Agricultural Systems Journal Impact Factor & Information

Journal description

Current impact factor: 2.50

Impact Factor Rankings

2015 Impact Factor Available summer 2015
2011 Impact Factor 2.899

Additional details

5-year impact 2.84
Cited half-life 8.00
Immediacy index 0.52
Eigenfactor 0.01
Article influence 0.87
ISSN 1873-2267

Publications in this journal

  • Andrew Ash, Leigh Hunt, Cam McDonald, Joe Scanlan, Lindsay Bell, Robyn Cowley, Ian Watson, John McIvor, Neil MacLeod
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    ABSTRACT: The financial health of beef cattle enterprises in northern Australia has declined markedly over the last decade due to an escalation in production and marketing costs and a real decline in beef prices. Historically, gains in animal productivity have offset the effect of declining terms of trade on farm incomes. This raises the question of whether future productivity improvements can remain a key path for lifting enterprise profitability sufficient to ensure that the industry remains economically viable over the longer term. The key objective of this study was to assess the production and financial implications for north Australian beef enterprises of a range of technology interventions (development scenarios), including genetic gain in cattle, nutrient supplementation, and alteration of the feed base through introduced pastures and forage crops, across a variety of natural environments. To achieve this objective a beef systems model was developed that is capable of simulating livestock production at the enterprise level, including reproduction, growth and mortality, based on energy and protein supply from natural C4 pastures that are subject to high inter-annual climate variability. Comparisons between simulation outputs and enterprise performance data in three case study regions suggested that the simulation model (the Northern Australia Beef Systems Analyser) can adequately represent the performance beef cattle enterprises in northern Australia. Testing of a range of development scenarios suggested that the application of individual technologies can substantially lift productivity and profitability, especially where the entire feedbase was altered through legume augmentation. The simultaneous implementation of multiple technologies that provide benefits to different aspects of animal productivity resulted in the greatest increases in cattle productivity and enterprise profitability, with projected weaning rates increasing by 25%, liveweight gain by 40% and net profit by 150% above current baseline levels, although gains of this magnitude might not necessarily be realised in practice. While there were slight increases in total methane output from these development scenarios, the methane emissions per kg of beef produced were reduced by 20% in scenarios with higher productivity gain. Combinations of technologies or innovative practices applied in a systematic and integrated fashion thus offer scope for providing the productivity and profitability gains necessary to maintain viable beef enterprises in northern Australia into the future.
    Agricultural Systems 10/2015; 139. DOI:10.1016/j.agsy.2015.06.001
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    ABSTRACT: An economic theory-based land-use modelling framework is presented aiming to explain the causal link between economic decisions and resulting spatial patterns of agricultural land use. The framework assumes that farmers pursue utility maximisation in agricultural production systems, while considering alternative production options and making land-use decisions. Local utility is assumed to depend on a complex combination of different types of factors that together set the opportunities and constraints for different production options. The framework's ability to reproduce the current patterns is demonstrated for a case study in the Netherlands. The framework was implemented in a land-use modelling simulation tool rooted in economic theory, that was first specified according to the current trends in the driving forces assumed to steer land-use change. Alternative model specifications accounting for different sets of cash flows were implemented in order to explore the importance of uncertainties on model conceptualisation and structure. The allocation of agricultural land use was then simulated according to these specifications and the results were validated by comparing the simulated land-use patterns with observed ones. When cash flows accounting for path-dependency and land-use inertia were considered, the framework performed well in reproducing current patterns in the Netherlands, with a degree of correspondence of 82.2% in the pixel-by-pixel validation, up to 87.4% in the multiple resolution validation. Production costs and gross revenues seem to only partly explain the observed patterns, as shown by the lower degrees of correspondence (57.5% up to 65.0%) for the model specification solely accounting for these cash flows. In our case study, transportation costs did not seem to play a significant role in the allocation of agricultural land use, although that might be attributed to the relatively small size of the study area and the existence of a high-quality transport network. The model did not perform equally well for different production systems: land-uses specified at the crop level appeared to be particularly well allocated; those defined at the aggregated production system level performed poorer. The ability to link economic decision-making processes with the resulting agricultural land-use patterns, while incorporating complex interactions with different type of factors, implies that a coherent modelling approach for the simulation of future patterns of agriculture land use was established. This approach can be used to help policy-makers explore possible future socio-economic and environmental impacts resulting e.g. from climate change and/or policy reform, allowing them to devise strategies to cope with future challenges in agricultural systems.
    Agricultural Systems 10/2015; 139. DOI:10.1016/j.agsy.2015.06.002
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    ABSTRACT: Dairy farms that grow more perennial vegetation as grazing pastures or conserved forages can offer many environmental benefits but may show reduced milk production relative to farms feeding higher amounts of grain and corn silage. Because yields of annual and perennial crops vary with soil type, an accurate comparison of the productive potential of these systems over county or regional scales may require taking into account spatial variation in soil quality. In this study, we present a novel approach to calculate the production from dairy systems that adjusts average crop yields to the productive potential of local soils using the National Commodity Crop Productivity Index (NCCPI). We used on-farm survey data to define confinement and grazing systems with varying amounts of perennial forage and applied our method to a sample of five counties in the northeast United States. High corn silage farm systems produced 21 to 168% more milk per hectare of farmland than grazing-based farm systems, but variation among counties was greater than variation among systems, with the best (Lancaster, PA) producing as much as 5.3 times more than the least (Orange, VT). Adjusting yields for soil productivity had smaller effects on milk production than differences in farm system or county. On average, grazing farm systems generally produced slightly more milk when yields were adjusted using the NCCPI (8%) while high corn silage systems showed a moderate decrease (13%). Compared to scenarios of all local crop production, scenarios with unlimited corn and soybean imports often more than doubled county-scale milk production. Restricting grain imports to prevent excess phosphorus resulted in a 3–15% decrease in milk production relative to unlimited imports, but still produced far more milk than in the all local production scenarios. Sensitivity analysis of the model showed that milk production in each county was very responsive to changes in perennial forage yields (especially for grazing systems), responsive to changes in average daily milk production per cow, and generally not responsive to changes in the productive lifetime of lactating cows. This study demonstrates a persistent tradeoff between perenniality and production in dairy systems, but suggests that opportunities may exist to maintain current milk production levels in the Northeast while also expanding land cover in perennial vegetation.
    Agricultural Systems 10/2015; 139. DOI:10.1016/j.agsy.2015.06.004
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    ABSTRACT: Management of animal manure in livestock and crop production is a major cause of nitrogen (N), phosphorus (P), and carbon (C) loss. The losses of N, P, and C contribute to adverse environmental impacts, such as climate change, terrestrial acidification, and marine eutrophication. Manure management technologies to reduce losses and impacts have been developed, but often focus on a single compound only or a single stage in the management system and lead to trade-offs, such as pollution swapping. The aim of this study was to design strategies for integrated manure management (IS) which prevent pollution swapping and show that the environmental impact can be reduced throughout the manure management system. We used a structured design approach based on engineering design (ED) that consists of eight main steps: 1. define the goal of the design task and the system boundaries, 2. formulate a brief of requirements stating the needs for environmental reduction, 3. analyze the functions in the current manure management system, 4. list and describe emission processes and their process variables that lead to N, P, and C losses and resource use, 5. describe the functions needed in the manure management system to limit the emission processes or resource use, 6. generate principle-options that can fulfill the functions, 7. generate technical solutions for the principle-options, and 8. combine the principle-options and technical solutions into strategies for integrated manure management. In the design of strategies we considered the management of liquid and solid dairy cattle manure applied to grass and maize, and liquid pig manure applied to wheat, all under North West European conditions. The IS included the segregation of pig and dairy cattle urine and feces to reduce CH4, NH3, and N2O emission, addition of zeolite to solid cattle manure to reduce NH3 emission, bio-energy production from biogas that avoids fossil-based electricity and heat, acidification of urine during storage and acidification of feces prior to application, sealed storages, and improved application timing, place, and method of application. It was concluded that we were able to successfully design IS with high potential to reduce environmental impact. The design approach adapted from ED proved to be useful to structure the design process to provide insight into interactions of emission processes and find principle-options and technical solutions to prevent pollution swapping.
    Agricultural Systems 10/2015; 139:29-37. DOI:10.1016/j.agsy.2015.05.010
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    ABSTRACT: Manure management contributes to adverse environmental impacts through losses of nitrogen (N), phosphorus, and carbon (C). In this study, we aimed to assess the potential of newly designed strategies for integrated manure management (IS) to reduce environmental impact. An important aspect of the strategies was that they prevented pollution swapping. Life cycle assessment was used to compute climate change (CC), fossil fuel depletion (FFD), terrestrial acidification (TA), marine eutrophication (ME), particulate matter formation (PMF), N use efficiency (NUE), and phosphorus over application rate (POA), relative to the crop demand for N. We applied the IS to North West European practice (Ref) and included the Dutch current situation of progressive manure management (NL) to illustrate the potential of the IS to reduce environmental impact. Manure management in Ref included production and management of liquid and solid dairy cattle manure applied to maize and grass, and liquid pig manure applied to wheat. A Monte Carlo uncertainty simulation was done to assess the effect of variation in N and C losses and N uptake by crops on the comparison with Ref, IS, and NL. Results showed that the IS reduced all environmental impacts in all manure product and crop combinations and more than doubled the NUE (70% compared with maximum 33% in Ref). Main causes were: segregation of pig and dairy cattle urine and feces inside the housing system reduced methane (CH4) and ammonia (NH3) emissions; addition of zeolite to solid dairy cattle manure reduced NH3 emission; sealed storages in all IS reduced volatilization of N and C; bio-energy production from the feces reduced the production of fossil electricity and heat; and finally N emissions in the field were reduced by ammonia emission reducing application techniques and improved application management (tillage, field traffic en synchronization of manure product application with crop demand). Compared with the Ref, NL had lower TA, PMF, POA, and higher NUE, except for solid cattle manure applied to grass. This result indicates that the Dutch regulations to reduce NH3 emissions were successful, but that CC can be improved. Compared with NW EU practice, IS reduced environmental impact up to 185% for CC, up to > 700% for FFD, up to 96% for TA, up to 99% for ME, up to 100% for PMF, up to 110% for POA and more than doubled the NUE. We concluded that the designed IS avoid pollution swapping in the entire manure management system.
    Agricultural Systems 09/2015; 138. DOI:10.1016/j.agsy.2015.05.006
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    ABSTRACT: Despite large efforts there are still methodological challenges to bring life cycle modeling closer to agricultural reality. Here, we focus on the inclusion of the effects occurring between the crops grown in the same agricultural field in temporal succession. These so called crop-rotation effects are caused by changes in physical, chemical and biological properties of the agricultural land over time (presence and availability of different micro and macronutrients, soil structure, soil texture, phytosanitary conditions, presence of weeds, etc.) due to the rotation of crops. Since a huge number of parameters contribute to crop-rotation effects, they cannot be easily measured. Therefore, LCA (Life Cycle Assessment) studies with system boundaries containing only one vegetation period have a limited ability to include these effects — unless explicit modeling measures have been taken to include individual crop-rotation effects. Existing approaches for the inclusion of crop-rotation effects are described, e.g. via transferring certain amounts of nutrients and their environmental burdens to subsequent crops. Still, many crop-rotation effects between crops are not covered in recent LCA methodology; corresponding gaps are identified and described. Examples include reduced input of agrochemicals via improved phytosanitary conditions, stabilization of yields via reduction of harvest failures, improved yields via improved soil texture, soil structure and improved conditions for soil organisms. Overall, most crop-rotation effects are not properly addressed in current LCA practice. Thus, LCA results and the quality of derived recommendations are negatively affected — for example incentives for the (unlimited) removal of crop residues are set based on LCA results without considering potential adverse effects on soil fertility. In other words, these gaps might lead to unintended free-rider problems. A new approach for the modeling of crop-rotation effects is suggested. It consists of six steps. First, align the system boundary during the inventory analysis to the level of the whole crop rotation system; second, determine all inputs of the whole crop rotation; third, do the same for the outputs; fourth, convert all outputs to a common agriculture-specific denominator, the so-called Cereal Unit; fifth, calculate an output-specific allocation share using the ratio of each individual output to the sum of all outputs of the crop rotation; and sixth, apply the allocation shares to the sum of each input-type — resulting in the output-specific allocated input. One major advantage of this approach is the integration of crop-rotation systems into LCA, including all relationships between the individual crops of the crop rotation. Using this approach, LCA practice becomes able to depict crop rotations more accurately and to avoid the current practice of ignoring the effects between individual crops. It might enable LCA to consider the fundamental agricultural principle of crop rotations and to include interactions between one crop and the subsequent crop. Since these crop-rotation effects influence soil fertility, yields and overall sustainability of agricultural systems, the reliability of the evaluation of environmental impacts might be affected. Thus, the ability to consider the entire spectrum of crop rotation effects should be integrated into agricultural LCAs.
    Agricultural Systems 09/2015; 138. DOI:10.1016/j.agsy.2015.05.008
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    ABSTRACT: We present a tactical level planning tool to address the issue of coordinating production of perishable specialty crops under decentralized control and incomplete information. The objective of this research is to address an emerging problem seen in the business model of agricultural cooperatives. These vertically expanded farmer associations market their products jointly. However, within the cooperatives farmers remain competitors seeking their own best interest, simultaneously seeking contracts for the most profitable crops in the most desirable part of the season; this behavior can work to the detriment of the group. The model developed considers the problem of asymmetric information and internal competition within the cooperative, as well as traditional factors relevant to agricultural planning. Thereafter, an auction based coordination mechanism is formulated, which leads production decisions toward a coordinated outcome despite each individual acting independently and on his/her best interest. The mechanism is shown to approximate optimal production targets through focused information discovery and a well-structured contract allocation methodology. The results presented show the viability of implementing such planning scheme in practice as well as the optimality gap under a variety of settings.
    Agricultural Systems 09/2015; 138. DOI:10.1016/j.agsy.2015.04.008
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    ABSTRACT: Livestock manure management regulations are transitioning from being nitrogen-based to phosphorus (P2O5)-based in many countries, including regions of the United States and Canada, due to environmental concerns about phosphorus loadings. For example, in the province of Manitoba (Canada) concerns about phosphorus loadings in Lake Winnipeg and other water bodies led to the introduction of phosphorus-based nutrient management regulations. This paper develops a method to analyze the economics of changing systems of manure management to comply with the transition from nitrogen-based to phosphorus-based regulations. The method employs GIS mapping to determine the minimum short-run and medium-run costs of compliance at levels of the individual livestock operation, which can be aggregated up to the levels of rural municipality or county, watershed, and the province or state. The method is applied in a case study for pig producers from the province of Manitoba. The results of the case study estimate the added annual short-run cost to the Manitoba pig industry under a maximum threshold regulation of twice phosphorus removal to be CAD 17.88 million and the estimated added annual cost to the industry under a maximum threshold regulation of once phosphorus removal to be CAD 27.86 million. The costs work out to be $40.57 and $63.22 per animal unit and represented 18% and 28% of the estimated annual net income accruing to pig producers in the Province, respectively. The estimated added annual medium-run cost to pig producers in the Province under a maximum threshold regulation of twice phosphorus removal work out to between CAD 25.48 and 27.46 million. Due to the sheer size of the compliance costs, results should be of interest to livestock producers, their industry organizations, the greater livestock industry, policy makers, and politicians, as well as environmental economists.
    Agricultural Systems 09/2015; 138. DOI:10.1016/j.agsy.2015.04.002
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    ABSTRACT: Brazil has a key role in the global market for sugar and ethanol, but its future role depends on the industry's financial viability, which has been affected by low and variable prices, credit shortages, and policies that affect price of substitutes like gasoline. Our objective was to assess the financial viability of Brazil's sugar and ethanol industries under alternative future price outlooks for the 10-year period through 2022. A Monte Carlo simulation model was developed in order to evaluate the economic performance of a representative sugar mill in São Paulo State, Brazil. The economic feasibility study was conducted using four different price scenarios forecasted by FAPRI-ISU, OECD-FAO, USDA and World Bank. The model starts each year with a stochastic annual sugarcane yield and area harvested. Monthly production is simulated for white sugar, very high polarization (VHP) sugar, anhydrous and hydrated ethanol based on stochastic monthly sugar cane production. In the next section, the cost section, total costs are simulated for cane production and processing into products, and are used with simulated revenues to calculate net cash income, annual cash flows, balance sheet components and profitability measured in terms of net present value (NPV) and rate of return on equity (ROE). The results showed a high probability of success for a sugar mill if the OECD-FAO, USDA and World Bank price forecasts were to prevail. Under these price forecasts the NPV and ROE show a zero probability of values less than zero. The FAPRI price scenario presented a small probability of negatives values for NPV and ROE, and indicated the largest relative risk for these two variables. These results help to better understand the outlook for the Brazilian sugar and ethanol industry over the next 10 years. The Brazilian sugar and ethanol industry will continue to experience a high degree of risk and uncertainty from production, macroeconomic variables, demand, costs of production and market price. As a result, the industry will likely see considerable risk in rates of return, net cash income, and ending cash; however, there is a high probability that the industry will be profitable.
    Agricultural Systems 09/2015; 138:77-87. DOI:10.1016/j.agsy.2015.05.004
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    ABSTRACT: The present study analyses the environmental impact of the process to produce mycelium seeds of the Agaricus bisporus variety. This study integrates the life cycle assessment (LCA) within models of production systems as a tool for decision making regarding the environmental impact of the process and subprocesses conducted. The present research shows the value of the environmental impacts of the product, according to the standards established in the identification and evaluation of impacts through the LCA. Each subprocess, including the overall process, has been deeply analysed. All entries involved in the process were considered, and all processes were simulated with the software SimaPro® using Leiden 2000 CML as the calculus methodology.
    Agricultural Systems 09/2015; 138:38-45. DOI:10.1016/j.agsy.2015.05.003
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    ABSTRACT: Technical assistance is expected to close the gap between actual and potential agricultural production and increase its inter-annual stability. We here hypothesize that its impact may be greater on complex activities, such as livestock production, than on simpler activities, such as soybean production. To our knowledge, this difference has not been quantified. We gathered livestock and soybean production data from the Argentine Pampas, and contrasted the performance of farmers under high level of technical assistance, in the form of professional advice and feedback from other farmers, against the performance of the rest of the political district, which receive much less technical assistance. The difference in productivity and stability between the two types of farmer was much greater for livestock than for crop production. Livestock production was 96% higher and 70% more stable (lower coefficient of variation of annual output) in farms that received more technical assistance than in the rest of the political district. In contrast, soybean production and stability in farms that received more assistance were similar to the rest of the district. If all farms produced at the level of those under more technical assistance, county-level beef production would increase by 74% and require an increase of employment equivalent to 5.6% of the current working population. These results suggest that extension policies in the region should prioritize animal production because of a greater potential to significantly increase production and lower risk.
    Agricultural Systems 07/2015; 137. DOI:10.1016/j.agsy.2015.04.007
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    ABSTRACT: Due to their ability to convert human-inedible fibrous plant materials into high quality animal products, ruminants have always played an important role as net food producers. However, to meet the animals' nutritional requirements, today's rations for high yielding dairy cows also contain substantial amounts of potentially human-edible feeds (e.g. cereals and pulses), which increases competition between animal feed and human food availability. The aim of the present study was therefore to calculate the human-edible feed conversion efficiency (heFCE) for 30 Austrian dairy farms operating under different production systems in order to evaluate their contribution to net food production. The heFCE was calculated at farm gate level on a gross energy and crude protein basis, and was defined as potentially human-edible output in the form of animal products (milk and meat) divided by the input of potentially human-edible feedstuffs. The potentially human-edible fraction of all feedstuffs used on the 30 farms was estimated based on available literature using a “low,” “medium,” and “high” scenario, representing low, average, and above average extraction rates of human-edible nutrients from feedstuffs, respectively. The human-edible fraction ranged from 0% for some fibrous feedstuffs up to 100% for some cereals in the high scenario. For the “medium” scenario, heFCE ranged from 0.50 up to 2.95 for energy and from 0.47 up to 2.15 for protein. About half of the analysed farms showed a heFCE below 1, indicating a net loss in food supply. For both energy and protein, heFCE was negatively correlated with the amount of concentrates per kg milk and the total amount of concentrates per cow and year. In addition, we found a positive correlation between heFCE and the area of grassland utilized per ton of milk, as well as a negative correlation between heFCE and the area of arable land required per ton of milk. Therefore, feeding large amounts of concentrates to dairy cows has to be questioned in terms of the heFCE. The results of this study clearly show that grass-based dairy production highly contributes to net food production, particularly if the amount of concentrates per kg milk is reduced.
    Agricultural Systems 07/2015; 137. DOI:10.1016/j.agsy.2015.04.004
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    ABSTRACT: Defining an agenda is critical to a research process, and a transdisciplinary approach is expected to improve relevance of an agenda and resultant research outputs. Given the complexity of farming systems, farmer differences and the involvement of different stakeholders, as well as the expectations of research funders, what contributions can be made by different interest groups to the construction of an actionable research agenda that produces locally relevant yet original, empirical and transferable findings? In a case study of smallholder irrigation in South Africa, we analyze how, using a transdisciplinary approach, a balance can be struck between the priorities of different stakeholders in defining a research agenda. A transdisciplinary approach was interpreted to entail full participation of diverse stakeholders and integration of different issues as key features. Stakeholder participation was mediated through formal platforms: the Learning and Practice Alliance (LPA) and the Community of Practice (CoP). Farmers and local extension workers participated through the CoP, while other stakeholders, including the public and private sector participated through the LPA. A five step participatory process aimed at allowing stakeholders to fully understand issues, contribute to and validate the research agenda was followed, utilizing a combination of methods, including field observation, photography and discussion. We observed that farmer and researcher participation occurred along two main continua, which we define as a ‘participation matrix’ – one continuum relating to the contribution of knowledge and information, and the other to decision making. The participation matrix can be used as a reference framework for guiding the transdisciplinary definition of research agendas, to aid in balancing knowledge and priorities including local relevance, ownership, originality, and transferability of findings. We argue that the transdisciplinary process, mediated through structured stakeholder participation, open dialogue and continual validation by all stakeholders was time and resource intensive, but enabled each stakeholder group to contribute to the process distinctly, resulting in a research agenda that integrated different needs and expectations.
    Agricultural Systems 07/2015; 137. DOI:10.1016/j.agsy.2015.03.008
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    ABSTRACT: Biodiversity loss in Europe is caused to a large extent by agricultural intensification. To halt this loss, agri-environment schemes have been introduced to compensate farmers for (costly) biodiversity conservation measures. Current agri-environment schemes often consider only a few conservation measures which is insufficient to conserve all endangered biodiversity in an agricultural region. This problem is particularly pertinent in grasslands where many different mowing and grazing dates are required to protect the variety of species breeding in the grassland at different times. A key requirement to design agri-environment schemes for grassland conservation is therefore to offer specific compensation for more measures based on a systematic approach that calculates farmers' opportunity costs in relation to the timing of grassland use which is still lacking. This will at best attract more farmers and offer compensation calculated in line with EU requirements for co-financed measures through the Rural Development Programme. We fill this gap by developing a systematic approach to assess the costs of different mowing and grazing dates. Our approach is general enough to be applicable on a large spatial scale but can still sensitively differentiate among different timings. Moreover it is straightforward and time-saving enough to be suitable for implementation in regional scale optimisation procedures. We demonstrate this by applying the systematic cost assessment in the decision support software DSS-Ecopay using the example of grassland biodiversity conservation measures in the German federal state of Saxony.
    Agricultural Systems 07/2015; 137. DOI:10.1016/j.agsy.2015.03.010
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    ABSTRACT: 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.
    Agricultural Systems 07/2015; 137. DOI:10.1016/j.agsy.2015.04.009