Plant nutritional potency of recent volcanic materials from the southern flank of mt. Merapi, Indonesia

摘要

The explanation of the vegetation growth rate on land buried by volcanic eruption material has not been done from the point of view of nutrient supply. The main objective of the research was to find out the distribution of pyroclastic material bearingweatherable minerals potentially as nutrient resources for plant growth. The field survey method was applied for landscape characterizations and soil sampling. The map and imageries interpretation was done to determine the slope units at the southern flank of Merapi into: cone, upper slope, middle slope, lower slope, and foot slope. The samples distribution were not covering the cone area. Samples of surface materials and the developed soils underneath were collected and measured the minerals, macronutrients and micronutrients content. The results revealed that the recent volcanic material contained primary minerals such as volcanic glass, plagioclase, hornblende, quartz and opaque with proportion of 50,30,10, 6 and 4%, respectively. While in the soilobserved was plagioclase, pyroxene, and hornblende with proportion at range of90.7-95.2,2.5-4.1, and 1.04-3.88%, respectively. The highest total nutrient content was Fe, and followed by Ca, > Mg > P > K > Na > Zn. The three primary minerals were categorized as weatherable minerals. The geomorphological' unit had a very important role in nutrient distribution where the nutrient content for each unit was in sequence as upper slope > foot slope > lower slope > middle slope. Weatherable mineral in volcanicmaterial was quite potential as nutrient resources for plant growth.