Estimated Water Savings in an Agricultural Field Amended With Natural Zeolites

Agricultural practices can jeopardize soil and water quality, thus mitigation measures to reduce nutrient loss and to protect water resources have to be implemented in order to ensure a sound environmental quality and, at the same time, a high crop yield. Natural zeolites have been tested as soil conditioner to diminish nutrient leaching and increase irrigation efficiency. In this study, an experimental site of 6 ha was monitored for two years to assess whether amending the soil with natural zeolite may induce a considerable impact on the water balance. Three control parcels were cultivated and irrigated according to the traditional way; two parcels were amended with coarse-grained natural zeolite at different zeolite/soil ratio (5 and 15 kg/m2) and two parcels were amended with fine-grained zeolite (7 and 10 kg/m2). Soil electrical conductivity, temperature and volumetric water content were continuously monitored via TDR probes at different depths. Climatic variables for water balance calculation were obtained by a meteorological station installed on-site. Continuous monitoring highlighted an increase of soil water availability in the amended parcels with respect to the control ones. The parcel amended with 10 kg/m2 of fine-grained natural zeolite showed an average water content always higher than the control ones, in the upper soil horizon. In addition, after intense rainfall, this parcel showed an increased field capacity and a reduced percolation towards the deeper soil horizon. Finally, the residual water content was improved by 1.2 ± 0.4 % throughout the summer droughts.