Which crop production system is more efficient in energy use: wheat or barley?

Efficient use of energy helps to achieve increased production and productivity and contributes to the economy, profitability, and competitiveness of agricultural sustainability of rural communities. Evaluation of wheat and barley production systems in view of energy balance was conducted in Khorasan Razavi Province, Iran. Data were collected by using a face-to-face questionnaire from wheat and barley fields in 2011. Results revealed that total energy input for wheat was 51,040 MJ ha^?1 and for barley 44,866; in wheat and barley systems, renewable energy was consumed by 25.43 and 23.53 %, while non-renewable energy was consumed by 74.57 and 76.47 %, respectively. Energy use efficiency, energy productivity, and net energy were 1.7 kg MJ^?1, 0.088 kg MJ^?1, and 35,987 MJ ha^?1 in wheat system and 1.83 kg MJ^?1, 0.092 kg MJ^?1, and 33,833 MJ ha^?1 in barley system, respectively. Energy intensiveness in wheat fields (61.84 MJ $^?1) was higher than in barley fields (58.71 MJ $^?1). Also, benefit-to-cost ratio in wheat system (1.59) was higher than in barley system (1.35). In general, production in barley fields was more sustainable than wheat production because, in view of ecological indices such as amount of energy use and renewable energy consumption, it was more environment-friendly production.     

Ecological and economic impacts of different irrigation and fertilization practices: case study of a watershed in the southern Iran

Best management practices, such as conservation tillage, the optimum level of irrigation, fertilization, are frequently used to reduce non-point source pollution from agricultural land and improve water quality. In this study, we used the soil and water assessment tool to model the impacts of different irrigation (adjusted to crop need), cropping and fertilization practices on total nitrogen loss. The economic impacts of these practices on crop net farm income were also evaluated. For this purpose, the model was calibrated through comparing model outputs with observations to ensure reliable hydrologic, crop yield and nitrate leaching simulations. The results showed that by reducing water or fertilizer or combination of both, we can reduce nitrate leaching. For wheat and corn, the best scenario was S1n1 (combination between reduction by 10 % of water and nitrogen fertilizer application, simultaneously) and S2n3 (combination of 20 and 30 % reduction in water and fertilizer application), respectively. These scenarios are both ecologically and economically desirable. Also, decreasing nitrogen fertilization by 50 % for corn would decrease the nitrate pollution from 101.1 to 32.3 kg N ha^?1; therefore, this strategy is ecologically desirable but economically unsound. So, there are opportunities for environmental decision makers to encourage farmers to implement these strategies. Also, since the nitrogen leaching cannot decrease without a reduction in net farm income for crops such as corn; hence, the losses of farmers should be compensated.     

Mitigation of greenhouse gas emissions from an abandoned Baltic peat extraction area by growing reed canary grass: life-cycle assessment

Abandoned peat extraction areas are continuous emitters of GHGs; hence, abandonment of peat extraction areas should immediately be followed by conversion to an appropriate after-use. Our primary aim was to clarify the atmospheric impact of reed canary grass (RCG, Phalaris arundinacea L.) cultivation on an abandoned peat extraction area and to compare it to other after-treatment alternatives. We performed a life-cycle assessment for five different after-use options for a drained organic soil withdrawn from peat extraction: (I) bare peat soil (no management), (II) non-fertilised Phalaris cultivation, (III) fertilised Phalaris cultivation, (IV) afforestation, and (V) rewetting. Our results showed that on average the non-fertilised and fertilised Phalaris alternatives had a cooling effect on the atmosphere (?10,837 and ?477 kg CO₂-eq ha^?1 year^?1, respectively), whereas afforestation, rewetting, and no-management alternatives contributed to global warming (9,511, 8,195, and 2,529 kg CO₂-eq ha^?1 year^?1, respectively). The main components influencing the global warming potential of different after-use alternatives were site GHG emissions, carbon assimilation by plants, and emissions from combustion, while management-related emissions played a relatively minor role. The results of this study indicate that, from the perspective of atmospheric impact, the most suitable after-use option for an abandoned peat extraction area is cultivation of RCG.     

Factors influencing farmers’ decisions on nitrogen fertilizer application in the Liangzihu Lake basin,Central China

Overuse of nitrogen (N) fertilizers in agriculture activities has caused severe water pollution in China. The lack of data at producer level hampers decision makers in the development and implementation of efficient policies to curb excessive N-fertilizer use. In a survey of 300 farm households in the Liangzihu Lake basin, we identified factors associated with farmers’ decisions on N-fertilizer use and application rate. Household survey and multiple linear regression models indicate that the average application rate in the study region is 229 kg N ha^?1, which exceeds the recommended rate for maximum profit for cereal crops (maize, wheat, and rice) in China of 150–180 kg N ha^?1. High N-application rates are associated with low farmland productivity (coefficient = ?15.66, p = 0.02), a high share of off-farm income (coefficient = 27.14, p = 0.003), and a low education level of the household head (coefficient = ?10.83, p = 0.039). Neither physical infrastructure nor access to input markets appears to be related to N-application rates. It may be concluded that excessive use of N in agriculture of Central China is mainly a problem of insufficient awareness and high share of off-farm income.     

How changes in diet and trade patterns have shaped the N cycle at the national scale: Spain (1961–2009)

During the last five decades (1961–2009), Spain has experienced a considerable expansion in the nutrient cycle of its agricultural sector and, in particular, a threefold increase in anthropogenic reactive nitrogen inputs, from 536 Gg N year^?1 in 1961–1965 to 1673 Gg N year^?1 in 2005–2009. Import of feed (soybean, cereals, and cakes) from America and Europe to supply a growing livestock population constitutes the largest share of this increase, along with intensification of synthetic fertilizer use. While in the early 1960s, Spain was nearly self-sufficient in terms of food and feed supply, the net import of agricultural products presently equals domestic crop production, when expressed in terms of nitrogen content (ca. 650 Gg N year^?1). The most important driver of this shift appears to be the rapid change in domestic consumption patterns, which evolved from a typical Mediterranean diet to an animal-protein-rich diet similar to the North European and American diets. Besides livestock production mostly for national consumption, the Spanish agricultural system has specialized in vegetal products with low N content such as olive oil, wine, vegetables, and citrus fruit, which are for the most part exported. The nitrogen load exported outside the Spanish borders by rivers is very low (6.5 % of the total net N input). As a result of the high import and low export of reactive nitrogen, the Spanish mainland is suffering from considerable pollution by local emissions of reactive nitrogen forms to air and water.     

Greenhouse gas emissions from a semi-arid tropical reservoir in northeastern Brazil

We estimated carbon dioxide (CO₂) and methane (CH₄) emissions by diffusion, ebullition, and degassing in turbines from a semi-arid hydropower reservoir in northeastern Brazil. Sampling sites were allocated within the littoral and deeper waters of one embayment, the main-stream, and at turbines. Annual carbon emissions were estimated at 2.3?×?10⁵?±?7.45?×?10⁴ t C year^?1, or in CO₂-equivalents (CO₂-eq) at 1.33?×?10⁶?±?4.5?×?10⁵ t CO₂-eq year^?1. Diffusion across the water surface was the main pathway accounting for 96% of total carbon emissions. Ebullition was limited to littoral areas. A slight accumulation of CO₂, but not of CH₄, in bottom waters close to the turbines inlet led to degassing emissions about 8?×?10³ t C year^?1. Emissions in littoral areas were higher than in main-stream and contribute to 40% of the total carbon. Carbon (C) emissions per electricity generated, at 60% of installed capacity, is 0.05 t C-CO₂-eq MWh^?1. The ratio increases to 0.09 t C-CO₂ MWh^?1, equating 80% of the emissions from natural gas and 40% of diesel or coal power plants. Retention time and benthic metabolism were identified as main drivers for carbon emissions in littoral areas, while water column mixing and rapid water flow are important factors preventing CH₄ accumulation and loss by degassing. Our results indicate that Itaparica Reservoir, located in the semi-arid region of Northeastern Brazil, acts as a source of GHGs. Management measurements are needed to prevent emissions to raise in the future.     

Use patterns of natural resources supporting livelihoods of smallholder communities and implications for climate change adaptation in Zimbabwe

Declining crop and livestock production due to a degrading land resource base and changing climate among other biophysical and socio-economic constraints, is increasingly forcing rural households in Zimbabwe and other parts of Southern Africa to rely on common natural resource pools (CNRPs) to supplement their household food and income. Between 2011 and 2013, we combined farmer participatory research approaches, remote sensing and geographic information systems (GIS) to (1) understand the contribution of CNRPs to household food and income in Dendenyore and Ushe smallholder communities in Hwedza District, eastern Zimbabwe and (2) assess changes of the CNRPs in both space and time, and their implications on climate change adaptation. Across study sites, wetlands and woodlands were ranked as the most important CNRPs. Extraction and use patterns of products from the different pools differed among households of different resource endowment. Resource-constrained households (RG3) sold an average of 183 kg household^?1 year^?1 of wild loquats fruits (Uapaca kirkiana), realising about US$48, while resource-endowed farmers (RG1) had no need to sale any. The RG3 households also realised approximately US$70 household^?1 year^?1 from sale of crafts made from water reeds (Phragmites mauritianus). Empirical data closely supported communities’ perceptions that CNRPs had declined significantly in recent years compared with two to three decades ago. More than 60 % of the respondents perceived that the availability of natural resources drawn from wetlands and woodlands, often used for food, energy and crafts, has decreased markedly since the 1980s. Classification of land cover in a GIS environment indicated that CNRPs declined between 1972 and 2011, supporting farmers’ perceptions. Overall, woodlands declined by 37 % in both communities, while the total area under wetlands decreased by 29 % in Ushe, a drier area and 49 % in Dendenyore, a relatively humid area. The over-reliance in CNRPs by rural communities could be attributed to continued decline in crop yields linked to increased within-season rainfall variability, and the absence of alternative food and income sources. This suggests limited options for rural communities to adapt to the changing food production systems in the wake of climate change and variability and other challenges such as declining soil fertility. There is therefore a need to design adaptive farm management options that enhance both crop and livestock production in a changing climate as well as identifying other livelihood alternatives outside agriculture to reduce pressure on CNRPs. In addition, promotion of alternative sources of energy such as solar power and biogas among rural communities could reduce the cutting of trees for firewood from woodlands.     

Direct N2O emission from agricultural soils in Poland between 1960 and 2009

Nitrogen fertilization (N) is commonly known as a main source of direct nitrous oxide (N₂O) emission from agricultural soils. An area of 38 % of the total land surface of Poland was covered by agricultural soils in 2009. In this paper, we aimed at analyzing data regarding the land exploitation for 13 selected subareas of Poland between 1960 and 2009. Seven out of the 13 subareas studied are located in the West (area A), and six subareas are located in southeast of Poland (area B). The total area covered by large farms (>20 ha) differed largely, between area A (10.6 %) and area B (0.9 %) in 2009. Both areas varied in terms of the amount of fertilizers used annually, average crop yield and crop structure. Average direct emissions of N₂O from agricultural soils were 1.66 ± 0.09 kg N₂O–N ha^?1 a^?1 for area A, 1.39 ± 0.07 kg N₂O–N ha^?1 a^?1 for area B and 1.46 ± 0.07 kg N₂O–N ha^?1 a^?1 for the whole country between 1960 and 2009.     

Extractable soil nutrient effects on feed quality traits of crop residues in the semiarid rainfed mixed crop–livestock farming systems of Southern India

In the mixed crop–livestock systems, while general relation among feed quality, productivity and soil nutrient management have been reported, information on the effects of extractable soil nutrients on crop residue (CR) feed quality traits is scarce (e.g. in semiarid regions of Karnataka, India). In view of the increasingly important role of CR as feed components, in these farming systems, generating such information is a relevant research issue for sustainable development. Here, we report the occurrence and strength of relationships among extractable nutrients in soils and CR feed quality traits, and the effects of improved nutrients input on feed availability and feed quality of CR. Soil samples were collected from farmers’ fields in the semiarid zone of Karnataka and analyzed for available phosphorus (P), potassium (K), sulphur (S), zinc (Zn) and boron (B) using standard laboratory methods. Soil test results were clustered as low, medium or high based on the level of nutrient concentration. Four major farming systems involving nine crops and 419 farms were selected for on-farm trials. Under every sample farm, a plot with farmer’s practice (control) and improved fertilizer inputs (combined application of nutrients found deficient by soil testing) were laid. Performance of crops was recorded. Samples were collected for CR feed quality trait analysis using Near Infrared Reflectance Spectroscopy. The result showed that for cereal and oil crops, extractable soil S was significantly negatively associated with anti-feed quality traits such as neutral detergent fibre (NDF), acid detergent fibre (ADF), acid detergent lignin (ADL) (P < 0.01), but significantly positively related to metabolizable energy (ME) and in vitro digestibility (P < 0.01). Extractable B and K levels were associated positively and significantly with NDF, ADF and ADL for oil crops and cereals. Crop level associations, for most crops, showed similar trend. Improved fertilizer inputs affected CR yield much more than it did the quality. It increased ME productivity (ME ha^?1) and thereof the potential milk yield ha^?1 by as high as 40 % over the control. Therefore, balanced nutrient inputs on crop land positively impact productivity of the livestock compartment of mixed crop–livestock farming system, and this knowledge can build on the currently perceived need and benefits of balanced nutrient replenishment in crop–livestock system.     

Elevation change and the vulnerability of Rhode Island (USA) salt marshes to sea-level rise

Salt marshes persist within the intertidal zone when marsh elevation gains are commensurate with rates of sea-level rise (SLR). Monitoring changes in marsh elevation in concert with tidal water levels is therefore an effective way to determine if salt marshes are keeping pace with SLR over time. Surface elevation tables (SETs) are a common method for collecting precise data on marsh elevation change. Southern New England is a hot spot for SLR, but few SET elevation change datasets are available for the region. Our study synthesizes elevation change data collected from 1999 to 2015 from a network of SET stations throughout Rhode Island (RI). These data are compared to accretion and water level data from the same time period to estimate shallow subsidence and determine whether marshes are tracking SLR. Salt marsh elevation increased at a mean overall rate of 1.40 mm year^?1 and ranged from ?0.33 to 3.36 mm year^?1 at individual stations. Shallow subsidence dampened elevation gain in mid-Narragansett Bay marshes, but in other areas of coastal RI, subsurface processes may augment surface accretion. In all cases, marsh elevation gain was exceeded by the 5.26 mm year^?1 rate of increase in sea levels during the study period. Our study provides the first SET elevation change data from RI and shows that most RI marshes are not keeping pace with short- or long-term rates of SLR. It also lends support to previous research that implicates SLR as a primary driver of recent changes to southern New England salt marshes.     

Energy and land use in worldwide agriculture: an application of life cycle energy and cluster analysis

Agriculture is expected to provide food in a sustainable manner while also partially contributing to the energy problem as well as to bio-material supply. Moreover, fossil fuels scarcity calls for an increase of energy efficiency in agricultural processes. This study evaluates patterns, trends, driving factors and trade-offs of energy use in selected agricultural systems and aims at grouping them into clusters with similar energy and social performances. Results show that in 2010 the highest power densities and energy intensities of production are found by crop sector of cluster 5 (China: 59.19 GJ/ha, 15.29 MJ/kg dm) and cluster 3 (Japan: 50.11 GJ/ha, 12.32 MJ/kg dm) as well as by livestock sector of cluster 3 (Japan: 328.47 GJ/ha, 103.08 MJ/kg dm), while the lowest values in clusters 2 and 4, including selected developing countries and USA. Cluster 3 (Japan) also shows the lowest energy intensity of economic value of crops (2.75 MJ/$), while cluster 5 (China) the highest one (23.96 MJ/$). Cluster analysis also sheds light on trends, identifying two groups: cluster 1*, gathering most European countries, USA and Japan, characterized by a decreasing trend of all energy indicators; and cluster 2*, including developing countries, the Netherlands and Spain, characterized by an increasing trend of indicators. Results highlight the importance of an integrated framework for evaluating energy use as well as of a multi-criteria approach to understand the trade-offs and interplay of performance indicators.     

Vegetation dynamics and climate change on the Loess Plateau,China: 1982–2011

Monitoring the dynamics of vegetation growth and its response to climate change is important to understand the mechanisms underlying ecosystem behaviors. This study investigated the relationship between vegetation growth and climate change during the growing seasons on the Loess Plateau in China by analyzing the normalized difference vegetation index (NDVI) derived from the Land Long Term Data Record dataset from 1982 to 2011. Results showed that growing-season NDVI had increased at an annual rate of 0.0028, particularly in the semi-arid and semi-humid regions. By contrast, the NDVI first increased from 1982 to 1994 (0.0013 year^?1, P < 0.05) and then decreased from 1994 to 2011 (0.0016 year^?1, P < 0.05) in the arid region. Temperature had a positive effect on NDVI in most periods within and across seasons in the semi-humid region but had no significant effect in the arid region. Precipitation had a positive effect on NDVI in the arid region in summer and in the semi-arid region in autumn. Summer precipitation was important for autumn vegetation growth in the arid region, whereas summer temperature increased autumn vegetation growth in the semi-arid and semi-humid regions. Further analyses supported the lag-time effects of climate change on vegetation growth on the Loess Plateau. Precipitation shifts had 15- to 18-month time lag effects on vegetation growth in the three climate regions. Vegetation NDVI had a 17-month lag response to temperature in the semi-arid region. Human activities should not be neglected in analyzing the relationship between vegetation growth and climate change on the Loess Plateau.     

Dynamic simulation of a decentralized polygeneration plant providing SNG,steam and power

The behaviour of a decentralized polygeneration plant providing synthetic natural gas (SNG), steam and electrical power is simulated in three scenarios in this study. The plant size is based on an assumed capacity of decentralized polygeneration plants processing 1070 m³ h^?1 (STP) of syngas. 396 m³ h^?1 (STP) of raw SNG, 0.4 t h^?1 of steam at 5 bar and 670 kW of electrical power can be generated by the plant at the reference scenario. Methanation reactor and steam generator are modelled in detail. Further results indicate that such a polygeneration plant can provide positive and negative operation reserves for the electricity network to the extent of 100% of the reference power output, while the amount of generated steam varies by less than 40%. At the same time, the generated SNG quality keeps constant. Lower variations in the amount of generated steam are applicable when reducing the operation reserve capacity.     

Regional carbon cycle responses to 25 years of variation in climate and disturbance in the US Pacific Northwest

Variation in climate, disturbance regime, and forest management strongly influence terrestrial carbon sources and sinks. Spatially distributed, process-based, carbon cycle simulation models provide a means to integrate information on these various influences to estimate carbon pools and flux over large domains. Here we apply the Biome-BGC model over the four-state Northwest US region for the interval from 1986 to 2010. Landsat data were used to characterize disturbances, and forest inventory data were used to parameterize the model. The overall disturbance rate on forest land across the region was 0.8 % year^?1, with 49 % as harvests, 28 % as fire, and 23 % as pest/pathogen. Net ecosystem production (NEP) for the 2006–2010 interval on forestland was predominantly positive (a carbon sink) throughout the region, with maximum values in the Coast Range, intermediate values in the Cascade Mountains, and relatively low values in the Inland Rocky Mountain ecoregions. Localized negative NEPs were mostly associated with recent disturbances. There was large interannual variation in regional NEP, with notably low values across the region in 2003, which was also the warmest year in the interval. The recent (2006–2010) net ecosystem carbon balance (NECB) was positive for the region (14.4 TgC year^?1). Despite a lower area-weighted mean NECB, public forestland contributed a larger proportion to the total NECB because of its larger area. Aggregated forest inventory data and inversion modeling are beginning to provide opportunities for evaluating model-simulated regional carbon stocks and fluxes.     

Estimating the effect of nitrogen fertilizer on the greenhouse gas balance of soils in Wales under current and future climate

The Welsh Government is committed to reduce greenhouse gas (GHG) emissions from agricultural systems and combat the effects of future climate change. In this study, the ECOSSE model was applied spatially to estimate GHG and soil organic carbon (SOC) fluxes from three major land uses (grass, arable and forest) in Wales. The aims of the simulations were: (1) to estimate the annual net GHG balance for Wales; (2) to investigate the efficiency of the reduced nitrogen (N) fertilizer goal of the sustainable land management scheme (Glastir), through which the Welsh Government offers financial support to farmers and land managers on GHG flux reduction; and (3) to investigate the effects of future climate change on the emissions of GHG and plant net primary production (NPP). Three climate scenarios were studied: baseline (1961–1990) and low and high emission climate scenarios (2015–2050). Results reveal that grassland and cropland are the major nitrous oxide (N₂O) emitters and consequently emit more GHG to the atmosphere than forests. The overall average simulated annual net GHG balance for Wales under baseline climate (1961–1990) is equivalent to 0.2 t CO₂e ha^?1 y^?1 which gives an estimate of total annual net flux for Wales of 0.34 Mt CO₂e y^?1. Reducing N fertilizer by 20 and 40 % could reduce annual net GHG fluxes by 7 and 25 %, respectively. If the current N fertilizer application rate continues, predicted climate change by the year 2050 would not significantly affect GHG emissions or NPP from soils in Wales.     

Greenhouse gases emissions from a closed old landfill cultivated with biomass crops

Closed landfills need after-closure rehabilitation. The chosen option should ensure greenhouse gases release, from the landfill, is not promoted once settled. The objective of this study was to estimate and confront, during different seasons, CH₄, CO₂ and N₂O emissions under three vegetation covers in a closed landfill in Buenos Aires, Argentina. CH₄ (methane), CO₂ (carbon dioxide) and N₂O (nitrous oxide) emissions from landfill’s technosol under spontaneous vegetation (control), Pennisetum purpureum and Miscanthus giganteus (biomass crops), were quantified with non-steady-state non-flow-through chambers, in July 2014 and from February to July 2015. A linear regression analysis was performed to relate the variables “flux of a gas” and “concentration of that gas” from the 3 treatments and 6 dates, separating the 5 sampling times. A high correlation between concentrations and fluxes of CO₂ and N₂O was found, but no correlation was established for CH₄. Mean emissions (2014–2015) varied from: ?2.3 to 639.41 mgCH₄ m^?2 day^?1, 3884 to 46,365 mgCO₂ m^?2 day^?1 and 0.40 to 14.59 mgN₂O m^?2 day^?1. Vegetation covers had no significant effect on CH₄ and N₂O concentration in time, but they had on CO₂ concentration. Season of the year had a significant effect on concentration of the three gases. This is the first study on CH₄, CO₂ and N₂O emissions from a landfill closed 27 years ago covered with biomass crops.     

Agronomic adaptation strategies under climate change for winter durum wheat and tomato in southern Italy: irrigation and nitrogen fertilization

Agricultural crops are affected by climate change due to the relationship between crop development, growth, yield, CO₂ atmospheric concentration and climate conditions. In particular, the further reduction in existing limited water resources combined with an increase in temperature may result in higher impacts on agricultural crops in the Mediterranean area than in other regions. In this study, the cropping system models CERES-Wheat and CROPGRO-Tomato of the Decision Support System for Agrotechnology Transfer (DSSAT) were used to analyse the response of winter durum wheat (Triticum aestivum L.) and tomato (Lycopersicon esculentum Mill.) crops to climate change, irrigation and nitrogen fertilizer managements in one of most productive areas of Italy (i.e. Capitanata, Puglia). For this analysis, three climatic datasets were used: (1) a single dataset (50?km?×?50?km) provided by the JRC European centre for the period 1975–2005; two datasets from HadCM3 for the IPCC A2 GHG scenario for time slices with +2°C (centred over 2030–2060) and +5°C (centred over 2070–2099), respectively. All three datasets were used to generate synthetic climate series using a weather simulator (model LARS-WG). Adaptation strategies, such as irrigation and N fertilizer managements, have been investigated to either avoid or at least reduce the negative impacts induced by climate change impacts for both crops. Warmer temperatures were primarily shown to accelerate wheat and tomato phenology, thereby resulting in decreased total dry matter accumulation for both tomato and wheat under the +5°C future climate scenario. Under the +2°C scenario, dry matter accumulation and resulting yield were also reduced for tomato, whereas no negative yield effects were observed for winter durum wheat. In general, limiting the global mean temperature change of 2°C, the application of adaptation strategies (irrigation and nitrogen fertilization) showed a positive effect in minimizing the negative impacts of climate change on productivity of tomato cultivated in southern Italy.     

Addressing food supply chain and consumption inefficiencies: potential for climate change mitigation

Globally, more than 30 % of all food that is produced is ultimately lost and/or wasted through inefficiencies in the food supply chain. In the developed world this wastage is centred on the last stage in the supply chain; the end-consumer throwing away food that is purchased but not eaten. In contrast, in the developing world the bulk of lost food occurs in the early stages of the supply chain (production, harvesting and distribution). Excess food consumption is a similarly inefficient use of global agricultural production; with almost 1 billion people now classed as obese, 842 million people are suffering from chronic hunger. Given the magnitude of greenhouse gas emissions from the agricultural sector, strategies that reduce food loss and wastage, or address excess caloric consumption, have great potential as effective tools in global climate change mitigation. Here, we examine the challenges of robust quantification of food wastage and consumption inefficiencies, and their associated greenhouse gas emissions, along the supply chain. We find that the quality and quantity of data are highly variable within and between geographical regions, with the greatest range tending to be associated with developing nations. Estimation of production-phase GHG emissions for food wastage and excess consumption is found to be similarly challenging on a global scale, with use of IPCC default (Tier 1) emission factors for food production being required in many regions. Where robust food waste data and production-phase emission factors do exist—such as for the UK—we find that avoiding consumer-phase food waste can deliver significant up-stream reductions in GHG emissions from the agricultural sector. Eliminating consumer milk waste in the UK alone could mitigate up to 200 Gg CO₂e year^?1; scaled up globally, we estimate mitigation potential of over 25,000 Gg CO₂e year^?1.     

Estimation of the nutrient inputs into river systems – experiences from German rivers

The nutrient discharges from point and diffuse sources in more than 200 German river basins were estimated for the periods 1983–1987 and 1993–1997 employing the MONERIS model. This model distinguishes between six diffuse pathways and point source emissions from waste water treatment plants and direct industrial discharges. It was estimated that the total nitrogen input into the German river systems amounts to about 819,000 t N year^–1 in the period 1993 to 1997. These emissions have decreased since the mid-eighties by about 266,000 t N year^–1, mainly caused by the reduction of point discharges. For phosphorus the emissions have been reduced by 56,290 t P year^–1 and amount to 37,250 t P year^–1 in the period 1993–1997. Based on emission data a retention module estimates riverine nutrient loads. The comparison of the model output with the observed loads shows a deviation as low as 30% and 50% for nitrogen and phosphorus, respectively. The regional resolution of the model indicates the relative importance of different pathways for phosphorus and nitrogen input into river systems. Electronic Publication     

Environmental externalities in relation to agricultural sector in Thailand with trade-linked analysis

Thailand plays an important role in the international trade of food and agricultural products, which is in alignment with its national strategy of serving as the “kitchen of the world.” When looking at its agricultural promotion and export policies, the country only counts the value gains from exports while neglecting environmental externalities related to plantation practices. The purpose of this study was to perform a trade-off analysis between consumptive water, land, and fertilizer use together with the economic values of major crops for export and consumption in the country. The results show that to gain income from agricultural exports, the country has exploited various natural resources. The area used to harvest rice, sugarcane, cassava, and rubber adds up to approximately 15.3 million ha: 7.2 million ha of which is for domestic consumption and 8.1 ha for export. To produce Thailand’s agricultural exports, total water use is estimated to be 49.8–67.5 billion m³ per year (61–65 %), while the amount used to produce crops for domestic consumption is 26.5–43.7 billion m³ per year (35–39 %). Meanwhile, 1,056–1,826 thousand tons (54 %) of fertilizer was used on crops for domestic consumption, and 1,222–1,370 thousand tons (46 %) of fertilizer was used on export crops. The best crop choice for export in terms of its export value, land use, fertilizer use, and water consumption is rubber. The worst crop choices for export are rice and cassava. More sustainable agricultural practices are needed to effect improvements such as increased yields and reduced fertilizer and water use.