Enriched rice husk biochar minimizes ammonia loss from applied urea fertilizer under waterlogged environment

Abstract

A laboratory-scale closed dynamic air flow system was carried out to assess the effect of enriched rice husk biochar on ammonia volatilization, soil exchangeable ammonium, and available nitrate from the applied urea in comparison to urea alone under waterlogged conditions. Treatments with enriched rice husk biochar (5, 10, 15, and 20 t ha-1) significantly minimized ammonia volatilization, however, only biochar with rates of 5, 10, and 15 t ha-1 had significantly retained more soil exchangeable ammonium by 14% – 43%. Additionally, soil available nitrate was lower in all treatments except in T1 (urea alone). This indicates that enriched rice husk biochar minimizes ammonia volatilization, retains more ammonium, and slows down the conversion of ammonium to nitrate under a waterlogged environment. Mixing urea with rice husk biochar at rates of 5 t ha-1 and 10 t ha-1 offers a significant advantage over urea alone by minimizing ammonia volatilization by > 33.8% over urea alone. The mixture successfully increased retention of ammonium ions and has the potential to minimize ammonia loss and increase nitrogen availability in the soil.