Soil quality degradation under horticulture practices in volcanic slope soil, East Java - Indonesia

Volcanic slope soils in Indonesia may have degradation due to forest conversion to intensive agriculture since more than three decades. This research aimed to assess soil characteristics from different land uses and slopes in volcanic slope soil, East Java. Three different land uses, namely crops, apple orchard and forest were chosen as different land-use factors, where each land-use was examined in four slope classes (e.g. 0-8 %, 8-15 %, 15-25 %, and > 25 %), except forest with three slopes area, and each plot repeated three times. Soil samples were taken from three sub-plots at 0-10, 10-30, and 30-50 cm. Variables measured included soil texture, bulk density, pH, CEC, and soil nutrients. Degradation soil quality under horticulture practices (i.e. crops and apple orchard) is shown by the increases of 27-40% soil bulk density and decreases of 17-65% soil nutrient content (i.e. C, N) as compared to forest. The impact of slope on soil fertility degradation was more pronounced in the forest soil as compared to horticulture land. Our study suggested the benefit of tree density and diversity in the forest to maintain soil fertility, and proper soil conservation in the horticultural lands to slow down volcanic slope soil degradation.