Staff Publications

Staff Publications

  • external user (warningwarning)
  • Log in as
  • language uk
  • About

    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

    Full text documents are added when available. The database is updated daily and currently holds about 240,000 items, of which 72,000 in open access.

    We have a manual that explains all the features 

Records 1 - 20 / 288

  • help
  • print

    Print search results

  • export
    A maximum of 250 titles can be exported. Please, refine your queryYou can also select and export up to 30 titles via your marked list.
  • alert
    We will mail you new results for this query: q=Ven
Check title to add to marked list
Relative preference for wooden nests affects nesting behaviour of broiler breeders
Oever, Anna C.M. van den; Rodenburg, T.B. ; Bolhuis, J.E. ; Ven, Lotte J.F. van de; Hasan, Md Kamrul ; Aerle, Stephanie M.W. van; Kemp, Bas - \ 2019
Applied Animal Behaviour Science (2019). - ISSN 0168-1591
Behaviour - Broiler breeder - Nest design - Preference test - Welfare

Optimising nest design for broiler breeders has benefits for both the animals and the producers. The welfare of the hens will increase by providing preferred housing, while also reducing eggs laid outside the nests. These floor eggs cause economic losses by compromised automatic egg collection and reduced saleability and hatchability. Attractiveness of nests can involve factors such as seclusion, material and microclimate. In this study, four nest box designs were offered in a relative preference test: a plastic control nest, a plastic nest with a partition to divide the nest in two areas, a plastic nest with a ventilator underneath to create air flow inside the nest and a wooden nest. Six groups of 100 hens and 9 roosters had access to these four nests in a randomised location during the ages of 20 to 34 weeks. Nest and floor eggs were collected five days a week. Camera images from inside the nests made during the ages of 24–25 weeks and 26–27 weeks were analysed for behaviour. This included general activity, nest inspections, nest visits and social interactions. At 32 weeks of age the wooden nests were closed, and the subsequent response of the hens was monitored in terms of number of eggs. We found a clear preference in number of eggs for the wooden nest (69.3 ± 1.0%) compared to the control nest (15.1 ± 0.8%), partition nest (10.2 ± 0.5%) and the ventilator nest (5.4 ± 0.4%; p<0.0001 for difference between all nest designs). The preference for the wooden nest was also reflected in an increased time spent sitting, together with fewer nest inspections and visits per egg laid in the wooden nest. The preference for the wooden nest led to crowding, which caused an increased amount of piling, nest displacement, aggression and head shaking. The fact that the hens were willing to accept the crowded circumstances in these nests, underlines the strength of this preference. After the wooden nests were closed, the hens chose a new nest based on a combination of nest design and location. The control nest was still preferred over the other two plastic designs, although the neighbouring nests were overall preferred to the non-neighbouring nests. This study shows how the material used for nests is an important factor in suitability and should therefore be taken into account when designing nests.

Soil greenhouse gas emissions from inorganic fertilizers and recycled oil palm waste products from Indonesian oil palm plantations
Rahman, Niharika ; Bruun, Thilde Bech ; Giller, Ken E. ; Magid, Jakob ; Ven, Gerrie W.J. van de; Neergaard, Andreas de - \ 2019
Global change biology Bioenergy 11 (2019)9. - ISSN 1757-1693 - p. 1056 - 1074.
methane - nitrogen fertilizer - nitrous oxide - nutrient management - organic amendment - plant residue

A continuous rise in the global demand for palm oil has resulted in the large-scale expansion of oil palm plantations and generated environmental controversy. Efforts to increase the sustainability of oil palm cultivation include the recycling of oil mill and pruning residues in the field, but this may increase soil methane (CH4) emissions. This study reports the results of yearlong field-based measurements of soil nitrous oxide (N2O) and CH4 emissions from commercial plantations in North Sumatra, Indonesia. One experiment investigated the effects of soil-water saturation on N2O and CH4 emissions from inorganic fertilizers and organic amendments by simulating 25 mm rainfall per day for 21 days. Three additional experiments focused on emissions from (a) inorganic fertilizer (urea), (b) combination of enriched mulch with urea and (c) organic amendments (empty fruit bunches, enriched mulch and pruned oil palm fronds) applied in different doses and spatial layouts (placed in inter-row zones, piles, patches or bands) for a full year. The higher dose of urea led to a significantly higher N2O emissions with the emission factors ranging from 2.4% to 2.7% in the long-term experiment, which is considerably higher than the IPCC standard of 1%. Organic amendments were a significant source of both N2O and CH4emissions, but N2O emissions from organic amendments were 66%–86% lower than those from inorganic fertilizers. Organic amendments applied in piles emitted 63% and 71% more N2O and CH4, respectively, than when spread out. With twice the dose of organic amendments, cumulative emissions were up to three times greater. The (simulated) rainwater experiment showed that the increase in precipitation led to a significant increase in N2O emissions significantly, suggesting that the time of fertilization is a critical management option for reducing emissions. The results from this study could therefore help guide residue and nutrient management practices to reduce emissions while ensuring better nutrient recycling for sustainable oil palm production systems.

Improving the precision and accuracy of animal population estimates with aerial image object detection
Eikelboom, Jasper A.J. ; Wind, Johan ; Ven, Eline van de; Kenana, Lekishon M. ; Schroder, Bradley ; Knegt, Henrik J. de; Langevelde, Frank van; Prins, Herbert H.T. - \ 2019
Methods in Ecology and Evolution (2019). - ISSN 2041-210X
computer vision - convolutional neural network - deep machine learning - drones - game census - image recognition - savanna - wildlife survey

Animal population sizes are often estimated using aerial sample counts by human observers, both for wildlife and livestock. The associated methods of counting remained more or less the same since the 1970s, but suffer from low precision and low accuracy of population estimates. Aerial counts using cost-efficient Unmanned Aerial Vehicles or microlight aircrafts with cameras and an automated animal detection algorithm can potentially improve this precision and accuracy. Therefore, we evaluated the performance of the multi-class convolutional neural network RetinaNet in detecting elephants, giraffes and zebras in aerial images from two Kenyan animal counts. The algorithm detected 95% of the number of elephants, 91% of giraffes and 90% of zebras that were found by four layers of human annotation, of which it correctly detected an extra 2.8% of elephants, 3.8% giraffes and 4.0% zebras that were missed by all humans, while detecting only 1.6 to 5.0 false positives per true positive. Furthermore, the animal detections by the algorithm were less sensitive to the sighting distance than humans were. With such a high recall and precision, we posit it is feasible to replace manual aerial animal count methods (from images and/or directly) by only the manual identification of image bounding boxes selected by the algorithm and then use a correction factor equal to the inverse of the undercounting bias in the calculation of the population estimates. This correction factor causes the standard error of the population estimate to increase slightly compared to a manual method, but this increase can be compensated for when the sampling effort would increase by 23%. However, an increase in sampling effort of 160% to 1,050% can be attained with the same expenses for equipment and personnel using our proposed semi-automatic method compared to a manual method. Therefore, we conclude that our proposed aerial count method will improve the accuracy of population estimates and will decrease the standard error of population estimates by 31% to 67%. Most importantly, this animal detection algorithm has the potential to outperform humans in detecting animals from the air when supplied with images taken at a fixed rate.

Relative preference for wooden nests affects nesting behaviour in broiler breeders
Oever, Anne van den; Rodenburg, T.B. ; Bolhuis, J.E. ; Ven, L.F.J. van de; Kemp, B. - \ 2019
In: Proceedings of the 53rd Congress of the International Society for Applied Ethology (ISAE). - Wageningen, The Netherlands : Wageningen Academic Publishers - ISBN 9789086863389 - p. 310 - 310.
Optimising nest design for broiler breeders has benefits for both the animals and producer.The welfare of the hens will increase by providing preferred housing, while also reducing eggslaid outside the nests. These floor eggs cause economic losses by compromised automaticegg collection and reduced saleability and hatchability. Attractiveness of nests can involvefactors as seclusion, material and nest climate. In this study, four nest box designs are offeredin a relative preference test: a plastic control nest, a plastic nest with a partition to divide thenest in two areas, a plastic nest with a ventilator underneath to create air flow inside the nestand a wooden nest. Six groups of 100 hens and 9 roosters had access to these four nests in arandomised location during the ages of 20 to 34 weeks. Nest and floor eggs were collected fivedays a week. Camera images from inside the nests made during the ages 25-26 wk and 27-28wk were analysed on behaviour. This included general activity, nest inspections, nest visitsand social interactions. At 32 wk of age the wooden nests were closed, and the subsequentresponse of the hens was monitored in terms of number of eggs. We found a clear preferencefor the wooden nest in number of eggs (69.3±1.0%) compared to the control nest (15.1±0.8%),partition nest (10.2±0.5%) and the ventilator nest (5.4±0.4%; P<0.0001). This preference wasalso reflected in increased time spent sitting, together with fewer nest inspections and visitsper egg laid in the nest. The preference for the wooden nest led to crowding, which caused anincreased amount of piling, nest displacement, aggression and head shaking. After the woodennests were closed, the hens still had preference for nest design, although this was stronglyinfluenced by the location of the nest. We conclude that the broiler breeder hens in this studyhad a strong preference for the wooden nests and the fact that they were willing to accept thecrowded circumstances in these nests, shows the strength of this preference. When deniedaccess to their preferred nest, the hens chose a new nesting location based on nest designdepending on proximity to their original nesting location. This study shows how the materialused for nests is an important factor in suitability and should therefore be taken into accountwhen designing nests. In future experiments we will investigate gregariousness nesting furtherin addition to studying the influence of genetics and mobility on nesting behaviour.
Effects of nest design preference on nesting behaviour in broiler breeders
Oever, Anne van den; Rodenburg, T.B. ; Bolhuis, J.E. ; Ven, L.J.F. van de; Kemp, B. - \ 2019
In: Trade-offs in science – Keeping the balance. - Wageningen University & Research - p. 35 - 35.
LiGAPS-Beef, a mechanistic model to explore potential and feed-limited beef production 3: model evaluation
Linden, A. van der; Ven, G.W.J. van de; Oosting, S.J. ; Ittersum, M.K. van; Boer, I.J.M. de - \ 2019
Animal 13 (2019)4. - ISSN 1751-7311 - p. 868 - 878.
LiGAPS-Beef (Livestock simulator for Generic analysis of Animal Production Systems – Beef cattle) is a generic, mechanistic model designed to quantify potential and feed-limited growth, which provides insight in the biophysical scope to increase beef production (i.e. yield gap). Furthermore, it enables identification of the bio-physical factors that define and limit growth, which provides insight in management strategies to mitigate yield gaps. The aim of this paper, third in a series of three, is to evaluate the performance of LiGAPS-Beef with independent experimental data. After model calibration, independent data were used from six experiments in Australia, one in Uruguay and one in the Netherlands. Experiments represented three cattle breeds, and a wide range of climates, feeding strategies and cattle growth rates. The mean difference between simulated and measured average daily gains (ADGs) was 137 g/day across all experiments, which equals 20.1% of the measured ADGs. The root mean square error was 170 g/day, which equals 25.0% of the measured ADGs. LiGAPS-Beef successfully simulated the factors that defined and limited growth during the experiments on a daily basis (genotype, heat stress, digestion capacity, energy deficiency and protein deficiency). The simulated factors complied well to the reported occurrence of heat stress, energy deficiency and protein deficiency at specific periods during the experiments. We conclude that the level of accuracy of LiGAPS-Beef is acceptable, and provides a good basis for acquiring insight in the potential and feed-limited production of cattle in different beef production systems across the world. Furthermore, its capacity to identify factors that define or limit growth and production provides scope to use the model for yield gap analysis.
LiGAPS-Beef, a mechanistic model to explore potential and feed-limited beef production 2 : sensitivity analysis and evaluation of sub-models
Linden, A. van der; Ven, G.W.J. van de; Oosting, S.J. ; Ittersum, M.K. van; Boer, I.J.M. de - \ 2019
Animal 13 (2019)4. - ISSN 1751-7311 - p. 856 - 867.
beef cattle - mechanistic modelling - production ecology - sensitivity analysis - yield gap

The model LiGAPS-Beef (Livestock simulator for Generic analysis of Animal Production Systems – Beef cattle) has been developed to assess potential and feed-limited growth and production of beef cattle in different areas of the world and to identify the processes responsible for the yield gap. Sensitivity analysis and evaluation of model results with experimental data are important steps after model development. The first aim of this paper, therefore, is to identify which parameters affect the output of LiGAPS-Beef most by conducting sensitivity analyses. The second aim is to evaluate the accuracy of the thermoregulation sub-model and the feed intake and digestion sub-model with experimental data. Sensitivity analysis was conducted using a one-at-a-time approach. The upper critical temperature (UCT) simulated with the thermoregulation sub-model was most affected by the body core temperature and parameters affecting latent heat release from the skin. The lower critical temperature (LCT) and UCT were considerably affected by weather variables, especially ambient temperature and wind speed. Sensitivity analysis for the feed intake and digestion sub-model showed that the digested protein per kg feed intake was affected to a larger extent than the metabolisable energy (ME) content. Sensitivity analysis for LiGAPS-Beef was conducted for ¾ Brahman×¼ Shorthorn cattle in Australia and Hereford cattle in Uruguay. Body core temperature, conversion of digestible energy to ME, net energy requirements for maintenance, and several parameters associated with heat release affected feed efficiency at the herd level most. Sensitivity analyses have contributed, therefore, to insight which parameters are to be investigated in more detail when applying LiGAPS-Beef. Model evaluation was conducted by comparing model simulations with independent data from experiments. Measured heat production in experiments corresponded fairly well to the heat production simulated with the thermoregulation sub-model. Measured ME contents from two data sets corresponded well to the ME contents simulated with the feed intake and digestion sub-model. The relative mean absolute errors were 9.3% and 6.4% of the measured ME contents for the two data sets. In conclusion, model evaluation indicates the thermoregulation sub-model can deal with a wide range of weather conditions, and the feed intake and digestion sub-model with a variety of feeds, which corresponds to the aim of LiGAPS-Beef to simulate cattle in different beef production systems across the world.

LiGAPS-Beef, a mechanistic model to explore potential and feed-limited beef production 1 : model description and illustration
Linden, A. van der; Ven, G.W.J. van de; Oosting, S.J. ; Ittersum, M.K. van; Boer, I.J.M. de - \ 2019
Animal 13 (2019)4. - ISSN 1751-7311 - p. 845 - 855.
beef cattle - growth - mechanistic modelling - production ecology - yield gap

The expected increase in the global demand for livestock products calls for insight in the scope to increase actual production levels across the world. This insight can be obtained by using theoretical concepts of production ecology. These concepts distinguish three production levels for livestock: potential (i.e. theoretical maximum) production, which is defined by genotype and climate only; feed-limited production, which is limited by feed quantity and quality; and actual production. The difference between the potential or limited production and the actual production is the yield gap. The objective of this paper, the first in a series of three, is to present a mechanistic, dynamic model simulating potential and feed-limited production for beef cattle, which can be used to assess yield gaps. A novelty of this model, named LiGAPS-Beef (Livestock simulator for Generic analysis of Animal Production Systems – Beef cattle), is the identification of the defining factors (genotype and climate) and limiting factors (feed quality and available feed quantity) for cattle growth by integrating sub-models on thermoregulation, feed intake and digestion, and energy and protein utilisation. Growth of beef cattle is simulated at the animal and herd level. The model is designed to be applicable to different beef production systems across the world. Main model inputs are breed-specific parameters, daily weather data, information about housing, and data on feed quality and quantity. Main model outputs are live weight gain, feed intake and feed efficiency (FE) at the animal and herd level. Here, the model is presented, and its use is illustrated for Charolais and Brahman × Shorthorn cattle in France and Australia. Potential and feed-limited production were assessed successfully, and we show that FE of herds is highest for breeds most adapted to the local climate conditions. LiGAPS-Beef also identified the factors that define and limit growth and production of cattle. Hence, we argue the model has scope to be used as a tool for the assessment and analysis of yield gaps in beef production systems.

Effects of different nest designs on nesting behaviour in broiler breeders
Oever, A.C.M. van den; Rodenburg, T.B. ; Bolhuis, J.E. ; Ven, Lotte van de; Kemp, B. - \ 2018
In: Behavioural Biology in Animal Welfare Science - p. 15 - 16.
Floor eggs are a common issue in broiler breeders flocks, which are unwanted for two reasons: higheconomic costs and reduced animal welfare. The extra costs are caused by an increase of manual labourrequired, in addition to a reduced saleability and hatchability of floor eggs. The welfare of floor laying hensis reduced as the housing, in terms of nest attractiveness, is suboptimal. The goal of this study was toinvestigate which nest design is preferred by broiler breeder hens to lay their eggs. In a relative preferencetest four nest designs were provided to six groups of 100 females housed with 8 males during ages 20-33weeks. The four designs had the following characteristics: nest with a partition wall, nest with a subtle airflow inside created by a ventilator under the nest, nest with wooden walls and control nest. Eggs per nestwere collected daily. Videos were made for one day of each pen at ages 24-26 weeks and 27-29 weeksduring 3-5h and 7-9h after lights-on. Behaviour inside and outside the nests was scored continuouslyduring 5 minutes per half hour for point behaviours and scan sampled at a 10 minute interval for eventbehaviours. At 32 weeks of age the most preferred nest in each pen was closed to observe subsequentpreference. We found a relative preference for the nest with wooden walls compared to the other nestdesigns as more eggs, nest inspections and nest entrances were recorded for that nest. Signs of crowdingwere recorded inside the nest with wooden walls in the form of increased aggression, displacement andpiling behaviour. After closing the nests with wooden walls, the hens laid their eggs in the adjacent nest,independent of the design of this nest.
The devil is in the detail! : Sustainability assessment of African smallholder farming
Marinus, Wytze ; Ronner, E. ; Ven, G.W.J. van de; Kanampiu, Fred ; Adjei-Nsiah, Samuel ; Giller, K.E. - \ 2018
In: Routledge Handbook of Sustainability Indicators / Bell, S., Morse, S., Routledge - ISBN 9781138674769 - p. 427 - 450.

Indicators for sustainability are a hot and debated topic. Sustainable intensification of agriculture is also widely debated due to the divergent views on the future of agriculture and the wide variety of indicators used. Legumes are seen as a key option for sustainable intensification of smallholder farming systems in sub-Saharan Africa (SSA). We developed a framework for assessing the sustainability of contrasting farming systems to illustrate the complex balancing act involved, using a case study of the N2Africa project. N2Africa offers legume options to farmers in SSA (www.N2Africa.org). We worked at farm household level and used a hierarchical framework of principles and criteria to select the indicators for sustainability.

One of the main outcomes is a list of questions and hurdles we ran into when developing the framework. This can be used by others as guidance both when choosing indicators and to critically evaluate existing sustainability assessments. We illustrate that many of the decisions made in developing an indicator framework are subjective and that they include important but easily overlooked details. We conclude that, only by being explicit about the steps taken and the assumptions and decisions made, one can develop a sustainability framework that results in meaningful outcomes.

Developing an atlas of yield potential and yield gaps for current oil palm plantation area in Indonesia
Grassini, Patricio ; Rattalino Edreira, Juan I. ; Andrade, Jose ; Ven, G.W.J. van de; Hekman, Willem ; Beuken, Rob van den; Ittersum, M.K. van; Rahutomo, Suroso ; Sutarta, Edy Sigit ; Agus, F. ; Oberthür, Thomas ; Slingerland, M.A. - \ 2018
Estimating yield gaps in oilpalm in Indonesia using PALMSIM to inform policy on the scope of intensification
Hekman, Willem ; Slingerland, M.A. ; Beuken, Rob van den; Ven, G.W.J. van de; Grassini, Patricio ; Andrade, Jose ; Rattalino Edreira, Juan I. ; Rahutomo, Suroso ; Sutarta, Edy Sigit ; Agus, F. - \ 2018
Benchmarking living income for rural households in less developed countries
Valença, Anne de; Marinus, Wytze ; Hekman, Willem ; Thuijsman, E.C. ; Jager, I. de; Ven, G.W.J. van de; Descheemaeker, K.K.E. ; Giller, K.E. - \ 2018
Astaxanthine 2.0 : hoogwaardige inhoudsstoffen uit algen in kassen
Boer, Lex de; Bos, Jelle van den; Graman, Wim ; Hazewinkel, Sander ; Hemming, Silke ; Kerkhof, Gerwien ; Lans, Cees van der; Luijendijk, Teus ; Prins, Robert ; Roebroek, Eurgene ; Ruijven, Jim van; Streminska, Marta ; Ven, Joost van de; Vermeer, Chris ; Voogt, Wim ; Wisse, Wilko - \ 2018
Bleiswijk : Wageningen Plant Research, Business unit Glastuinbouw (Wageningen Plant Research, Business unit Glastuinbouw rapport WPR 807) - 86
Het doel van dit project was de realisatie van een proof-of-principle keten voor de productie van astaxanthine als oleoresin uit de alg Haematococcus pluvialis in fotobioreactoren in Nederlandse kassen. Astaxanthine is een sterk antioxidant dat bij kan dragen aan een gezonde voeding voor consumenten. Astaxanthine kan in Nederlandse kassen duurzaam worden geproduceerd (kassen als zonnecollector, gebruik afval CO2 uit industrie, reinigen afvalwater). Binnen dit project is onderzoek verricht naar de selectie van natuurlijke algenstammen op kasniveau, klassieke stamverbetering op labniveau (uitgangsmateriaal), procesverbetering in alle fases van de productie (voorkweek, opkweek, groene fase, rode fase) door optimalisatie teeltfactoren en hygiënisatie (teelt en productie) en het maken van een proof-of-principle eindproduct (eindformulering) volgens marktspecificatie (markt en economie). Met het project is kennis vergaard om een nieuw verdienmodel voor de productie van een hoogwaardige stof (astaxanthine) in de tuinbouw te realiseren. Er is een proof-of-principle van een economisch rendabele productieketen van uitgangsmateriaal over productie tot product eindformulering volgens specificaties van de markt aangetoond voor de productie van astaxanthine uit Haematococcus pluvialis.---The aim of this project was the realization of a proof-of-principle value chain for the production of astaxanthin as oleoresin from the algae Haematococcus pluvialis in photobioreactors in Dutch greenhouses. Astaxanthin is a strong antioxidant that can contribute to a healthy diet for consumers. Astaxanthin can be produced sustainably in Dutch greenhouses (greenhouses as solar collectors, usage of waste CO2 from industry, cleaning and recycling of waste water). Within this project, research was carried out into the selection of natural algae strains at the greenhouse level, classical strain improvement at lab level (starting material), process improvement at all stages of production, from pre-cultivation, cultivation, green phas and red phase, by the optimization of all cultivation factors and sanitation (growth and production) and designing a proof-of-principle end product (formulation) according to market specification (market and economy). With the project, knowledge has been gathered to realize a new revenue model for the production of a high-quality substance (astaxanthin) in horticulture. A proof-of-principle of an economically viable production chain of starting material from production to product final formulation according to market specifications has been demonstrated for the production of astaxanthin from Haematococcus pluvialis.
Changes in soil organic carbon stocks after conversion from forest to oil palm plantations in Malaysian Borneo
Rahman, Niharika ; Neergaard, Andreas de; Magid, Jakob ; Ven, Gerrie W.J. van de; Giller, Ken E. ; Bruun, Thilde Bech - \ 2018
Environmental Research Letters 13 (2018)10. - ISSN 1748-9318
deforestation - land use change - oil palm - organic residue management - SOC stocks - tropics

The continuous rise in the global demand for palm oil has resulted in large-scale expansion of industrial oil palm plantations - largely at the expense of primary and secondary forests. The potentially negative environmental impacts of these conversions have given rise to closer scrutiny. However, empirical data on the effects of conversion of forests to industrial oil palm plantations on soil organic carbon (SOC) stocks is scarce and patchy. We evaluated the changes in SOC stocks after conversion of tropical forest into oil palm plantations over the first and second rotation period in Sarawak, Malaysian Borneo. Soil samples were collected from three age classes of oil palm plantations converted from forest (49, 39 and 29 years ago respectively) with three replicate sites and four adjacent primary forest sites as reference. In each site under oil palm, the three management zones, namely weeded circle (WC), frond stacks (FS), and between palm (BP), were sampled separately. All soil samples were collected from five soil layers (0-5, 5-15, 15-30, 30-50 and 50-70 cm). Samples were analysed for SOC concentration, soil bulk density, pH and soil texture. Results showed SOC stocks declined by 42%, 24% and 18% after 29, 39 and 49 years of conversion respectively. Significant differences in SOC stocks were found among different management zones in the oil palm plantations, and the trend was similar for all age classes: FS > WC > BP, demonstrating the necessity of considering within-plantation variability when assessing soil C stocks. The largest differences between SOC stocks of the reference forest and converted plantations were found in the topsoil (0-15 cm depth) but differences were also found in the subsoil (>30 cm). Our results will contribute towards future modelling and life cycle accounting to calculate the carbon debt from the conversion of forest to oil palm plantations.

Meeting the dual demand for animal products and climate change mitigation by narrowing yield gaps
Linden, A. van der; Gerber, P.J. ; Ven, G.W.J. van de; Ittersum, M.K. van; Boer, I.J.M. de; Oosting, S.J. - \ 2018
In: Book of abstracts of the 69th Annual Meeting of the European Federation of Animal Science. - Wageningen : Wageningen Academic Publishers (Book of abstracts 24) - ISBN 9789086863235 - p. 340 - 340.
Reply to comment by Van de Ven et al. on our paper “Crop yield gap and stability in conventional and organic systems”
Schrama, M. ; Haan, J.J. de; Kroonen, M. ; Verstegen, H. ; Putten, W.H. van der - \ 2018
Agriculture, Ecosystems and Environment 267 (2018). - ISSN 0167-8809 - p. 83 - 86.
Can farming provide a way out of poverty for smallholder farmers in central Mozambique?
Leonardo, Wilson ; Ven, Gerrie W.J. van de; Kanellopoulos, Argyris ; Giller, Ken E. - \ 2018
Agricultural Systems 165 (2018). - ISSN 0308-521X - p. 240 - 251.
Farm model - Gross margin - Maize sales - Optimization model - Trade-offs

Given that agriculture is a key economic activity of the majority of people living in rural Africa, agricultural development is at the top of the agenda of African leaders. Intensification of agriculture is considered an entry point to improve food security and income generation in sub-Saharan African (SSA). We used a farm optimization model to perform ex-ante assessment of scenarios that could improve gross margin, a farmer's objective, and maize sales, a national policy objective to improve food security, of large and small farms in maize-based farming systems in two posts representative of rural Mozambique (Dombe and Zembe Administrative Posts in Central Province). For selling maize, farmers first had to be maize self-sufficient. We explored two options for increasing agricultural productivity: (i) extensification, to expand the current cultivated area; and (ii) intensification, to increase input use per unit of land. We considered two scenarios for each of the two options. Extensification: current situation (SC1), hired labour (SC2) and labour-saving (SC3). Intensification: land-saving (SC4) and combined improvement (SC5). For each scenario, we maximized gross margin and maize sales for large and small farms and assessed the trade-offs between the two goals. We further explored the impact of increasing labour and land availability at farm level beyond the current observed levels. SC4 substantially increased both gross margin and maize sales of large and small farms in both posts. Minor trade-offs were observed between the two goals on large farms whereas we saw synergies between the goals for small farms. In Dombe, the gross margin of large farms increased from $ 5550 to $ 7530 y-1 and maize sales from 12.4 t to 30.4 t y-1. In Zembe, the annual gross margin increased from $ 1130 up to $ 2410 per farm and annual maize sales from 5.1 t up to 9.5 t per farm. For small farms in Dombe, the gross margin increased from $ 1820 to $ 2390 y-1 and maize sales from 3.0 t to 9 t y-1. In Zembe, the annual gross margin increased from $ 260 to $ 810 and annual maize sales from 2.0 t to 3.6 t per farm. With the most optimistic scenarios and conditions of more hired labour and labour-saving technologies, both farm types substantially increased both gross margin and maize sales. We conclude that with available resources, the possibilities for increasing gross margin and maize sales are greater where agroecological conditions are more favourable and are much higher for larger farms. Without interventions that allow small farms to access more labour and land, intensification of agriculture is likely to happen only on farms of better-resourced households, indicating the need for alternative forms of on- and off-farm income generation for poorer farmers. The contribution of agriculture to national food security has to come from the large farms, requiring policy support.

Comment on Schrama et al. (2018) “Crop yield gap and stability in conventional and organic farming systems.” [Agric. Ecosyst. Environ. (256) 123–130]
Ven, G.W.J. van de; Schröder, J.J. ; Hijbeek, R. ; Velthof, G.L. ; Ittersum, M.K. van - \ 2018
Agriculture, Ecosystems and Environment 261 (2018). - ISSN 0167-8809 - p. 133 - 135.
LiGAPS-Beef 2018
Linden, A. van der; Ven, G.W.J. van de; Oosting, S.J. ; Ittersum, M.K. van; Boer, I.J.M. de - \ 2018
LiGAPS-Beef is a mechanistic model to assess potential and feed-limited beef production in different beef production systems across the world. The model is one of the first using concepts of production ecology to simulate livestock production. LiGAPS-Beef consists of a thermoregulation sub-model, a feed intake and digestion sub-model, and an energy and protein utilization sub-model. Energy and protein flows are included. Livestock production can be assessed for individual animals and herds. LiGAPS-Beef simulates cattle growth based on defining growth factors (genotype or breed and climate) and limiting growth factors (feed quality and feed quantity). The model can be used to assess yield gaps in beef production systems, and to explore improvement options for yield gap mitigation.
Check title to add to marked list
<< previous | next >>

Show 20 50 100 records per page

 
Please log in to use this service. Login as Wageningen University & Research user or guest user in upper right hand corner of this page.