Impact of ploughless tillage on soil physical properties and winter wheat productivity

The demonstrational short-term on-farm field experiment (agricultural farm Gruduva, Sakiai reg., Lithuania, 2003-2004) and precise long-term field experiment (Aleksandras Stulginskis University, Research Station, 2009-2010) were carried out on silty loam soils. The aim of experiments was to evaluate impact of ploughless soil tillage on some soil physical properties and winter wheat productivity parameters. Three different soil tillage systems were investigated-conventional (CT, deep mouldboard ploughing), reduced (RT, disc harrowing) and zero (ZT, direct drilling). Short-term (3 years) ploughless soil tillage had higher influence on soil physical properties than in steady conditions of long-term (10 years) practice. The amount of microstructure was significantly less in RT and ZT plots; amount of water-stable soil aggregates and water content were significantly higher in ZT plots than in CT. In short-term experiment the compaction of ZT soil was least because of higher soil moisture (due to residues cover on soil surface) content and more favourable conditions of soil structure. In long-term experiment RI and ZT data of soil compaction showed nearly the same results, however, CT soil was more friable. Higher coverage of soil surface with oilseed rape plant residues (up to 68%) influenced on sowing quality decrease, that mostly affected significantly lower winter wheat seed germination and formation of productive stems in both experiments. In condition of less density crop, winter wheat formed higher mass of grains and influenced on mostly higher grain yields in RI and ZT (r(2004) = 0.953; r(2010) = 0.691).