Effects of Date Palm Residues Derived Biochar on GHG Emissions and NO3-N Leaching in Urea-Fertilized Desert Soil

Biochar (BC) addition to soil has received a growing interest worldwide due to its numerous agricultural and environmental benefits, including nutrient retention in soil and reduction of greenhouse gas emissions. The aim of this study was to evaluate the impact of date palm residue (DPR) and its BC on greenhouse gases (CO2 and N2O) emissions and NO3-N leaching following the addition of urea fertilizer to a desert soil. The BC was produced at four temperatures: 300, 400, 500 and 600 °C (BC300, BC400, BC500 and BC600) and mixed with the soil, followed by urea addition and incubated for 40 days. The CO2 and N2O were measured periodically on day 1, 3, 6, 10, 15, 20, 25, 30, 35 and 40, whereas NO3-N in leachate was measured weekly up to five weeks. Cumulative CO2 emissions were the greatest in DPR followed by BC300 treatment, whereas the BC600 treatment exhibited the lowest CO2 emissions. The urea alone treatment showed the highest N2O emission, but this was significantly reduced with any other treatment, with the BC300 treatment providing the most pronounced effect on N2O reduction. The DPR followed by BC300 and BC400 remained the most effective treatments in reducing the amount of leached NO3-N during the whole period of incubation.