Impact of Using Boiler Ash as Soil Ameliorant and Nitrogen Fertilizer on CO2 Emission in Oil Palm Plantations on Peat Soil

Abstract

Peat soil has an important role in water and carbon storage. However, the utilization of peatland as an agricultural field requires drainage of water and the application of fertilizer or soil ameliorants to increase peat soil’s fertility; this will increase greenhouse gas emissions, particularly CO2, so the function of peat as a carbon sink turns into a source of greenhouse gas emissions. The research aims to determine the effect of using boiler ash as a soil ameliorant and nitrogen fertilizer on CO2 emission and FFB yield in oil palm plantations on peat soil. The treatment consisted of three levels of boiler ash (0-ton/ha/yr, 1.5-ton/ha/yr and 3-ton/ha/yr) and three levels of nitrogen fertilizer (0 kg N/palm/yr, 0.45 kg N/palm/yr and 0.9 kg/palm/yr). CO2 emission was measured using the closed chamber method. A PVC pipe with a length of 80 cm is the chamber. 60 cm of pipe was buried in the soil, and the other 20 cm was on the soil surface to catch CO2 released into the air. The application of a high rate of N fertilizer significantly increased CO2 emission from 0.56 g/m2/hour to 0.67 gr/m2/hour. Applying boiler ash at a low rate reduces CO2 emission from 0.63 g/m2/hour to 0.58 g/m2/ hour. The application of boiler ash as a soil ameliorant not only has an impact on CO2 emissions but also improves peat soil chemical properties by significantly increasing soil pH, total phosphate, available phosphate, and exchangeable Calcium. The high boiler ash and low nitrogen fertilizer rates produce 29.13 t FFB/ha/yr with a CO2 emission of 0.63 g/m2/hour.