Synergistic Effects of Multicomponent Bioameliorants on Soil Fertility and Doubling Soybean Yield under Dryland Conditions in Indonesia

Abstract

Indonesia's soybean output averages 0.6−0.8 t·ha⁻¹, far lower than the potential yield of 2−3 t·ha⁻¹. Imports still account for more than 60% of national need. The prevalence of dryland areas with low fertility and inadequate water-holding capacity remains a major barrier to enhancing domestic soybean productivity. This study evaluated how bioameliorants improved soil chemical characteristics and soybean productivity. A randomized block design was used with six treatments: P1 (bioameliorant mixture at 30 t·ha⁻¹), P2 (bioameliorant mixture at 20 t·ha⁻¹), P3 (chicken manure at 30 t·ha⁻¹), P4 (cow manure at 30 t·ha⁻¹), P5 (control, no bioameliorant), and P6 (rice husk charcoal at 30 t·ha⁻¹). Each treatment had three replications. The criteria studied were vegetative growth, physiological indices, leaf area index (LAI), net assimilation rate (NAR), relative growth rate (RGR), and yield components. Data was evaluated using analysis of variance (ANOVA) and HSD at 5%. The results demonstrated that bioameliorants considerably increased growth and yield over the control. P2 had the most leaves (204 per plant), leaf area (5,417.94 cm²), and dry biomass (168.72 g/plant), but P1 had the highest grain output (2.8 t·ha⁻¹). The control yielded just 1.2 t·ha⁻¹, and the 1000-seed weight was consistent among treatments (about 175 g). Bioameliorant mixes, especially at 20−30 t·ha⁻¹, improve soil quality, increase soybean growth, and double yield in dryland conditions, while also supporting sustainable waste utilization and soil health restoration.

Keywords: chicken manure, cow dung, rice husk charcoal, soil amendment, soil fertility