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

Abstract

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.

Investigating the role of bentonite clay with different soil amendments to minimize the bioaccumulation of heavy metals in Solanum melongena L. under the irrigation of tannery wastewater

“…This might be due to the higher number of available active/exchangeable sites through the addition of the highest rate of bentonite (6%) ( Table 2 ). A similar trend was observed in which Cu and Pb ions were adsorbed onto the bentonite; this might be due to the accessibility of a higher surface area with a greater number of ion exchange locations when the initial concentration is constant ( Tian et al, 2014 ; Hussain et al, 2021 ). Moreover, bentonite can immobilize PTEs in soil owing to its isomorphic substitution, negative charge, and environmental compatibility ( Xie et al, 2018 ).…”

“…However, in the initial stages, the removal efficiency might be higher due to a larger number of available exchangeable sites ( Table 2 ). Similarly, Hussain et al (2021) observed that the process of ion exchange (Cu and Pb) is fast at the initial stage due to the presence of a larger number of active sites, which efficiently removed Cu (87%) and Pb (89%) through the application of bentonite relative to control; with time, the reaction reached the equilibrium stage ( Bharwana et al, 2014 ; Khan et al, 2014 ; Daud et al, 2015 ).…”