Response of soil physical properties and dehydrogenase activity to contrasting tillage systems Dirvožemio fizikinės savybės ir dehidrogenazės aktyvumas taikant įvairias žemės dirbimo sistemas

The aim of this study was to compare the influence of conventional tillage (CT) and no tillage (NT) on sandy loam and loamy sand soils in three sites of Estonia: 1) Viljandi county (Gleic Albeluvisol), 2) Valga county (Fragi-Stagnic Albeluvisol) and 3) Parnu county (Mollic Gleysol). The dry bulk density, gravimetric water content and dehydrogenase activity of the soils were determined in the spring of 2013 and 2014. In addition, a soil density index based on soil dry bulk density differences was introduced. Soil samples were collected from 0-10 and 10-20 cm layers in spring. The no tillage treatment had higher soil dry bulk density than the conventional tillage in Gleic Albeluvisol and Mollic Gleysol, where the no tillage fields had not been ploughed for 10 and 2 years, correspondingly. The index of soil density varied between 0.289-0.511, when compared the no tillage and conventional tillage treatments the lowest values were obtained in Gleic Albeluvisol and Mollic Gleysol. Gravimetric water content was significantly lower 2-5% (p < 0.05) in the conventional than in no tillage treatments. No tillage fields showed higher soil dehydrogenase activity in the upper 0-10 cm layer, conventional tillage treatments had no significant differences between the layers. Soil dehydrogenase activity had significant positive correlation (p < 0.01) with soil gravimetric water content and organic carbon, and negative correlation (p < 0.05) with soil dry bulk density and soil density index.