Pergamon Comput., Environ. and Urban Systems, Vol. 19, No. 2, pp. 117-122, 1995

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SOIL TRACE-ELEMENTS AVAILABILITY MAPS OF HUNGARY

Mihaly Szucs

Pannon University of Agricultural Sciences, Mosonmagyarovar, Hungary

ABSTRACT. The trace-element status of soil can be a measure for soil fertility and, at the same time, it is an indicator of possible environmental hazard in the case of excess values. Large numbers of soil samples have been analyzed for five trace elements (B, Cu, Mn, Mo, Zn), considered the most important for plant production. Availability indexes were calculated using analytical data in combination with other properties o f the soil. Evaluation of the results was based on field experiments and the trace-element contents o f plants.

The unevenly distributed point data were processed with GIS software. The work was carried out within a COSTproject. The basic data capture was made with Arc/lnfo. For the rest of the work, after proper data conversion, 1DRISI was used. Some missing data were calculated by multiple regression based on the sampling of images for soil properties correlated with the trace-elements availability-index numbers. Then, the built-in geostatistical functions were used to convert the point data into raster map images.

The classified images proved that nearly half the territory has a low value for Zn and one third is high in Mn. These data indicate the possible deficiency or toxicity occurrences and their locations in the country.

The work leading to this paper contains the necessary steps for data processing, the classified maps of soil trace-elements availability-index values, reveals the problems and shows the use of GIS application for agricultural and environmental management purposes.

INTRODUCTION

Because of the recognised significance of trace elements for plant growth, systematic analyses of soils were started by B. Kerszteny (Nagy, 1984) at the beginning of the 1970s. Despite the large number of analyzed samples, no mapping was possible by traditional m e t h o d s , b e c a u s e of the uneven d i s t r ibu t ion of s ampl ing si tes. A C O S T p ro j ec t (ERB3510PL920700) providing GIS software with geostatistical functions offered a solution to this problem. Compared to the data supplied by the network of the agrochemistry labora- tories, the maps below provide additional estimates of the trace-element status of soils, because of the difference in the applied solvents and owing to the increased number of inves- tigated trace elements.

Paper prepared for the GIS/LIS '95 • Central Europe Conference, to be held in Budapest, Hungary, June 12-16, 1995. Requests for reprints should be sent to Mihaly Szucs, Pannon University of Agricultural Sciences, Lucsony u. 15-17,

9200 Mosonmagyarovar, Hungary, e-mail: h 10846szu @ ella.hu.

117

118 M. Szucs

MATERIAL AND METHODS

Soluble trace-element content (B, Cu, Mn, Mo, Zn) of about 5,000 soil samples repre- senting 250 sampling areas was determined using an individual extraction procedure for every trace element. The absolute values were converted into relative availability indexes (Kereszteny & Nagy, 1980), calculated with special formulas taking into consideration the basic parameters of the soils (texture, pH, organic matter content).

Multiple-regression equations were calculated for the availability indexes, with envi- ronmental factors such as soil texture, soil pH, soil clay mineral composition, soil type, and geographic region of sampling. For quality factors, rank-order correlation was used (Thorndike, 1978). The 1:500,000 scale maps of the environmental factors were digitized using Arc/Info software. A new point vector was obtained by on-screen digitizing sites of the polygons created by the IDRISI overlay of the polygon vectors of the environmental factors. Data extracted by the "Query" option from the digitized environmental maps for the point vector were used to calculate the trace-element indexes on the basis of multiple- regression formulas accepted from the measured data series. For every trace element, the point vectors with measured and calculated values were joined, and the resulting point vector was used to interpolate the trace-element index values for each pixel. The final availability maps were created by reclassifying the index values. The original index con- version formulas based on literature data and field experiment measurement provided the conditions for classification of the results.

DISCUSSION

The majority of sampling areas were situated in the Noz~-West part of the country (Figure 1). Because of the microheterogenity, the whole range of values for the most important envi-

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Soil Trace-Element Maps of Hungary 119

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ronmental factors (texture, pH, etc.) was detected during sampling. It made it possible to extend the validity of calculated multiple-regression equation to the points selected in the

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FIGURE 3. Availsbllily of Boron in Hungarian Soils.

LOW I

MEDIUM 2

GOOD 3 I

HIGH 4 I

LAKES B

RIUERS 6

120 M. Szucs

LOH I B

MEDIUM 2

GOOD 3

HIGH 4 m

L~KES 5

RIVERS 6

FIGURE 4. Availebilty of Copper In Hungarian Soils.

unsampled areas (Figure 2). The trace-element availability maps are shown in Figures 3-7. Areas with different trace-element availability are detected. High values are presented for Mn

LOW !

MEDIUM 2

GOOD 3

HIGH 4 l

RIVERS 6

FIGURE 5. Avallsbllty of Manganese In Hungarian Soils.

Soil Trace-Element Maps of Hungary 121

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MEDIUM 2

GOOD 3 I

HIGH 4 I

LAKES 5

RIUERS 6

FIGURE 6. Availability of Molybdenum in Hungarian Soils.

on acidic soils, and there are large areas with low Zn availability on calcareous or alkaline soils. As shown in Table 1, a large proportion of low values was observed in the case of Zn, but

LON I

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GOOD 3 I

HIGH , I

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FIGURE 7. Availability of Zinc in Hungarian Soils.

122 M. Szucs

TABLE 1. Rates of Trace-element Availability Classes

Percentages of different availability classes

Elements Low Medium Good High

Boron 10.46 88.76 0.77 Copper 3.66 27.10 68.00 1.25 Manganese 6.61 12.09 47.11 34.18 Molybdenum 13.56 78.31 8.13 - - Zinc 46.30 42,48 10.14 1.10

practice would prove this only in cases of plants sensitive to Zn deficiency. High Mn values can lead to toxici ty in the case of long anaerobic conditions.

R E F E R E N C E S

Kereszteny, B., & Nagy, L. (1980). Meszezes hatasa pszeudoglejes bama erdotalajok mikroelem-ellatottsagara [Impact of liming on trace element availability of planosols]. Mosonmagyarovari Mezogazdasagtudomanyi Kar Kozlemenyei, XX/I(7), 293-307.

Nagy, L. (1984). Dr. Kereszteny Bela mikroelem kutatasi tevekenysege; Dtmantul egyes talajfoldrajzi tajainak mikroelem ellatottsaga [Trace element availability for some geographic regions of Transdanubia]. Mosonmagyarovari Mezogazdasagtudomanyi Kar Kozlemenyei. Dr. Kerszteny Bela emlekules. 74-84.

Thomdike R. M. (1978): Correlational procedures for research. New York: Gardner Press.