Staff Publications

Staff Publications

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    '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.

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    Stochastic uncertainty and sensitivities of nitrogen flows on diary farms in The Netherlands
    Oenema, J. ; Burgers, S. ; Keulen, H. van; Ittersum, M.K. van - \ 2015
    Agricultural Systems 137 (2015). - ISSN 0308-521X - p. 126 - 138.
    manure management-practices - nutrient management - use efficiency - systems - balances - budgets - losses - europe
    Nutrient management decisions and environmental policy making must be based on sound data and proper analysis. Annual data collection and monitoring of farm and nutrient performance are wrought with uncertainties. Such uncertainties need to be addressed as it may lead to ambiguities and wrong conclusions. We developed an input-output N balance model to describe and quantify N flows in dairy farming systems. Input for this model was based on monitored data for one year (2005) from one experimental (detailed monitoring) and 14 pilot commercial dairy farms (less detailed monitoring). A Monte Carlo approach was used to quantify effects of uncertainty of input data on annual farm N surplus, soil surface N surplus and N intake during grazing, followed by a sensitivity analysis to apportion the different sources of uncertainty. Uncertainties in data input were described with probability density functions. Farm N surplus of the 14 pilot farms ranged between 81 and 294¿kg¿ha-1, soil surface N surplus between 35 and 256¿kg¿ha-1, and N intake during grazing between 27 and 108¿kg¿ha-1. The uncertainties of N flows – both relative and absolute – increased from farm N surplus (CV¿=¿8%; SD¿=¿15¿kg¿N¿ha-1) to soil surface N surplus (CV¿=¿12%; SD¿=¿16¿kg¿N¿ha-1) to N intake during grazing (CV¿=¿49%; SD¿=¿28¿kg¿N¿ha-1). Variation in uncertainty among farms in farm and soil surface N surplus and N intake during grazing was substantial and was related to the farm structure and farm characteristics such as production intensity, N fixation by clover and annual changes in stocks of roughage and manure. We found that a monitoring program based on more measurements instead of estimates and/or fixed rate values from literature will not always result in a better quantification of farm and soil surface N surplus on clover-based dairy farms. However, on farms with no N fixation, an intensive monitoring program reduced the uncertainty in farm and soil surface N surplus by 23% and the uncertainty of N intake during grazing was reduced by more than 30%. Knowledge about uncertainties of N flows is necessary to correctly interpret the N performance on dairy farms and its evolution through time. A first step is to get insights into the most uncertain N flows on a dairy farm. The next step, where possible, is to improve the estimation of the most uncertain N flows. Based on the insights from this study, these steps will underpin the validation of trends in N performance and justify decisions in environmental policy making and/or decisions for making on-farm improvements.
    Nutrient use efficiency: a valuable approach to benchmark the sustainability of nutrient use in global livestock production
    Gerber, P.J. ; Uwizeye, U.A. ; Schulte, R.P.O. ; Opio, C.I. ; Boer, I.J.M. de - \ 2014
    Current Opinion in Environmental Sustainability 9-10 (2014). - ISSN 1877-3435 - p. 122 - 130.
    nitrogen use efficiency - phosphorus use-efficiency - dairy production systems - substance flow-analysis - farm-scale - management-practices - animal production - balances - agriculture - indicators
    Livestock have a large impact on nutrient cycles, with repercussions on environmental and public health issues. Designing interventions for better environmental sustainability will require indicators adapted to the increasingly long and complex supply chains. Nutrient use efficiency is a well know approach to benchmark nutrient management at the animal level, and to some extent at the farm level. Integrating the life cycle approach into NUE allows for the computation of supply chain level NUE, which is proposed as a valuable indicator of nutrient management sustainability. It characterizes the use of finite nutrient and energy resources and the losses of nutrients per unit of product, likely to have impacts on the environment and public health. Further research is required to harmonize life-cycle-NUE and test its validity as an indicator of nutrient management sustainability
    Key role of China and its agriculture in global sustainable phosphorus management
    Sattari, S.Z. ; Ittersum, M.K. van; Giller, K.E. ; Zhang, F. ; Bouwman, A.F. - \ 2014
    Environmental Research Letters 9 (2014)5. - ISSN 1748-9326 - 8 p.
    environmental impacts - soil-phosphorus - crop yield - food-chain - fertilizer - nitrogen - perspective - scarcity - balances - industry
    Growing global demand for food leads to increased pressure on phosphorus (P), a finite and dwindling resource. China is the largest producer and consumer of P fertilizer in the world. A mass balance analysis of historical P use on China's arable land shows that P input substantially exceeds crop P uptake leading to the accumulation of residual soil P. A Dynamic P Pool Simulator (DPPS) model is applied to estimate future P demand in China's arable land. Our simulations show that more sustainable use of P accounting for the residual P can save ca. 20% of the P fertilizer needed until 2050 in China relative to the Rio + 20 Trend scenario. This saving would be equivalent to half of the P required in Africa or sufficient for Western Europe to achieve target crop P uptake in 2050.
    Energy use and greenhouse gas emissions in organic and conventional farming systems in the Netherlands
    Bos, J.F.F.P. ; Haan, J.J. de; Sukkel, W. ; Schils, R.L.M. - \ 2014
    NJAS Wageningen Journal of Life Sciences 68 (2014). - ISSN 1573-5214 - p. 61 - 70.
    life-cycle assessment - southern germany - dairy - agriculture - efficiency - biodiversity - balances - impacts - model - milk
    Organic agriculture is often considered to contribute to reducing energy use and greenhouse gas (GHG) emissions, also on a per unit product basis. For energy, this is supported by a large number of studies, but the body of evidence for GHGs is smaller. Dutch agriculture is characterized by relatively intensive land use in both organic and conventional farming, which may affect their performance in terms of energy use and GHG emissions. This paper presents results of a model study on energy use and GHG emissions in Dutch organic and conventional farming systems. Energy use per unit milk in organic dairy is approximately 25% lower than in conventional dairy, while GHG emissions are 5-10% lower. Contrary to dairy farming, energy use and GHG emissions in organic crop production are higher than in conventional crop production. Energy use in organic arable farming is 10-30% and in organic vegetable farming 40-50% higher than in their respective conventional counterparts. GHG emissions in organic arable and vegetable farming are 0-15% and 35-40% higher, respectively. Our results correspond with other studies for dairy farming, but not for crop production. The most likely cause for higher energy use and GHG emissions in Dutch organic crop production is its high intensity level, which is expressed in crop rotations with a large share of high-value crops, relatively high fertiliser inputs and frequent field operations related to weeding
    Skill of a global seasonal streamflow forecasting system, relative roles of initial conditions and meteorological forcing
    Yossef, N.C. ; Winsemius, H. ; Weerts, A.H. ; Beek, R. van; Bierkens, M.F.P. - \ 2013
    Water Resources Research 49 (2013)8. - ISSN 0043-1397 - p. 4687 - 4699.
    united-states - hydrological model - water-resources - climate-change - discharge - predictability - availability - prediction - validation - balances
    We investigate the relative contributions of initial conditions (ICs) and meteorological forcing (MF) to the skill of the global seasonal streamflow forecasting system FEWS-World, using the global hydrological model PCRaster Global Water Balance. Potential improvement in forecasting skill through better climate prediction or by better estimation of ICs through data assimilation depends on the relative importance of these sources of uncertainty. We use the Ensemble Streamflow Prediction (ESP) and reverse ESP (revESP) procedure to explore the impact of both sources of uncertainty at 78 stations on large global basins for lead times upto 6 months. We compare the ESP and revESP forecast ensembles with retrospective model simulations driven by meteorological observations. For each location, we determine the critical lead time after which the importance of ICs is surpassed by that of MF. We analyze these results in the context of prevailing hydroclimatic conditions for larger basins. This analysis suggests that in some basins forecast skill may be improved by better estimation of initial hydrologic states through data assimilation; whereas in others skill improvement depends on better climate prediction. For arctic and snowfed rivers, forecasts of high flows may benefit from assimilation of snow and ice data. In some snowfed basins where the onset of melting is highly sensitive to temperature changes, forecast skill depends on better climate prediction. In monsoonal basins, the variability of the monsoon dominates forecasting skill, except for those where snow and ice contribute to streamflow. In large basins, initial surface water and groundwater states are important sources of skill.
    Management, regulation and environmental impacts of nitrogen fertilization in northwestern Europe under the Nitrates Directive; a benchmark study
    Grinsven, H.J.M. van; Berge, H.F.M. ten; Dalgaard, T. ; Fraters, B. ; Durand, P. ; Hart, A. ; Hofman, G. ; Jacobsen, B.H. ; Lalor, S.T.J. ; Lesschen, J.P. ; Osterburg, B. ; Richards, K.G. ; Techen, A.K. ; Vertes, F. ; Webb, J. ; Willems, W.J. - \ 2012
    Biogeosciences 9 (2012)12. - ISSN 1726-4170 - p. 5143 - 5160.
    agriculture - losses - groundwater - balances - denmark
    Implementation of the Nitrates Directive (NiD) and its environmental impacts were compared for member states in the northwest of the European Union (Ireland, United Kingdom, Denmark, the Netherlands, Belgium, Northern France and Germany). The main sources of data were national reports for the third reporting period for the NiD (2004-2007) and results of the MITERRA-EUROPE model. Implementation of the NiD in the considered member states is fairly comparable regarding restrictions for where and when to apply fertilizer and manure, but very different regarding application limits for N fertilization. Issues of concern and improvement of the implementation of the NiD are accounting for the fertilizer value of nitrogen in manure, and relating application limits for total nitrogen (N) to potential crop yield and N removal. The most significant environmental effect of the implementation of the NiD since 1995 is a major contribution to the decrease of the soil N balance (N surplus), particularly in Belgium, Denmark, Ireland, the Netherlands and the United Kingdom. This decrease is accompanied by a modest decrease of nitrate concentrations since 2000 in fresh surface waters in most countries. This decrease is less prominent for groundwater in view of delayed response of nitrate in deep aquifers. In spite of improved fertilization practices, the southeast of the Netherlands, the Flemish Region and Brittany remain to be regions of major concern in view of a combination of a high nitrogen surplus, high leaching fractions to groundwater and tenacious exceedance of the water quality standards. On average the gross N balance in 2008 for the seven member states in EUROSTAT and in national reports was about 20 kg N ha(-1) yr(-1) lower than by MITERRA. The major cause is higher estimates of N removal in national reports which can amount to more than 50 kg N ha(-1) yr(-1). Differences between procedures in member states to assess nitrogen balances and water quality and a lack of cross-boundary policy evaluations are handicaps when benchmarking the effectiveness of the NiD. This provides a challenge for the European Commission and its member states, as the NiD remains an important piece of legislation for protecting drinking water quality in regions with many private or small public production facilities and controlling aquatic eutrophication from agricultural sources.
    Weegsysteem voor vleesvarkens en biggen PigScale
    Genugten, M.M. van; Peet-Schwering, C.M.C. van der - \ 2012
    Lelystad : Wageningen UR Livestock Research - 4
    varkens - biggen - varkenshouderij - weegschalen - weegapparaten voor varkens - pigs - piglets - pig farming - balances - pig weighers
    Binnen het project ‘Vitale vleesvarkens’ is onderzoek uitgevoerd naar de nauwkeurigheid en praktische toepasbaarheid van weegsystemen voor vleesvarkens. Op praktijkbedrijven is er grote behoefte aan het automatisch verzamelen van gewichten van vleesvarkens gedurende het vleesvarkenstraject zodat de groei van de vleesvarkens gemonitord en, indien nodig, bijgestuurd kan worden.
    Improving nitrogen management on grassland on commercial pilot dairy farms in the Netherlands
    Oenema, J. ; Ittersum, M.K. van; Keulen, H. van - \ 2012
    Agriculture, Ecosystems and Environment 162 (2012)nov. - ISSN 0167-8809 - p. 116 - 126.
    use efficiency - nutrient management - system - agriculture - carbon - regulations - phosphorus - balances - project - impact
    Nitrogen (N) use efficiency (NUE), the ratio of N output and N input, is rather low on dairy farms with high stocking densities and high N input on grassland resulting in high N losses to the environment. This study describes and analyses the development and variation in N management on grassland on 16 commercial pilot dairy farms in the project ‘Cows & Opportunities’ (C&O) over a 12-year period (1998–2009, with the aim that applying this knowledge to other farmers may provide insight in the (im)possibilities to improve management. Farm milk production ranged from 11 to 23 Mg ha-1 and grassland occupied ca. 80% of the total land area (between 63 and 97%). Mean N application rate (kg total N ha-1 year-1) on grassland (in manure, chemical fertilizer, excreta during grazing, biological N fixation and atmospheric deposition) on the pilot farms decreased from 540 in 1998 to 450 in 2001, while in the remainder of the period the inter-annual variation was low (between 400 and 450). Mean dry matter yields on grassland (11 Mg ha-1) varied among years and farms (between 7.7 and 16 Mg ha-1), without any significant temporal trend. We observed no trend of diminishing returns of dry matter yields at farm scale up to an N application rate on grassland of ca. 600 kg ha-1 because farms with a high production intensity (Mg milk ha-1) need more dry matter than farms with a lower intensity and were able to increase nitrogen management on grassland with high N input levels. Management options that result in improved NUE include reduced grazing time which results in increased dry matter yields and NUE as a consequence of better utilization of organic manure.
    Residual soil phosphorus as the missing piece in the global phosphorus crisis puzzle
    Sattari, S.Z. ; Bouwman, A.F. ; Giller, K.E. ; Ittersum, M.K. van - \ 2012
    Proceedings of the National Academy of Sciences of the United States of America 109 (2012)16. - ISSN 0027-8424 - p. 6348 - 6353.
    dairy farming system - term crop response - fertilizer phosphorus - perspective - balances - nitrogen
    Phosphorus (P) is a finite and dwindling resource. Debate focuses on current production and use of phosphate rock rather than on the amounts of P required in the future to feed the world. We applied a two-pool soil P model to reproduce historical continental crop P uptake as a function of P inputs from fertilizer and manure and to estimate P requirements for crop production in 2050. The key feature is the consideration of the role of residual soil P in crop production. Model simulations closely fit historical P uptake for all continents. Cumulative inputs of P fertilizer and manure for the period 1965–2007 in Europe (1,115 kg·ha-1 of cropland) grossly exceeded the cumulative P uptake by crops (360 kg·ha-1). Since the 1980s in much of Europe, P application rates have been reduced, and uptake continues to increase due to the supply of plant-available P from residual soil P pool. We estimate that between 2008 and 2050 a global cumulative P application of 700–790 kg·ha-1 of cropland (in total 1,070–1,200 teragrams P) is required to achieve crop production according to the various Millennium Ecosystem Assessment scenarios [Alcamo J, Van Vuuren D, Cramer W (2006) Ecosystems and Human Well-Being: Scenarios, Vol 2, pp 279–354]. We estimate that average global P fertilizer use must change from the current 17.8 to 16.8–20.8 teragrams per year in 2050, which is up to 50% less than other estimates in the literature that ignore the role of residual soil P.
    Vertical distribution of heavy metals in wastewater-irrigated vegetable garden soils of three West African cities
    Abdu, N. ; Abdulkadir, A. ; Agbenin, J.O. ; Buerkert, A. - \ 2011
    Nutrient Cycling in Agroecosystems 89 (2011)3. - ISSN 1385-1314 - p. 387 - 397.
    farming systems - balances - agroecosystems - pollution - scale - lead - pb
    Application of untreated wastewater to irrigate urban vegetable gardens is raising serious concern about possible health risks associated with the consumption of these vegetables particularly with regard to the concentrations of heavy metals (HM) in their edible portions. The soil concentrations of cadmium (Cd), chromium (Cr), copper (Cu), nickel (Ni), lead (Pb) and zinc (Zn), were investigated in seven vegetable gardens from the three West African cities of Kano (Nigeria), Bobo Dioulasso (Burkina Faso) and Sikasso (Mali). Also determined were input–output balances of Cd and Zn from five vegetable gardens under 30 years of wastewater irrigation in Kano. In these gardens Cd (2.3–4.8 mg kg-1) and Zn (13–285 mg kg-1) concentrations throughout the profile attained unsafe levels. The concentrations of Cu (0.8–18 mg kg-1), Cr (1.8–72 mg kg-1), Ni (0–17 mg kg-1) and Pb (0.6–46 mg kg-1) were below the safety thresholds for arable soils. Overall, concentrations of Zn, Cd, Pb and Ni were higher in Kano than in Bobo-Dioulasso and Sikasso. Input–output analyses in Kano indicated that irrigation wastewater contributed annually 400–3,700 g Cd ha-1 and 7,200–22,300 g Zn ha-1, fertilizer 30–2,100 g Cd ha-1 50–17,600 g Zn ha-1, harmattan dust 0.02–0.4 g Cd ha-1 and 40–200 g Zn ha-1 while 300–500 g Cd ha-1 and 2,700–4,700 g Zn ha-1 came from rainwater inputs. Input–output calculations subtracting the amounts of HM taken out in vegetable biomass and that lost to leaching from total inputs yielded an annual net positive balance of 700–4,160 g Cd ha-1 and 9,350–39,700 g Zn ha-1. If such balances remain unchanged for another 10–20 years vegetables raised in these garden fields are likely to be unsuitable for human consumption
    Comparison of land nitrogen budgets for European agriculture by various modeling approaches
    Vries, W. de; Leip, A. ; Reinds, G.J. ; Lesschen, J.P. ; Bouwman, A.F. - \ 2011
    Environmental Pollution 159 (2011)11. - ISSN 0269-7491 - p. 3254 - 3268.
    no emissions - forest soils - n2o - inventory - ecosystems - balances - losses - fields - carbon - water
    A comparison of nitrogen (N) budgets for the year 2000 of agro-ecosystems is made for the EU 27 countries by four models with different complexity and data requirements, i.e. INTEGRATOR, IDEAg, MITERRA and IMAGE. The models estimate a comparable total N input in European agriculture, i.e. 23.3–25.7 Mton N yr-1, but N uptake varies more, i.e. from 11.3 to 15.4 Mton N yr-1 leading to total N surpluses varying from 10.4 to 13.2 Mton N yr-1. The estimated overall variation at EU 27 is small for the emissions of ammonia (2.8–3.1 Mton N yr-1) and nitrous oxide (0.33–0.43 Mton N yr-1), but large for the sum of N leaching and runoff (2.7–6.3 Mton N yr-1). Unlike the overall EU estimates, the difference in N output fluxes between models is large at regional scale. This is mainly determined by N inputs, differences being highest in areas with high livestock density.
    Participatory farm management adaptations to reduce environmental impact on commercial pilot dairy farms in the Netherlands
    Oenema, J. ; Keulen, H. van; Schils, R.L.M. ; Aarts, H.F.M. - \ 2011
    NJAS Wageningen Journal of Life Sciences 58 (2011)1-2. - ISSN 1573-5214 - p. 39 - 48.
    nitrogen use efficiency - nutrient management - european-community - systems - opportunities - regulations - perceptions - performance - strategies - balances
    Regulations in the Netherlands with respect to nutrient use force dairy farmers to improve nutrient management at the whole-farm level. On experimental farm ‘De Marke’, a coherent set of simple measures at farm level has been implemented, which has resulted in a drastic reduction in input of nutrients without affecting production intensity (milk production; kg milk per ha). To promote adoption of these measures in commercial dairy farming, the project ‘Cows & Opportunities’ was initiated in which 16 commercial pilot farms participated. Data were collected over a 6-year period (1998–2003). This paper describes and analyses the different farm management strategies adopted on these farms, using two classifications of the farms at the start of the project (the base situation), one based on nitrogen (N) surplus (kg ha-1), the other on production intensity. In both classifications, the farms were split in two equal groups. Changes over time in farm characteristics (farm development) were described through linear regression for each group and the variance among farms within a group was used to test for differences between groups. Under the influence of economic driving forces, the pilot farms, on average, expanded land area and increased their milk quota. However, the most intensive farms could comply with regulations only by reducing production intensity. From 1998 to 2002, average nutrient surpluses on the pilot farms decreased by 33% for N and 53% for phosphorus (P). Important measures were reducing the use of inorganic fertilizer, optimizing the use of home-produced organic manure, reducing grazing time, reducing the number of replacement stock and lowering crude protein content in the ration. Over the years, variation in N surpluses among farms (inter-farm variation) remained almost constant. Differences in farm management strategy could not unequivocally be related to farm typology (high/low N surplus; high/low production intensity). It was concluded that decisions by individual farmers on farm development are not always based on ‘rational’ arguments, but are co-determined by ‘emotional’ perceptions.
    Managing soil fertility diversity to enhance resource use efficiencies in smallholder farming systems: a case from Murewa District, Zimbabwe
    Zingore, S. ; Tittonell, P.A. ; Corbeels, M. ; Wijk, M.T. van; Giller, K.E. - \ 2011
    Nutrient Cycling in Agroecosystems 90 (2011)1. - ISSN 1385-1314 - p. 87 - 103.
    nutrient use efficiencies - organic-matter - western kenya - management - scale - balances - field - variability - strategies - gradients
    Smallholder farms in sub-Saharan African exhibit substantial heterogeneity in soil fertility, and nutrient resource allocation strategies that address this variability are required to increase nutrient use efficiencies. We applied the Field-scale resource Interactions, use Efficiencies and Long-term soil fertility Development (FIELD) model to explore consequences of various manure and fertilizer application strategies on crop productivity and soil organic carbon (SOC) dynamics on farms varying in resource endowment in a case study village in Murewa District, Zimbabwe. FIELD simulated a rapid decline in SOC and maize yields when native woodlands were cleared for maize cultivation without fertilizer inputs coupled with removal of crop residues. Applications of 10 t manure ha-1 year-1 for 10 years were required to restore maize productivity to the yields attainable under native woodland. Long-term application of manure at 5 and 3 t ha-1 resulted in SOC contents comparable to zones of high and medium soil fertility observed on farms of wealthy cattle owners. Targeting manure application to restore SOC to 50–60% of contents under native woodlands was sufficient to increase productivity to 90% of attainable yields. Short-term increases in crop productivity achieved by reallocating manure to less fertile fields were short-lived on sandy soils. Preventing degradation of the soils under intensive cultivation is difficult, particularly in low input farming systems, and attention should be paid to judicious use of the limited nutrient resources to maintain a degree of soil fertility that supports good crop response to fertilizer application
    Heterogeneity in farmers’ production decisions and its impact on soil nutrient use: Results and implications from northern Nigeria
    Berkhout, E.D. ; Schipper, R.A. ; Keulen, H. van; Coulibaly, O. - \ 2011
    Agricultural Systems 104 (2011)1. - ISSN 0308-521X - p. 63 - 74.
    sustainable agricultural intensification - south-western niger - resource use - systems - management - policy - model - scenarios - dynamics - balances
    Sustainable use (in terms of nutrients) of soil resources by farmers in Sub-Saharan Africa is constrained by institutions and markets. This paper explores the case of northern Nigeria, by using a combination of multi-attribute utility theory and bio-economic modelling. This approach allowed us to identify heterogeneity in production strategies and to quantify its effect on the use of soil nutrient resources. We find that farmers with larger land holdings place more emphasis on gross margins in their utility function, while those with larger holdings of fertile fadama fields place more emphasis on sustainability. Risk aversion, operationalised through variance minimization, appears an important attribute in the utility function of many farm households that are more dependent on agriculture for their overall income. A regression analysis shows that differences in production strategies significantly affect nutrient balances, but also shows that such effects are heterogeneous across locations. We find more favourable nutrient balances for some of the more market-oriented farm households who place more emphasis on sustainability. In farm plans of the most risk-averse households, the production of cereals for subsistence consumption dominates and leads to negative soil nutrient balances, especially for potassium. Farmers who place a large importance on gross margins are likely to benefit most from policies aimed at enhancing profitability through improving functioning of markets. The large group of risk-averse farmers will have the largest immediate gain in utility from policies and technologies aimed at reducing production risk in high-value crops. Additional policies aimed at creating a stronger market-oriented production by the least-endowed farm households could play a role in reducing intensity of soil fertility mining. Under these conditions, the efficient cropping pattern shifts partially from cereal cropping to high-value crops, associated with higher input use. The main results are similar to those in other studies, although some of the nutrient balances are less negative. The results do appear to be sensitive to the type of cropping activities included in the analysis, and additional methodological research is required. Extensions of the used method should further account for temporal and spatial differences in soil fertility, leading to differences in nutrient uptake and production, as well as potential temporal heterogeneity in production strategies.
    Changes in the soil phosphorus status of agricultural land in the Netherlands during the 20th century
    Reijneveld, J.A. ; Ehlert, P.A.I. ; Termorshuizen, A.J. ; Oenema, O. - \ 2010
    Soil Use and Management 26 (2010)4. - ISSN 0266-0032 - p. 399 - 411.
    temporal variability - phosphate status - nitrogen - losses - europe - trends - water - dynamics - balances - quality
    The Netherlands has a high cumulative mean phosphorus (P) balance. In the 20th century, cumulative mean P surpluses were ca. 4500 kg P2O5/ha. The annual surpluses have levelled off because of manure application limits from 1984 onwards. We report the effect of soil type, land use, and manure policy on changes in soil P of fields in the Netherlands during the 20th century. We used data (> 5 million soil P tests) from the soil analysis laboratory BLGG AgroXpertus. Our results show that soil P has increased on average to fairly high and high ratings. Differences between regions and between land use have remained high from the first records in the 1930s; on arable land the increase continued until the end of our study period while on grassland no changes are evident in the last decades. In general regions with high livestock density have high soil P status. Soil P increased in the order bulbfields
    Nutrient loss pathways from grazed grasslands and the effects of decreasing inputs: experimental results for three soil types
    Beek, C.L. ; Salm, C. van der; Plette, A. ; Weerd, H. van de - \ 2009
    Nutrient Cycling in Agroecosystems 83 (2009)2. - ISSN 1385-1314 - p. 99 - 110.
    surface-water - agricultural land - nitrogen - phosphorus - denitrification - netherlands - balances - ammonia - model - volatilization
    Agriculture is a main contributor of diffuse emissions of N and P to the environment. For N the main loss pathways are NH3-volatilization, leaching to ground and surface water and N-2(O) emissions. Currently, imposing restraints on farm inputs are used as policy tool to decrease N and P leaching to ground water and to surface water, and the same measure is suggested to combat emissions of N2O. The response, however, to these measures largely depends on the soil type. In this study nutrient flows of three dairy farms in The Netherlands with comparable intensity on sand, peat and clay soils were monitored for at least 2 years. The first aim was to provide quantitative data on current nutrient loss pathways. The second aim was to explore the responses in partitioning of the nutrient loss pathways when farm inputs were altered. Mean denitrification rates ranged from 103 kg N ha(-1) year(-1) for the sandy soil to 170 kg N ha(-1) year(-1) for the peat soil and leaching to surface water was about 73 kg N ha(-1) year(-1) for the sandy soil, 15 kg N ha(-1) year(-1) for the clay soil and 38 kg N ha(-1) year(-1) for the peat soil. For P, leaching to surface water ranged from 2 kg P ha(-1) year(-1) for the sandy site to 5 kg P ha(-1) year(-1) for the peat site. The sandy soil was most responsive to changes in N surpluses on leaching to surface water, followed by the peat soil and least responsive was the clay soil. For P, a similar sequence was found. This article demonstrates that similar reductions of N and P inputs result in different responses in N and P loss pathways for different soil types. These differences should be taken into account when evaluating measures to improve environmental performance of (dairy) farms
    Farm nitrogen flows of four farmer field schools in Kenya
    Beek, C.L. ; Onduru, D.D. ; Gachimbi, L.N. ; Jager, A. de - \ 2009
    Nutrient Cycling in Agroecosystems 83 (2009)1. - ISSN 1385-1314 - p. 63 - 72.
    monitoring nutrient flows - sub-saharan africa - economic-performance - systems nutmon - 3 districts - management - balances - highlands
    Re-use of nutrients within farming systems contributes to sustainable food production in nutrient limited production systems. Re-use is established when nutrients pass through several farm compartments before they leave the farm via marketable products. In this paper re-use of nitrogen is examined as an indicator for sustainable soil fertility management. Re-use (RU, kg farm-1) was defined as the amount of nitrogen that was translocated within one farm divided by the sum of transitions between farm compartments within a farm. In 2002, a total of 101 farms belonging to 4 farmer field schools in Kenya were analysed using the NUTMON (now known as MonQI) toolbox. The farms were distributed over 4 farmer field schools located in two agro-ecological zones.RUwas positively related to the net farm income and to crop yields. However, data were scattered and often local farm conditions veiled the relation between nitrogen management strategies and farm performances. The results of this paper demonstrate that different agro-ecological zones with diverse production constraints have developed different in-farm nitrogen management strategies that are best adapted to the local conditions, but may have different environmental impacts.
    Assessment of nutrient deficiencies in maize in nutrient omission trials and long-term field experiments in the West African Savanna
    Nziguheba, G. ; Tossah, B.K. ; Diels, J. ; Franke, A.C. ; Aihou, K. ; Iwuafor, E.N.O. ; Nwoke, C. ; Merckx, R. - \ 2009
    Plant and Soil 314 (2009)1-2. - ISSN 0032-079X - p. 143 - 157.
    sulfur - soil - management - systems - balances - nigeria - regions - copper - wheat - yield
    Low soil fertility is one of the main constraints to crop production in the West African savanna. However, the response of major cereals to fertilizer applications is often far below the potential yields. Low fertilizer efficiency, inadequacy of current fertilizer recommendations, and the ignorance of nutrients other than N, P, and K may limit crop production. Nutrient limitations to maize production were identified in on-farm trials in Togo and in several long-term experiments in Nigeria and Benin. Maize ear leaf samples were analyzed for macro and micro-nutrients, and the Diagnosis and Recommendation Integrated Systems (DRIS) was applied to rank nutrients according to their degree of limitation to maize. In the on-farm trials, both yield and DRIS results indicated that, when N is supplied, P limited maize production in all fields, reducing yields by 31% on average. Sulfur was limiting in 81% of the fields and was responsible for an average yield reduction of 20%. In the long-term experiments where N, P, and K had been annually applied, Ca and Mg indices were strongly negative, indicative of deficiency. Zn indices were negative in all trials. Despite N-fertilizer additions, N indices remained negative in some of the long-term experiments, pointing to low efficiency of applied fertilizers. There was a direct link between DRIS indices and the management imposed in the different experiments, indicating that DRIS is a useful approach to reveal nutrient deficiencies or imbalances in maize in the region.
    Nutrient management regulations in The Netherlands - Discussion
    Schipper, L.A. ; Goulding, K.W.T. ; Whitmore, A.P. ; Bouma, J. - \ 2008
    Geoderma 144 (2008)3-4. - ISSN 0016-7061 - p. 426 - 434.
    soils - fertilizer - balances - system - manure - scale - farms - land
    Critical loads of metals and other trace elements to terrestrial environments.
    Lofts, S. ; Chapman, P. ; Dwyer, R. ; McLaughlin, M. ; Schoeters, I. ; Sheppard, S. ; Adams, W. ; Alloway, B. ; Antunes, P. ; Campbell, P. ; Davies, B. ; Degryse, F. ; Vries, W. de; Groenenberg, J.E. - \ 2007
    Environmental Science and Technology 41 (2007)18. - ISSN 0013-936X - p. 6326 - 6331.
    forest soils - heavy-metals - cadmium - copper - balances - quality - risk
    Nitrate in upper groundwater on farms under tillage as affected by fertilizer use, soil type and groundwater table
    Ruijter, F.J. de; Boumans, L.J.M. ; Smit, A.L. ; Berg, M. van den - \ 2007
    Nutrient Cycling in Agroecosystems 77 (2007)2. - ISSN 1385-1314 - p. 155 - 167.
    organic-carbon - surface-water - sandy regions - nitrogen use - netherlands - agriculture - denitrification - availability - management - balances
    Indicators are needed to check whether policies on protection of groundwater are effective and if regulations are complied with. We evaluated various indicators at different scales, both in space and in time, and at different degrees of complexity. Groundwater was sampled on 34 arable farms for 3 years. Nitrate concentration in upper groundwater was low on clay soil. On sandy soil, peat layers reduced the nitrate concentration with about 80 mg/l on average. Sandy soils with high groundwater tables had nitrate concentrations that were less than half of those at sandy soils with low groundwater tables. The relationship between different fertilization variables and nitrate in groundwater was investigated for sandy soils without peat layers. N surplus poorly correlated with nitrate concentrations in groundwater when individual sampling points were studied, but clearly increased when data were averaged at the farm level. Soil mineral nitrogen correlated best with nitrate concentrations in groundwater. The relationships show that especially on well drained soil drastic measures will be inevitable to reach good water quality.
    Sensitivity of a crop growth simulation model to variation in LAI and canopy nitrogen used for run-time calibration
    Jongschaap, R.E.E. - \ 2007
    Ecological Modelling 200 (2007)1-2. - ISSN 0304-3800 - p. 89 - 98.
    leaf-area index - hyperspectral vegetation indexes - chlorophyll density - light reflectance - soil-water - maize - field - balances - equation - system
    Run-time calibration, i.e. adjusting simulation results for field observations of model driving variables during run-time, may allow correcting for deviations between complex mechanistic simulation model results and actual field conditions. Leaf area index (LAI) and canopy nitrogen contents (LeafNWt) are the most important driving variables for these models, as they govern light interception and photosynthetic production capacity of the crop. Remote sensing may provide (spatial) data from which such information can be estimated. How, when and at what frequency such additional information is integrated in the simulation process may have various effects on the simulations. The objective of this study was to quantify the effects of different run-time calibration scenarios for final grain yield (FGY) simulations in order to optimize remote sensing image (RS) acquisition. The PlantSys model was calibrated on LAI and LeafNWt for maize in France and used to simulate maize crop growth in the Argentina and the USA, for which non-destructive estimates of LAI and leaf chlorophyll contents were acquired by optical measurement techniques. Leaf chlorophyll data were used to estimate LeafNWt. Due to its structure, the PlantSys model was more susceptible to run-time calibration with LeafNWt than with LAI. Run-time calibration with LAI showed the largest effect on FGY before and around flowering, and could mainly be related to maintenance respiration costs. Run-time calibration with LeafNWt showed the largest effect on FGY at and after flowering and could mainly be related to the change in effective radiation interception due to change in leaf life. The accuracy of LAI estimates showed a major effect on FGY for underestimations but was small in absolute sense. The accuracy of LeafNWt estimates had significant impact at all crop development stages, but was the strongest after flowering where crop growth and nitrogen uptake are less able to recuperate from changes in LeafNWt. In absolute sense, the effect on FGY was as strong as the accuracy of the LeafNWt estimates when applied in the early reproductive stages. Based on these results it was concluded that remotely sensed in-field variability of LAI and LeafNWt is valuable information that can be used to spatially differentiate model simulations. Run-time calibration at sub-field level may lead to more accurate simulation results for whole fields.
    Evaluating farm performance using agri-environmental indicators: Recent experiences for nitrogen management in The Netherlands
    Langeveld, J.W.A. ; Verhagen, A. ; Neeteson, J.J. ; Keulen, H. van; Conijn, J.G. ; Schils, R.L.M. ; Oenema, J. - \ 2007
    Journal of Environmental Management 82 (2007)3. - ISSN 0301-4797 - p. 363 - 376.
    nutrient management - pilot farms - dairy farms - balances - systems - soil - agriculture - budgets - impact - level
    Intensive agriculture, characterized by high inputs, has serious implications on the environment. Monitoring and evaluation of projects aiming at designing, testing and applying more sustainable practices require instruments to asses agronomic as well as environmental performance. Guidelines for Good Agricultural Practice (GAP) or Good Farming Practice (GFP) define sustainable practices but give limited insight into their environmental performance. Agri-environmental indicators (AEIs) provide information on environmental as well as agronomic performance, which allows them to serve as analytical instruments in research and provide thresholds for legislation purposes. Effective AEIs are quantifiable and scientifically sound, relevant, acceptable to target groups, easy to interpret and cost-effective. This paper discusses application of four AEIs for nitrogen (N) management in three Dutch research projects: `De Marke¿, `Cows and Opportunities¿ and `Farming with a future¿. `De Marke¿ applied Nitrogen Surplus and Groundwater Nitrate Concentration in the design and testing of environmentally sound dairy systems. `Cows and Opportunities¿, testing and disseminating dairy systems designed at `De Marke¿, mainly applied Nitrogen Surplus, while `Farming with a future¿ used Nitrogen Surplus, Groundwater Nitrate Concentration and Residual Mineral Soil Nitrogen to support arable farmers in complying with Dutch legislation (MINAS). Nitrogen Surplus is quantifiable, appealing and easy to interpret, but lacks scientific soundness or a good relationship with groundwater quality. Nitrogen Use Efficiency is sensitive to changes in management, while Residual Mineral Soil Nitrogen is appealing and cheap, but has difficulties in scaling. Groundwater Nitrate Concentration lacks clear rules for sampling, is labor consuming, expensive and mainly used in combination with other indicators. AEIs enhanced improvements in N management by facilitating (i) definition of project goals, (ii) design of desired systems, (iii) evaluation of applied systems and (iv) improving effective communication. AEI applications in other countries show a similar pattern as found in The Netherlands. Limitations to AEI application relate to inconsistencies between different indicators, heterogeneity of soil characteristics and linkages of N, carbon and water management. AEIs should be applied in an integrated evaluation, at a scale that reflects the farm's spatial variability. Simple AEIs like Nitrogen Surplus should be supported by other indicators and/or model calculations. The paper concludes that AEIs proved their value in design, implementation and testing of farming systems, but they should be used with care, always keeping in mind that indicators are simplifications of complex and variable processes.
    Nutrient flows in smallholder production systems in the humid forest zone of southern Cameroon
    Kanmegne, J. ; Smaling, E.M.A. ; Brussaard, L. ; Gansop-Kouomegne, A. ; Boukung, A. - \ 2006
    Nutrient Cycling in Agroecosystems 76 (2006)2-3. - ISSN 1385-1314 - p. 233 - 248.
    burn agriculture - cropping systems - soil fertility - management - balances - dynamics - farmers - district - africa
    The flows and balances of N, P and K were studied in 20 farms in the Campo Ma'an area in Cameroon between March and August 2002 to assess the nutrient dynamics in smallholder farms. Data were collected through farmer interviews, field measurements and estimates from transfer functions. Nutrient input from mineral (IN1), animal feed (IN2a) and inorganic amendments (IN2b) was absent. Major outputs were through crop (OUT1a) and animal (OUT1b) products sold. Partial budgets for farmer managed flows were negative: -65 kg N, -5.5 kg P and -30.8 kg K ha-1 year-1. For inflows not managed by farmers, deep capture (IN6) was the major source: 16.6, 1.4 and 6.6 kg ha -1 year-1 of N, P and K, respectively. Atmospheric deposition (IN3) was estimated at 4.3 kg N, 1.0 kg P and 3.9 kg K ha -1 year-1, and biological nitrogen fixation (IN4) at 6.9 kg N ha-1 year-1. Major losses were leaching (OUT 3a): 26.4 kg N, and 0.88 kg K ha-1 year-1. Gaseous losses from the soil (OUT 4a) were estimated at 6.34 kg N, and human faeces (OUT 6) were estimated at 4 kg N, 0.64 kg P and 4.8 kg K ha-1 year-1. The highest losses were from burning (OUT 4c), i.e. 47.8 kg N, 1.8 kg P and 14.3 kg K ha-1 year-1. Partial budgets of environmentally controlled flows were negative only for N -4.8 kg N, +2.4 kg P and +9.6 kg K ha-1 year-1. The overall farm budgets were negative, with annual losses of 69 kg N, 3 kg P and 21 kg K ha-1. Only cocoa had a positive nutrient balance: +9.3 kg N, +1.4 kg P and +7.6 kg K ha-1 year-1. Nutrients reaching the household waste (1.9 kg N, 2.8 kg P and 18.8 kg K ha-1 year-1), animal manure (4.9 kg N, 0.4 kg P and 1.6 kg K), and human faeces (4 kg N, 0.64 kg P and 4.8 kg K ha -1 year-1) were not recycled. Five alternative management scenarios were envisaged to improve the nutrient balances. Recycling animal manure, household waste and human faeces will bring the balance at -62.6 kg N, 0 kg P and +1 kg K ha-1 year-1. If, additionally, burning could be avoided, positive nutrient balances could be expected
    Animal in balance
    Beldman, Alfons - \ 2005
    farm management - sustainability - dairy farms - dairy cows - balances
    Nutrient losses by wind and water, measurements and modelling
    Visser, S.M. ; Stroosnijder, L. ; Chardon, W.J. - \ 2005
    Catena 63 (2005)1. - ISSN 0341-8162 - p. 1 - 22.
    northern burkina-faso - sediment transport - farming systems - erosion - soil - productivity - balances - fields - flows - niger
    In the Sahelian zone of West-Africa, erosion by both wind and water causes a serious decline in fertility of the already low fertile soils. Despite the fact that the flow of nutrients has been intensively investigated by the use of nutrient balances, little attention has been paid to the contribution of the soil erosion to the nutrient balance. Two physically based models (WEPS and EUROSEM, both written in PCRaster) were extended with nutrient modules to investigate the role of wind and water erosion in tire loss and gain of nutrients at the scale of a Sabetian field. The models are applied at three geomorphic units in the Katchari catchment in northern Burkina Faso. WEPS can predict spatial patterns of erosion and deposition due to wind-blown particle transport. Depending on wind direction, crusting and vegetation cover net erosion or deposition can occur. When erosion occurs considerable amounts of nutrients are lost, but when deposition occurs, most of these nutrients may be regained. Soil loss by water erosion is closely related to the crust type present, which regulates infiltration and thus runoff. Nutrient losses by water erosion are small compared with those by wind erosion, but are forever lost for the area. Sediment transport by wind in saltation mode results in the largest soil and nutrient loss at the time scale of an event. (c) 2005 Elsevier B.V. All rights reserved.
    Turning the tides of soil degradation in Africa: capturing the reality and exploring opportunities
    Muchena, F.N. ; Onduru, D.D. ; Gachini, G.N. ; Jager, A. de - \ 2005
    Land Use Policy 22 (2005)1. - ISSN 0264-8377 - p. 23 - 31.
    monitoring nutrient flows - farming systems nutmon - sub-saharan africa - of-the-art - fertility management - economic-performance - balances - productivity - kenya - agriculture
    Soil degradation means loss of biological and economic productivity of the land. Measurements of land degradation need to take cognizance of land properties (e.g. soil, water and vegetation) as well as productivity indicators. While land degradation in sub-Saharan Africa is a subject of an on-going debate, conflicting perspectives arise about its extent at regional and at lower scales, about methodologies and robustness of indicators and the impacts of past and present degradation on food security, about rural livelihoods in general, and on African posterity. This paper presents evidence of land degradation from selected case studies across East Africa, and analyses them against the robustness of indicators used at regional, national and lower scales in order to unravel the hidden myths and realities of land degradation. The results are corroborated against time-series such as yields of major crops, environmental data (rainfall, soil fertility) and management data. Land degradation assessments need to move away from empty rhetoric to capturing reality by integrating effects of farm management practices and technologies, including their social and institutional dimensions, on soil loss, yields and nutrient budgets. Influencing factors and socio-economic environments surrounding land degradation and the specific environments under which degradation takes place should not be overlooked
    Facilitated learning in soil fertility management: assessing potentials of low-external-input technologies in east African farming systems
    Jager, A. de; Onduru, D. ; Walaga, C. - \ 2004
    Agricultural Systems 79 (2004)2. - ISSN 0308-521X - p. 205 - 223.
    monitoring nutrient flows - economic-performance - resource-management - balances - nutmon - kenya
    The paper describes the facilitated learning process of farm households and district policy makers in addressing the problem of soil nutrient depletion. The process is applied in a case study in four districts in Kenya and Uganda during the period 1997-1999, where the potentials of low-external input technologies (LEIA) in addressing the soil nutrient depletion problem were assessed. Working through an inclusive process of dialogue, observation, diagnosis, experimentation and exposure to different types of knowledge, participants made a thorough analysis of the current soil fertility situation and tested various LEIA options for improving soil fertility management. In all four research sites the future agricultural productivity is threatened by soil nutrient depletion. Maximal use of locally available nutrients through LEIA techniques, combined with optimal use of external nutrients appears to be the most appropriate strategy in the existing economic environment. Long-term and intensive collaboration between research institutions on the one hand and extension services, non-government and community based organisations on the other are a prerequisite for a successful and sustainable implementation of a facilitated learning approach. Involvement of stakeholders in the various stages of the research process, including the planning and project formulation is essential for an effective follow-up and implementation of the results. More attention needs to be paid to the development of communication tools to enable an effective interaction between policy makers and researchers. (C) 2003 Elsevier Ltd. All rights reserved.
    The contribution of dairy farming on peat soil to N and P loading of surface water
    Beek, C.L. ; Eertwegh, G.A.P.H. van den; Schaik, F.H. van; Velthof, G.L. ; Oenema, O. - \ 2004
    Nutrient Cycling in Agroecosystems 70 (2004)1. - ISSN 1385-1314 - p. 85 - 95.
    waterverontreiniging - denitrificatie - drainagewater - melkveehouderij - stikstof - fosfor - uitspoelen - veengronden - nederland - water pollution - denitrification - drainage water - dairy farming - nitrogen - phosphorus - leaching - peat soils - netherlands - denitrification rates - inhibition - acetylene - balances
    In agriculturally used peat land areas, surface water quality standards for nitrogen (N) and phosphorus (P) are frequently exceeded, but it is unclear to what extent agriculture is responsible for nutrient loading of the surface water. We quantified the contribution of different sources to the N and P loading of a ditch draining a grassland on peat soil (Terric Histosol) used for dairy farming in the Netherlands. Measurements were performed on N and P discharge at the end of the ditch, supply of N and P via inlet water, mineralization of soil organic matter, slush application, composition of the soil solution, and on N losses through denitrification in the ditch for 2 years (September 2000 to September 2002)
    In agriculturally used peat land areas, surface water quality standards for nitrogen (N) and phosphorus (P) are frequently exceeded, but it is unclear to what extent agriculture is responsible for nutrient loading of the surface water. We quantified the contribution of different sources to the N and P loading of a ditch draining a grassland on peat soil (Terric Histosol) used for dairy fanning in the Netherlands. Measurements were performed on N and P discharge at the end of the ditch, supply of N and P via inlet water, mineralization of soil organic matter, slush application, composition of the soil solution, and on N losses through denitrification in the ditch for 2 years (September 2000 to September 2002). Discharge rates at the end of the ditch were 32 kg N ha(-1) y(-1) and 4.7 kg P ha(-1) y(-1). For N, 43 to 50% of the discharge was accounted for by applications of fertilizers, manure and cattle droppings, 17 to 31% by mineralization of soil organic matter, 8 to 27% by nutrient-rich deeper peat layers, 8 to 9% by atmospheric deposition and 3 to 4% by inlet water. For P, these numbers were 10 to 48% for applications of fertilizers, manure and cattle droppings, 2 to 14% mineralization of soil organic matter, 33 to 82% nutrient-rich peat layers and 5 to 6% inlet water. The results of this paper demonstrate that nutrient loading of surface water in peat land areas involves several sources of nutrients, and therefore, reducing one source to reduce nutrient inputs to surface water is likely to result in modest effectiveness.
    Effects of soil properties, mulch and NPK fertilizer on maize yields and nutrient budgets on ferralitic soils in southern Benin
    Saidou, A. ; Janssen, B.H. ; Temminghoff, E.J.M. - \ 2003
    Agriculture, Ecosystems and Environment 100 (2003)2. - ISSN 0167-8809 - p. 265 - 273.
    forest ecosystem - cote-divoire - balances - africa
    Four on-farm experiments examined whether modest applications of fertilizers in combination with prunings from native agroforestry trees would be an alternative to maintain the fertility of ferralitic soils in Benin. An application of about 1.9tha-1dry matter of mulch of Senna siamea combined with 30kgNha-1, 22kgPha-1 and 25kgKha-1 as compound fertilizer was compared with (1) 60kgNha-1, 43kgPha-1 and 50kgKha-1 as compound fertilizer alone, (2) mulch of S. siamea alone (about 3.2tha-1 dry matter), and (3) a control treatment. Criteria were soil properties, yields, nutrient uptakes, and nutrient budgets. Application of sole mulch had no significant effects (P>0.05) on maize yields, while combined application of prunings and NPK fertilizers or sole NPK increased yields significantly (P
    Vleeskuikenouderdieren: Het tijdstip van wegen bij een automatisch dierweegsysteem
    Haar, J.W. van der - \ 1997
    Praktijkonderzoek voor de Pluimveehouderij 8 (1997)2. - ISSN 0924-9087 - p. 11 - 15.
    groei - ontwikkeling - gewicht - massa - weegschalen - weegapparaten - lichtregiem - landbouwbedrijven - vleeskuikenouderdieren - bedrijfsinformatiesystemen - growth - development - weight - mass - balances - weighers - light regime - farms - broiler breeders - management information systems
    Om bij vleeskuikenouderdieren de voerkosten laag te houden, moet de voergift goed worden afgestemd op het legpercentage en de groei van de dieren. Met een automatisch dierweegsysteem krijgt men een goed inzicht in de groei gedurende de laatste weken. Door de variatie in de dagelijkse gewichten, is de informatie over de groei gedurende de laatste dagen minder betrouwbaar. Het Praktijkonderzoek Pluimveehouderij Het Spelderholt (PP) heeft onderzocht of deze betrouwbaarheid verbeterd kan worden door alleen gewichten te registreren in het dagdeel dat de dieren nog geen voer en water hebben opgenomen.
    Automatische dierweging bij kalkoenen, de stand van zaken
    Verbij, E. ; Veldkamp, T. - \ 1996
    Praktijkonderzoek voor de Pluimveehouderij 7 (1996)3. - ISSN 0924-9087 - p. 21 - 24.
    automatisering - weegschalen - mechanisatie - kalkoenen - weegapparaten - automation - balances - mechanization - turkeys - weighers
    In het verleden heeft het PP 'Het Spelderholt' diverse weegsystemen voor kalkoenen getest. Deze systemen hadden elk overeenkomst dat de nauwkeurigheid van de weging en/of het aantal wegingen vanaf 10 weken leeftijd dusdanig terugliep, dat geconcludeerd moest worden dat de systemen niet bruikbaar waren. In dit artikel gaan we in op twee ontwikkelingen die enige hoop voor de toekomst van de automatische dierweging bij kalkoenen kunnen geven: het individueel weegplateau en het gemeenschappelijk weegplateau.
    Vleeskuikenouderdieren: het gebruik van een automatisch dierweegsysteem bij het voeren naar legpercentage en groei
    Haar, J.W. van der - \ 1996
    Praktijkonderzoek voor de Pluimveehouderij 7 (1996)1. - ISSN 0924-9087 - p. 22 - 26.
    diervoedering - automatisering - weegschalen - ontwikkeling - eierproductie - groei - mechanisatie - ovipositie - weegapparaten - vleeskuikenouderdieren - animal feeding - automation - balances - development - egg production - growth - mechanization - oviposition - weighers - broiler breeders
    Bij vleeskuikenouderdieren komt een belangrijk deel van de kosten voor rekening van het voer. Om de voerkosten laag te houden moet de voergift afgestemd worden op het legpercentage en de groei van de dieren. Naast een goed inzicht in de eiproduktie moet men ook een goed inzicht hebben in de gewichtsontwikkeling van de dieren. Bij Praktijkonderzoek Pluimveehouderij (PP) is onderzocht welke rol een automatisch dierweegsysteem hierbij kan spelen.
    Automatische bepaling van het individuele lichaamsgewicht van vleesvarkens in het hok met een voorhandweger
    Ramaekers, P.J.L. ; Huiskes, J.H. ; Vesseur, P.C. - \ 1995
    Rosmalen : Praktijkonderzoek varkenshouderij (Proefverslag / Praktijkonderzoek Varkenshouderij P1.123) - 32
    weegschalen - lichaamsgewicht - massa - meting - varkens - grootte - volume - volumebepaling - gewicht - gewichtsbepaling - balances - body weight - mass - measurement - pigs - size - volume - volume determination - weight - weight determination
    Automatisch wegen van vleesvarkens in het hok
    Ramaekers, P. ; Huiskes, J. - \ 1994
    Praktijkonderzoek varkenshouderij 8 (1994)6. - ISSN 1382-0346 - p. 18 - 20.
    weegschalen - massa - varkens - weegapparaten - gewicht - weegapparaten voor varkens - groepshuisvesting - balances - mass - pigs - weighers - weight - pig weighers - group housing
    Het lichaamsgewicht van vleesvarkens wordt vaak geschat op basis van het aantal dagen dat de vleesvarkens in het hok liggen en de ervaring van de varkenshouder. Het regelmatig wegen van vleesvarkens tijdens de mestperiode is arbeidsintensief. Met behulp van een voorhandweegsysteem in het hok kan het individuele lichaamsgewicht van vleesvarkens automatisch worden bepaald.
    Automatische dierweging bij vleeskuikenouderdieren
    Verbij, E. - \ 1993
    Praktijkonderzoek voor de Pluimveehouderij 4 (1993)3. - ISSN 0924-9087 - p. 28 - 31.
    automatisering - weegschalen - kippen - massa - mechanisatie - pluimvee - weegapparaten - gewicht - vleeskuikenouderdieren - automation - balances - fowls - mass - mechanization - poultry - weighers - weight - broiler breeders
    In het tweede periodiek van 1990 is een artikel gewijd aan automatische dierweging bij vleeskuikenouderdieren. De conclusie van dat artikel was dat automatische dierweging waarbij beide sexen gewogen dienden te worden niet mogelijk was tenzij de dieren op de een of andere manier herkend konden worden.
    Automatisch dierweegsysteem bij kalkoenen
    Veldkamp, T. - \ 1993
    Praktijkonderzoek voor de Pluimveehouderij 4 (1993)1. - ISSN 0924-9087 - p. 21 - 21.
    weegschalen - computers - gegevensverwerking - massa - microcomputers - minicomputers - kalkoenen - weegapparaten - gewicht - machines - balances - computers - data processing - mass - microcomputers - minicomputers - turkeys - weighers - weight - machines
    Dit artikel is bedoeld als toelichting op eerder verschenen publikaties over dit onderwerp.
    Automatische dierweging bij kalkoenen
    Veldkamp, T. ; Arts, R. ; Verbij, E. - \ 1992
    Praktijkonderzoek voor de Pluimveehouderij 3 (1992)4. - ISSN 0924-9087 - p. 25 - 27.
    automatisering - weegschalen - mechanisatie - kalkoenen - weegapparaten - automation - balances - mechanization - turkeys - weighers
    In één ronde is een automatisch dierweegsysteem voor kalkoenen getest. Tot een leeftijd van 17 weken werden betrouwbare resultaten verkregen en daarna niet meer.
    Betrouwbaarheid gegevens automatische dierweegsystemen
    Reuvekamp, B.F.J. - \ 1991
    Praktijkonderzoek voor de Pluimveehouderij 2 (1991)3. - ISSN 0924-9087 - p. 12 - 14.
    automatisering - weegschalen - kippen - massa - mechanisatie - pluimvee - weegapparaten - gewicht - automation - balances - fowls - mass - mechanization - poultry - weighers - weight
    Het registreren van het gemiddeld gewicht en uniformiteit met een automatisch dierweegsysteem heeft een aantal voordelen. De gegevens moeten wel voldoende betrouwbaar zijn.
    Automatisch dierweegsysteem in de opfokperiode van slachtkuikenouderdieren
    Haar, J.W. van der - \ 1990
    Beekbergen : Centrum voor Onderzoek en Voorlichting voor de Pluimveehouderij (Onderzoekverslag praktijkonderzoek voor de pluimveehouderij 1990, no. 2) - 19
    weegschalen - kippen - massa - pluimvee - weegapparaten - gewicht - balances - fowls - mass - poultry - weighers - weight
    Dierweegsystemen bij opfok en leg
    Reuvekamp, B.F.J. - \ 1990
    Praktijkonderzoek voor de Pluimveehouderij 1 (1990)3. - ISSN 0924-9087 - p. 7 - 9.
    automatisering - weegschalen - hennen - massa - mechanisatie - weegapparaten - gewicht - automation - balances - hens - mass - mechanization - weighers - weight
    Automatische dierweegsystemen bij grondhuisvesting kunnen goed worden gebruikt bij de opfok leghennen en in de legperiode. Het gemiddeld diergewicht, gewichtsverloop en de uniformiteit van de koppel kan dagelijks met weinig werk worden vastgesteld.
    Automatische dierweging bij slachtkuikenouderdieren
    Verbij, E. - \ 1990
    Praktijkonderzoek voor de Pluimveehouderij 1 (1990)2. - ISSN 0924-9087 - p. 12 - 14.
    automatisering - weegschalen - mechanisatie - weegapparaten - vleeskuikenouderdieren - automation - balances - mechanization - weighers - broiler breeders
    Automatische dierweging bij slachtkuikenouderdieren levert de nodige problemen op. Aangegeven wordt op welke wijze deze haken en ogen kunnen worden opgelost.
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