Land use and soil types affect macropore network, organic carbon and nutrient retention, Lithuania

Quantifying the macropore structure of a soil is critical for understanding plant growth and the movement of water or solutes in the soil. X-ray computed tomography was implemented for macroporosity investigation in the profiles of Cambisol (grassland), Retisol (forest, arable land) and Luvisol (forest). In this study, we explored soil macropore network in relation to macropore structure, soil organic carbon, total nitrogen, total phosphorus, total potassium, and bulk density. Cambisol, Luvisol and Retisol had a heterogeneous architecture of the pore space with an abundance of macropores (2-11% for the upper horizons and to 1.5-3.2% for the underlying layers). Retisol had higher macroporosity compared to Luvisol, and lower than Cambisol. Soil organic carbon had the highest significant effect on medium and fine macropores in all soil types, irrespective to land use. N-total, P-total and K-total retention depended on medium and fine macropores. Anthropogenic activity in Retisol (conventional tillage) decreased SOC and N-total within the whole profile compared to undisturbed Retisol (forest), while P-total and K-total concentration within the whole profile was higher in the soil of arable land. The concentration of SOC, N-total, P-total and K-total in perennial grassland and forest soil was similar irrespective of soil type. The highest macroporosity and total surface area of macropores within the whole soil profile was in Cambisol (grassland). The high concentration of organic matter in forest topsoil layer of Luvisol and Retisol promoted soil podzolization.

Automated summary

Quantifying the macropore structure of soil is crucial for understanding plant growth and water movement. The study found that Cambisol and Retisol had higher macroporosity compared to Luvisol, with soil organic carbon having a significant impact on medium and fine macropores. Nitrogen, phosphorus, and potassium retention depended on medium and fine macropores.