Impact of tillage systems on chemical, biochemical and biological composition of soil

The influence of reduced tillage (RT) on the biochemical properties of soil and crops has been studied thoroughly worldwide. In contrast, we lack regular results on long-term (more than 20 years) RT and especially no-till (NT) impact on the composition of soil and main crops in semi-humid subarctic climate of the Baltic States. For this reason, investigations were carried out at the Research Station of Aleksandras Stulginskis University, Lithuania, in 2009–2012. The aim was to investigate the influence of RT and NT on soil pH, phosphorus (P) and potassium (K) concentrations, enzymatic activity and abundance of earthworms. This study comprised soils which were conventionally (CP) and shallowly (SP) ploughed, deeply chiselled (DC), shallowly disked (SC) and not tilled (NT). Primary tillage systems did not have significant impact on the soil pH or its P and K content but initiated the separation of soil layers into an upper one (0–15 cm), with a higher P and K status (55.5% P and 59.0% K of the total content), and a bottom one (15–25 cm), with lower concentrations of the elements (44.5 and 41.0%). Non-inversion tillage systems and NT raised the activity of soil enzymes such as saccharase by 32.2 to 60.8% and urease by 1.6- to 3.1-fold. The most marked rise in enzyme activity occurred in SC and NT soil. RT systems lead to an increase in the number and biomass of earthworms in the soil under wheat but the highest rise of the earthworm number and biomass was observed in NT plots, where the average count of earthworms doubled and their biomass increased by 3.7-fold compared with CP. In general, NT was the most efficient system in terms of the enrichment of soil biochemical properties.