The Relationship between Pyrite Depth and Oil Palm Trees in Drought Stress

The research has been conducted in oil palm plantation on acid sulphate soils with Typic Sulfaquepts and Sulfic Endoaquepts soil type in Arut Selatan, Kotawaringin Barat, Central Kalimantan. The objective of this research is to know the relationship between pyrite depth and oil palm trees in drought stress. The research was conducted by quantitative method to climate parameter, plant conditions, pyrite depth, and soil nutrient status on a 300 ha area. There was drought for 4 months and during the drought, there was dry spell for 2 months that caused water deficit up to 411 mm in 2015. During the drought, there were more than four un-opened spear leaves, fracture spear, early dry leaves, and fracture fronts. The soil pH was very acid (2.9-3.4) with low to very low concentrations of K, Ca, and Mg due to pyrite oxidation. In the soil with 40-60 cm pyrite depth, the average dried and fallen trees reached 4.5 trees per hectare. In addition, the average dried and fallen trees in soils with 60-100 cm, 100-150 cm, 150-200 cm pyrite depth could reach up to 2.5; 2.7; 0.7 trees per hectare. In drought stress, the pyrite depth is significantly correlated with the condition of the plant and the number of dried and tumbled trees.