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Oil palms (Elaeis guineensis) are generally able to grow economically and feasibly on various soil types, mostly in tropical countries. However, oil palms planted on acid sulfate soils were producing lesser Fresh Fruit Bunches (FFB) as compared to those on non-acid sulfate soils. The poor performance of oil palms planted on acid sulfate was mainly attributed to the presence of excess sulfates, which limits the FFB yields and vegetative growth.1 Generally, acid sulfate soils have significant amounts of free and absorbed sulfate. Jarosite generally occurs as pale yellow mottles along old root channels and on ped faces in acid sulfate soils. pH in these horizon is less than 4.0.2,3 These soils often are also high in Aluminium (Al), Al saturation and often with phosphorus (P) fixation capacity. These acid sulfate soils are known for having poor values for organic matter, bases, cation exchange capacity, water retention, water holding capacity and microbial activity, which contributes towards their low soil fertility and hence limitations in soil productivity. Of these limitations, Al toxicity and excess sulfates are two major constraints to FFB yields in oil palms. The important relationship of soil and water for managing a sustainable productivity of oil palms on acid sulfate soil are discussed in details in this paper.

Abstract. Sembiring M, Munawaroh H, Mukhlis, Hidayat B, Sabrina T. 2021. Soil macrofauna diversity in andisol after eight years of Mount Sinabung eruption in Sumatra, Indonesia. Biodiversitas 22: 3024-3030. The eruption of Mount Sinabung resulted in volcanic ash covering the soil of various thicknesses. That will affect the population and diversity of macrofauna in it. This research aimed to determine the Andisol soil macrofauna in Karo District with various thicknesses of volcanic ash covering from Mount Sinabung. This research was conducted in May 2019. Plots were placed in four locations, Location I: processed land (0 cm), Location II: Land covered by thin ash (?2 cm), Location III: Land covered by medium ash (2-5 cm), Location IV: Land covered by thick ash (?5 cm). Sampling was conducted by using the Pitfall trap, Monolith squared, and Hand sorting methods. The research results indicated that the thicker the volcanic ash covering the soil surface, it would reduce soil moisture, soil water content, organic C, and soil pH, but on the other hand, increase the soil temperature. A total of 20 species were able to live on the Andisols affected by the eruption of Mount Sinabung.