C.A. van Diepen

Land Evaluation: From Intuition to Quantification

According to Stewart (1968), land evaluation is “the assessment of the suitability of land for man’s use in agriculture, forestry, engineering, hydrology, regional planning, recreation, etc.” Many disciplines have contributions to make to land evaluation in its widest sense. The present review focuses on the role of soil science in land evaluation.

Changes in agriculture and land use in Europe

Changes in land use and agriculture have occurred frequently during the last millennium in Europe. Now at the start of the millennium a review of how and why changes took place may lead to a better understanding of these developments. This insight based on scientific analysis and understanding may be combined with explorative studies to gain a view on future possibilities. Such an explorative study for Europe is described. It demonstrates that contraction of agricultural area in the coming decades is inevitable and in line with an historic development where periods of expansion and contraction of agricultural area were intermingled. The new millennium will start with a period of changes in land use to fulfill societal goals in an optimum way. The research agenda that helps to define optimal land use and agricultural methods is based on this analysis and helps to develop the policy agenda for the near future.

Integration of Systems Network (SysNet) tools for regional land use scenario analysis in Asia

Abstract This paper introduces the approach of the Systems research Network (SysNet) for land use planning in tropical Asia with a focus on its main scientific–technical output: the development of the land use planning and analysis system (LUPAS) and its component models. These include crop simulation models, expert systems, GIS, and multiple goal linear programming (MGLP) models for land evaluation and optimization. LUPAS was designed as a decision support system (DSS) for strategic land use planning. Integration of LUPAS components in four case studies was performed in a network with national research teams and local stakeholders. This network allowed iterative evaluation and refinement of LUPAS for scenario analysis on technical and policy changes. Several interactive sessions with stakeholders led to more detail in scenarios (goals and constraints), model features and databases. To facilitate negotiation among stakeholders, the MGLP user interface (UI) was developed. In interactive sessions, goal restrictions are tightened to quantify trade-offs between conflicting goals. Choice and degree of tightening reflect the specific priorities for sustainable land use. The development of LUPAS is exemplified for one case study, Ilocos Norte, Philippines. Weak points of the system include inadequate spatial differentiation of socio-economic characteristics, scarce database for quantifying perennials and mixed cropping systems, and insufficient consideration of long-term effects of production technologies on resource quality. However, a promising perspective for effective policy support lies in the possible link of the regional LUPAS approach with farm household models.

Effects of climate change on grain maize yield potential in the European community

Grain maize yield in the main arable areas of the European Community (E.C.) was calculated with a simulation model, WOFOST, using historical weather data and average soil characteristics. The sensitivity of the model to individual weather variables was determined. Subsequent analyses were made using climate change scenarios with and without the direct effects of increased atmospheric CO2. The impact of crop management (sowing date, irrigation and cultivar type) in a changed climate was also assessed. Scenario climate change generally results in larger grain yields for the northern E.C., similar or slightly smaller yields for the central E.C. and considerably smaller yields for the southern E.C. The various climate change scenarios used appear to give considerably different changes in grain yield, both for each location and for the E.C. as a whole. Management analyses show that for both current and scenario climates the largest grain yield will be attained by varieties with an early start of grain filling, that average irrigation requirements to attain potential grain yield in the E.C. will increase with climate change but will decrease with both increased CO2 and climate change, and that sowing at both current and scenarios climate should occur as early as possible.

Physical land evaluation methods and GIS to explore the crop growth potential and its effects within the European communities

Abstract Qualitative and quantitative physical land evaluation methods were developed and linked with a geographical information system (GIS) to evaluate crop growth potential in the European Communities (EC). Evaluation methods comprised expert knowledge and crop growth modelling. The predicted crop growth potential is primarily meant for exploring land use options. In this paper, the wheat crop is used to illustrate the methodology. All potentially suited land units were identified first using computer-captured expert knowledge, followed by calculation of the potential and water-limited yields on these land units with a simulation model. Land unsuited for wheat-growing amounts to up to 55% of the EC area and is mainly concentrated in the Mediterranean countries. Without increasing the EC wheat area, the wheat production volume can still substantially increase by 65% under water-limited and 120% under potential production conditions. Results obtained were used to quantify the impact of set-aside of either highly productive land or marginal land on production reduction. In many EC regions marginal land used for wheat-growing produces at least 50% less than highly productive land. The production potential should be incorporated in set-aside measures to be imposed.

Crop growth modelling and crop yield forecasting using satellite-derived meteorological inputs

Distributed crop simulation models are typically confronted with considerable uncertainty in weather variables. In this paper the use of MeteoSat-derived meteorological products to replace weather variables interpolated from weather stations (temperature, reference evapotranspiration and radiation) is explored. Simulations for winter-wheat were carried for Spain, Poland and Belgium using both interpolated and MeteoSat-derived weather variables. The results were spatially aggregated to national and regional level and were evaluated by comparing the simulation results of both approaches and by assessing the relationships with crop yield statistics over the periods 1995–2003 from EUROSTAT. The results indicate that potential crop yield can be simulated well usingMeteoSat-derivedmeteorological variables, but thatwater-stress hardly occurs in thewater-limited simulations. This is caused by a difference in reference evapotranspiration whichwas 20–30%smaller in case ofMeteoSat. As a result, the simulations usingMeteoSat-derivedmeteorological variables performed considerably poorer in a regression analyseswith crop yield statistics on national and regional level. Our results indicate that a recalibration of the model parameters is necessary before the MeteoSatderived meteorological variables can be used operationally in the system.

Urban and peri-urban agricultural production in Beijing municipality and its impact on water quality

This paper reviews water use and water resource issues in Beijing Municipality, the main trends in the agricultural production systems in and around the city with respect to land use, input use, production and economic role, and the impacts of agricultural activities on water quality. Rapid urbanization and strong intensification of agricultural production have meant that the quantity and quality of available water resources have become matters of concern. The agricultural sector still has a major role in supplying the municipality’s population with food products, but it is also a major water user and has contributed to large gaps between water supply and demand and to high levels of water pollution. Among the main changes in agriculture in the last decade are the loss of arable land to urbanization, the rapid reduction in the area under grain, and the rapid increase in livestock numbers and in areas under vegetables and orchards. Intensive crop and vegetable production and intensive livestock rearing are major water polluters. The paper also points to some measures being taken to address these problems.

Effects of climate change on silage maize production potential in the European Community.

Abstract Silage maize production in the main arable areas of the European Community (EC) was calculated with a simulation model, WOFOST (World Food Studies model), using historical weather data and average soil characteristics. The sensitivity of the model to individual weather variables was determined. Subsequent analyses were made using climate change scenarios with and without the direct effects of increased atmospheric CO 2 . The impact of crop management (sowing date and cultivar type) in a changed climate was also assessed. A climate change scenario results generally in larger production for the northern EC and identical or smaller productions for the central and southern EC. The various climate change scenarios used appear to yield considerably different changes in production, both for each location and for the EC as a whole. Management analyses show that for both present and scenario climates the greatest production will be attained by varieties with a long growth duration, and that for climate change as in the scenarios the sowing date should be advanced.

Simulation and systems analysis tools for crop yield forecasting

System-analytical tools such as crop growth models, GIS, and remote sensing are increasingly being explored for their use in crop monitoring and yield forecasting. The key to the optimum use of these techniques lies in their mutual combination, and in their combination with other sources of information. This paper describes the Crop Growth Monitoring System (CGMS), developed for the Joint Research Centre of the European Union for seasonal crop status monitoring and yield forecasting. The core of CGMS consists of a Geographic Information System (GIS), a set of data bases (weather, crop, soil) and a systems-analysis component: a weather module, the WOFOST crop growth simulator and a statistics module. CGMS has been operational at JRC since 1994 and the outputs are used in the preparation of its monthly crop bulletins. Options are discussed for the improvement of crop growth simulation by the use of optical, thermal-infrared and radar remote sensing. Methods are presented by which crop parameters estimated from remote sensing can be used to adjust model simulations.

Two alternative methods for evaluating regional crop yield potential in the European Community

Abstract Two methodological options for the evaluation of the biophysical crop yield potential of the regions in the European Community are compared: the agro-ecological zones (AEZ) method and the Wageningen method. Special attention is given to the incorporation of the effects of moisture variability in the procedures. Both methods use crop growth modelling, but they apply different levels of analytical detail, and of regional generalization. Examples of application of both methods for the evaluation of crop yield potential of winter wheat in two agro-climatically contrasting regions in France are presented. It is discussed how refinements in process description, more intensive use of available data and the use of more detailed data can contribute to make the results more specific. A major constraint to making refined methods effective at the European level is formed by the insufficiency of physical soil data, needed in a simple soil water balance model, while weather data are less problematic. Some procedures for increasing the level of analytical detail through using more detailed data and models are outlined. A better handling of temporal and spatial variability in soil and weather data in model applications are suggested, while maintaining a proper balance between model process description and input data.