Overcoming of Soil Contamination with Pesticides in Forest Nurseries Using the Activity of Microorganisms

Abstract

The use of pesticides during cultivation of pine seedlings in forest nurseries results in the formation two phenotypes of teratomorph seedlings – conditionally normal and abnormal. Growing forest cultures from teratomorph seedlings leads to their low survival rate. It is known that pesticides and their metabolic products can remain in soil for many years. It is therefore impossible to rely only on natural degradation of pesticides in soil. A promising way of removing pesticides from soil is their microbiological decomposition. This method is preferable because there is a meliorative organic substance not far from forest nurseries – i.e. forest litter rich in microorganisms. The purpose of these experiments was to examine the influence of forest litter applied on pesticide decomposition in soil and morphology of pine seedlings. The rates of forest litter that were most effective in decomposition of pesticides and the activity of microbial communities in litter, depending on forest stand structure, were determined. Estimation of that action was based on the morphology of seedlings (rate of pine seedlings with normal, conditionally normal and abnormal phenotypes), intensity of CO2 emission from soil and catalase activity, which correlates with the number of soil microorganisms. The results of these experiments showed the most effective activity of forest litter at the application rate of 20 kg/m2. The number of seedlings with normal phenotype rose from 32% up to 40%. Besides, it was noted that saprophytes were most effective in pine forest litter, which is characterized by a more acid reaction of soil solution, while most others were rich in fungi. The highest number of normal phenotype seedlings, intensity of CO2 emission and activity of soil catalase were correlated with the microbiological activity of the applied pine forest litter.

Korišćenje pesticida u gajenju borovih izdanaka u šumskim rasadnicima dovodi do formiranja dva fenotipa teratomorfnih izdanaka, uslovno normalnih i abnormalnih. Uzgajanje šumskih kultura iz teratomorfnih izdanaka ima za rezultat nizak nivo njihovog preživljavanja. Poznato je da se pesticidi i njihovi produkti metabolizma mogu zadržati u zemljištu veći broj godina. Otuda se ne možemo osloniti samo na prirodan proces razgradnje pesticida u zemljištu. Mikrobiološka razgradnja predstavlja perspektivan način uklanjanja pesticida iz zemljišta. Toj metodi se daje prednost zbog postojanja meliorativne organske materije koja se nalazi u blizini šumskih rasadnika, tj. šumskog otpada koji je bogat mikroorganizmima. Cilj ovih eksperimenata bio je da se ispita uticaj šumskog otpada na razgradnju pesticida i morfologiju borovih izdanaka. Određene su količine šumskog otpada koje su najdelotvornije za razgradnju pesticida i delovanje mikrobioloških zajednica u otpadu u zavisnosti od strukture šumskih zasada. Ocenjivanje tog delovanja zasnovano je na morfološkom stanju izdanaka (učestalost borovih izdanaka normalnog, uslovno normalnog i abnormalnog fenotipa), intenzitetu emisije CO2 iz zemljišta i aktivnosti katalaze, koja je u korelaciji sa brojnošću mikroorganizama. Rezultati ovih eksperimenata pokazali su da je najefikasnije delovanje šumskog otpada u količini primene od 20 kg/m2. Brojnost izdanaka sa normalnim fenotipom povećala se sa 32% na 40%. Pored toga, primećeno je da su saprofitni mikroorganizmi najefikasniji u otpadu iz borove šume, koji karakteriše veća kiselost zemljišnog rastvora, dok su drugi šumski otpadi bili bogati gljivama. Najveća brojnost izdanaka sa normalnim fenotipom, kao i intenziteta emisije CO2 i aktivnosti katalaze u zemljištu bili su u korelaciji sa mikrobiološkim delovanjem primenjenog otpada iz borove šume.