Impact of Nitrogen Fertilization on Soil and Aquifers in the Humid Pampa, Argentina

Abstract

There is great concern worldwide about air and water pollution arising from N-fertilizer. Considering the expansion of agriculture and fertilization practices in Argentina, the objective of this study was to determine the effect of Nfertilizers on soil N dynamics and then relationship with nitrate concentration in aquifers. Soil samples were taken during a maize crop cycle in two agricultural farms under different fertilization treatments: UAN (urea, ammonium nitrate and ammonium tiosulfate, 110 kg N ha^-1); and UREA (urea, 60 kg N ha^-1). UAN and UREA treatment produced an increase in soil nitrate content (from 6 to 550 and 60 mg N kg^-1 respectively) and the 71% of aquifers sampled exceeded 45 mg l^-1. Our results indicate that uan application produced great N losses and did not increase soil residual N, suggesting that the high amount of nitrates in aquifers would arise from the soil N losses.