Nitrate (NO₃^-1) leaching from soils results in the lower soil fertility, reduced crop productivity and increased water pollution. The effects of bentonite clay mixed with various nitrogen (N) fertilizers on NO₃^-1leaching from sandy soils haven’t been extensively studied. Therefore, the present lysimetric study determined NO₃^-1leaching from bentonite [0, 2 and 4% (m/m)] treated sandy soil under three N sources (calcium nitrate [Ca(NO₃)₂], ammonium chloride [NH₄Cl], and urea [CO(NH₂)₂] at the rate of 300 kg N ha^-1). Results showed that bentonite markedly reduced NO₃^-1release in the leachate, while 4% bentonite retained higher NO₃in the soil. The NO₃^-1leaching from sandy soil varied with N sources as Ca(NO₃)₂> NH₄Cl > (CO(NH₂)₂. At early stages of leaching, higher concentrations of NO₃^-1were detected in leachate with both NH₄Cl and Ca(NO₃)₂, but leaching of NO₃^-1increased with urea at later leaching stages. The amount of total NO₃^-1retained in soil was conversely related to the amount of NO₃^-1in the leachate. This study indicated that soil amendment with bentonite could efficiently mitigate NO₃^-1leaching from sandy soil and hence prevent N fertilizer losses and groundwater pollution.

Nitrate (NO₃) leaching from soils results in lower soil fertility, reduced crop productivity and groundwater pollution. The present study determined NO₃ leaching from bentonite [0, 2 and 4% (m/m)] treated sandy soil, under three N sources (calcium nitrate [Ca(NO₃)₂], ammonium chloride [NH₄Cl], urea [CO(NH₂)₂] @ 300 kg N ha^-1) with a leaching fraction of 0.3-0.4. Bentonite markedly reduced NO₃ release in leachate, while 4% bentonite retained higher NO₃ in soil. The NO₃ leaching varied with N sources as Ca(NO₃)₂>NH₄Cl>(CO(NH₂)₂. This study indicated that soil amendment with bentonite could efficiently mitigate NO₃ leaching from soil and hence prevent N fertilizer losses and groundwater pollution.