## 2 Materials and Methods
### Experimental Field Setting  
The experimental field is located near Codigoro town (Italy), 40 km eastward of Ferrara (Figure 1, 44\({}^{\circ}\)50\({}^{\prime}\)33\({}^{\prime\prime}\) N and 12\({}^{\circ}\)05\({}^{\prime}\)45\({}^{\prime\prime}\) E) and 15 km from the Adriatic Sea in a reclaimed area at an average altitude of 3 m below sea level. The average daytime temperatures ranges from 3\({}^{\circ}\)C in January and 25 \({}^{\circ}\)C in July and the marine thermoregulation generally maintains the minima over zero, reducing the number of night frosts. The average rainfall is between 500 and 700 mm per year, representing the regional pluviometric minimum with peaks in autumn and summer (sub-continental climate).  
The area belongs to the eastern Po River plain, where ancient interdistributary bays and brackish marshes were recently (1860-1960) reclaimed (25,26). The soil of the experimental field belongs to the cartographic unit FOR1-LCOI of the Emilia Romagna 1:50,000 Soil Map (www.regione.emiliaromagna.it), and consisting of recent interfluvial silty-clay deposits classifiable as Calcaric Gleyic Cambisol (26,27). The average grain size of the upper soil horizon is constituted by 0.6 \(\pm\) 0.1% of medium sand (200-630 \(\upmu\)m), 7.4 \(\pm\) 0.3% of fine sand (63-200 \(\upmu\)m), 49.2 \(\pm\) 3.1 of silt (2-63 \(\upmu\)m) and 42.0 \(\pm\) 3.4% of clay (<2 \(\upmu\)m) (28). The average organic matter content is 8.1 \(\pm\) 1.5%, hydraulic conductivity of the soil is 1.7 \(\pm\) 2.4 m day\({}^{-1}\) while the average bulk density is 1.15 \(\pm\) 0.05 kg m\({}^{-3}\)(28). The upper soil horizon is also generally well drained due to the presence of a sub-surface drainage system at -1 m.b.g.l. Soil mineralogical composition is characterized by quartz, feldspar, calcite and clay minerals (illite, smectite, clorite, serpentine and mixed-layer) (10).  
The experimental field was parceled in order to compare the different zeolitite treatments with the traditional practices. The parcels were designed linear and continuous in order to facilitate the movements of farm machines. In each parcel, three different sub-parcels were considered to consider inter parcel variability and to have statistical significance. One parcel (0.5 ha) was amended with 7 kg m\({}^{-2}\) (7 CZ) of NEZ (\(\O<\) 3 mm); two parcels (1 ha each) were amended with 5 (5 NZ) and 15 (15 NZ) kg m\({}^{-2}\) of coarse-grained (\(\O\) 3-6 mm) NZ, respectively, and 3.5 ha were used as control (CNTR). The smaller size of 7 CZ parcel was due to the long time required to produce the NEZ using the \"ZeoLIFE\" prototype tank (23,24), which has a limited production rate of about 250 kg day\({}^{-1}\). Addition and spreading into the field of NZ and NEZ were carried out between October 7 th and  
Figure 2: Particle size analysis of the employed zeolitites.  
November 6 th, 2012. NEZ supplied approximately 410 kg N ha\({}^{-1}\) in the 7 CZ parcel. Immediately after spreading, the field was plughed and the zeoliitite was located until an approximate depth of 30-40 cm. According to ZeoLIFE plan, in the first year of field experiment, sorghum (_Sorghum vulgare Pers._) was sowed on May, 9 th, 2013. Nitrogen fertilizers were distributed in two steps: di-ammonium phosphate during the sowing, with an application of 21.6 kg N ha\({}^{-1}\) in all parcels and urea on June 3 rd, 2013, with different doses in the various parcels. In the CNTR parcel, an average of 170 (\(\pm\)16) kg N ha\({}^{-1}\) were supplied, while a reduction of approximately 30% and 50% of urea in NZ (both 5 NZ and 15 NZ for 122 and 127 kg N ha\({}^{-1}\), respectively) and NEZ parcels (81 kg N ha\({}^{-1}\)) was applied, respectively. Harvest occurred in September, 23 rd, and the yield was separately evaluated for each treatment.