Title : Nitrate leaching from agricultural lands by means of mini lysimeter
Abstract:
Groundwater quantity and quality are of great importance for people's well-being and economic development. It is a very important resource for drinking water, irrigation and industrial uses. Different pollutants, including nutrients from agricultural areas, enter the groundwater due to various anthropogenic activities on the surface of the aquifer. According to the European Water Framework Directive (WFD), in every EU country all water bodies must be in good chemical and quantitative status.
The transport and dynamics of pollutants are among the most important processes in the aquifer, however many times they are not so well known. The transport of water and pollutants in aquifer depends, among others, on the characteristics of the unsaturated zone. The unsaturated zone of an aquifer serves as a water reservoir which discharges water and potential pollutants to the saturated zone for a relatively long time. Nitrate pollution in groundwater, originating mainly from agricultural activities, remains a worldwide issue. Understanding the mechanisms and rates of movement of nitrate in the unsaturated zone is an important issue in the process of groundwater protection.
Water and nitrate transport processes under different agricultural land uses have been studied with mini lysimeters to tests on water percolation and flux of dissolved nitrogen compounds on lysimeters, and groundwater age distribution. For the purpose of sampling the infiltrated water which flows into the agricultural land and through the unsaturated zone downward into the saturated aquifer zone, lysimeters were installed below the agricultural field. These captured the infiltrated water that actually feeds the aquifer and also transports pollutants from the surface to the groundwater. The knowledge of the chemical status of the infiltrated water helps us understand the impact of agricultural activity on groundwater quality under real weather conditions. Therefore, the water from lysimeter pans were periodically collected and analysed for pollutant content.
As expected, preliminary results show that the leaching of nitrates from agricultural land is much more significant in the case of agricultural use than in the case of grassland. On the test fields, we measured the average nitrate concentrations between 132 - 219 mg/l, while the average nitrate concentrations under the meadow were 16 and 23 mg/l. The results, therefore, show that from the point of view of water protection, meadow land use is much more favourable than arable land. The results will help reduce the impact of agricultural activity on groundwater and thus contribute to the preservation of groundwater quality.
This research is funded by the Slovenian Research and Innovation Agency ARIS (operation no. J1-4412 and P1-0020).
Keywords: groundwater pollution, nitrate, agricultural activity, lysimeter, precision agriculture
