Optimizing edamame [Glycine max (L.) Merr., 1917] production through bioactive charcoal compost application on alluvial soils

Abstract

Importance of the work: Edamame production in tropical regions is constrained by limited arable land and
poor soil fertility, particularly on nutrient-deficient alluvial soils. Sustainable soil management using organic
amendments, such as bioactive charcoal compost (BCC), is therefore needed to improve soil health and crop
productivity.
Objectives: To evaluate the effects of varying BCC dosages on growth parameters and yield components of
edamame cultivated on alluvial soil under tropical conditions.
Materials and Methods: The field experiment was conducted at Rasau Jaya III Research Station, West
Kalimantan, Indonesia, from February to April 2024. A randomized complete block design was used with five
treatments: a control (a0); corn-stem compost at 4,500 g/plot (a1); and bioactive charcoal compost at 1,500 g/
plot (a2), 3,000 g/plot (a3) and 4,500 g/plot (a4). Each treatment was replicated six times with 75 plants per
experimental unit (3.0 m × 1.0 m plot size) over a growing period of 60 d (harvest at R6 stage, 60 days after
planting). The parameters measured were growth variables (plant height, leaf number, and branch number),
yield variables (numbers of filled and empty pod, pod weight, and filling percentage), plant tissue nutrient
content (N, P, K, Ca, and Mg), nutrient uptake and post-harvest soil chemical properties. Data were analyzed
using analysis of variance followed by Tukey's honestly significant difference test at a significance level of p
< 0.05.
Results: The BCC applications significantly enhanced plant growth metrics and yield components (p < 0.05).
The highest dosage treatment (a4: 4,500 g/plot bioactive charcoal compost) demonstrated superior performance
compared to the control treatment (a0), with plant height increasing 12.4% (29.17 cm versus 25.94 cm), leaf
number improved 35.0% (19.72 versus 14.61), filled-pod count increased 72.8% (36.28 versus 21.00) and filledpod weight increased 64.6% (96.67 g versus 58.72 g). Soil pH improved from 4.42 to 5.12, while nutrient uptake
efficiency increased substantially for nitrogen (68%), phosphorus (81%) and potassium (65%).
Main finding: BCC application at 4,500 g/plot (equivalent to 15 t/ha on a 3.0 m² plot) was an effective
sustainable soil management strategy for optimizing edamame productivity on alluvial soils, achieving up to
72.8% increased pod production and 64.6% increased pod weight compared to the control, while providing both
immediate yield benefits and long-term soil health improvement in tropical agricultural systems.