Oil palm intercropping system: A potential nature-based solution to improve soil biology activities in North Sumatra plantation, Indonesia

Aims: Intercropping system in oil palm plantation is recognized as one of a nature-based solution as well as a promising sustainable practice. This study aimed to observe the advantages of existing intercropping system in one of North Sumatra's oil palm plantation. It is achieved by analyzing the population of soil bacteria and fungi in oil palm intercropping fields with sorghum and cassava, compared with the non-intercropping field that using Mucuna bracteata (MB) as a common legume cover crop in oil palm plantations. Methodology and results: Soil samples were collected from the weeded circle and windrow area (the area between palms within the row). The results showed that the highest and the lowest soil bacteria populations were in sorghum (1.7 +/- 1.4 x 10(8) CFU/g) and MB (1.7 +/- 0.4 x 10(7) CFU/g), while the highest and the lowest soil fungi populations were in sorghum (4.3 +/- 2.9 x 10(6) CFU/g) and cassava (2.1 +/- 0.8 x 10(6) CFU/g). Conclusion, significance and impact of study: The intercropping system in this study showed a significant difference in the bacteria population, while the fungi population had no difference compared to the non-intercropping system. The bacterial and fungi population results also indicate that the intercropping system potentially enhances the soil's biological activity as an indicator of improved soil health. It is also followed by a slightly higher soil organic carbon value in intercropping system. This research suggests that further studies should be done to identify specific soil functional microbes (nutrients fixers and solubilizers). The future research will be used as a reference for promising biofertilizer agents in supporting sustainable crop production.