Changes in soil quality indicators under oil palm plantations following application of ‘best management practices’ in a four-year field trial

Abstract

Increasing the yield of existing oil palm plantations is one means of accommodating some of the growing demand for palm oil. The International Plant Nutrition Institute (IPNI) has developed and tested a process to deploy a series of ‘best management practices’ (BMPs) that cover a range of agronomic practices intended to intensify oil palm production and improve yield at a given site using cost-effective, practical methods. Many of these BMPs include techniques that should also improve soil quality, such as the addition of organic matter to the soil surface, and improved timing and tailored application of mineral and organic fertilisers. Six plantations in Kalimantan and Sumatra applied BMPs prescribed by IPNI (BMP treatment), and standard management practices (REF treatment) in paired blocks of oil palm over four years; 30 pairs of blocks were included in the research. Soils were sampled in both treatments before and after the field trial, from beneath weeded circles surrounding individual palms and beneath frond piles in between rows of palms, at 0–20cm depth and 20–40cm depth. Soils were tested for a range of properties, including soil pH, % soil organic carbon (% SOC), total N, available P, and exchangeable cations. No clear, consistent differences were found in the degree of change in soil properties between BMP and REF treatments over four years. However, improvements in some soil properties were noted for both treatments, particularly for soil pH and % SOC. There was no significant deterioration in the measured soil properties over the four years. The results suggest that appropriate management practices for oil palm can improve several aspects of soil quality. Further research on the mechanisms by which BMPs can improve soil quality, and monitoring over longer periods of time is recommended to give plantation managers a clearer picture of the potential ‘co-benefits’ that can be obtained with adoption of BMPs designed to increase oil palm yield.