Synergistic Effects of Biochar and Palm Fiber Amendments on Soil Water Retention and Pak Choi (Brassica rapa subsp. chenensis) Growth

Abstract

This study evaluated the synergetic effects of coconut husk biochar and palm fiber as soil amendments on moisture retention and Pak Choi (Brassica rapa subsp. chenensis) growth under water-limited conditions. An experiment was performed through a completely randomized design pot with four treatments: control (T₀), 5% biochar (T₁), 5% palm fiber (T₂), and 5% biochar + 5% palm fiber (T₃) and restricted irrigation of about 200 mL poultice by pot every two days for the period of experimental phase which last for over duration of time up until n=3 pots were completed in milestone. At the final harvest, combined amendment T3 was significantly more effective than all treatments for plant height (15.67 ± 0.58 cm), leaf count (12.00 ± 0.00), fresh biomass (34.67 ± 0.58 g) and dry biomass (3.50 ± 0.00 g) representing an increase of 36.9% and 180% in fresh and dry biomass compared to the control, respectively. At Week 5, soil moisture was highest in T3 (32.67 ± 2.52%) while increased electrical conductivity in biochar-amended treatments reflected enhanced potassium availability not salinisation. These results demonstrate to validate that biochar and palm fiber work synergistically, as the biochar improves water and nutrient retention while the palm fiber enhances soil aggregate stability, representing a promising and inexpensive amendment for arid or semi-arid sandy loam under limited irrigation in many farming systems.