Abstract

Soybean production on Indonesia’s acid sulfate peatlands is constrained by low soil pH, Al/Fe toxicity, and limited mechanization, yielding labor-intensive systems with high physical energy demands. This study quantified labor, energy, and cost flows across field operations (land preparation, planting, maintenance, harvest, postharvest) and converted inputs/outputs to energy equivalents. Total labor reached 652.2 h ha⁻¹ (≈91.45 HOK), with planting and weeding dominating human energy use; chemical inputs (fertilizers, pesticides) contributed >80% of external energy. Yield averaged 1,470 kg ha⁻¹, producing 5.29×10⁶ kcal ha⁻¹ and an output:input energy ratio of ~3.73. Results indicate that labor efficiency and energy performance can be improved by combining soil amelioration (lime, compost/biochar, inoculants) with simple mechanization for sowing and weed control, thereby reducing hours per hectare and fossil-derived energy without compromising crop care. We recommend extension packages that integrate low-cost tools, organic/biological inputs, and labor-timing guidance to increase returns to labor and lower specific energy per kilogram of soybeans produced on peat-influenced acid sulfate soils.