The genesis of rainfed agricultural soils in Indonesian lowlands with two different climate types

This study analyzes the genesis of rainfed agricultural soil derived from carbonate rocks in two climates types of the South Sulawesi Indonesian lowlands. Soil analysis included the physical and chemical characteristics of soil, clay minerals, and oxide minerals. Rock samples were analyzed using petrography analysis. There are ten soil profiles, 51 soil samples, and ten rock samples. Correlation statistics were used to determine the correlation between climate and soil characteristics. The Bantimurung District has a C-2 climate type, and Bangkala District has a D-3 climate type. The Bantimurung District as a wet area has a positive correlation between rainfall and cation exchange capacity but negative correlation with soil pH and base saturation. The dry Bangkala District shows a positive correlation between c-organic with base saturation and a negative correlation between water content and soil bulk density. Finding shows that the process of mineral transformation is strongly influenced by hydropedology activity. Kaolinite minerals are more commonly found in Bantimurung District, while nontronite montmorillonite minerals are more common in Bangkala District. The pan-oxide plow was only found in Bantimurung District with a thickness of up to 3–8cm, indicating intensive land cultivation. Soil derived from carbonate rocks with high hydropedological activity demonstrates a faster soil formation process. To maintain soil fertility, C-organic levels of the soil need to be increased by returning harvest waste to the soil. Increasing the soil water content can be done with water harvesting and the use of perennial rivers for irrigation.