Effect of organic farming on a Stagnic Luvisol soil physical quality Tomasz Głąb a, ⁎, Katarzyna Pużyńska b , Stanisław Pużyński c , Joanna Palmowska a , Klaudia Kowalik a a Institute of Machinery Exploitation, Ergonomics and Production Processes, University of Agriculture in Krakow, ul. Balicka 116B, 31-149 Krakow, Poland b Department of Agrotechnology and Agricultural Ecology, University of Agriculture in Krakow, Krakow, Poland c Department of Agronomy, West Pomeranian University of Technology, Szczecin, Poland abstract article info Article history: Received 3 April 2016 Received in revised form 3 July 2016 Accepted 5 July 2016 Available online xxxx The organic farming system is reported as having an influence on soil chemical, biological and physical features. The objectives of this study were to examine the physical quality of Stagnic Luvisol soil subject to organic and conventional farming with crop rotations that included root crops and legumes. The experiment was established in 2008 as a split-plot randomised block design to examine the effects of these farming systems, i.e. conventional (CFS) and organic (OFS), and the sub-plot treatment of the crop species in the following crop rotation: potatoes, winter wheat, oats/common vetch mixture and winter spelt wheat. Undisturbed soil samples were collected in 2014 to determine the water retention parameters and morphomet- ric characterization of soil pores. The soil moisture characteristic curve was determined in pressure chambers with ceramic plates. The macropore system for the investigated soil was characterised using image analysis on sections of soil samples hardened with polyester resin. With OFS treatment, significantly higher values for the soil bulk density were recorded than with CFS. The bulk density was also affected by crop species. Higher values were characterised for winter wheat and oat/vetch mix- ture than for potatoes and spelt. The highest porosities in terms of transmission pores and fissures were noted for potatoes cultivated in the CFS system, whereas with CFS the soil under winter wheat was characterised by the lowest contribution of large pores. The highest water retention in terms of PWC (productive water retention) and AWC (available water retention) was obtained for the CFS system. Organic farming resulted in lower macroporosity, 0.65% on average, whereas with conventional farming this was 0.82%. These differences were more pronounced in terms of small pores with diameters 50–100 μm. For different crops, the level of macroporosity significantly changed. Soil housing potatoes and spelt was characterised by a higher macropore volume, in the diameter ranges 50–1000 μm. The farming systems applied significantly changed all tested plant biomass production. The highest grain and potato tuber yields were characterised for CFS. However, the highest root biomass crop species produced in the OFS treatment than in the CFS. © 2016 Elsevier B.V. All rights reserved. 1. Introduction Organic farming is defined as a production system that sustains the health of soils, ecosystems and people. It relies on ecological processes, biodiversity and cycles adapted to local conditions (IFOAM, 2005). The main standard excludes the use of artificial fertilisers, pesticides and ge- netic engineering. The organic system includes the maintenance of long-term soil fertility, compatibility with natural cycles, and the main- tenance of agricultural and natural biodiversity (de Ponti et al., 2012). Many comparative studies between conventional and organic farming systems have reported that organic farming influences soil chemical, bi- ological and physical features and affects biomass quantity and quality production. Organic farming has an important effect on soil chemical quality. The improvement in soil quality is probably connected with higher organic fertiliser rates. From a long-term perspective, organic management is expected to increase soil organic matter content (Sacco et al., 2015; Stockdale et al., 2001). Schjønning et al. (2002) observed that conven- tional agriculture without the application of organic manure reduces the soil's ability for crop production by worsening its fertility. However, the beneficial effect of organic farming on soil chemical properties is sometimes questioned. Gosling and Shepherd (2005) reported no sig- nificant differences in total soil organic matter, total nitrogen or C:N ratio between conventionally and organically managed soils. The results obtained so far indicate that organic management signif- icantly enhances biological activity and has positive effects on the envi- ronment (Papadopoulos et al., 2006). Microbial biomass has been found to be higher in organically managed soils than in conventionally man- aged ones (Schjønning et al., 2002). Some findings have shown that or- ganic farming is associated with a significantly higher level of biological Geoderma 282 (2016) 16–25 ⁎ Corresponding author. E-mail address: rtglab@cyf-kr.edu.pl (T. Głąb). http://dx.doi.org/10.1016/j.geoderma.2016.07.008 0016-7061/© 2016 Elsevier B.V. All rights reserved. Contents lists available at ScienceDirect Geoderma journal homepage: www.elsevier.com/locate/geoderma