The impact of tillage, Ca-amendment and cover crop on the physical state of a clay loam soil

Changes in the physical state of a clayey soil are determined by the soil type, soil moisture, weather conditions and tillage intensity. Possibilities to reduce tillage clayey soil have not been sufficiently investigated in Lithuania before. Research was carried out during 2014-2016 at the Joniskelis Experimental Station of the Lithuanian Research Centre for Agriculture and Forestry on a clay loam (siltic, drainic), Endocalcary-Endohypogleyic Cambisol (CMg-n-w-can) in the experiment, established in 2006. The aim of the present study was to evaluate the long-term effects of different tillage intensity as well as its combinations with supplementary agronomic practices (deep ploughing at 21-23 cm depth and shallow ploughless tillage at 10-12 cm depth as well as shallow ploughless tillage with incorporation of lime sludge and no-till in the autumn with a cover crop for winter mulch) on the indicators of soil physical state, investigated in a field pea crop. Ploughless tillage alone demonstrated the significantly higher soil water content before pre-sowing tillage in spring, higher soil dry bulk density, lower soil total porosity and soil water capacity before crop harvesting in topsoil; however, soil dry bulk density decreased, soil water capacity and soil total and air-filled porosity increased in the subsoil compared to deep ploughing. Incorporation of lime sludge (Ca-amendment) in the ploughless tillage plots resulted in higher soil water content before pre-sowing tillage, lower soil water content after crop emergence and before harvesting, higher air-filled porosity and amount of stable soil aggregates in topsoil, lower soil dry bulk density, higher total and air-filled porosity in subsoil before harvesting. Due to no-till in the autumn, with a cover crop for winter mulch, soil water content increased before pre-sowing tillage, it decreased after crop emergence and before harvesting in topsoil, soil dry bulk density decreased and total and air-filled porosity increased in subsoil; however, the amount of most agronomically valuable (0.25-5.6 mm) soil aggregates decreased in topsoil before harvesting compared to ploughing.