Fertility status of Chernozems and Phaeozems under different moisture regimes in southwestern Poland

Abstract

Chernozems and Phaeozems, consider the most fertile soils in the world, are of particular interest in Poland due to their little contribution to soil cover, which does not exceed 1.5 %. The study focused on the characterization and regional and global comparison of SOC and fertility status of chernozemic soils in SW Poland to provide arguments for their further protection. The soils developed from loess were cross-analyzed in relation to their classification (Chernozems versus Phaeozems) and moisture status (well-drained versus imprefectly-drained soils). The soils have a silt loam texture and a greater thickness of humus horizon, pH, base saturation, content of SOC, nitrogen, and plant-available P, K and Mg than majority soils in Poland. The mean values were comparable or higher than in the other chernozemic regions in Poland and the world; only pH and SOC were lower than in Chernozems of the steppe zones. On a regional scale, Chernozems had a higher pH, base saturation, SOC, P and K concentrations and pools than Phaeozems. Whereas, the moisture status did not significantly differentiate the fertility of chernozemic soils, which confirms that long-term moisture control of historically waterlogged soils allowed for their cultivation with the same intensity as well-drained soils. Comparison with historical data suggested that SOC and nutrients increased or remained at a similar level over the 70 years. The study confirmed a high and stable SOC and fertility status of chernozemic soils in SW Poland, maintained rather than degraded by agricultural use. Considering an ongoing climate change, leading to increasing frequency of droughts in Central Europe, as well as rapid urbanization, resulting in destruction of native soils, the results argue for permanent monitoring and legal protection of Chernozems and Phaeozems as soils of great importance for national food security and SOC sequestration.