## 1 Introduction  
The intensification of agricultural and zootechnical technology has brought food production to a high cost in terms of environmental quality [1; 2; 3; 4]. The large use of fertilizers, as well as the need to apply manure, increase nutrients leaching and runoff risk to ground and surface water (e.g., eutrophication), soil desertification, biodiversity reduction and to an increase in greenhouse gases production (e.g., NH3, N2O, CO2) [4; 5]. In this respect, natural zeolites (NZ), particularly those containing clinoptilolite and chabazite, have been widely used in agriculture and horticulture. Zeolitites are rocks containing more than 50% of zeolites [6], hydrated minerals capable of binding NH4\({}^{+}\) from solutions in their extra-framework sites, preventing NH4\({}^{+}\) leaching by rainfalls and/or irrigation. In this way, zeolitites can increase nitrogen use efficiency (NUE) and behave as slow-releasing fertilizers, resulting in a more sustainable agriculture, where the amount of fertilizers can be decreased without lowering the production yield [6; 7; 8; 9; 10; 11; 12]. Due to their physic-chemical characteristics, zeolites can be used as soil conditioners, carriers of fertilizers, antibacterial agents, insecticides, pesticides, as enhancer of soil biological activity and additional reducer of the Sodium Adsorption Ratio (SAR) index [13; 14; 15; 16; 17; 18; 19]. A yield increases of up to 65% in several crops (sorghum, wheat, corn, rice, marrow, chard, basil, tomato, radish, watermelon, lettuce, sunflower) in soils amended with natural or NH4\({}^{+}\)-enriched zeolitite (NEZ) were reported by several studies [6; 20; 21]. Analogously, [PERSON] et al. [14] found an increase of roots biomass in parsley (_Petroselinum sativum_), carrots (_Daucus carota_), and onions (_Allium cepa_). The same authors detected an increase in strawberry (_Senga sensana_) yield and green biomass of 70% and 49%; respectively, when natural zeolitite was applied as fertilizer. The aforementioned studies provide very important and useful information regarding the beneficial effects obtained using NZ in terms of crop yield, environmental protection (reduction of nitrate leaching) and water use efficiency. Notwithstanding these promising results, a detailed study on the N and C pools dynamics in a zeolitite-amended field is still lacking. The implementation of the Water Framework Directive (2000/60/EC) and the Nitrate Directive (91/976/EEC) led to the designation of large areas vulnerable to nitrate pollution (Nitrate Vulnerable Zone, NVZ) such as the Ferrara Province (Emilia Romagna, Italy). It lays at the end of the Po Plain where the intensive agricultural practices of the entire Emilia-Romagna are conveyed. The high number of breeding farms located on this territory and the consolidate agricultural practice of animal slurry spreading (liquid mixture of urine, water and feces), increases N2O emission by nitrification/denitrification and NO3\({}^{-}\) leaching, further emphasizing the vulnerability of this province [22]. In this framework, ZeoLIFE project (LIFE10+ ENV/IT/00321) was conceived to test different zeolitite treatments (ZT) at the field scale aiming at reducing the input of N from fertilizers and the irrigation water in agriculture. This project exploits the high cation exchange capacity (CEC) of this material by up-taking NH4\({}^{+}\) from pig slurry using an especially designed prototype tank [23] or, alternatively, from chemical fertilizers directly in the field after addition to the soil [24]. The current scientific literature lacks field studies in which a detailed investigation of the dynamics of N and C pools in soil modified with natural zeolitites was conducted. In this paper, we present a detailed study on the dynamics, of both organic and inorganic N and C pools in soils amended with NZ and NEZ (e.g., exchangeable and fixed NH4\({}^{+}\) in clay interlayers, nitrate, microbial biomass N and C, total organic carbon and carbon in humic substances).