THE USE OF HEU-TYPE ZEOLITIC TUFF IN SUSTAINABLE AGRICULTURE: EXPERIMENTAL STUDY ON THE DECREASE OF NITRATE LOAD IN VADOSE ZONE LEACHATES

Abstract

A HEU-type zeolitic tuff of very-high quality (88 wt.% clinoptilolite-heulandite) has been used as an additive to natural soils, aiming to reduce the produced nitrate load in leachates, following a common irrigation scheme. Zeolitic tuff has been added and mixed with agricultural soil in three different proportions (0.2, 0.4 and 0.6%) corresponding to an application of 500, 1000 and 1500 kg per acre. The control soil (without zeolitic tuff) and the three mixtures were exposed in a ten weeks experiment, in which, specific doses of irrigation water enriched in nitrates were added. Results of leachates analyses revealed that the addition of 0.2% zeolitic tuff is not effective and the mixture of soil-zeolitic tuff appears to have similar behaviour with the untreated (reference) soil sample. On the contrary, zeolitic tuff additions by 0.4% and 0.6% showed remarkable results and reduced the nitrate load of leachates by 81 and 86%, respectively. Hence, the impacts from the application of very-high quality HEUtype zeolitic tuff in agricultural soils could be rather positive towards environmental protection and rational farming, an in line with the goals and objectives of the new common agricultural policy imposed by European Union