Recultivation of soil damaged by pyritic slag Remise en culture de sols endommagés par des scories de pyrite

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1 Scientific registration n : 1854 Symposium n : 38 Presentation: poster Recultivation of soil damaged by pyritic slag Remise en de sols endommagés par des scories de pyrite MILUTINOVIC Sinisa, MARIC Miroslava, ALEKSIC Valentina Agricultural Research Institute "Serbia", Agricultural and Technological Research Center, Zajecar, Grljanski put bb, Yugoslavia Introduction In the valley of the Veliki Timok River 2000 hectares of alluvial high-quality soil have been destroyed by pouring out of the pyrite slag from the Copper mine in Bor. During 1950 s the pyrite slag was deposited on the before mentioned area for a few times. When the flotation of barren soil started in 1970 s, further storage was stopped; so that it was possible the destroyed soil to submit to cultivation. Thickness of the pyrite layer on the deteriorated soil ranges from 0.40 to 1.20 m. No vegetation has been there since the moment of pyrite slag pouring out. In the course of the last 15 years the Agricultural Research Institute "Serbia" in Belgrade, that in has been working intensively on finding out the method of recultivating the destroyed soil. Material and Methods Aiming to find out proper method for recultivation of such destroyed soil and its submission to cultivation, the Centre for Agricultural and Technological Research in Zajecar has opened the necessary number of pedological profiles on the area of 55 hectares and performed the pedological analysis, such as: a) mechanical content and watery-physical properties, b) agrochemical analysis of soil, c) microbiological analysis of soil. At the same time the investigations in vegetation trials were carried out as well in which the pyrite slag was used as a substract. The trails variants were the following: 1 st - control (pyrite slag) 2 nd - pyrite slag + (20 t/ha) 3 rd - pyrite slag + (20 t/ha)+californian eartworm fertilizer (10t/ha) (20 t/ha) + straw (10 t/ha) Rye was used as experimental. In all variants the microbiological analysis, ph value, number of plants, content of microelements and heavy metals were performed. 1

2 Results and Discussion The following analysis have been done aiming the realization of recultivation of the soil: - Mechanical content - Table 1: -Mechanical content of the Damaged Soil Coarse sand mm Fine sand Powder Clay and Powder Clay <0.002 Determina tion of s sand clay sand clay sand clay clay clay clay On the basis of the mechanical analysis results, it is evident that it is mainly fine - sand clay and clay (Antonovic, 1973). The layer below 104 cm is of pure earth over wich there is the deposited pyrite layer of the similar structure as the whole soil horizon. - Watery-physical Properties - Table 2 - Watery - physical properties of damaged soil Specific Weight (g/cm 3 ) Volume Weight Retention Capacity Air Capacity Quantity of available water Accordingly, it can be concluded that the results from the analysis of the watery - physical properties are similar to those referring to the soil over which the pyrite barren soil had been deposited. - Chemical Properties - 2

3 Table 3 - Chemical properties of damaged soil ph Humus P 2 O 5 (mg/100g) K 2 O (mg/100g) On the basis of the results shown in the Table 3 it is clear that beside evident acidity per profiles other elements such as humus, P and K are the same as in the layer of 104 to 129 cm where the soil is quite pure without any addition of pyrite slag. - Microbiological Properties - Investigating the damaged soil characteristics, the mikrobiological research of of profile depth has been performed as well. It included the total number of microorganisms: cellulisators, actinomyces, fungi and ammonia forming bacteria. Although there was a prominent acidity in the soil samples, it was grown the individual colonies of fungi. None group of micro-organisms has vegetated. The reason for such behaviour of micro-organisms is a prominent acidity of pyrite and the anaerobic condition along the horizons of profiles. - Results of Analysis in Vegetation Trials - tables: The results of analysis of variants with pyrite slag are shown in the following Table 4: - Number and activity of micro-organisms in variants with pyrite slag Total number of bacteria (10 4 x g -1 ) Azotobacteria (10 2 x g -1 ) Dehydrogenesis (µg TMF x g -1 ) 1 st - control nd - pyrite slag rd - pyrite slag lumbrico + straw In relation to the pyrite slag (variant 1 st - control) the total number of bacteria has increased. The presence of azotobacteria depends on the applied measures and has the tendency of increase in the variants in which organic matter has been added. The enzyme activity is still low in all variants. 3

4 On the basis of the results it can be concluded that the microbiological processes have been activated by adding, fresh and humified organic matter. In that way it is possible to affect the improvement of the soil properties. Table 5: - ph value and number of plants in variants with pyrite slag ph value Number of plants at the in the end at the in the end beginning beginning 1 st - control nd - pyrite slag rd - pyrite slag lumbrico + straw From the above data it is evident that, by addition of, lumbrico and straw, ph value increases while the acidity is reduced. However, in the end of vegetation ph value decreases. Most probably, the reason for repeated acidity increase can be the oxidation of pyrite from the pyrite slag and appearance of SO 4 2- ions, that is sulphur acid (2H + + SO 4 2- ) (Antonijevic, 1995). The number of plants that completed vegetation is smaller than the number of new-emerged plants. Table 6: - Microelements and heavy metals of the variants with pyrite slag Fe Cu Zn Pb 1 st - control nd - pyrite slag rd - pyrite slag lumbrico + straw Table 7: - Microelements and heavy metals in plants Fe Cu Zn 1 st - control / / / 2 nd - pyrite slag

5 3 rd - pyrite slag + + lumbrico + straw Among heavy metals and microelements, the quantities of Fe and Cu were above usual values (table 6) but in plants those elements were present in permitted limits (table 7). Conclusions According to the results, it can be concluded the following: At the territory of the towns of Bor, Zajecar and Negotin over 2000 hectares of fertile soil have been destroyed by depositing of the pyrite slag. There is no any vegetation on those deteriorated areas which represent a great ecological problem of the region. The damaged soil can be made capable for plant production by applying recultivation measures. The process of recultivation has to last for a pretty long period of time. The basic recultivation means are limestone fertilizer and organic matter. References Antonovic G., Aleksic Z. (1972): Uticaj sumpornih gasova na promene nekih osobina zemljista u okolini borskog rudnika. Zemljiste i biljka, Beograd, vol. 21, No. 2. Antonovic G. (1973): Prilog proucavanju aluvijalnih nanosa ostecenih flotacijskim materijalom poreklom iz borskog rudnika. Arhiv za poljoprivredne nauke, Beograd, vol. XXVI sv. 94. Filipovic Dj. (1967): Zastita zemljista i obnova vegetacije na krecnjackom podrucju Istocne Srbije. Zemljiste i biljka, Beograd, vol. 16, No Antonijevic M., Dimitrijevic M., Jankovic Z., Vukanovic B. (1995): Mogucnost zagadjivanja zemljista i voda usled oksidacije pirita. Zbornik radova "Nasa ekoloska istina", Borsko jezero, Key words: pyritic slag, recultivation, organic matter, chemical analyses, vegetational experiments Mots clés : scories de pyrite, remise en, matière organique, analyses chimiques, expérimentations végétales 5