Soil Quality Analysis and Management Direction on Land in the UNDA Watershed of Bali Province, Indonesia

Abstract

Land productivity in the Unda Watershed has decreased due to the Regosol soil type which is very susceptible to erosion; as well as 45.64% of the shape of the area including undulating, hilly to mountainous, and the development of illegal C excavation sites in several places. The soil quality data obtained can be used as a reference for soil management that can improve soil quality to increase land productivity in the Unda watershed. The objectives of the study were to determine the soil quality on land in the Unda watershed; to determine what factors are limiting factors on soil quality in the Unda watershed; to determine the spatial distribution of soil quality in the Unda watershed; to provide direction for soil management based on the limiting factors obtained in the Unda watershed. The research was conducted on land in the Unda watershed which crosses Bangli, Karangasem and Klungkung regencies, Bali Province. and at the Soil Science Laboratory, Faculty of Agriculture, Udayana University. This study used survey methods, soil analysis in the laboratory, and determination of soil quality. Soil quality indicators measured as minimum data set (MDS): soil volume weight, soil texture, porosity, field capacity moisture content, pH, C-organic, CEC, KB, nutrients (N, P and K), and C-biomass. The results showed that soil quality at the research site was poor, high levels of soil erosion and lack of organic matter content in the soil at SLH 2, 5, 7, 15, 16 and 17. In SLH 3, 4, 6, 8, 9, 10, 11, 12, 13, 18, 19, 20, 21, 22, 23, 26, 27 and 28 showed moderate soil quality due to several factors such as high soil moisture, low organic matter content, unbalanced nutrient content, less than ideal soil morphological conditions, and inappropriate fertilizer use, low pH and soil density. In contrast to SLH 1 (Pempatan Village), 14 (Menanga Village), 24 (Gunaksa Village) and 25 (Telaga Tawang Village) with an IKT value of 25 classified as good quality. Limiting factors in the study area include: soil pH, soil texture, porosity, P-availability, N-total, C-organic and C-Biomass. Soil treatment using fertilization with organic fertilizer and Urea is recommended at SLH 1, 4, 8, 9, 10, 11, 13, 14, 16, 18, 20, 22, 23, 26, and 27. Sp-36/Tsp fertilization is recommended at SLH 12, 24, 25, and 28.