Effects of Silica-NPK mixed fertilizer application on milling quality of Malaysian rice

Abstract

Rice husk ash (RHA) containing high content of silica is a practical alternative to produce a variety of value-added products in various industries. In this study, the role of silica from rice husk ash was further investigated to test its effect on the milling quality of Malaysian rice. Silica was produced from RHA using acid treatment with 1N HCl and calcination at 700 °C for 2 hours. Silica having an average size of 200 nm was characterized using SEM. A single peak at 22º 2q angle from XRD result confirms the amorphous phase of silica produced. EDX result shows presence of carbon element in silica, justifying the greyish-white silica formed is due to incomplete combustion. FTIR further confirms the functional group present in silica. The synthesized silica was mixed with NPK fertilizer at concentrations of 0 kg/ha, 200 kg/ha, 400 kg/ha and 600 kg/ha on two varieties of rice (MR 219 and MR 263). Harvested rice were dried to 14% moisture content and sent for milling test at MARDI Pendang where milling qualities were investigated. Results revealed that silica had positive impact on milling quality of rice by improving both milled rice yield (MRY) and head rice yield (HRY) for the two rice varieties. Additionally, it was noted that silica also reduced the amount of chalky grains and cracked grains produced. However, the optimal concentration of silica-NPK fertilizer was undiscovered due to lack of similar pattern among the three main aspects of rice milling quality.