Bentonite Clay Mixed With Different N Sources Have Variable Effect on Nitrate Leaching From Sandy Soil

Nitrate (NO 3 ) leaching from soils results in lower soil fertility, reduced crop productivity and groundwater pollution. The present study determined NO 3 leaching from bentonite [0, 2 and 4% (m/m)] treated sandy soil, under three N sources (calcium nitrate [Ca(NO 3 ) 2 ], ammonium chloride [NH 4 Cl], urea [CO(NH 2 ) 2 ] @ 300 kg N ha -1 ) with a leaching fraction of 0.3-0.4. Bentonite markedly reduced NO 3 release in leachate, while 4% bentonite retained higher NO 3 in soil. The NO 3 leaching varied with N sources as Ca(NO 3 ) 2 >NH 4 Cl>(CO(NH 2 ) 2 . This study indicated that soil amendment with bentonite could efficiently mitigate NO 3 leaching from soil and hence prevent N fertilizer losses and groundwater pollution.