Physical properties of a Rendzic Phaeozem during a ten-year period of fallowing under the conditions of south-eastern Poland

The study was concerned with the physical properties of a soil which was under natural fallow for ten years (1996–2005). The experimental sites were situated on a Rendzic Phaeozem originating from cretaceous bedrock. Two adjoining arable plots (0.2 ha area of each) cultivated during the period were compared with the fallowed plot (0.1 ha area). The soil under study has been in use as arable land for over 100 years. The crops most frequently cultivated included cereals, sugar beet and potato. The primary soil tillage system applied was the conventional plough tillage system. An oat and barley mix was grown on this plot immediately before the fallowing started. The paper provides a presentation of results concerning the following physical properties of the soil: bulk density (BD), total porosity (TP), field air capacity (content of macropores Φ > 20 μm — FAC), field air permeability (FAP), moisture at the sampling moment (SM), field water capacity (FC), available water retention (AWC), unavailable water retention — wilting point (UWC), and the calculated ratio FC/TP. After the ten-year period of lying fallow the physical condition of the studied soil improved markedly. What should be noted as particularly valuable was the fact that after six years of exclusion from cultivation there was an improvement of soil compaction (BD) and an increase in total porosity (TP), field air permeability (FAP), field water capacity (FC) and available water retention (AWC). The ten-year (1996–2005) mean value of BD of the fallow soil was 1.11 Mg m− 3, that of the soil from Field I — 1.17 Mg m− 3, and from Field II — 1.15 Mg m− 3; TP: fallow — 0.550 m3 m− 3, Field I — 0.531 m3 m− 3, Field II — 0.543 m3 m− 3; FAP: fallow — 104.1 × 10− 8 m2 Pa− 1 s− 1, Field I — 47.9 × 10− 8 m2 Pa− 1 s− 1, Field II — 66.9 × 10− 8 m2 Pa− 1 s− 1; FC: fallow — 0.374 kg kg− 1, Field I — 0.353 kg kg− 1, Field II — 0.354 kg kg− 1; AWC: fallow — 0.221 kg kg− 1, Field — 0.202 kg kg− 1, Field II — 0.201 kg kg− 1. In view of the acquired data it should assumed that long-term fallow of arable fields is one of the methods leading to the physical regeneration of soil. Favourable changes in the physical structure of soil can be achieved through the application of reduced or no-till tillage systems.