J. agric. Engng Res. (2000) 76, 227}236doi:10.1006/jaer.2000.0573, available online at http://www.idealibrary.com on

KEYNOTE PAPER

Strategic Themes in Agricultural and Bioresource Engineering in the 21st Century

A. A. Jongebreur

Institute of Agricultural and Environmental Engineering (IMAG), P.O. Box 43, 6700 AA Wageningen, The Netherlands;e-mail: a.a.jongebreur@imag.wag-ur.nl

(Keynote address for the plenary session, presented at AgEng 2000, 2}7 July 2000)

During the 20th century, agricultural engineering became a really multidisciplinary "eld of science. Besidestraditional mechanical engineering, fundamental developments in microelectronics, systems and control engin-eering, chemical engineering and physics have opened wide perspectives for agricultural engineering. During thelast century, agricultural engineering has e!ected major changes in agriculture with regard to labour productiv-ity and specialization in the di!erent sectors of plant production and livestock production. Public concern forenvironmental issues, e.g. emissions of volatile compounds, water pollution through plant nutrients andagrochemicals, has resulted in research and technology development in the "eld of environmental engineering.In developing activities for more sustainability in production, agricultural enterprises have to reclaim the trustof society and earn &the licence to produce'! Agricultural engineers have the chances to contribute in this process.They must be also aware that new technologies and techniques require thorough full technology assessmentprocedure to make clear aspects of acceptability to di!erent groups in the community. To achieve optimalresults for agribusiness and the society, the expertise of agricultural engineers must be integrated with expertisefrom the biological and socio-economic sciences. In agricultural engineering, a dynamic balance betweeneconomy, technology and ecology must always be found in order to satisfy the requirements of government andthe changing preferences of consumers. Recognition of trends in the society and networking and participation indebates are important activities for agricultural engineers in the 21st century. &Breakthrough' technologies areneeded for agricultural enterprises to meet the increasing list of standards and norms, for example in the areas ofenergy, animal welfare, product quality, water and volatile emissions.

As this was the case in the last century, agricultural engineering has therefore to keep pace with trends inscience and technology, e.g. fundamental developments in the information and communication technology,biotechnology, materials technology, microelectronics and mechatronics. Technology watch, networking andcooperation are key words for agricultural engineers.

In line with these challenges, strategic themes for the agricultural engineering science are: the conceptsfor sustainable bioproduction systems in the greenhouse and livestock sector; the further progress inprecision agriculture; the use of biomass and wastes as energy sources: electronic communication with modelsand databases without human interference (green net); and innovative measurement and biomonitoringsystems.

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1. Introduction

Hall (1992) described major trends initiated or in-#uenced by the discipline of agricultural engineering.Early agricultural engineering activities were connectedto horseshoeing, drainage, building construction, ruralroads and steam power. Less support was given to long-

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range problems. The main developments started whenreplacing animals by tractors and integration of units forsowing, cultivating and harvesting with the tractor. Elec-tric power has improved productivity in livestock pro-duction and labour productivity on the farmsteads. Thepossibilities of steel, fuel, lubricants and rubber played animportant role in the design of the power units, the

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attached machinery and equipment. In the years beforethe Second World War (WWII), soil erosion and theuse of water were important subjects for agriculturalengineers. After WWII in Europe, the labour productiv-ity in agriculture improved rapidly and the availability ofindustrial jobs, the adaptation of the farming system andthe increasing demand for speci"c agricultural productssupported further mechanization. The expertise of agri-cultural engineers on material characteristics, climatecontrol, structures, quality control of products wasneeded in these period. To bene"t from the economy ofscale and professional capabilities farmers specialized inarable crops (cereals, potatoes, sugar-beet), vegetablecrops, dairy, poultry, pigs and greenhouse products. To-day, this specialization does raise questions with regardto sustainability and risk management. Farmers wereinterested in machinery devices and equipment not onlyfor labour-saving or labour-serving reasons, but also forthe quality of the process and the products. The produc-tivity was also stimulated by scienti"c knowledge inother "elds, such as: animal breeding, health and nutri-tion; plant breeding and nutrition; and the use offertilizers and agrochemicals. Already in the period1950}1970, application of chemicals resulted in require-ments of the spraying devices with regard to distribution,accuracy and safety to the environment and the workers.Inventions in the "eld of agricultural machinery, farmbuildings and equipment in#uenced the productionmethod to a larger extent, e.g. the cubicle, milking par-lour and milking tank in dairy production, the pick-upwagon for forage harvesting, precision drills and fertilizerbroadcasters. From the 1950s onwards, other disciplines,such as electrical engineering, systems and control engin-eering, chemical engineering, and information techno-logy, are crucial for the scienti"c progress in the enlarged"eld of agricultural engineering. This means that, on theone hand, agricultural engineering needs basic know-ledge of these disciplines and at the other, that coopera-tion with these basic disciplines is necessary. This makesagricultural engineering a really multi-disciplinary work-ing "eld.

From the 1970s onwards, the concern for our livingenvironment (soil, water, air), conservation of natureareas and biodiversity has increased. In the USA, therehas always been much interest for the soil as a naturalresource, e.g. Soil Conservation Service (Hall, 1992). Thedemands for a clean environment once more havebroadened the agricultural engineering "eld. Measure-ment technology and monitoring of emissions, e.g. ofgreenhouse gases, bad odours, agrochemicals and plantnutrients became opportune. These last-mentioned pol-lution sources required new equipment for the improve-ment of the distribution accuracy, uniformity of coverageand special nozzles to restrict emissions of droplets to the

surface water. Farmers have become real entrepreneurs,who have to take di$cult decisions on several levels, i.e.strategic, tactical and operational. This &decision taking'has grown in interest during the last decades for theagricultural engineering disciplines. One important "eldof interest for agricultural engineering, which may not beforgotten, is energy. The support for an increasing use ofrenewable energy and decreasing the use of fossil fuels isalso a mission for agricultural engineers.

The 20th century has brought for agricultural engin-eering quite a number of extensions of the &playing "eld'.Especially the &breakthroughs' from other disciplines,such as microelectronics in transponders, sensors andinformation technology, have opened wide perspectives.Problems are studied and tackled in the frame of a systemor a sub-system. In other words, the &problem context' isimportant for the optimal solution.

The approach in this paper is for the larger part con-nected to agricultural and horticultural production, soagricultural engineering in a smaller sense. The areas offood processing (despite its increasing importance in the21st century), land use, and soil and water will not betaken into account.

2. Trends in the society

2.1. General

General trends in society are that the working life andthe private situation will be mixed more and more, theworkplace will be #exible, with more interest for humanhealth and welfare and thus healthy food. Also newconsumer demands require that fast changes, environ-ment-friendly products and &green building and living'will be stimulated. Expansion of the use of Internet o!ersnew possibilities worldwide for the distribution ofknowledge and to compete in business.

Alexander and Foley (1999) have worked out the&Green Future' in an illustrated article in Time. Somespeci"c ideas are telecommuting with our computers,cars will drive on clean fuel cells, fruits and vegetableswill grow on nearby organic farms and energy will bedelivered from renewable sources.

2.2. Food and agriculture

The public concern for sustainable development de-"ned as the strategy to meet the needs of the presentwithout compromising the ability of future generationsto achieve their own needs (Anon., 1987) is still growing.The global food security and the sustainable resource

229STRATEGIC THEMES IN AGRICULTURAL AND BIORESOURCE ENGINEERING

management are key issues for agricultural production.About 840 million people in developing countries do notget su$cient protein and energy (Brown, 1999). Resourcemanagement is linked to land use, energy and water. Theuse of energy from fossil fuels is related with the emissionof greenhouse gases. At the Kyoto conference, a reduc-tion of the emission of greenhouse gases for Europe forthe year 2010 of 6% in comparison with the year 1990was determined. From several governments, support isgiven to the use of renewable energy sources as wind,solar energy, biomass and geothermal energy. It may benoticed that during the 20th century the use of energyfrom renewable sources was decreased by approx. 23%(Flavin & Dunn, 1999). The present consumer is in#uenc-ing not only the product (shape, quality and safety), butalso the production method. In the food productionchain, there is more and more the necessity for the con-trol of quality, also in terms of absence of toxic com-pounds. However, our food was never so good and sosafe. Nevertheless, the consumer requires against thebackground of the dioxin contamination more guaran-tees for food-safety.

Besides these, more general, trends, it is doubtless thatagriculture has to renew the contract with the society andfarming enterprises need a licence to produce. This alsoimplies that a licence to pollute is not accepted anylonger. The quality of the society is in the 21st century thechallenging theme, also for agriculture. Agricultural busi-ness can contribute to di!erent values of the society,namely the rural area, ecological standards, culturalvalues and psycho-social values and, last but not least, tothe economy.

Food production can retrieve a &licence to produce'with trust building between partners in business andbetween producer and consumer. The strategy for thecreation of trust consists of the aspects of tracing thedilemmas, development of innovative solutions, connect-ing information and processes and the establishment ofguarantee systems. Organic farms produce in the Nether-lands under the EKO-standard. Some horticulturalproducts are produced under the Environment-Con-scious Cultivation (in Dutch: Milieu Bewuste Teelt,MBT). Also the total chain management (in Dutch: Inte-grale Ketenbewakings, IKB) can be a product trademark(Donkers, 1999).

3. Trends in science and technology

3.1. General

Especially in agriculture, we are confronted withfundamental changes, e.g. the reversal of the chain (con-sumer/user is governing instead of the producer) and the

already mentioned turn-around to sustainable systems(environment, energy, water, agrochemicals). This impliesthat the generation of knowledge, technology develop-ment and innovation play a crucial role in the processesof transformation. In the frame of environmental loadsrelated to agricultural activities, e.g. energy use, wateruse, emission of greenhouse gases, waste disposal, use ofagrochemicals, &breakthroughs' in knowledge, technolo-gies and innovation are necessary. In a &high-tech' in-formation society, we have observed breakthroughs inhuman mobility, biotechnology and computerization, asrealized through mechanization for farm labour produc-tivity. Computerization increased productivity in indus-try and services.

Knowledge generation, technology development andinnovation must be distinguished. These three elementsare important for the agricultural engineering discipline.Scientists must not only have analytical skills, but alsothe competence for the design or redesign of, for example,biosystems contributing to the development of new foodchains. Knowledge generation implies new facts, theoriesand insights, such as the formation of volatile gases inanimal slurry, whereas dielectric measurement principlesfor the water content in soil or concrete can be de"ned asa technology. Innovation is a concept, which means morethan expertise and knowledge. Innovation is related tonew products, processes or concepts for integrated sys-tems and is market oriented (Verkaik, 1997). We alsohave to distinguish between the explicit knowledge ori-gination in the world of universities and the tacit know-ledge. The latter type of knowledge is subjective andconnected to experience, context and practice. Therefore,participation in challenging, innovative projects must bebroader than between scientists and manufacturers ofagricultural machinery only. The success of innovationsdepends also on the participation and commitment of,for example, growers, auctioneers, supermarket man-agers and bankers. Innovation of products, processes andsystems is as important for manufacturers of agriculturalmachinery as to earn and secure the licence to producefor the farmers and growers (Brega, 1998). In the Nether-lands, a special programme is developed for sustainabletechnology development (STD). The goal is to achieve ane$ciency, that is 20 times better than today. In otherwords, the ambitious goal is the reduction of the environ-mental strain by a factor of 20. The central issue of thisprogramme is: &No prosperity without sustainability.'The focus is on completely new technologies or combina-tions of them, that push back the frontiers of science andtechnologies (Anon., 1997). Networking between di!er-ent stakeholders in industry, institutions and agricultureis necessary to achieve the ambitious goals in projects onfood production, sustainable land use and use of solarenergy.

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Besides scienti"c developments in technology "elds, itis interesting to be aware of the central challenges of theneurobiology of cognition. For the goal of adding intelli-gence to agricultural machinery and equipment, it isimportant to follow discoveries and growing insights inunderstanding of the higher brain functions (Nichols &Newsome, 1999). Also for the architecture of decisionsupport systems, the brain function is an exciting bound-ary. Professionals in agricultural engineering "elds havenot always foreseen possible e!ects of innovativeconcepts or systems. In the larger part of Europeancountries, criteria such as improvement of productione$ciency and scaling-up of farm enterprises have nolonger priority in the society. Illustrative is the exampleof automatic milking systems, on which a technologyassessment procedure is carried out. One of the results ofthe procedure was the special point of combining theautomatic milking system and grazing. Also farmersmust be aware of working with an automatic milkingsystem. Complex innovative technologies require a tech-nology assessment procedure, e.g. automatic picking offruit vegetables. This is also in#uenced by the changingrelation between science and society. Gibbons (1999) isconvinced that in the 21st century knowledge must besocially robust. Socially robust knowledge is that whichis evaluated, validated, tested and retested in many moreconditions and situations. The current debate on geneti-cally modi"ed organisms is an example that the dis-cussions on food safety and risks must be carried outwith larger groups of the community. Science todayneeds to enter a dynamic process where it must belegitimized again and again.

3.2. ¹echnology foresights

Which technologies are strategic for the agriculturalbusiness in general and the agricultural engineering "eldin particular? In &Technology Radar' (Rand Europe et al.,1998), the strategic technologies within the next ten yearsfor the di!erent business segments are mentioned. A tech-nology would be considered strategic if it has a strongpotential for creating opportunities than can be pro"t-ably exploited across the spectrum of business and indus-try in the Netherlands. In the technology chain basicresearch, applied research, technology development andtechnology use play a role. In the mentioned report,biotechnology (breeding of plant and animals, gene tech-nology), discrete production (production automationtechnologies) and information and communication tech-nologies (data and knowledge systems, computer-aideddesign, computer modelling and simulation) are stated asstrategic linked to the agribusiness and "shing. Thesetechnologies are related to the system development in

precision farming, quality improvement of products andreduction of environmental load. From nine technologyclusters, including materials technology, biotechnology,and energy technologies, with 46 technology "elds (e.g.surface treatments, bioprocess technology, renewableenergy technologies), 15 technology "elds were classi"edas strategic. From those 15 technologies, the bioprocesstechnology, data and knowledge systems, energy savingtechnologies, gene technology, measurement and processcontrol, mechatronics, microelectronic components (sen-sors and actuators), production automation technolo-gies, software engineering and separation technologiesare strategic for the agricultural engineering discipline. Incomparison with other technology foresight studies inthe USA, UK, Germany, France and Japan with a timescale from 5 to 20 years, some additional strategictechnologies were identi"ed, such as nanotechnology(electron/ion microbeams with relevance for miniaturi-zation) and computer and network systems. Besides theeconomic and scienti"c criteria, social criteria also playa role in identifying strategic technologies in the last-mentioned technology foresight studies.

4. Challenges for the agricultural engineering discipline

Kitani (1994) describes the dilemmas of population,poverty and pollution and economical development,energy and environment. There is an increasing need forfood and feed in the world, feed because of the fact of thegrowing demand for meat in the Asian countries. Theissue of energy in agriculture has a strong relation withthe knowledge and application of knowledge of the agri-cultural engineering discipline. The higher quality of lifedesired by mankind is observed by the growing demandsfor food, feed, fuel and energy. Kitani (1994) supports thewidening of the horizon into a broader area of biop-roduction instead of expanding the traditional livestockproduction. The role of agricultural engineering is tosupport bioproduction through meteorology and envir-onmental technology support and expertise in the "eld ofenergy, power, work-study and ergonomics. Importanttrends in Western Europe's agriculture are the shift fromproducer to consumer orientation, changing consumerpreferences, globalization (a!ects both agricultural enter-prises and markets), mass individualization (custom-made products), competition through knowledge and theformation of new agrochains. An example are thegrowers of ornamentals which renew continuously theirassortment and marketing methods (Van Oosten, 1998).On the basis of the general trends in the society thechallenges for agricultural and environmental engineer-ing are the contributions to sustainable agricultural prac-tices. The characteristics of sustainable agriculture must

231STRATEGIC THEMES IN AGRICULTURAL AND BIORESOURCE ENGINEERING

be rethought and &translated' in terms of the di!erentworking areas, e.g. ecotechnology, biodiversity, workingconditions and quality of products and systems. It mustbe underlined that in the change to and the developmentof a sustainable agriculture the combination of economy,ecology and technology is crucial for the social accept-ance and support.

In the frame of the European Commission, Sevila andSteinmetz (1994) have published a comprehensive reporton the role of agricultural and environmental engineer-ing. The mentioned challenges are the #exibility ofproduction systems through diversi"cation, the improve-ment of quality management on environment, animalwelfare, safety, reduction of production costs (competi-tive), contributions to the improvement of the ecosystem(landscape, watershed, waste recycling, rural employmentand the development of technical support (planning anddecision support).

The next logical step is the connection of challengeswith strategic themes (Jongebreur, 1999a). The trends inthe more classic "elds of agricultural engineering, namelymechanization and automation, structures and environ-ment, labour and management, energy and water andmeasurement technology are analysed by Jongebreurand Speelman (1997).

The agriculture engineering discipline is broad and theattention in this paper is focussed on strategic themesrelated to crop production, greenhouse production andlivestock production. But even with this restriction thereview is not complete and the choices are often relatedto the Dutch situation.

5. Strategic themes

The demand in the di!erent sectors of agriculture iscomparable in the "elds of information and communica-tion technology (data systems, data communicationalgorithms), microelectronic components (sensors andactuators), energy technology (energy saving, renewableenergy sources) and materials technology. Special expert-ise within these technologies must be linked to the agri-cultural engineering "elds. Data systems, modelling andsimulation, for example, are important for further pro-gress in precision agriculture, emission prevention andreduced application of agrochemicals. Energy and mater-ials technology are related to the necessary achievementsin innovative design of structures and energy saving.Whereas the research and development in the "elds ofsensors and mechatronics are related to the further pro-gress in advanced systems for livestock, crop and green-house production. Ecotechnological design of systems orsubsystems on the basis of indicators for sustainability(e.g. energy e$ciency, labour quality, water e$ciency,

animal welfare indicators, emission factors) is an impor-tant area in the playing "eld of the agricultural engineer.

6. Greenhouse engineering

6.1. Integrated system concept

In the working "eld of greenhouse engineering speci"cstrategic themes can be mentioned, such as energy savingand application of renewable energy sources (reductionof CO

2emission), automation (product and labour qual-

ity), design of greenhouses (climate control, energy savingand landscape quality), water use and closed growingsystems (prevention of nutrient emission). Di!erent con-cepts and designs with the aim of achieving a low or zerofossil energy use in a period from 10 to 20 years from nowonwards are developed.

One of these concepts is the &solar greenhouse' witha fundamental approach on three lines namely:

f reduction of the energy demand of the greenhousethrough an improvement of the insulation value of thestructure and an adapted climate control throughdehumidi"cation;

f optimal supply and demand of renewable energy (solarenergy, wind power, geothermal); and

f dynamic control of the complex system with the aim tomaximize the output and quality of the products, anda low use of agrochemicals.

Calculations have indicated that the energy demandfor maintaining temperature in a greenhouse structurewith a low heat loss of 3 W/m2 K can be met by the solarradiant energy. A substantial energy saving can beachieved with a heat pump and an underground aquifer(Huijs et al., 1999).

In order to integrate di!erent requirements the basicdesign for a sustainable crop production system (SCPS)was made (Bakker, 1998; Achten et al., 1999). The basicprinciples for the design were energy supply from renew-able sources, optimal use of solar light, closed systems forwater, plant nutrients and carbon dioxide and improve-ment of the support from the society through combina-tion of functions. This design requires breakthroughs inthe "elds of greenhouse construction, cover materials,climate control and bioproduction technology. Relative-ly new is the integration of the greenhouse complex in theliving environment, e.g. perception and acceptability. Theoverall goal of this greenhouse concept is to reduce theenvironmental strain, e.g. the emission of plant nutrients,CO

2, less energy-intensive materials by a factor of 20.

For this reason, we may not expect that this type ofinnovative concept can be built before 2020. The initialconcept for the SCPS was a circulation production area

A. A. JONGEBREUR232

(diameter 200 m), height of 45 m, a central mast anda cover of insulating plastic material (see Fig. 1). In thecentral mast, a wind turbine is "xed. The chimney shapeis forcing natural ventilation. The production area (#oor)consists of separate circular segments, which can bemoved independently from each other. The growingcircles are #oating on the water surface of a basin whichcan be used for the storage of heat. The feasibility studyof this concept has indicated that the environmentalimpact can be reduced by a factor of 6}7. Naturalsolar light in combination with long-term storage of heatwill meet the energy demand. Central dehumidi"cationin the top to save latent heat is di$cult because of thehigh wind speed (Huijs et al., 1999). Dehumidi"cation ofthe air is in the frame of a more or less closed systemwithout or with less ventilation a key point in the furtherprogress of these concepts. Completely closed biosystemson the aspects of light, heat, CO

2, water, plant nutrients

will remain the object of strategic studies (Kozai& Kubota, 1997).

6.2. Energy, water and nutrients

From the materials technology area, the cover mater-ials for greenhouse construction play a strategic role inbioproduction and energy saving. In the future, we mayexpect new materials with excellent insulation and lighttransmission and special constructions, e.g. &zig-zag con-structions' (Kozai & Kubota, 1997; Sonneveld, 1999b).A multi-functional approach of complete closed green-house production (light, heat, water, CO

2, plant nutri-

ents) combined with urban living area can also beworked out for di!erent situations. Also the combinationwith the reclamation of water from sea with help ofgreenhouse bioproduction can be the result of this ap-proach (Sonneveld, 1999a).

Fig. 1. Impression of the sustainable crop production system

Worldwide 70% of all the water is used for irrigation(Brown & Flavin, 1999). Water use in the Dutch green-house business is quite substantial namely approximately20 times more than the produced biomass. Strategicthemes in the frame of the increasing priority of the&scarcity of water' are decreasing the need for leachingand the reuse of drain water in hydroponics. The develop-ment of water-e$ciency indicators is important bothtechnologically and economically (Stanghellini, 1999).Sensor technology and related algorithms play a crucialrole in the control of water supply in non-closed systems(Balendonck et al., 1998). For closed growing systems theenvironmental pollution of nutrients and water spillagecan be tackled with help of the chemically modi"ed "elde!ect transistor sensor system. This sensor system hasa high selectivity for sodium, potassium, nitrate, calciumand dihydrogen phosphate (Jongebreur et al., 1999b).

6.3. Automation

In &Technology Radar' (Rand Europe et al., 1998)mechatronics is de"ned as an integration of precisionmechanical engineering, electronic control and systemsthinking. This approach is applied to develop a func-tional model for the automatic harvesting of fruit veg-etables (Bontsema et al., 1999). Automation research forreasons of the replacement of monotonous labourand the improvement of product quality are the basicarguments in the future.

6.4. Information and communication technology

Information and communication technologies areemerging and penetrating life and work with a highvelocity and this process is irreversible. In the greenhousesector, an information network is available. Nowadays inthe research institutes, models are available to maximizethe output for the grower on the basis of auction price,weather forecast and energy costs. Decision support canbe delivered through an electronic network in order toadjust the set points of the climate control in connectionwith plant growth and energy costs. To "t these tools to anelectronic network also with the help of reliable and avail-able databases without human interference is a real chal-lenge for the future. Greenhouse bioproduction mayexpect progress from the approach of the &speaking plant'in order to develop models with intelligent technology, e.g.algorithms, fuzzy logic and neural networks (De Baer-demaeker & Hashimoto, 1994). Further progress may beexpected from the combination physiological approach inplant growth, plant quality and health and a learning fromthe data approach (Meuleman & Van Weel, 1997).

233STRATEGIC THEMES IN AGRICULTURAL AND BIORESOURCE ENGINEERING

7. Crop production engineering

7.1. General

Opinions, values and norms in todays society is a dy-namic process of movements. Farmers must meet thegrowing world food demand with sustainable productionmethods. Diversity in technology applications, integ-rated pest management with high pathogen-resistantplants and conditions, crops with high water e$ciencyare skills to be managed by the farmer (Trewavas, 1999).The application of genetic-manipulated organisms mayplay a crucial role, however, there is an increasing debate onthese applications in di!erent organizations of consumers.

7.2. Perspectives precision agriculture

The challenges, amongst others, for the crop producersare achieving the maximal yield of high-quality cropswith low inputs on plant nutrients, agrochemicals andlow costs for machinery. In this frame, yield mappingsystems for non-grain crops, variable rate technology,decision support systems and sensing techniques, e.g. forweed control must be developed in the 21st century. Onthe basis of the within-"eld variability, these tools canhelp to reduce environmental strain. The public opinionis aware of the potential perspectives of precision farm-ing. However, much research and development (R&D)remains to be done for reasons of the fact that detailedinformation of variability in yield and soil characteristicsleads to unanswered questions, for example, of the econ-omics of variable rate fertilization (Goense, 1998; Searcy,1999). On a site-speci"c basis, the interactions betweenplant and soil, pest and weather conditions require inten-sive agronomic research e!orts. The application of cropgrowth models, databases (soil characteristics, pest con-trol, yields) and standardization of data interchange arealso substantial research tasks. Sensor technology andvision must bring further progress in weed detection,yield mapping and use of weather data (Searcy, 1999).The research and development on autonomous vehiclesbecomes more and more important for the agriculturalmachinery industry and research institutes (Brega, 1998;Tillett et al., 1999).

7.3. Plant spray technology

In the Netherlands, many of the crop production "eldsare surrounded by ditches. In order to achieve acceptablelevels of ecotoxicological risk in surface water, spray driftresearch remains strategic for the future. With the help ofa spray drift model (Holterman et al., 1997), measure-

ments in the laboratory with a phase Doppler particleanalyser (PDPA) and "eld experiments the drift reduc-tion of speci"c devices in di!erent conditions could becalculated and validated (Van de Zande et al., 2000)Strategic for the future is the &zero-application' of agro-chemicals with the help of sensor technology and visionand integrated agronomic research. Application of biolo-gical plant protection agents can improve sustainability.However, spray drift is an actual problem to be tackled,very little is known about the evaporation of the agro-chemicals to the air. This is really a substantial source foremission.

7.4. Innovative system concepts

Biotechnology may bring agriculture new crops for theproduction of special compounds, e.g. pharmaceuticals,vitamins and &green' chemicals. The development of bio-plastics and bio"lms and other bioproducts can bea niche-market for crop growers. To satisfy the con-sumer, requirements with respect to product qualitychain approach and chain management o!ers perspect-ives, e.g. for potato growers. Molema (1999) comes to theconclusion that potatoes can be almost free of subcu-taneous tissue discolouration if the number and intensityof impacts by mechanical forces can be reduced. Poten-tial improvements in the handling chain from land to theconsumer are improved utilization of better harvestingmachinery, better planning of bunker storage, box hand-ling and improved temperature control during storage.

Biomass as a renewable energy source by energy crops,such as willow, poplar, miscanthus and hemp, can beutilized for the production of heat and electricity. Due tothe high costs, the interest in energy crops is low in theNetherlands; however, in some countries, energy cropsare grown on a commercial basis. After harvesting of thewillow, it is necessary to dry it before supplying it to theenergy plant (Gigler, 2000). The combination of growingenergy and the puri"cation of sludge from canals de-posed as a layer on the land is presently being tested. Thismethod involves a combination of land use for producingenergy and the environmental puri"cation business. Thiscan be attractive because of the negative value of thesludge.

8. Livestock production engineering

8.1. General

Today's livestock production challenges are the foodsafety (contamination of animal feed with polychlo-rinated biphenyls and furans) control of infectious

Fig. 2. Hercules, a clean and sustainable production method

A. A. JONGEBREUR234

diseases (bovine spongiform encephalopathy, swine fe-ver), the clean treatment and utilization of animal ma-nure, the prevention of emissions and the guarding ofanimal welfare conditions. In di!erent branches, e.g. thepig industry, the entrepreneur is more or less urged toimplement improvements in di!erent "elds at the sametime. The storage, treatment and utilization of manurewith low emissions of ammonia, greenhouse gases, badodours and "ne dust particles, and the housing systemadapted to the welfare requirements (e.g. space, the #oordesign and construction) all require technical solutionsand thus investments. A logical approach is then todevelop innovative husbandry systems together withstakeholders from society, government, consumers,supermarkets and producers. Without further explana-tion, it must be underlined that these systems are eco-nomic for the entrepreneur.

8.2. Integrated system concept

In di!erent countries, research e!orts are paid to thedevelopment of alternative housing systems of layinghens, especially concepts of the aviary housing systemwith &bottlenecks' on the aspects of ammonia emission,labour conditions and economics (Blokhuis & Metz,1992, 1995). Reduction of ammonia emissions in theaviary system compared to battery cages is achievable(Groot Koerkamp et al., 1999) whereas improvement oflabour conditions is possible.

From the research carried out both in laboratoryexperiments and on a practical pilot scale, we havelearned that &"ne-tuning' is necessary before the initialgoals of a sustainable system (emission, labour, economy)can be achieved. In the frame of a ban on the cage system,this is important to remember. For integrated systemdevelopment, it is a prerequisite that the project is sup-ported by a broad group of &stakeholders'. For the pigindustry, a multi-disciplinary approach is worked out inthe Hercules project in cooperation with research institu-tions and private companies. In this approach, the systemdevelopment is carried out along the chain from animalfeed via digestion by pigs in innovative housing systems(health, welfare) to fertilizer production from faeces andurine (see Fig. 2).

Sustainability of the system is evaluated by a life cycleanalysis method on building materials, mineral manage-ment, volatile emissions and energy and water inputs(Ogink et al., 1998). Part of this project is the emissioncontrol of ammonia, odours and greenhouse gases. Pre-vention of these emissions by knowledge generationthrough measurements, modelling, data mining, know-ledge mining, system design and redesign remain stra-tegic in the 21st century (Monteny & Erisman, 1998).

Development of integral concepts for livestock produc-tion is not easy because of high number of parts oflivestock buildings and equipment (Scott, 1984) and theincreasing complexity of external conditions to be met bythe livestock producer.

8.3. Advanced technology

The overall management of dairy operations requiresmaybe in the future more specialized experts on, forexample, animal health and nutrition, environmentalprotection, milking technology. For milking technology,a clear comparison of di!erent technical designs is lack-ing. Automatic milking systems are coming as a &break-through' for practical dairy enterprises. The rather longR&D period needed for this mechatronic equipment canbe explained by several factors. These factors are a com-bination of di!erent technologies, e.g. sensor technology,software engineering, precision mechanical engineering,and the radical in#uences on barn design, farm routineand management practice. The last-mentioned aspectscan for a greater part be solved by modelling and simula-tion (Halachmi, 1999). We must also be aware that theapplication of automatic milking systems must not beargued from the labour saving point but much more bythe improvement of the welfare conditions through morefrequent milking of the dairy cow. Biomonitoring is stra-tegic from the side of the physiology, ethology and path-ology sciences and for the agricultural engineeringscience. In the Livestock Monitoring Workshop at SilsoeResearch Institute it became clear that quite someresearch work is carried out in Europe (Anon., 1999).However, it is well known that research and developmentfor biosensors (milk quality) or intelligent animal trans-ponders require high investments, and we must concludethat this equipment is necessary to achieve progress in

235STRATEGIC THEMES IN AGRICULTURAL AND BIORESOURCE ENGINEERING

the control of several processes. In cooperation withhuman medicine and animal science groups, the &learningfrom the data' approach (Meuleman & Van Weel, 1997)can bring agricultural engineers advantages for fasterprogress.

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