Optimization of Soil Sampling for Layered Amelioration Trials Through Homogeneous Land Unit Mapping in Sandy Agricultural Landscapes

Improving soil quality in sandy farming areas needs more than just adding amendments. It requires careful planning, structure, and adapting to the specific conditions of each site. This study presents an integrated approach to optimize soil sampling for layered amelioration trials, using representative soils from sandy agriculturally areas in Cilacap Regency, Indonesia. The proposed experiment applies an engineered soil layering model, incorporating waste-derived silica-cellulose ameliorants such as rice husk ash, cocopeat, coffee husk and bentonite, to enhance moisture retention and minimize nutrient leaching. To ensure the study is relevant and can be repeated, the soil sampling was based on Homogeneous Land Unit (HLU) mapping. This divided the land into 8 groups based on soil type, slope, and land use. From these, 8 purposively selected soil samples were collected, representing diverse field conditions. These samples are used in lab experiments that mimic real underground soil processes. By matching the experiment to the variety in the landscape, this study makes the soil layering method more accurate and useful. The results aim to offer a flexible and sustainable way to manage damaged sandy soils in tropical farming areas.