Cambodia plans to expand its rice sector and become a prominent rice exporter. A key concern is that soil fertility is a crucial factor affecting rice production, and nutrient leaching into the environment can lead to reduced nutrient uptake and lower rice yield. Carbonized waste biochar has gained recognition not only as a potential soil fertility enhancer but also as a significant nutrient leaching reducer. It is currently being introduced in many regions. The study was to evaluate how a combination of chemical fertilizers and rice husk biochar affects nutrient leaching into the topsoil layer and plow sole of soil columns during direct seeding with continuous flooding, and to assess their combined effects on rice growth and yield. In the leachate from these two soil layers, except for ortho-phosphate (PO43-), the combination of CHEM+BIO2 or+BIO4 treatment (chemical fertilizers-+-biochar at a rate of 2t ha-1 or+biochar at a rate of 4t ha-1) significantly decreased ammonium (NH4+) and nitrate (NO3-) levels more than CHEM alone, particularly in the plow sole, suggesting that their combination and biochar sorption capacity are beneficial for nitrogen use by plants. CHEM+BIO2 had varying effects, whereas CHEM+BIO4 led to a significant increase in rice yield, plant biomass, tiller number, panicle length, grains per panicle, and grain weight per panicle.These findings suggest that incorporating biochar amendments in rice production can reduce N leaching. However, there is no evidence to support its effectiveness in reducing P leaching. Therefore, further studies are needed to determine the usefulness of this approach.