A Coupled Mathematical Model to Predict the Influence of Nitrogen Fertilization on Crop, Soil and Groundwater Quality

Abstract

Intensified use of nitrogen based fertilizers in agriculture has resulted in a significant increases in soils and groundwater nitrate concentrations all over the world. Here we propose a new coupled model which describes the physical transport and biogeochemical dynamics of the water and nitrogen compounds in a soil-water-plant-groundwater system. Our model takes into account water infiltration into an unsaturated porous medium, the complex biogeochemical cycle of nitrogen in soils, nitrate leaching from the agricultural system toward the aquifer's water table, and the dispersion of nitrates in the groundwater. We calibrate our model and analyse the influence of soil type, precipitation or irrigation regime and fertilization schedules on leaching to groundwater as well as the temporal and spatial evolution of the nitrate pollutant plume in the aquifer. Simulations indicate that in order to achieve high crop yields while minimizing nitrogen loading to soils and groundwater we need to create an optimal balance between the amount of chemical fertilizers and water applied to crops on one hand, and the amount of nitrate and water used by plants on the other. We find that medium soils are more suitable for a sustainable corn production than coarse soils, ensuring both higher yield and less nitrate pollution of the aquifer. Regardless of soil type and irrigation schedule, a gradual fertilization throughout the plant life cycle reduces the potential for leaching and aquifer pollution. For medium soils, a more modest irrigation schedule results in more nitrate available for crops and less net leaching to the groundwater.

Mathematical Modeling of Nutrient Release from Capsulated Fertilizers

“…At the same time, in order to assess the ecological component of the process of washing out the components of agrochemicals in a row layer, a number of researchers apply separate mathematical models based on experimental investigations carried out in groundwater wells [7,8]. The expediency of this method is based on the possibility of experimental fixation of water-soluble forms of substances in washing water.…”

Hydrogeochemical Characteristics and Groundwater Quality Assessment of a Relatively- Pristine Agricultural Basin (Palas Basin)

“…However, in some stations the electrical conductivity is the most common type of pollutant in groundwater systems [25]. Fertilizers used in agriculture contain nitrate, ammonium, and organic nitrogen, and their excessive use causes nitrogen pollution due to mixing of agricultural drainage with groundwater [26]. The average value in nitrate measurements varied between 9-65 mg/L.…”

Fertilizers and nitrate pollution of surface and ground water: an increasingly pervasive global problem

“…The modelling system also indicated that implementation of best fertilizer management practices should be able to reduce and control the amount of nitrate-N leaching into the shallow groundwater in the study area. Marinov and Marinov [96] simulated biogeochemical dynamics of the water and N in the soil-plant system and flow of nitrate-N to the ground water by coupling a 1D water transfer model for the unsaturated soil, a biochemical N transformation model for the soil, and a 2D model for dispersion of N in the groundwater. Simulations with this model system suggested that high crop yields along with minimal N loading to soils and groundwater can be achieved by creating an optimal balance between the amount of fertilizers and water applied to crops as well as the amount of nitrate-N and water used by plants.…”