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See detailRotational and continuous grazing does not affect the total net ecosystem exchange of a pasture grazed by cattle but modifies CO2 exchange dynamics
Gourlez de la Motte, Louis ULiege; Mamadou, Ossenatou; Beckers, Yves ULiege et al

in Agriculture, Ecosystems & Environment (2018), 253

Grassland carbon budgets are known to be greatly dependent on management. In particular, grazing is known to directly affect CO2 exchange through consumption by plants, cattle respiration, natural ... [more ▼]

Grassland carbon budgets are known to be greatly dependent on management. In particular, grazing is known to directly affect CO2 exchange through consumption by plants, cattle respiration, natural fertilisation through excreta, and soil compaction. This study investigates the impact of two grazing methods on the net ecosystem exchange (NEE) dynamics and carbon balance, by measuring CO2 fluxes using eddy covariance in two adjacent pastures located in southern Belgium during a complete grazing season. Rotational (RG) grazing consists of an alternation of rest periods and short high stock density grazing periods. Continuous grazing (CG) consists of uninterrupted grazing with variable stocking rates. To our knowledge, this is the first study to assess the impact of these grazing methods on total net ecosystem exchange and CO2 exchange dynamics using eddy covariance. The results showed that NEE dynamics were greatly impacted by the grazing method. Following grazing events on the RG parcel, net CO2 uptake on the RG parcel was reduced compared to the CG parcel. During the following rest periods, this phenomenon progressively shifted towards a higher assimilation for the RG treatment. This behaviour was attributed to sharp biomass changes in the RG treatment and therefore sharp changes in plant photosynthetic capacity. We found that differences in gross primary productivity at high radiation were strongly correlated to differences in standing biomass. In terms of carbon budgets, no significant difference was observed between the two treatments, neither in cumulative NEE, or in terms of estimated biomass production. The results of our study suggest that we should not expect major benefits in terms of CO2 uptake from rotational grazing management when compared to continuous grazing management in intensively managed temperate pastures. [less ▲]

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See detailIncreasing plant functional diversity is not the key for supporting pollinators in wildflower strips
Uyttenbroeck, Roel ULiege; Piqueray, Julien; Hatt, Séverin ULiege et al

in Agriculture, Ecosystems & Environment (2017), 249

Intensification of agriculture has been one of the major drivers for biodiversity loss in recent decades. Pollinators, which serve an important role in pollinating crops as well as wild plants, have shown ... [more ▼]

Intensification of agriculture has been one of the major drivers for biodiversity loss in recent decades. Pollinators, which serve an important role in pollinating crops as well as wild plants, have shown a decline in species richness. Flower strips can be used to support pollinators in agro-ecosystems, however the question remains as to how their design can be optimized in order to best benefit pollinators. Increasing plant species diversity has been shown to be beneficial for pollinators, and it is often suggested that functional traits are driving this relationship. Therefore, increasing plant functional diversity could be a tool to support pollinator abundance and diversity. As experimental evidence on this relationship is scarce, we developed a field study with experimental sown flower strips with four functional diversity levels, based on multiple flower traits and with equal plant species richness. We monitored vegetation development, as well as the flower-visiting pollinator community and their interaction networks with flowers. We were able to create a functional diversity gradient while controlling for plant species richness and evenness. However, in contrast to our expectations, pollinator species richness and evenness were not influenced by functional diversity, and increasing functional diversity even resulted in lower flower visitation rates. Network stability metrics showed no effect or negative relationships with functional diversity. We conclude that increasing functional diversity was not the key for supporting pollinators in wildflower strips. Our results also suggest that, for a constant amount of flower resources, increasing plant functional diversity and thus decreasing redundancy of potential pollinator feeding niches, decreases the amount of flower resources present per feeding niche. As pollinator species tended to have less overlap in their feeding niches in flower strips with increased functional diversity, this may lead to a reduction of flower resources available for pollinator species with a more specialized feeding niche. [less ▲]

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See detailEffects of the conversion of intensive grasslands into Christmas tree plantations on bird assemblages
Gailly, Robin ULiege; Paquet, Jean-Yves; Titeux, Nicolas et al

in Agriculture, Ecosystems & Environment (2017), 247

Over the last decade, the conversion of annual-rotation based crops or grassland areas into non-food perennial crops has been increasingly prevalent in European farming systems. This shift is associated ... [more ▼]

Over the last decade, the conversion of annual-rotation based crops or grassland areas into non-food perennial crops has been increasingly prevalent in European farming systems. This shift is associated with major changes in management practices and has created new environmental conditions and resources for wildlife. Impacts on birds have been examined for bioenergy agricultural systems, such as miscanthus plantations and short-rotation willow coppice. However, they remain largely unknown for Christmas tree plantations (CTPs) that have recently increased considerably in some European countries. We examined the extent to which CTPs alter bird species assemblages in the farmland areas of southern Belgium, where they mainly replace intensive grassland. The abundance of birds was recorded during the breeding season in randomly selected sites located in grassland and in CTP. Results show that introduction of CTP into landscapes dominated by grassland with low hedge densities locally increases bird species richness and abundance without leading to biotic homogenization. Differences in species richness and abundance between grassland and CTP decrease with increasing hedge densities. A community analysis indicates that the plantation of Christmas trees enriches the bird assemblage of intensive grassland areas. In intensive grassland with few hedges, small-size CTPs could constitute an option to increase structural heterogeneity and provide new potential breeding conditions for some farmland birds. However, questions remain about the genuine quality of the resources available in CTP and further research is needed to examine the breeding success and survival of birds that settle in this type of habitat. [less ▲]

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See detailIncreased expression of bacterial amoA during an N2O emission peak in an agricultural field
Theodorakopoulos, Nicolas ULiege; Lognoul, Margaux ULiege; Degrune, Florine ULiege et al

in Agriculture, Ecosystems & Environment (2017), 236

Levels of N-cycle gene transcripts (nirK, nirS, nosZ, amoA) were measured during an N2O emission peak in an agricultural soil. Automated dynamic closed chambers were used to monitor an N2O emission peak ... [more ▼]

Levels of N-cycle gene transcripts (nirK, nirS, nosZ, amoA) were measured during an N2O emission peak in an agricultural soil. Automated dynamic closed chambers were used to monitor an N2O emission peak on a maize crop after a natural rainfall. The peak occurred rapidly after the rainfall began. Spatial and temporal variability in N2O emission was observed between chambers. An analysis of N-cycle gene transcript levels revealed an increase in bacterial amoA gene transcripts (but not in archaeal amoA transcripts), correlating strongly with N2O emission. This suggests the involvement of nitrification enzymes, despite a high water-filled pore space (80%). Reverse transcription of bacterial 16S rRNA followed by partial sequencing of the resulting cDNAs revealed few rainfall-induced changes in the potentially active bacterial community, and notably no significant change in the relative abundance of 16S rRNAs from the nitrifier genus Nitrosospira. Expression of the amoA gene appears as a possible proxy for monitoring the N2O emission peak. To our knowledge, this is the first experiment to evaluate the expression of N-cycle genes during an N2O emission peak on an agricultural field. [less ▲]

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See detailNo favorable effect of reduced tillage on microbial community diversity in a silty loam soil (Belgium)
Degrune, Florine ULiege; Theodorakopoulos, Nicolas ULiege; Dufrêne, Marc ULiege et al

in Agriculture, Ecosystems & Environment (2016), 224

Among the soil management practices used to promote sustainable agriculture, reduced tillage and retention of residues from the previous crop are reported to enhance significantly both soil fertility and ... [more ▼]

Among the soil management practices used to promote sustainable agriculture, reduced tillage and retention of residues from the previous crop are reported to enhance significantly both soil fertility and crop productivity. Here, high-throughput sequencing (454 technology) was used to see how the tillage regime (conventional vs. reduced tillage) and the fate of crop residues (retention or removal) affect microbial communities at two sampling depths (top soil: 0–5 cm and deeper soil: 15–20 cm) in a fertile silty loam soil in Belgium. All combinations of these three factors were studied. After 6 years of conversion from conventional to reduced tillage, depth emerged as the main factor responsible for variation in microbial diversity, tillage regime ranked second, and finally, crop residue fate had no influence on microbial diversity. For both bacteria and fungi, the diversity appeared higher in the top soil than in the deeper soil, and surprisingly, higher under conventional than under reduced tillage. These differences are explained by changes in community composition due to taxon loss rather than taxon replacement. The specific local set of environmental conditions (a loess-derived soil and an oceanic temperate climate) may explain these results. These observations raise the question: does impoverishment in indicator taxa influence soil processes, and thus crop production? To answer this question, we discuss how the presence of certain indicator taxa liable to play an ecological role might relate to crop productivity. [less ▲]

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See detailInvading or recolonizing? Patterns and drivers of wild boar population expansion into Belgian agroecosystems
Morelle, Kévin; Fattebert, Julien; Mengal, Coralie ULiege et al

in Agriculture, Ecosystems & Environment (2016), 222

Native species can also exhibit invasive-like spreading patterns, and identifying mechanisms driving spread of native species is a recent but essential challenge in ecology. In Europe, wild boar Sus ... [more ▼]

Native species can also exhibit invasive-like spreading patterns, and identifying mechanisms driving spread of native species is a recent but essential challenge in ecology. In Europe, wild boar Sus scrofa populations and range increased for decades. While patterns of population growth are well studied, those related to range expansion are still poorly understood. In this study, we aimed to understand patterns and mechanisms that promoted wild boar population expansion in agricultural landscapes of Southern Belgium between 1981 and 2010. Using hunting-based knowledge on colonization history and an information-theoretic approach, we evaluated support to four a priori hypotheses explaining mechanisms of wild boar colonisation in an agro-ecosystem: natural forested landscape as recolonization mechanism, and cultivated landscape, propagule pressure and climate change as invasion mechanisms. We found that wild boar population expansion in Belgian agroecosystems was a relatively slow process driven by the natural landscape, propagule pressure, and climatic changes. This suggests a combination of invasive and recolonization mechanisms was in play in the expansion of wild boar over the last three decades. Our study provides insights in the mechanisms that enable the species’ recovery in Europe since the mid-20th century, and underline the need for adapted management strategies taking into account the invasive components of wild boar population expansion. [less ▲]

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See detailReview on greenhouse gas emissions from pig houses: Production of carbon dioxide, methane and nitrous oxide by animals and manure
Philippe, François-Xavier ULiege; Nicks, Baudouin ULiege

in Agriculture, Ecosystems & Environment (2015)

The environmental impacts of livestock production are attracting increasing attention, especially the emission of greenhouse gases (GHGs). Currently, pork is the most widely consumed meat product in the ... [more ▼]

The environmental impacts of livestock production are attracting increasing attention, especially the emission of greenhouse gases (GHGs). Currently, pork is the most widely consumed meat product in the world, and its production is expected to grow in the next few decades. This paper deals with the production of carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O) by animals and by manure from pig buildings, with a focus on the influence of rearing techniques and nutrition. GHG emissions in piggeries originate from animals through CO2 exhalation and CH4 enteric fermentation, and from manure through the release of CO2, CH4 and N2O. The level of the CO2 exhalation (E-CO2, pig) depends on the physiological stage, the body weight (BW), the production level and the feed intake of the animals concerned. Enteric CH4 (E-CH4, pig) is principally related to dietary fibre intake and the fermentative capacity of the pig’s hindgut. Based on a review of the literature, the following equations are proposed in order to estimate E-CO2, pig (in kg day_1) and E-CH4,pig (in g day_1) for fattening pigs: E-CO2, pig = 0.136 _ BW0.573; E-CH4,pig = 0.012 _ dRes; with BW (in kg) and dRes for digestible residues (in g day_1). Numerous pathways are responsible for GHG production in manure. In addition, the microbial, physical and chemical properties of manure interact and modulate the level of emissions. Influencing factors for removal systems for both liquid and solid fractions of manure have been investigated. A large range of parameters showing an impact on the level of GHG production from pig houses has been reported. However, few of these can be considered unquestionably as GHG mitigation techniques because some strategies have shown contradictory effects depending on the gas, the circumstances and the study. Nevertheless, frequent manure removal seems to be an efficient means to reduce concurrently CO2-, CH4- and N2O-emissions from pig buildings for both slatted and bedded floor systems. Manure removal operations may be associated with specific storage conditions and efficient treatment in order to further reduce emissions. Several feeding strategies have been tested to decrease GHG emissions but they seem to be ineffective in reducing emissions both significantly and durably. In general, good management practices that enhance zootechnical performance will have beneficial consequences on GHG emission intensity. Taking into account the results described in the literature regarding CO2-, CH4- and N2O-production from animals and manure in pig houses, we estimate total GHG emissions to 448.3 kg CO2equiv. per slaughter pig produced or 4.87 kg CO2equiv. per kg carcass. The fattening period accounts for more than 70% of total emissions, while the gestation, lactation and weaning periods each contribute to about 10% of total emissions. Emissions of CO2, CH4 and N2O contribute to 81, 17 and 2% of total emissions from pig buildings, representing 3.87, 0.83 and 0.11 kg CO2equiv. per kg carcass, respectively. [less ▲]

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See detailImpact of grazing on carbon dioxide exchanges in an intensively managed Belgian grassland
Jerome, Elisabeth ULiege; Beckers, Yves ULiege; Bodson, Bernard ULiege et al

in Agriculture, Ecosystems & Environment (2014), 194

Given that the soil carbon (C) sequestration potential by grasslands can be used to partly mitigate the total greenhouse gas emissions of livestock production systems, a better understanding of the ... [more ▼]

Given that the soil carbon (C) sequestration potential by grasslands can be used to partly mitigate the total greenhouse gas emissions of livestock production systems, a better understanding of the effects of management practices, and especially grazing, on grassland carbon dioxide (CO2) exchanges has become a major concern. This study aimed at quantifying grazing impact on CO2 fluxes measured by eddy covariance by using innovative data analyses and experiments. For that, we distinguished direct and indirect grazing impact. Indirect impact results from biomass consumption, excretion deposits and soil compaction by cattle that modify CO2 exchanges. Direct impact results from livestock CO2 emissions through respiration that add to total ecosystem respiration. For the indirect impact, the variation during periods with fixed stocking rate of gross primary productivity at light saturation (GPPmax) and normalized dark respiration (Rd,10) was analyzed. On average, GPPmax decreased during grazing periods and increased during non-grazing periods which could be explained by aboveground biomass reduction and re-growth, respectively. In addition, GPPmax variations were negatively correlated to grazing intensity (defined as the product of the stocking rate and the grazing duration). On the contrary, no significant evolution of Rd,10 was found during both grazing and non-grazing periods, probably due to a combination of opposing effects of grazing on the total ecosystem respiration components. The direct impact was emphasized through four specific designed confinement experiments. Each experiment extended over three successive days. On the first and third day, there was no cattle on the plot, while, on the second day, cattle were confined in the main wind direction area of the eddy covariance set-up to increase the stocking rate (≈26livestockunitsha-1). The average livestock CO2 emissions during confinement, FCO2,livestock, were deduced from the differences between half-hourly measurements taken at 24h interval with or without cattle and under similar environmental conditions. They were estimated to be 2.59±0.58kgClivestockunit-1d-1 on average. This result was corroborated by independent estimates based on the C ingested by cattle during confinement. Using an annual average stocking of 2livestockunitsha-1, we found that livestock CO2 emissions represent only 8% of this grassland annual total ecosystem respiration. To our knowledge, this study is the first to quantify both direct and indirect livestock contribution to CO2 fluxes exchanged at the ecosystem scale using the eddy covariance technique. © 2014 Elsevier B.V. [less ▲]

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See detailFifty years of contrasted residue management of an agricultural crop: impacts on the soil carbon budget and on heterotrophic respiration.
Buysse, Pauline ULiege; Roisin, Christian; Aubinet, Marc ULiege

in Agriculture, Ecosystems & Environment (2013), 167

Crop management exerts a strong influence on the soil carbon (C) balance. This study investigated a long-term experiment initiated in 1959 at a site in the Hesbaye region of Belgium and focused on three ... [more ▼]

Crop management exerts a strong influence on the soil carbon (C) balance. This study investigated a long-term experiment initiated in 1959 at a site in the Hesbaye region of Belgium and focused on three contrasted treatments: residue export (RE), farmyard manure (FYM) addition and residue restitution (RR) after harvest. The objectives were to quantify the components of the C budget of croplands from a 50-year perspective and to identify the impact of the treatments on this budget and soil C sequestration, given the relatively low levels of esidue application. The soil C budget was calculated for each treatment on the basis of total soil organic C (SOC) content measurements and C input data collected since the experiment had begun and drawn from the literature. To evaluate the robustness of this approach, the budget-based output estimates were compared with annual heterotrophic respiration (HR) averages extrapolated from seasonal field HR measurements carried out at the same experimental site in 2010. The soil C budgetbased output estimates accorded well with field-based HR measurements and with most HR estimates in the literature, suggesting that, despite the many uncertainties affecting the soil C budget, these results were robust. The three treatments investigated in this study had different impacts on SOC stocks, mainly during the first 20 years of the experiment. RE and FYM caused significant SOC decreases (on average, −7 ± 5 g C m−2 year−1 over the 50 years) and increases (10 ± 5 g C m−2 year−1), espectively, whereas RR had no significant impact on the SOC stocks. The study also showed (i) the very large part (about twothirds of the total input) that represented the below-ground input, weeds and other left-over residues in the C budget, (ii) the important role probably played by residue quality in C sequestration and (iii) the large proportion of C lost annually rom the soil (which represents 93–98, 100 and 102–107% of the amounts of fresh residue rought to the soil each year in the FYM, RR and RE treatments, respectively). [less ▲]

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See detailAmmonia and greenhouse gas emissions during the fattening of pigs kept on two types of straw floor
Philippe, François-Xavier ULiege; Laitat, Martine ULiege; Nicks, Baudouin ULiege et al

in Agriculture, Ecosystems & Environment (2012), 150

Pig production is an important contributor to polluting gases emissions like ammonia (NH3) and greenhouse gases (GHG). Apart from environmental aspects, animal welfare is also an issue of growing ... [more ▼]

Pig production is an important contributor to polluting gases emissions like ammonia (NH3) and greenhouse gases (GHG). Apart from environmental aspects, animal welfare is also an issue of growing importance. The fattening of pigs on deep litter bedded system is consider as more animal friendly than the fattening on slatted floor, but it is also more expensive and requests more labour. The use of straw flow rather than straw deep litter could be a good compromise because of a reduced need for surface area, straw, labour and manure storage, combined with satisfying animal welfare. In order to evaluate the environmental impact of this rearing technique, a study was designed to quantify pollutant gas emissions of this system compared to the deep litter system for fattening pigs. Three successive batches of 32 Landrace fattening pigs were used. They were divided into 2 homogeneous groups of 16 animals randomly allocated to two treatments: straw deep litter or straw flow. The groups were kept simultaneously for a period of 4 months and separately in two identical rooms in volume (103 m3) and surface (30.2 m2) and fitted either with a deep litter pen (1.2 m2/pig) or with a straw flow system (0.75 m2/pig). Throughout the fattening period, 46.9 and 34.4 kg straw were used respectively per pig. In deep litter pen, the litter was removed after each batch. In the straw flow pen, the straw, mixed with dung, travelled down the slope by pig motion and went out of the pen to a scraped passage. The solid fraction was scraped every day, stored in a heap in the room and removed every month, 1 week before each period of gaseous emission measurement. The liquid fraction was automatically pumped from the scraped passage into a hermetic tank, which was emptied at the end of each fattening period. In both rooms, ventilation was automatically adapted to maintain a constant ambient temperature. Once a month, the emissions of ammonia (NH3), nitrous oxide (N2O), methane (CH4), carbon dioxide (CO2), and water vapour (H2O) were measured continuously for 6 consecutive days by infra-red photoacoustic detection. Animal performance (final body weight, body weight gain, and feed conversion ratio), some carcass quality parameters and manure characteristics were not significantly affected by floor type. With fattening pigs kept in a straw flow pen, gaseous emissions were significantly greater (P < 0.05) for NH3 (+10%) and significantly lower (P < 0.001) for N2O (−55%), CH4 (−46%), CO2 equivalents (−47%), CO2 (−10%) and H2O (−23%) compared to pigs housed on straw-based deep litter. Thus, the use of straw flow system for pig fattening allows reducing the GHG emissions but presents the disadvantage of increasing the NH3 emissions. [less ▲]

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See detailComparison of carbon fluxes, growth and productivity of a winter wheat crop in three contrasting growing seasons
Dufranne, Delphine ULiege; Moureaux, Christine ULiege; Vancutsem, Françoise ULiege et al

in Agriculture, Ecosystems & Environment (2011), 141

Three winter wheat growing seasons were compared in order to analyse crop development, CO2 fluxes and inter-annual variability in productivity. Crop development monitoring, leaf scale measurements and ... [more ▼]

Three winter wheat growing seasons were compared in order to analyse crop development, CO2 fluxes and inter-annual variability in productivity. Crop development monitoring, leaf scale measurements and continuous eddy-covariance measurements were conducted in a production crop at the Lonzée experimental site in Belgium. The 3 years were characterised by similar soil proprieties (same site), similar management (sowing, harvesting, plant protection and nitrogen application, adhering to regional standards), and the use of recommended cultivars (the most productive ones for this region). The comparison of carbon fluxes, growth and productivity in the three growing seasons highlighted mechanisms affected by meteorological conditions and, in some cases, modulated by a cultivar effect. In particular, it was shown that (a) precociousness or lateness in stage development was triggered mainly by cumulated temperature during winter and early spring; (b) early development in one season could explain the larger ecosystem net carbon sequestration that year, but had no impact on grain yield; (c) low grain yield in one season was the result of a complex mechanism including drought in early spring, which hindered flag leaf development, and moist conditions in late spring, which restrained radiation and favoured the development of fungal diseases. In all cases, it was found that grain yield could not be related to gross primary productivity or net ecosystem exchange, suggesting that reallocation and translocation processes play a substantial role in grain filling. [less ▲]

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See detailAmmonia emissions from pig houses: Influencing factors and mitigation techniques
Philippe, François-Xavier ULiege; Cabaraux, Jean-François ULiege; Nicks, Baudouin ULiege

in Agriculture, Ecosystems & Environment (2011), 141(3-4), 245-260

Pig houses are important sources of ammonia (NH3) emissions. For decades, investigations were carried out in determine the influencing factors and to point out opportunities of mitigation. In Europe ... [more ▼]

Pig houses are important sources of ammonia (NH3) emissions. For decades, investigations were carried out in determine the influencing factors and to point out opportunities of mitigation. In Europe, current NH3 emissions associated to pig production are about 24% lower than in 1990. However, further reduction seems necessary to avoid noxious effects on ecosystems. The main factors influencing NH3 production are the floor type, the manure removal system, the climatic conditions inside the building, the diet composition and the feed efficiency of animals. In pig production, the main floor types are the slatted floor and the bedded floor systems. In both systems, numerous variants and adaptations can be found with consequently a range of emission levels for each housing condition. Therefore, decision in favour of a floor type as regards NH3 emissions is difficult, especially as effective reducing strategies are available for both systems. For litter-based systems, the nature and the amount of substrate greatly influence the NH3 production with usually lower emission in case of generous bedding. For slatted floor systems, most of the studies resulted in lower emissions with partly slatted floor on condition that the solid part of the floor remains clean. Indeed, hot conditions, high animal density or inadequate pen design can increase the soiling of the solid floor and lead to increased NH3 emissions. In any case, emissions are lower if concrete slats are replaced by smooth materials like iron cast, metal or plastic slats. Several slurry pit designs and manure removal strategies were developed to mitigate emissions. The reduction of the slurry pit surface thanks to sloped pit walls are related to proportional reductions of NH3 emissions. Frequent manure removal, flushing and separating urine from faeces by V-shaped scraper or conveyor belts reduce the NH3 releases from the buildings by about 50%. However, the emissions during the storage period outside the building have to be taken into account for a whole assessment of the technique. Climate conditions inside the building also influence the emissions which are positively correlated with ambient temperature and ventilation rate. Consequently, ammonia emissions present seasonal and nychtemeral patterns. But, reducing the NH3 production by modulation of the climate conditions is rather unpractical because the ambient parameters must primarily respect the bioclimatic requirements for animal comfort. A closer match between dietary intakes and requirement of the pigs according to the physiological and growth stage results in lower NH3 emissions. In this way, diets with reduced crude protein content are highly effective in reducing the emissions with almost a 10% reduction for every 10 g kg−1 reduction in dietary crude protein. Other dietary strategies are also effective in lowering emissions. Dietary fibre inclusion reduces NH3 emissions by about 40% by shifting the nitrogen from urine to faeces due to promotion of bacterial growth in the large intestine. Lowering the dietary electrolyte balance or supplementation with acidifying salts like benzoic acid or CaSO4 are related to significant reductions. Other feed additives like Yucca extract, zeolites, probiotics, humic substance or lactose were also validated by several experiments. Moreover, better feed efficiency obtained by genetic selection or modification of the hormonal status of the pigs is also related to reduced emissions. In conclusion, effective reduction of ammonia emissions from pig buildings can be reached operating both on housing conditions and feeding strategies. The former are very efficient but the assessment has to include the specificity of each system and involve the complete process. In some cases, investment and cost operating can hamper their development. Feeding strategies offer the advantage of being easy to implement and rapid to adapt function of particular circumstances. [less ▲]

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See detailAmmonia and greenhouse gas emission from group-housed gestating sows depends on floor type
Philippe, François-Xavier ULiege; Laitat, Martine ULiege; Wavreille, José et al

in Agriculture, Ecosystems & Environment (2011), 140

The ban by 2013 in the EU of individual accommodations for gestating sows and the renewed interest for litter systems could promote in the future the group-housing of gestating sows on litter. But what ... [more ▼]

The ban by 2013 in the EU of individual accommodations for gestating sows and the renewed interest for litter systems could promote in the future the group-housing of gestating sows on litter. But what are the environmental impacts of this rearing technique? To answer this question, a study was scheduled to quantify pollutant gas emissions (nitrous oxide -N2O-, methane -CH4-, carbon dioxide -CO2- and ammonia -NH3-) according to floor type in the raising of group-housed gestating sows. The trial was carried out in experimental rooms located at Liège University (Belgium). Three successive batches of 10 gestating sows were used for this trial. Each batch was divided into 2 homogeneous groups randomly allocated to one of two treatments: concrete slatted floor or straw-based deep litter. The groups were kept separately in two identical rooms equipped with a pen divided into a lying area (slatted floor or deep litter) and five individual feeding stalls. The feeding stalls were equipped with front feeding troughs and rear gates preventing access to the stalls outside of the feeding time. Between each batch of sows, the pens were cleaned. In both rooms, ventilation was automatically adapted to maintain a constant ambient temperature. The gas emissions were measured 3 times (weeks 2, 5 and 8 of stay) during 6 consecutive days by infra red photoacoustic detection. Sow performance (body weight gain, backfat thickness, number and weight of piglets) was not significantly affected by floor type. With sows kept on slatted floor, gaseous emissions were significantly greater for NH3 (12.77 vs. 9.05 g d-1 sow-1; P<0.001) and CH4 (10.12 vs. 9.20 g d-1 sow-1; P<0.01), and significantly lower for N2O (0.47 vs. 2.27 g d-1 sow-1; P<0.001), CO2 equivalents (0.44 vs. 0.94 kg d-1 sow-1; P<0.001) and CO2 (2.41 vs. 2.83 kg d-1 sow-1; P<0.001) compared to sows housed on straw-based deep litter. There was no significant difference for water vapour emissions (3.25 vs. 3.21 kg d-1 sow-1; P>0.05). In conclusion, the main environmental disadvantage of the deep litter system pointed to in this study was the greater N2O-emissions and thus greater CO2eq-emissions compared to slatted floor. However, the use of deep litter was related to reduced NH3- and CH4-emissions. [less ▲]

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See detailThe carbon balance of European croplands: A cross-site comparison of simulation models
Wattenbach, Martin; Sus, Olivier; Vuichard, Nicolas et al

in Agriculture, Ecosystems & Environment (2010), 139(3), 419-453

Croplands cover approximately 45% of Europe and play an important role in the overall carbon budget of the continent. However, the estimation of their carbon balance remains uncertain due to the diversity ... [more ▼]

Croplands cover approximately 45% of Europe and play an important role in the overall carbon budget of the continent. However, the estimation of their carbon balance remains uncertain due to the diversity of crops and cropping systems together with the strong influence of human management. Here, we present a multi-site model comparison for four cropland ecosystem models namely theDNDC,ORCHIDEESTICS, CERES-EGC and SPA models. We compare the accuracy of the models in predicting net ecosystem exchange (NEE), gross primary production (GPP), ecosystem respiration (Reco) as well as actual evapotranspiration (ETa) for winter wheat (Triticum aestivum L.) and maize (Zea mays L.) derived from eddy covariance measurements on five sites along a gradient of climatic conditions from eastern to southwesterly Europe. The models are all able to simulate daily GPP. The simulation results for daily ETa and Reco are, however, less accurate. The resulting simulation of daily NEE is adequate except in some cases where models fail due to a lack in phase and amplitude alignment. ORCHIDEE-STICS and PAshowthe best performance. Nevertheless, they are not able to simulate full crop rotations or the multiple management practices used. CERES-EGC, and especially DNDC, although exhibiting a lower level of model accuracy, are able to simulate such conditions, resulting in more accurate simulation of annual cumulative NEE. [less ▲]

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See detailMeasurements necessary for assessing the net ecosystem carbon budget of croplands
Smith, Pete; Lanigan, Gary; Kutsch, Werner L. et al

in Agriculture, Ecosystems & Environment (2010), 139(3), 302-315

There are a number of methods that can be used to help assess carbon budgets at the site to continental scales. Eddy covariance (EC) networks have been developed over the last decade and have been used to ... [more ▼]

There are a number of methods that can be used to help assess carbon budgets at the site to continental scales. Eddy covariance (EC) networks have been developed over the last decade and have been used to make many advances in our understanding. However, eddy covariance measurements of CO2 and water vapour exchanges quantify the fluxes only on short time scales, but do not assess the impacts of long-term processes that contribute to biogeochemical cycling in croplands, such as harvest or residue removal and other management practices, so many other supplementary measurements are required to attribute different components of the carbon flux. Such methods include isotope studies, chamber flux measurements of C and other greenhouse gases, inventories of above- and below-ground biomass as well as management in- and outputs, book-keeping modelling, process modelling, experimental manipulation and earth observation (e.g. remote sensing). In this review, we summarise the component fluxes that make up the total cropland carbon budget, describe the key fluxes and methods used to estimate them, and examine how they need to be integrated to obtain the net ecosystem carbon budget of European croplands. We describe the uncertainties and difficulties inherent at each stage and how these can be minimised. [less ▲]

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