FILCHEVA Ekaterina (1), CHAKALOV Konstantin (2), POPOVA Todorka (2)

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1 Scientific registration n 0 : 1743 Symposium n 0 : 6 Presentation: poster Possibility to manage soil-forming processes. New concept for humus conservation in agriculture Possibilité de gestion des processus de pédogenèse.nouveau concept pour la préservation de l humus en agriculture FILCHEVA Ekaterina (1), CHAKALOV Konstantin (2), POPOVA Todorka (2) (1) N.Poushkarov Institute of Soil Science and Agroecology, 7 Shosse Bankya str.,1080, Sofia, P.O.Box 1369, Bulgaria (2) Rudmetalurg project LTD., 205, Al. Stamboliiski bld., 1309 Sofia, Bulgaria Considerable amount of the organic matter transforms annually (after the biological cycle is completed) into stable organic substances of complicated composition called humus as a result of complex biochemical and chemical processes. Soil-forming processes, organic carbon amount and reserve, ratio C ha /C fa, humification degree, etc. are fluctuating in broad limits depending on: climate, pedoclimate, plant residue, bedrock and biological activity etc (Ivanov Y., 1988). To maintain humus content is one of the factors to keep soil fertlity. Farmyard manure, peat, barks, plant residues, slury and compost application is wellknown approach to maintain soil organic matter. Natural zeolite utilization as a soil conditioner and as a component of natural zeolite compost is a new concept to manage humus-forming processes. Transfornation of organic substances in soils leads to formation of organic acids (humic and fulvic acids). Humus acids in model system are affleted by the clay charge on their basal surface (Tarchitzky,D. et al., 1993). Clinoptilolite as a matrix probably forms much more complicated net configurated organic substances with a larger specific surface. Its stable structure and relatively uniformed desorption of cations keeps acceleration of condensed humus molecules during the equivalent conditions. This way it is possible to accumulate exchangeable acidity on the permanent charges of the organic adsorbent. Some types of zeolite accumulate predominantly exchangeable acidity (exch. H +, Al +3, Fe +3 and Mn +2 ) and redistribute permanent and variable charges in the media. The last one is an important factor to affect humus-forming processes and perhaps soil-forming processes (Chakalov K. et al., 1993; Filcheva E., et al., 1996; Filcheva et al., 1998; Sheppard R., 1984). The aim of this study is to determine the influence of natural zeolites (clinoptilolite) on the transformation of organic substances and the opportunity to impact on the humusforming processes as a part of soil-forming processes. 1

2 MATERIALS AND METHODS Natural and four modified zeolites; NH meq/100g; K meq/100g; Na meq/100g; Ca meq/100g of clinoptilolite (Cp) from Beli Plast (BP) deposit, Eastern Rhodopes, Bulgaria were investigated. These differnt forms were included in organic composts of hydrolyzed lignin (washed to remove the water-soluble organic components and SO 4 2- ); barks and peat (Batak, North-Western Rhodopes, Bulgaria). The components were mixed, ratio 1:1 (organic:mineral) without any biogenic elements in addition (model media). Two soils - Leached Smolnitza, BG (Vertisol, FAO) and Leached Cinnamonic Forest Soil, BG (Chromic Luvisol, FAO) were included in the study. Samples of the studied soils were mixed with NH 4 +, Ca +2, K + clinoptilolite (1%) and compost with peat and equivalent types of zeolite (1%) samples of Leached Smolnitza (Vertisol, FAO) was mixed with two more composts: lignin & NH 4, - zeolite and barks & NH 4 - zeolite. The experiment was carried out with both N and P - 10 mg/100g soil and samples were analyzed affer 20 days (~60% field capacity). Organic matter composition of the composts and soils were determined according to the method of Kononova & Belchikova. Cation exchange capacity (CEC) and exchangeable ions were determined with Schölenberg s (Handbook, 1972) and Ganev-Arsova (Ganev S., 1990) methods. RESULTS AND DISCUSSIONS Zeolite amended soils change their total reactivity. Data presented in table 1 and 2 show the effect of clinoptilolite and composts on the studied Chromic Luvisol. Cation exchange composition are affected proportionally to the content of the conditioner, especially the cation s ratio. It is proved that K-Cp and Ca-Cp and the respective composts decrease total and relative content of exch. Al +3 and H 8.2, respectively. Natural zeolites increase the level of exchangeable Fe +3 and decrease exch. Al +3. However, organo-zeolite composts affect sorption of both, Fe +3 and Al +3. It is established translocation of variable and permanent charges in the media, because of the decreasing of T A in zeolite amended soils. That way, clinoptilolite materials reduce formation of labile organo-mineral compounds i.e provide favourable condition for the humus maturity. It is established that total and relative content of humic acids increase at the end of the experiment with studied Chromic Luvisol. Organo-zeolite compost are more active (compare to natural zeolites) on the soil-forming processes. Clinoptilolites decrease the formation of Al and Fe -humates (NH 4 - and Ca-Z), because of the sorption of Al +3. and Fe +3 on the mineral adsorbent. The results obtained show that more condensed humic acids were formed in the initial stage using K-zeolites. NH 4 - and Ca - zeolites influenced this process but for a long time and that way they have favourable effects on the stabilization of young humic substances. Zeolite amendmenents of soil count on the sorption of potential determined ions. In the case of relatively low content of their own basic cations it will not be expected direct stabilization, peptization and precipitation of humic substances. Together with accumulative processes during the formation of humus horizon the most important role takes part the translocation of organic compounds. Fe, Al- and clay-humic compounds are base of this process (Filcheva E., 1983). Some zeolite types take an important part of soil-forming process. Exchangeable acidity, especially Al +3 in the studied Chromic Luvisol is determined by the clinoptilolite 2

3 influence on the soil acidity. This affects the mobility of Fe +3 (r=0.934) and Mn (r=0.443) and leads to the formartion of of more condensed humic acids K-clinoptilolit (Filcheva E., 1983). The last ones is proved by the relationships between K + and Fe +3 in the zeolite amended soils. The data of correlation analyses, presented in tables 4 and 5, show the most inportant influence of composts with Na-clinoptilolite on the content of total carbon. However, Na-clinoptilolite creates risk of salinnization. The ratio K/Ca anad Na/Ca are more important for this process and especially for the condensation of humic acids but iti is not uniform for the studied soils (Tables 3, 4, 5). It has been established that Mg is the factor for precipitarion and condensation of humic acids in connection of K/Fe ratio in soils. The process of stabilization of humus as a part of soil-forming process will be able to manage with a single or multiply application of zeolite conditioner. Clinoptilolite as a matrix probably forms much more condensed a net configurated organic substances with larger specific surface (Filcheva et al., 1996).Its stable structure and relatively uniformed desorption of cations keeps acceleration of condensed humus moleculas during the equivalent conditions. This way it is possible to accumulate exchangeable acidity on the permanent charges of the organic adsorbent. Because of the clinoptilolite cation exchange selectivity it is presumed an active ion exchange between organic and mineral adsorbent in the media.it has been established and proved so called mirror effect. Compost with a high level of variable charges (T A, part of the exchangeable acidity) forms low level of T A in the treated soils (Popova T., 1996). The last ones translocates zones for accumulation of potential dtermined elements in soils. This idea explains the influence of zeolite materials on the direction of soil-formiong processes. CONCLUSIONS Organo-zeolite composts influence on the soil-forming processes directly and indirectly. The level of compost s T CA and T A and their cation exchange composition is a base for managing soil-forming processes. - Direct influence: physical and physico-chemical adsorption of H +, Al 3+, high molecular organic compounds on zeolites as a matrix for the condensation of humic acids. - Indirect influence: translocation of total soil reactivity by so called mirror effect. Acknowledgement. This work was supported by National Science Fund, Ministry of Educatrion and Science, Bulgaria (Projects: CC 418, CC 589). REFERENCES 1. Chaney R., C. Green, E. Filcheva, S. Brown Effect of Iron, Manganese and Zn Enriched Biosolids composts on Uptake of Cadmium Contaminated Soils. In Sewage Sludge: Land Utilization and Environment. SSSA Misc. Publication, Madison, USA, Chakalov K., Y. Yoneva, T. Popova Influence of cation exchange composition of clinoptilolite on organo-zeolite composts quality. In: Proc. 4th Int. Conf. Zeo 93, Boise, Idako, USA 3

4 3. Filcheva E., P. Konishev, M. Antova Iron and alluminium attacking newly synthezed water soluble humic substances. Int.Symp. Interrelation man-mountain ecosystems, project 6, MAB, X, 1983, Bulgaria, v. 3, Filcheva E., K. Chakalov, T. Popova Modelling soil-forminmg processes in artificial zeolite soils. Symp. Carbon Sequestration in Soil, July, 1996, Ohio, USA 5. Filcheva E., K. Chakalov, T. Popova Model approach to improve soil quality using organo-zeolite compost. Balkan Ecology, v.1, 1, Ganev S Modern Soil Chemistry. Nauka and Izkustvo, Sofia, pp Handbook on Soil Science practical experiance (AtanasovI., M. Penkov, S. Stefanov, T. Penev, G. Dimitrov, T. Totev eds.). Publ. House Hristo G. Danov, Plovdiv, Bulgaria 8. Ivanov Y., R. Kotsilkova, T. Raichev, E. Filcheva Influence of the transformation of the plant residues upon the rheology of the clay minerals. Humus and Planta, IX, 22-26, August, 1988, Praha 9. Kononova M.M Soil Organic matter. It s Nature, it s Role in Soil Formation and in Soil Fertility. 2nd English edd. Pergammon Press. Inc., Elmsford M.V., pp Popova T., K. Chakalov Method for determining strong acid positions on substate adsorbent in organo-zeolite media. In: Proc. Int. Congr. ESSC, 1-5 September, 1996, Munich, Germany 11. Tarchitzky D., Y. Chen, A. Banin Humic substances and Effecs on Sodiumand Calcium-Montmorillonite Floculation and Dispersion. J.Soil Sci. Soc. of America, v.57, 2, Sheppard R Zeoagriculture. (W.G.Pound and F.A. Mumpton eds.). Westview Press, Boulder, Colorado, USA Keywords: compost, humic acids, fulvic acids, zeolite, soil forming process Mots clés : compost, acides humiques, acides fulviques, zéolite, pédogénèse 4

5 Table 1. CATION EXCHANGE CAPACITY (SCHÖLENBERG S METHOD) Treatments Na + K + Ca 2+ Mg 2+ Fe 3+ T Na + K + K Ca 2+ Ca 2+ Fe 3+ ph meq/100g 1. Control - soil 0.4± ± ± ± ± Soil + NH + 4 -Z 0.28±0 1.35± ± ± ± Soil + Ca +2 -Z 0.44± ± ± ± ± Soil + K + -Z 0.34± ± ± ± ± Soil + peat 0.28±0 0.57± ±0 2.77± ± Soil + peat + NH + 4 -Z 0.26± ± ± ± ± Soil + peat + Ca +2 -Z 0.28±0 0.8±0 9.51± ± ± Soil + peat + K + -Z 0.24± ± ± ± ± Table 2. SORPTION CAPACITY (GANEV, ARSOVA, 1990) Treatments T 8.2 T CA TA AL 3+ H 8.2 Ca+Mg T CA TA AL 3+ H 8.2 Ca+Mg mequ/100g % of T Control 24.33± ± ± ± ± ± Soil + NH + 4 -Z 25.81± ± ±0 0.84± ± ± Soil + Ca +2 -Z 26.63± ± ± ± ± ± Soil + K + -Z 25.18± ± ± ± ± ± Soil + peat 24.11± ± ± ± ± ± Soil + peat + NH + 4 -Z 20.40± ± ± ± ± ± Soil + peat + Ca +2 -Z 21.71± ± ± ± ± ± Soil + peat + K + -Z 22.91± ± ± ± ± ± Z - zeolite; Soil - chromic Luvisol, Gorni Bogrov; T Total sorption capacety; T CA - Permanent charges; TA - Variable charges; H Total acidity; AL 3+ - Exchangeable acidit 5

6 Table 3. HUMUS COMPOSITION OF ORGANO-ZEOLITE AMENDED SOILS Tretmens Corg. % C-total, % C h, % C h :C f C h - free E 4 :E Leached Cinnamonic forest soil (Chromic Luvisol, FAO), G.Bogrov 1. Control + soil Control+NH 4 -Z Control+Ca-Z Control+K-Z Control+Peat/P/ Control+P+ NH 4 -Z Control+P+ Ca-Z Control+P+ K-Z Leached Smolnitza forest soil (Vertisol, FAO), Sofia 1. Control + soil Control+NH 4 -Z Control+Ca-Z Control+K-Z Control+P Control+P+ NH 4 -Z Control+P+ Ca-Z Control+ P+K-Z Control+L+ NH 4 -Z Control+B+ NH 4 -Z begining of the experiment, 2 - end of the experiment; P - peat; L - lignin; B - barks; Z - zeolite 6

7 Table 4. Correlation coefficients between physico-chemical properties of the compost and soil humus composition Factors C-total C h C h :C f C h - free E 4 :E Leached Cinnamonic forest soil (Chromic Luvisol, FAO), G.Bogrov 1. Na K Ca Na/Ca K/Ca AL T A - compost T A org.ads T A mineral.ads Leached Smolnitza forest soil (Vertisol, FAO), Sofia 1. NA K Ca Na/Ca K/Ca T A mineral.ads r> p=5% begining of the experiment, 2 - end of the experiment; T A - Varieble charges

8 Table 5 INFLUENCE OF THE SOIL PHYSICO-CHEMICAL PROPERTIES ON THE HUMUS COMPOSITION (CHROMIC LUVISOL, FAO) r 12 r 13 r 23 r 12.3 r 1.23 r E 4 :E 6 Al 3+ K + /Fe E 4 :E 6 Mg 2+ K + /Fe E 4 :E 6 Mg 2+ K + /Ca E 4 :E 6 Mg 2+ Al C h free Mg 2+ K + /Fe C h free Al 3+ K + /Fe C h T CA K + /Fe r> p=5% 0.468

Regulation of soil adsorbent properties in copper polluted acid soils Régulation des propriétés d'adsorption de sols acides pollués par du cuivre

Scientific registration n o : 68 Symposium n o : 38 Presentation : poster Regulation of soil adsorbent properties in copper polluted acid soils Régulation des propriétés d'adsorption de sols acides pollués