Against this background, the great challenge of the 21st century is to continue to improve global wellbeing while mitigating environmental impacts. For most international organizations and scholars this can be achieved by decoupling economic growth from its environmental costs (as in green growth proposals). However, other scholars question the feasibility of sustaining growth with a sufficiently large fall in its ecological footprint, arguing instead for decoupling wellbeing from economic growth (as in post-growth strategies). How common were these two forms of decoupling in the past? When and where did societies manage to separate wellbeing improvements from environmental impacts? The answers to these questions can allow us to trace the long-run direction of travel of the global economy and to rethink the historical narrative of the emergence and consolidation of modern economic growth by considering its impacts on human wellbeing and environmental change at the same time. We offer the first long-term analysis of decoupling patterns between an augmented human development index (AHDI) and greenhouse gas emissions (GHGe). Moreover, we identify when these patterns were explained by ‘growth decoupling’ (GDP grows faster than GHGe), by ‘wellbeing decoupling’ (AHDI grows faster than GDP per capita), by both, or by neither. Our results show that at low income levels all world regions experienced episodes of wellbeing decoupling; as they became richer, growth decoupling became more common. Nevertheless, we find that such decoupling episodes have proved reversible and that no country in the world has yet managed to achieve very high levels of human wellbeing within planetary boundaries.
Abstract
Synthetic nitrogen (N) fertilization has helped boost agricultural yields, but it is also responsible for direct and indirect greenhouse gas (GHG) emissions. Fertilizer-related emissions are ...also promoted by irrigation and manure application, which has increased with livestock industrialization. Spanish agriculture provides a paradigmatic example of high industrialization under two different climates (temperate and Mediterranean) and two contrasting water management regimes (rainfed and irrigated). In this study, we estimated the historical evolution of the C footprint of N fertilization (including all the life cycle GHG emissions related to N fertilization) in Spanish agriculture from 1860 to 2018 at the province level (50 provinces) for 122 crops, using climate-specific N
2
O emission factors (EFs) adjusted to the type of water management and the N source (synthetic fertilizer, animal manure, crop residues and soil N mineralization) and considering changes in the industrial efficiency of N fertilizer production. Overall, N-related GHG emissions increased ∼12-fold, up to 10–14 Tg CO
2
e yr
−1
in the 2010s, with much higher growth in Mediterranean than in temperate areas. Direct N
2
O EFs of N fertilizers doubled due to the expansion of irrigation, synthetic fertilizers and liquid manure, associated with livestock industrialization. Synthetic N production dominated the emissions balance (55%–60% of GHGe in the 21st century). Large energy efficiency gains of industrial fertilizer production were largely offset by the changes in the fertilizer mix. Downstream N
2
O emissions associated with NH
3
volatilization and NO
3
−
leaching increased tenfold. The yield-scaled carbon footprint of N use in Spanish agriculture increased fourfold, from 4 and 5 Mg CO
2
e Mg N
−1
to 16–18 Mg CO
2
e Mg N
−1
. Therefore, the results reported herein indicate that increased productivity could not offset the growth in manufacture and soil emissions related to N use, suggesting that mitigation efforts should not only aim to increase N use efficiency but also consider water management, fertilizer type and fertilizer manufacture as key drivers of emissions.
Agrarian metabolism applies the social metabolism framework to agriculture. It focuses on the study of the exchange of material and energy flows between a society and its environment for producing ...useful biomass. These flows must maintain the fund elements of the agroecosystem in sufficient quantity and of sufficient quality for them to continue providing ecosystem services. This methodology was applied to Spanish agriculture between 1960 and 2008, a period characterized by a deep process of intensification based on external inputs (EIs). We specifically focused on nitrogen (N), phosphorus (P), potassium (K), carbon (C), and energy flows, and on the three fund elements that they sustain such as soil, biodiversity, and woodland. The results show that the growing incorporation of EIs has broken the equilibrium between land and biomass uses required by traditional farming, lowering the density of internal energy loops. On cropland, the relative fall in unharvested biomass had a negative effect on both biodiversity and the soil, which reduced the replenishment of organic C between 1960 and 1990. The sharp increase in internal and external flows of biomass for animal feed hardly contributed to increasing soil organic carbon (SOC) between 1990 and 2008 because of the fact that these flows had increasingly lower C:N ratios. The massive importation of N in feed and mineral fertilizers (553 and 1150 Gg in 2000, respectively) increased the surplus and the losses of N, which in turn could have a negative impact on biodiversity, water, and the atmosphere. The scenario constructed without imported animal feed would allow a reduction in the environmental impacts related to the excess of N, with hardly any negative effect on SOC replenishment, and improving energy return rates in the form of total, unharvested, and accumulated phytomass.
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► Radioisotopic and physicochemical background was established in an undisturbed Spanish archaeological site. ► Using the 137Cs method, erosion rates reaching 19tha−1yr−1 were ...evaluated in a nearby olive orchard field. ► Naturally occurring radionuclides (i.e. 40K, 226Ra and 232Th) and gamma dose rate varied according to soil redistribution processes.
Soil degradation is a major agrienvironmental issue under Mediterranean climatic conditions. To assess soil erosion magnitude under orchard plantation, soils in an undisturbed area – located within an archaeological protected site in southern Spain – were analysed to establish its physicochemical status, the initial 137Cs fallout and the natural level of radioactivity taking into account the content of naturally occurring radionuclides (NOR). The vertical profiles of NOR mass activities confirmed its non-disturbance. 90% of the 137Cs content was concentrated in the top 20cm and the physicochemical parameters confirmed as well the undisturbed status of the site. The base-line level of 137Cs was established at 1925±250Bqm−2 with a coefficient of variation of 23% and an allowable error of 11%. This 137Cs background was used to assess soil erosion magnitude in a close orchard field using the 137Cs method. The maximum erosion rates reached 19t−1ha−1yr−1 and a sediment delivery ratio of 29% was evaluated, both values confirming an unsustainable soil loss magnitude due to the combination of water and tillage erosion processes since the 1950s. The radium equivalent activity and the absorbed dose rate results highlighted a difference between eroded and deposition sectors in the cultivated field confirming that these parameters could be used to some extend to assess pedologic processes.
Abstract
Overuse of N fertilizers in crops has induced the disruption of the N cycle, triggering the release of reactive N (Nr) to the environment. Several EU policies have been developed to address ...this challenge, establishing targets to reduce agricultural Nr losses. Their achievement could be materialized through the introduction of fertilizing innovations such as incorporating fertilizer into soils, using urease inhibitors, or by adjusting N inputs to crop needs that could impact in both yields and environment. The Murcia region (southeastern Spain) was selected as a paradigmatic case study, since overfertilization has induced severe environmental problems in the region in the last decade, to assess the impact of a set of 8 N fertilizing alternatives on crop yields and environmental Nr losses. Some of these practices imply the reduction of N entering in crops. We followed an integrated approach analyzing the evolution of the region in the long-term (1860–2018) and considering nested spatial- (from grid to region) and systems scales (from crops to the full agro-food system). We hypothesized that, even despite reduction of N inputs, suitable solutions for the abatement of Nr can be identified without compromising crop yields. The most effective option to reduce Nr losses was removing synthetic N fertilizers, leading to 75% reductions in N surpluses mainly due to a reduction of 64% of N inputs, but with associated yield penalties (31%–35%). The most feasible alternative was the removal of urea, resulting in 19% reductions of N inputs, 15%–21% declines in N surplus, and negligible yield losses. While these measures are applied at the field scale, their potential to produce a valuable change can only be assessed at regional scale. Because of this, a spatial analysis was performed showing that largest Nr losses occurred in irrigated horticultural crops. The policy implications of the results are discussed.
•Optimized N fertilization and irrigation show a large potential for N2O mitigation.•Reduced tillage and crop residues management show a large potential for reducing net GHG emissions.•CH4 fluxes ...from paddies are controlled by management of water table and organic inputs.•Factors beyond the plot scale may outweigh mitigation measures.•Training to farmers on the application of practices will overcome barriers for implementation.
An integrated assessment of the potential of different management practices for mitigating specific components of the total GHG budget (N2O and CH4 emissions and C sequestration) of Mediterranean agrosystems was performed in this study. Their suitability regarding both yield and environmental (e.g. nitrate leaching and ammonia volatilization) sustainability, and regional barriers and opportunities for their implementation were also considered. Based on its results best strategies to abate GHG emissions in Mediterranean agro-systems were proposed. Adjusting N fertilization to crop needs in both irrigated and rain-fed systems could reduce N2O emissions up to 50% compared with a non-adjusted practice. Substitution of N synthetic fertilizers by solid manure can be also implemented in those systems, and may abate N2O emissions by about 20% under Mediterranean conditions, with additional indirect benefits associated to energy savings and positive effects in crop yields. The use of urease and nitrification inhibitors enhances N use efficiency of the cropping systems and may mitigate N2O emissions up to 80% and 50%, respectively. The type of irrigation may also have a great mitigation potential in the Mediterranean region. Drip-irrigated systems have on average 80% lower N2O emissions than sprinkler systems and drip-irrigation combined with optimized fertilization showed a reduction in direct N2O emissions up to 50%. Methane fluxes have a relatively small contribution to the total GHG budget of Mediterranean crops, which can mostly be controlled by careful management of the water table and organic inputs in paddies. Reduced soil tillage, improved management of crop residues and agro-industry by-products, and cover cropping in orchards, are the most suitable interventions to enhance organic C stocks in Mediterranean agricultural soils. The adoption of the proposed agricultural practices will require farmers training. The global analysis of life cycle emissions associated to irrigation type (drip, sprinkle and furrow) and N fertilization rate (100 and 300kgNha−1yr−1) revealed that these factors may outweigh the reduction in GHG emissions beyond the plot scale. The analysis of the impact of some structural changes on top-down mitigation of GHG emissions revealed that 3–15% of N2O emissions could be suppressed by avoiding food waste at the end-consumer level. A 40% reduction in meat and dairy consumption could reduce GHG emissions by 20–30%. Reintroducing the Mediterranean diet (i.e. ∼35% intake of animal protein) would therefore result in a significant decrease of GHG emissions from agricultural production systems under Mediterranean conditions.
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