Assessment and modeling the influence of nitrogen input in the soil on groundwater nitrate pollution: Plain of upper- cheliff (north algeria)

Abstract

The present study associates groundwater nitrate pollution with agricultural activity in the Upper-Cheliff wich is known for intensive farming practices. The indicatory kriging method is used in order to elaborate a map of the spatial probability distribution of nitrate concentration that exceeds a threshold value of 50ppm during high watering period for the year 2012. The obtained results show that the areas exceeding nitrate concentrations of 50 ppm, occupy more than 80% of the Upper-Cheliff aquifer area. It appears, from this map, the most affected areas are those for which the level of intensification of the N-fertilizers is the strongest (zone of garden farming, potatoes in particular) throw condensed.These results are coherent with the experimental data, which show an average nitrate concentration value of 75 ppm, significantly higher than the World Health Organization (WHO)’S standards. In this study, the total nitrogen brought to the soils of the Upper-Cheliff is estimated at 247 kg ha-1 for this year, and compared to the results of New Computer models such as PILOTEN used to analyze alternative management practices together with soil, plant, and climate characteristics to determine the amount of nitrogen leached under the potatoes crops. The result of this model show that 60% of nitrogen input is leaching under potato crops which is relevant to the map showing the spatial evolution of nitrate. Nitrate pollution in the groundwater of the Upper-Cheliff appears to be significant and driven by the application of both inorganic fertilizer and land use.