Implication of organic farming practice in changes in physical-chemical properties of plough pan layer in paddy soils

The impacts of organic farming practices on the physical-chemical properties of the plough pan layer in paddy soils are still not well-documented. This study was conducted by making nine soil profiles from three farming systems, namely conventional, semi-organic, and organic fields. The results revealed that the formation of the plough pan layer resulted in an increase in soil penetration resistance, modulus of rupture, and bulk density, while soil porosity and soil permeability decreased. The clay in the layer was composed of kaolinite, nacrite, dickite, with dissolved Fe>Mn>Al. After 10 years of organic farming practice, there was an increase in humic acid, fulvic acid, CEC, Fe-humic, Mn-Humic, soil porosity, and topsoil thickness, while the thickness of plough pan, modulus of rupture, and soil penetration decreased. The Fe-humic and Mn-humic content increased by 4.74 and 2.73 times, respectively, compared to the conventional system. This indicates that humic compounds derived from organic fertilizers play a crucial role in the complexation and dissolution processes of mineral components, resulting in improved soil physical and chemical properties. © 2025 Institute of Agrophysics, Polish Academy of Sciences.