Estimation of soil structure and physical state in the seedbed under different tillage and environmental conditions

Soil structure and physical state are the basis of the conditions in which the crops grow. Tillage is an important factor affecting soil physical environment. No or reduced tillage under Nordic conditions often causes deterioration of soil physical condition. The aim of the study is to estimate the soil structure and physical state in the seedbed under different tillage and environmental conditions in Estonia and Lithuania. The study involved conventional (ploughing), reduced (ploughless) and no tillage (direct drilling) treatments. The soil structure in the seedbed prepared for spring crops was estimated using the same equipment and the same methods of assessment. The soil structure was estimated by the structure ratio (K-str) and by the structure index (B-str) which were calculated according to the amount of wet-sieved mature soil. In Estonia, the experiments were carried out on different (Fragi-Stagnic Albeluvisol, Endoeutri-Mollic Cambisol, Endoeutri-Haplic Luvisol, Endosceleti-Mollic Gleysol, Gleyc Albeluvisol and Mollic Gleysol) sandy loam soils during the periods 1995-1997 and 2012-2014. The most favourable level of soil structure was determined in the conventionally tilled (ploughed) plots in Gleyic Albeluvisol, Fragi-Stagnic Albeluvisol and in Endoeutri-Haplic Luvisol. Different tillage under conditions of various soils in Estonia also had a significant impact on soil physical properties (bulk density, water content, field capacity) in the seedbed. In heavier soil (clay loam Endocalcari-Endohypogleyic Cambisol) in Lithuania 2011-2014 the most favourable soil structure level in the seedbed was also obtained using conventional ploughing. The worst seedbed structure in clay loam soil was under no tillage in autumn with a cover crop for winter mulch; however, in this treatment the seedbed contained higher soil water content compared to other tillage systems.