The impact of biological agents on properties of heavy-textured soil and productivity of organically grown crops
¹Department of Soil Science and Land Reclamation, University of Warmia and Mazury in Olsztyn, Plac Lodzki 3, PL10 727 Olsztyn, Poland
²Department of Agroecosystems, University of Warmia and Mazury in Olsztyn, Plac Lodzki 3, PL10 719 Olsztyn, Poland
³Institute of Agroecosystems and Soil Sciences, Aleksandras Stulginskis University, Studentų 11, Akademija, LT53 361 Kaunas distr., Lithuania
Soils with high content of particles φ ≤ 0.02 mm usually have nonfavourable physical and mechanical properties. In order to determine the impact of biological agents on properties of heavy-textured soils in organic farming systems, in the years of 2007–2009 an on-farm scale field experiment was carried out in Budziszewo, Pomeranian province in Poland. The farm was organically managed for 20 years and was characterized by proper management (an appropriate crop rotation and a high stand of dairy cows). Nevertheless, in spring there were problems with soil drying, which used to delay sowing of spring cereals by ca 2 weeks, which in turn resulted in low yielding. Therefore, the following biological agents, i.e. beneficial microorganisms, were applied in 3 consecutive years 3 times each year. Produced on-farm (biodynamic horn preparation) and the others produced by industry under the trademark of: effective microorganism (EM), Humobak and UGmax. In 2007 silage maize was grown, in 2008 – winter spelt wheat and in 2009 – spring common wheat. The soil samples to study soil properties were collected from 5–15 cm soil layer during the vegetation period. The following soil properties were analysed: granulometric composition, bulk density of dry soil, total porosity, soil humidity and air content during sampling, organic matter content, soil pH, content of macroelements (P, K, Mg), soil aggregation based on dry and wet sieving. Moreover in 2009 additional soil samples were taken from an adjusting neighboring field of the conventional farm with the aim of comparing soil physical properties developed both under organic and conventional management.
The authors concluded that the application of above mentioned biological agents did not affect significantly soil properties. The applied agents did not affect crop productivity, with the exception of Humobak which decreased yield of silage maize and spring common wheat in the range of 41, and 26% respectively. A proper organic management as opposed to application of biological agents has positive effect on soil physical properties.