Improving Soil Nitrogen Availability and Rice Growth Performance on a Tropical Acid Soil via Mixture of Rice Husk and Rice Straw Biochars

Abstract

Featured Application: This research focuses on using an environmentally friendly technology (mixture of rice straw and rice husk biochars) to sustainably minimize ammonia volatilization, increase soil nutrient retention, and improve rice plant nutrient uptake and use efficiency. The mixture of rice straw and rice husk biochars has a larger surface area and numerous pores to chelate ammonium and nitrate ions. This process will fundamentally reduce the loss of ammonia via volatilization from urea fertilizer being applied, thus reducing the excessive use of urea fertilizer in agricultural sector. The biochar at 5 and 10 t ha(-1) significantly minimized ammonia volatilization by 33.5-40.7%. It resulted in an increase of nutrient uptake, use efficiency, and dry matter production of rice plant. This work may not only contribute to the reduction of urea fertilizer import bill of Malaysia, but also pave the way for better means of adding value to the agricultural waste to avoid environmental pollution. It also contributes to increasing rice production by solving the problem of ammonia loss from urea fertilizer in tropical acid soil.

Nitrogen deficiency frequently occurs at agricultural soil because of NH3 volatilization to the environment which results in low urea-N use efficiency by rice plants. A pot experiment was conducted to assess the synergistic effects of a mixture of rice straw and rice husk biochars (RSRH) on (1) total N, soil exchangeable NH4+, and available NO3-, and (2) uptake of N, P, and K in rice plant. RSRH biochar at 5 and 10 t ha(-1) had significantly minimized ammonia volatilization by 33.5% and 40.7%. Further, RSRH biochars also had significantly increased available NH4+, NO3-, available P, and available K in the soil over T1. In line to increase in soil nutrient availability, the rice plant height, tiller number, greenness, and panicle number were increased. This resulted in an increase of nutrient uptake, use efficiency, and dry matter production of the rice plant. RSRH biochar altered the soil environment by minimizing NH3 loss and increasing soil nutrients for efficient plant uptake.