Interaction of Micro-Irrigation and Rice Husk Charcoal Amendment on the Physical and Chemical Properties of Coastal Sandy Soil

Sandy soils in coastal areas have low land productivity due to their coarse texture, low water-holding capacity, and high salinity. The application of micro-irrigation and rice husk charcoal serves as an alternative solution for soil improvement, however, field studies on their interaction remain limited. This study aimed to examine the interaction between micro-irrigation types and rice husk charcoal amendment on the physical and chemical properties of coastal sandy soils at Cangkring Beach, Bantul, Yogyakarta from July to September 2024. The experiment used a Split Plot Design based on a 2x2 factorial Randomized Complete Block Design with five replications. The treatments consisted of sprinkler irrigation+rice husk charcoal (A1B1), sprinkler irrigation+control (A1B2), mist irrigation+rice husk charcoal (A2B1), and mist irrigation+control (A2B2). Soil parameters observed included porosity, texture, moisture content, salinity (EC), and C-organic content. The results showed that the interaction between irrigation types and biochar amendments significantly influenced total porosity (p=0.031), moisture content (p=0.010), and salinity (p<0.001). The A1B1 combination emerged as the optimal treatment, yielding the highest total porosity (43.68±9.60%), maximizing water retention (>0.24 %vol), and maintaining a stably low soil salinity (<0.02 mS/cm). Furthermore, Pearson correlation confirmed a significant negative correlation (r=-0.571; p<0.001) between daily soil moisture and EC values.