Resource use efficiency, ecological intensification and sustainability of intercropping systems
Mao, L. ; Zhang, L. ; Zhang, S. ; Evers, J.B. ; Werf, W. van der; Wang, J. ; Sun, H. ; Su, Z. ; Spiertz, J.H.J. - \ 2015
Journal of Integrative Agriculture 14 (2015)8. - ISSN 2095-3119 - p. 1542 - 1550.
growth - maize - yield - wheat - water - agriculture - radiation - capture - cotton - model
The rapidly growing demand for food, feed and fuel requires further improvements of land and water management, crop productivity and resource-use efficiencies. Combined field experimentation and crop growth modelling during the past five decades made a great leap forward in the understanding of factors that determine actual and potential yields of monocrops. The research field of production ecology developed concepts to integrate biological and biophysical processes with the aim to explore crop growth potential in contrasting environments. To understand the potential of more complex systems (multi-cropping and intercropping) we need an agro-ecosystem approach that integrates knowledge derived from various disciplines: agronomy, crop physiology, crop ecology, and environmental sciences (soil, water and climate). Adaptation of cropping systems to climate change and a better tolerance to biotic and abiotic stresses by genetic improvement and by managing diverse cropping systems in a sustainable way will be of key importance in food security. To accelerate sustainable intensification of agricultural production, it is required to develop intercropping systems that are highly productive and stable under conditions with abiotic constraints (water, nutrients and weather). Strategies to achieve sustainable intensification include developing tools to evaluate crop growth potential under more extreme climatic conditions and introducing new crops and cropping systems that are more productive and robust under conditions with abiotic stress. This paper presents some examples of sustainable intensification management of intercropping systems that proved to be tolerant to extreme climate conditions.
Simulating the reactions of CO2 in aqueous monoethanolamine solution by Reaction Ensemble Monte Carlo using the Continuous Fractional Component method
Balaji, S.P. ; Gangarapu, S. ; Ramdin, M. ; Torres-Knoop, A. ; Zuilhof, H. ; Goetheer, E. ; Dubbeldam, D. ; Vlugt, T. - \ 2015
Journal of Chemical Theory and Computation 11 (2015)6. - ISSN 1549-9618 - p. 2661 - 2669.
chemical-reaction equilibria - sterically hindered amines - aerosol based emission - carbon-dioxide - molecular simulation - computer-simulation - phase-equilibria - capture - system - performance
Molecular simulations were used to compute the equilibrium concentrations of the different species in CO2/monoethanolamine solutions for different CO2 loadings. Simulations were performed in the Reaction Ensemble using the continuous fractional component Monte Carlo method at temperatures of 293, 333, and 353 K. The resulting computed equilibrium concentrations are in excellent agreement with experimental data. The effect of different reaction pathways was investigated. For a complete understanding of the equilibrium speciation, it is essential to take all elementary reactions into account because considering only the overall reaction of CO2 with MEA is insufficient. The effects of electrostatics and intermolecular van der Waals interactions were also studied, clearly showing that solvation of reactants and products is essential for the reaction. The Reaction Ensemble Monte Carlo using the continuous fractional component method opens the possibility of investigating the effects of the solvent on CO2 chemisorption by eliminating the need to study different reaction pathways and concentrate only on the thermodynamics of the system.
Genetic differences in root mass of Lolium perenne varieties under field conditions
Deru, J.G.C. ; Schilder, H. ; Schoot, J.R. van der; Eekeren, N.J.M. van - \ 2014
Euphytica 199 (2014)1-2. - ISSN 0014-2336 - p. 223 - 232.
grazing systems - soil - ryegrass - growth - architecture - defoliation - elongation - management - patterns - capture
Although grasses have dense rooting systems, nutrient uptake and productivity can be increased, and N-leaching reduced, if rooting is further improved. The variation in root mass of 16 varieties of Lolium perenne was studied under field conditions in two experiments on sandy soil in The Netherlands. The chosen varieties differed in genetic and aboveground characteristics such as ploidy, productivity and grass cover. Root dry matter (RDM) was measured in the 0–8, 8–16 and 16–24 cm soil layers. In summary, we found that RDM of perennial ryegrass differed significantly between varieties under field conditions. These differences were not linked to grass yield, which indicates that it is possible to select perennial ryegrass varieties that combine high aboveground productivityIn this experiment, total RDM was not influenced by ploidy but by grass cover type: high grass cover types had higher RDM. Differences in management between the two experiments possibly explain the differences in RDM and in the influence of chosen characteristics on RDM. Considering challenges in the areas of climate change, water availability, pollution and soil degradation, grass varieties with improved root systems could significantly contribute to a more efficient use of nutrients and water, erosion control, soil improvement and carbon sequestration. with high RDM. In the first experiment, which was managed by cutting, diploid varieties had higher RDM than tetraploid varieties. Grand mean RDM in the second experiment, which was managed by cutting as well as grazing, was lower than in the first experiment.
Energy from CO2 using capacitive electrodes – Theoretical outline and calculation of open circuit voltage
Par-Garcia, J.M. ; Schaetzle, O. ; Biesheuvel, P.M. ; Hamelers, H.V.M. - \ 2014
Journal of Colloid and Interface Science 418 (2014). - ISSN 0021-9797 - p. 200 - 207.
anion-exchange membranes - porous-electrodes - carbamate formation - aqueous-solution - acid anions - monoethanolamine - equilibrium - absorption - simulation - capture
Recently, a new technology has been proposed for the utilization of energy from CO2 emissions (Hamelers et al., 2014). The principle consists of controlling the dilution process of CO2–concentrated gas (e.g., exhaust gas) into CO2–dilute gas (e.g., air) thereby extracting a fraction of the released mixing energy. In this paper, we describe the theoretical fundamentals of this technology when using a pair of charge–selective capacitive electrodes. We focus on the behavior of the chemical system consisting of CO2 gas dissolved in water or monoethanolamine solution. The maximum voltage given for the capacitive cell is theoretically calculated, based on the membrane potential. The different aspects that affect this theoretical maximum value are discussed.
Impacts of increased bioenergy demand on global food markets: an AgMIP economic model intercomparison
Lotze-Campen, H. ; Lampe, M. von; Kyle, P. ; Fujimori, S. ; Havlik, P. ; Meijl, J.C.M. van; Hasegawa, T. ; Popp, A. ; Schmitz, C. ; Tabeau, A.A. ; Valin, H. ; Willenbockel, D. ; Wise, M. - \ 2014
Agricultural Economics 45 (2014)1. - ISSN 0169-5150 - p. 103 - 116.
greenhouse-gas emissions - land-use - energy - productivity - scenarios - policies - capture - storage - system
Integrated Assessment studies have shown that meeting ambitious greenhouse gas mitigation targets will require substantial amounts of bioenergy as part of the future energy mix. In the course of the Agricultural Model Intercomparison and Improvement Project (AgMIP), five global agro-economic models were used to analyze a future scenario with global demand for ligno-cellulosic bioenergy rising to about 100 ExaJoule in 2050. From this exercise a tentative conclusion can be drawn that ambitious climate change mitigation need not drive up global food prices much, if the extra land required for bioenergy production is accessible or if the feedstock, for example, from forests, does not directly compete for agricultural land. Agricultural price effects across models by the year 2050 from high bioenergy demand in an ambitious mitigation scenario appear to be much smaller (+5% average across models) than from direct climate impacts on crop yields in a high-emission scenario (+25% average across models). However, potential future scarcities of water and nutrients, policy-induced restrictions on agricultural land expansion, as well as potential welfare losses have not been specifically looked at in this exercise.
Harvesting Energy from CO2 Emissions
Hamelers, H.V.M. ; Schaetzle, O. ; Paz-García, J.M. ; Biesheuvel, P.M. ; Buisman, C.J.N. - \ 2014
Environmental Science & Technology Letters 1 (2014)1. - ISSN 2328-8930 - p. 31 - 35.
water salinity difference - capacitive deionization - carbon electrodes - extraction - power - capture
When two fluids with different compositions are mixed, mixing energy is released. This holds true for both liquids and gases, though in the case of gases, no technology is yet available to harvest this energy source. Mixing the CO2 in combustion gases with air represents a source of energy with a total annual worldwide capacity of 1570 TWh. To harvest the mixing energy from CO2-containing gas emissions, we use pairs of porous electrodes, one selective for anions and the other selective for cations. We demonstrate that when an aqueous electrolyte, flushed with either CO2 or air, alternately flows between these selective porous electrodes, electrical energy is gained. The efficiency of this process reached 24% with deionized water as the aqueous electrolyte and 32% with a 0.25 M monoethanolamine (MEA) solution as the electrolyte. The highest average power density obtained with a MEA solution as the electrolyte was 4.5 mW/m2, significantly higher than that with water as the electrolyte (0.28 mW/m2).
Volcanic disruption and drainage diversion of the palaeo-Hudut River, a tributary of the Early Pleistocene Gediz River, Western Turkey
Maddy, D. ; Veldkamp, A. ; Jongmans, A.G. ; Candy, I. ; Demir, T. ; Schoorl, J.M. ; Schriek, T. van der; Stemerdink, C. ; Scaife, R.G. ; Gorp, W. van - \ 2012
Geomorphology 165-166 (2012). - ISSN 0169-555X - p. 62 - 77.
se spain - terrace staircase - 2-stage extension - sorbas basin - graben - pliocene - uplift - evolution - capture - gordes
The importance of extrinsic drivers of fluvial system behaviour (climate, tectonics, eustatic sea level) over Quaternary timescales is well documented. However, comparatively fewer studies have been reported concerning the significance of more localised changes at reach to sub-catchment scale, over these extended (10exp4–10exp6 years) timescales. In this paper we examine the Early Pleistocene sedimentary record of the palaeo-Hudut River and compare it with the record from the trunk river into which it drains, the Gediz River of Western Turkey. Both the Gediz River and the Hudut River were subjected to major localised disruption during the Early Pleistocene as a consequence of volcanism but their respective responses to these events appear to differ. Observations are reported from the sedimentary sequence buried beneath the lavas which cap the Burgaz plateau. These sediments record a remarkable amount of detail for a significant period of the Early Pleistocene. These suggest that the palaeo-Hudut system responded largely to the creation and failure of downstream lava dams, both through channel incision and subsequent filling, and via route diversions around lava dams and their associated lakes. In contrast, the Gediz terrace record appears to demonstrate a river which was able to accommodate these changes more readily and hence, continue to undergo sedimentation–incision cycles consistent with a climate forcing.
Reconsidering the Consequences of Selective Fisheries
Garcia, S.M. ; Kolding, J. ; Rice, J. ; Rijnsdorp, A.D. - \ 2012
Science 335 (2012)6072. - ISSN 0036-8075 - p. 1045 - 1047.
managing fisheries - by-catch - management - ecosystem - fish - conservation - community - evolution - atlantic - capture
Concern about the impact of fishing on ecosystems and fisheries production is increasing (1, 2). Strategies to reduce these impacts while addressing the growing need for food security (3) include increasing selectivity (1, 2): capturing species, sexes, and sizes in proportions that differ from their occurrence in the ecosystem. Increasing evidence suggests that more selective fishing neither maximizes production nor minimizes impacts (4–7). Balanced harvesting would more effectively mitigate adverse ecological effects of fishing while supporting sustainable fisheries. This strategy, which challenges present management paradigms, distributes a moderate mortality from fishing across the widest possible range of species, stocks, and sizes in an ecosystem, in proportion to their natural productivity (8), so that the relative size and species composition is maintained
Extracoelenteric zooplankton feeding is a key mechanism of nutrient acquisition for the scleractinian coral Galaxea fascicularis
Wijgerde, T.H.M. ; Diantari, R. ; Lewaru, M.W. ; Verreth, J.A.J. ; Osinga, R. - \ 2011
Journal of Experimental Biology 214 (2011)20. - ISSN 0022-0949 - p. 3351 - 3357.
interspecific aggression - montastrea-cavernosa - madracis-mirabilis - hermatypic corals - field enclosure - reef corals - fatty-acid - flow - zooxanthellae - capture
Internal and external feeding on zooplankton may provide scleractinian corals with important nutrients. However, the latter process has never been properly quantified. To quantify the dynamics of zooplankton capture, digestion and release for a scleractinian coral, we performed detailed video analyses of Galaxea fascicularis feeding on Artemia nauplii. A highly dynamic process of prey capture, digestion and release was observed. A single G. fascicularis polyp (N=3) captured 558±67 and released 383±75 Artemia nauplii over a 6 h interval. On average, 98.6% of prey captured was not ingested. Instead, prey items were clustered into aggregates that were digested externally by mesenterial filaments. In addition, we employed carbon, nitrogen and phosphorus analysis of zooplankton before and after digestion by G. fascicularis colonies (N=6). For total organic carbon, 43.1% (0.298±0.148 µg Artemia–1) was lost after 6 h of digestion. For total organic nitrogen, total organic phosphorus and orthophosphate (PO43–), these values were 51.3% (0.059±0.028 µg Artemia–1), 50.9% (0.009±0.004 µg Artemia–1) and 84.6% (0.0019±0.0008 µg Artemia–1), respectively. For extracoelenteric zooplankton feeding alone, total estimated nutrient inputs for G. fascicularis colonies were 76.5±0.0 µg organic carbon, 15.2±0.0 µg organic nitrogen, 2.3±0.2 µg organic phosphorus and 0.5±0.8 µg inorganic phosphorus per cm2 coral tissue per day. These values exceed calculations based on intracoelenteric feeding by up to two orders of magnitude. Our results demonstrate that extracoelenteric zooplankton feeding is a key mechanism of nutrient acquisition for a scleractinian coral. These results are of importance to coral aquaculture and our understanding of benthic–pelagic coupling on coral reefs
How plant architecture affects light absorption and photosynthesis in tomato: towards an ideotype for plant architecture using a functional-structural plant model
Sarlikioti, V. ; Visser, P.H.B. de; Buck-Sorlin, G.H. ; Marcelis, L.F.M. - \ 2011
Annals of Botany 108 (2011)6. - ISSN 0305-7364 - p. 1065 - 1073.
carbon gain - leaf - interception - canopy - morphology - yield - assimilation - efficiency - avoidance - capture
Background and Aims - Manipulation of plant structure can strongly affect light distribution in the canopy and photosynthesis. The aim of this paper is to find a plant ideotype for optimization of light absorption and canopy photosynthesis. Using a static functional structural plant model (FSPM), a range of different plant architectural characteristics was tested for two different seasons in order to find the optimal architecture with respect to light absorption and photosynthesis. Methods - Simulations were performed with an FSPM of a greenhouse-grown tomato crop. Sensitivity analyses were carried out for leaf elevation angle, leaf phyllotaxis, leaflet angle, leaf shape, leaflet arrangement and internode length. From the results of this analysis two possible ideotypes were proposed. Four different vertical light distributions were also tested, while light absorption cumulated over the whole canopy was kept the same. Key Results Photosynthesis was augmented by 6 % in winter and reduced by 7 % in summer, when light absorption in the top part of the canopy was increased by 25 %, while not changing light absorption of the canopy as a whole. The measured plant structure was already optimal with respect to leaf elevation angle, leaflet angle and leaflet arrangement for both light absorption and photosynthesis while phyllotaxis had no effect. Increasing the length : width ratio of leaves by 1·5 or increasing internode length from 7 cm to 12 cm led to an increase of 6–10 % for light absorption and photosynthesis. Conclusions - At high light intensities (summer) deeper penetration of light in the canopy improves crop photosynthesis, but not at low light intensities (winter). In particular, internode length and leaf shape affect the vertical distribution of light in the canopy. A new plant ideotype with more spacious canopy architecture due to long internodes and long and narrow leaves led to an increase in crop photosynthesis of up to 10 %.
Policy options in a worst case climate change world
Swart, R.J. ; Marinova, N.A. - \ 2010
Mitigation and Adaptation Strategies for Global Change 15 (2010)6. - ISSN 1381-2386 - p. 531 - 549.
albedo enhancement - carbon-dioxide - schemes - capture - system - energy - cycle - air - co2
Climatic changes more rapid and extreme than assessed by the IPCC cannot be excluded, because of the possibility of positive earth system feedbacks and thresholds. Do today's policy makers have to take these into account, and if so, are the options different from those considered today? The paper briefly summarizes the types of extreme climatic changes noted in the literature and then evaluates the options to address them in a what-if manner. Different from other studies, which usually look at only one type of measure, we consider a broader portfolio of options: drastic emissions reduction programmes, drawing greenhouse gases from the atmosphere ("carbon dioxide removal"), "emergency cooling" through influencing the radiative balance of the atmosphere ("solar radiation management"), and finally adaptation beyond the options considered seriously today. Politics will have to decide on the choice or mix of "emergency" measures, but research can ensure that such decisions are based on the best scientific information. If through concerted international efforts to mitigate greenhouse emissions low stabilization levels could be reached, such decisions may never have to be made. However, research in support of some form of a "plan B" is now warranted, focusing on those options that have the most positive ratio between potential effectiveness and feasibility on the one hand, and environmental and political risks on the other hand. Such plan should not be limited to one set of options such as geo-engineering and should explicitly take into account not only the relationships between the options but also the wide variety in characteristics of the individual options in terms of effectiveness, feasibility, environmental risks, and political implications.
Selection of pH-related parameters in ion-exchange chromatography using pH-gradient operations
Ahamed, T. ; Chilamkurthi, S. ; Nfor, B. ; Wielen, L. van der; Verhaert, P. ; Dedem, G. ; Sandt, E. van de; Eppink, M.H.M. ; Ottens, M. - \ 2008
Journal of Chromatography. A, Including electrophoresis and other separation methods 1194 (2008)1. - ISSN 0021-9673 - p. 22 - 29.
recombinant protein-purification - monoclonal-antibody purification - liquid-chromatography - culture supernatant - mass-spectrometry - optimization - separation - retention - capture - design
This work demonstrates that the type of ion-exchanger (anion or cation), the mode of operation (bind-and-elute or flow-through), and the operational pH of ion-exchange chromatography (IEX) can be selected in a fast and rational way by analytical pH-gradient IEX operations, thereby eliminating the need for pH scouting or high-throughput screening. The developed approach was applied for the selection of an IEX process for the capture of a monoclonal antibody (MAb) from hybridoma cell culture supernatant (CCS). It was found within a day that MAb can optimally be captured by bind-and-elute mode cation-exchange chromatography (CEX) at pH 4.5 or anion-exchange chromatography (AEX) at pH 7.2 without lowering the salt concentration in the CCS. The performance of both CEX and AEX was predicted to be equal for this particular MAb capture.
Improved fallows: effects of species interaction on growth and productivity in monoculture and mixed stands
Gathumbi, S.M. ; Cadisch, G. ; Giller, K.E. - \ 2004
Forest Ecology and Management 187 (2004)2-3. - ISSN 0378-1127 - p. 267 - 280.
planted fallows - picea-abies - maize yield - nitrogen - plantations - dynamics - mixtures - capture - legumes
To derive optimal benefits from short-term planted legume fallows, farmers need to make important initial decisions on the establishment and growth performance of specific species in monoculture stands and in mixtures. We hypothesized that species with contrasting growth characteristics could be mixed to optimize aboveground resource capture due to their complementary or compensatory gains in resource acquisition. A selection of tree/shrub/herbaceous legumes planted in monoculture and mixed stands were evaluated for growth, biomass and nitrogen productivity on a Kandiudalfic Eutrudox in western Kenya. Species evaluated included: sesbania (Sesbania sesban (L.) Merr.), crotalaria (Crotalaria grahamiana Wight and Am.), pigeonpea (Cajanus cajan (L.) Millsp.), and siratro (Macroptilium arropurpureum (DC.) Urb). Total aboveground biomass ranged from 5 to 12 Mg ha(-1) (monocultures) and 3.4-8 Mg ha(-1) (mixtures). N yield per plant was linearly correlated with total plant biomass (R-2 = 0.95, slope = 0.018) across all of the fallows, despite different amounts of leaf and wood with widely differing N concentrations being present with the different species. Biomass and N yield of sesbania was negatively affected by mixing with other species. For instance, sesbania N yield decreased when mixed with pigeonpea (54%) or crotalaria (67%). Crotalaria and pigeonpea established best under relay cropping with maize and emerged to be better competitors in mixtures than sesbania and siratro. Results of this study suggest that mixing species in fallows provide a better risk management strategy through compensatory biomass and nutrient production gains obtained from the strongly competing species. (C) 2003 Elsevier B.V. All rights reserved.