Soil Quality Enhancement for Sustainable Shallot (Allium ascalonicum L.) Cultivation in Central Kalimantan

Shallot (Allium ascalonicum L.) is an economically valuable horticultural crop for Indonesia’s domestic market and rural livelihoods. However, its expansion into Central Kalimantan is constrained by acidic, nutrient-poor soils such as Ultisols and Spodosols, and erratic rainfall. This study aims to develop an integrated soil quality enhancement framework combining liming, organic amendments, and biofertilizers for sustainable shallot cultivation. The research was conducted through descriptive and comparative analysis of soil properties before and after treatment in a 500 m² demonstration plot. Laboratory analyses included soil pH, organic matter, cation exchange capacity (CEC), and available phosphorus (P-Bray). Data interpretation used descriptive statistics and literature benchmarking. Results showed that integrated soil management increased soil pH from 4.5 to 6.0, organic matter from 1.2% to 2.8%, CEC from 6 to 12.5 cmol(+)/kg, and available phosphorus from 5 ppm to 18 ppm. These improvements corresponded to potential yield increases of 30–40% under optimal irrigation. The novelty of this study lies in the adaptive integration of biological and chemical amendments tailored for humid tropical acid soils. The findings provide practical insights for sustainable horticulture and local food security enhancement in Central Kalimantan.