An internet based tool for land productivity evaluation in plot-level scale: the D-e-Meter system

Transcription

1 An internet based tool for land productivity evaluation in plot-level scale: the D-e-Meter system Tamas Hermann 1, Ferenc Speiser 1 and Gergely Toth 2 1 University of Pannonia, Hungary, tamas.hermann@gmail.com 2 Joint Research Centre, Italy Abstract Land productivity evaluation is a process to express production potential of lands in a relative way. A new land evaluation system, namely the D-e-Meter System has been developed in Hungary. The system applies large scale (1:10 000) digital soil maps, data on soil nutrient status and includes land evaluation algorithms to assess the production potential of agricultural parcels. The new land evaluation includes the possibility of expressing any decrease in productivity and production risks that originate from climatic effects and are realized through pedological and geological factors (drought, inland water, erosion risk). The system is an internet based application, which aims complex land use planning objectives, such as displaying soil quality by means of maps using on-line GIS tools and assistance for farmers to fulfill their obligations to provide information on the use of arable land. Using online modeling and editable digital maps, the relationship between yields of agricultural land and the natural resources become analyzable. The user interface of the system makes it possible to keep up-to-date and also historical records on plant production and environment management. Keywords: land evaluation, soil map, land use, GIS Introduction Soil maps are produced to visualize spatial soil information. Classification and grouping of soil data for special purposes can be automated to enhance the applicability of the maps. Soil map applications are manifold, among which land productivity evaluation is one of the most widespread. Land evaluation systems may vary in their goal, structure and data requirement. Borrough (1989) identifies three major types of land evaluation models: (1) empirical (2) deterministic and (3) stochastic models. These can be static or dynamic models (Van Lanen et al. 1992) and either qualitative, quantitative, or a combination of the two (Bouma 1989). Applicability of any land evaluation system depends on the accuracy of information delivered by soil maps. In preparing soil information for land evaluation system development, soil taxonomic classification, soil mapping and productivity classification need to be harmonized. The method of soil map preparation depends on the purpose of mapping, the available data and tools available. For land evaluation purposes (to support field-scale land use planning goals) maps of a scale of 1: are required. Although soil maps are very valuable for description of ecological conditions of a given area, by themselves they do not provide readily applicable information for decision making on land use. Land productivity classification (land evaluation) is one of the most widespread special applications of soil data for land use planning purposes. In land evaluation, soil maps can help 197

2 to convert raw data to readily applicable information for decision makers by weighting of soil properties to describe the productivity of the given soil unit. This paper aims to illustrate the structure of the newly developed Hungarian IT-based land evaluation system, the so-called D-e-Meter (D-e-Meter, 2004) system. Land evaluation principles of the D-e-Meter system The basis to work out the land evaluation system was a series of soil productivity analyses of databases available from various sources (national plot register, long-term field experiments and case study areas). The analyses meant statistical processing of pedological, climatic, plant production, soil and fertilizer application data. In addition to providing productivity information based on yield and soil analyses, the sample area database has been built for GIS development purposes (to assist land use planning). Land productivity indices have been worked out on the basis of soil classification, which provides a basis for soil mapping information as well. Soil classes are characterized by their relative productivity (related to the productivity of all other soils in the classification system) for major cultivated crops and groups of crops. During the productivity evaluation process, different soil attributes (texture, humus content, thickness of humus layer, ph, parent material etc.) have been characterized by numeric values (weighting factors) according to their relative importance in the production potential of different classes. A standard productivity index was set for each soil map unit corresponding to the relative productivity of the most common soil in that map unit. Meteorological variability, regional climatic conditions, hydrologic and terrain factors are also expressed in the land evaluation system. Above all, the land evaluation work has been based on the computerized statistical processing of available soil and plant cultivation information. The new land evaluation system was developed to support multiple tasks for land use planning and general criteria associated with a land evaluation system. Main characteristic of the new land evaluation system are: (1) It determines the production potential of agricultural lands in a quantitative way, (2) allows evaluations for major cultivated plants (or groups of plants), (3) includes the possibility of expressing any decrease in productivity and production risks that originate from climatic effects and are realized through pedological and geological factors (drought, inland water), (4) describes the conditions of production also on various intensity levels of cultivation. Data-model of the D-e-Meter IT system Database development of the D-e-Meter land evaluation system has followed the common practice of relational database development, starting from a generalized approach to specific solutions, to widen the functionality of the system. As a basis, the system uses large scale (1:10 000) digital soil maps, field data on soil nutrient status, vectorized cadastral maps and includes land evaluation algorithms to assess the production potential of agricultural parcels. Objects used in the system: Cadastral unit Land use unit Ortophotos Parcel (agricultural plot) Soil mapping unit 198

3 A soil mapping unit is a single polygon on the digital soil map. It represents an area of homogenous soils that is different from its bordering polygons in at least one attribute. It holds georeferenced data for land evaluation calculations. Soil attributes of any object can be described with the help of soil mapping units. Large scale (1:10 000) soil maps applied in land evaluation In order to be applicable on field-scale, digital versions of 1: scaled soil maps have been integrated to the land evaluation system. The original paper maps contained information on soil types (subtypes), parent material and texture. Five additional cartograms complement the soil map: humus cartogram (with information on depth of humic layer and humus content of the plough layer) ph and calcium carbonate content cartogram soil water cartogram (depth of soil water level) cartogram on soil salinity (with information on salt content and distribution in the soil profile) cartogram of soil characteristics that are important in soil productivity and management (rooting depth, erosion, stone content etc.) As an example of cartograms, Figure 1. introduces the coding system of a humus cartogram. Humus cartogram is coding two soil attributes with one digit each. The first digit codes the depth of the layer with humus content and the second digit codes the humus content of the plough layer (upper 30 cm of the profile). (Baranyai., 1989) Figure 1. Humus cartogram of a soil map The major change in the case of digital soil maps in comparison with traditional paper maps is that soil characteristics are represented in combination. Furthermore it is also possible to select and display single soil characteristics, or special combination of soil attributes. Neighboring soil plots that are similar in all of their attributes are joined to a common polygon. Soil maps are georeferenced, therefore its connections with other objects in the GIS system is easy to handle. 199

4 On the user interface of the D-e-Meter system, zooming function helps the user to manage geographic records of land use starting from small scale country map to large scale plot maps. Calculation of D-e-Meter land productivity indices Soil and terrain data and spatial information are used to calculate the land productivity index of any given field. Each soil variety (in the corresponding agro-meteorological region) is evaluated according to its productivity regarding the given crop. The land information system stores the following different indices: Crop-specific capability indices General capability index (index calculated by weighting of crop-specific indices according to crop ratio of the cultivated land) Input data Output data Soil mapping unit data Parcel data Field data Terrain data Meteorological data Land evaluation algorhytms General capability index Crop specific capability index Figure 2. Land evaluation calculation input and output data With the help of on-line editing GIS tools, land productivity indices can be calculated for any delineated area of the spatial database. In other words, the user of the D-e-Meter system can decide for which plot he or she wants to calculate productivity index, and after on-line delineation of the considered piece of land, the D-e-Meter system can automatically calculate the productivity indices. The basis of the index calculation for the delineated land is the composition of the underlying soil polygon fractions and the corresponding land productivity factor values. Database (of a database server) linked to the soil map provides data for land evaluation. The database server produces land evaluation calculations. Map edition and display is supported by a web server. Cadastral maps, ortophotos, are also stored on this web-server. System operation and visualization of the land evaluation model in digital maps Results of land evaluation research supported by GIS modeling have been united in the sample areas. Since the web-linked monitor is the meeting point of the system and it s user, it was especially important to give clear user-friendly design with full functionality to the interface. Digital orthophotos assist the users to locate interested areas, where vectorized digital cadastral maps are used for building farm spatial database on-line underlining soil maps (Figure 3.). Agricultural fields can be created on the selected areas. 200

5 Figure 3. Delineation of the cropping land After delineating the borders of the land use units (agricultural field or plot) the web-server sends the coordinates of these units to the data-server. With cutting the same image on the soil maps, the server can calculate the land evaluation index of the given piece of land (by weighting of the productivity indices of soil plots in the given area). Results of the calculations are sent in a form of a result matrix to the web-server for display (Figure 4.). During land use planning parcels can be delineated by taking land productivity into account. Discussion Figure 4. On-line computed land productivity indices of the selected parcel A land evaluation system based on a complex approach of expressing soil productivity together with the available tools of information technology (Internet, GIS, database manager software etc.) offers new possibilities that allow the harmonization of agricultural production and environmental management on a higher level. 201

6 It is important to note that in spite of the fact that the present research project is meant to give a comprehensive solution for land evaluation, the D-e-Meter system will need constant maintenance and development due to scientific progress and the changes in practical farming. References Baranyai, F., Útmutató a nagyméretarányú talajtérképezés végrehajtásához., Budapest. Agroinform Bouma J Using Soil Survey Data for Quantitative Land Evaluation. Advances in Soil Science, Vol. 9., p Burrough, P.A Matching spatial databases and quantative models in land resource assessment. Soil Use and Management, Vol. 5., No 1, p3-8. D-e-Meter, available at the official web site, Van Lanen, H. A. J., Van Diepen, C. A., Reinds, G. J. and Koning, G. H. J A comparison of qualitative and quantitative physical land evaluations, using an assessment of the potential for sugarbeet growth in the European Community. Soil Use and Management, Vol. 8. No