Changes in the soil properties as affected by conventional and minimal soil tillage systems

A stationary field trial was set up at the Vėžaičiai Branch of the Lithuanian Institute of Agriculture in 2003. The soil of the experimental site is Dystrict Albeluvisol (texture sandy light loam). The objective of the study was to estimate the effects of primary soil tillage methods on the changes in the soil structure; chemical, and biological soil properties. The field trial involved two factors: factor A – deep ploughing; shallow ploughing; shallow tillage in the autumn. Factor B – different organic fertilisers – green manure of perennial grasses, straw and manure incorporation in the crop rotation: winter wheat-spring rape – spring barley, and red clover. The herbage of the first cut and aftermath for green manure and farmyard manure were incorporated in the respective plots. The experimental findings of the first crop rotation during the period 2004–2007 are summarised in this paper. Each year, after crop harvesting the soil was limed by 400 kg ha-1 CaCO3. At the end of a four-year crop rotation in the deep and shallow ploughed soil the pH level increased by 0.2 units, while in the sallow tillage soil the pH value did not change compared with the initial level before the trial establishment. A reduction in organic carbon and nutrient content in the shallow tillage topsoil 10–20 cm layer was established. Deep and shallow ploughed soil was rich in phosphorus, potassium and nitrogen. The highest amount of nutrients was determined in the deep and shallow ploughed topsoil (0–10 cm) layer. After cultivation the structure of moraine loam soil deteriorated. A reduction in the content of water stable aggregates (>0.25 mm) by 4–7 per cent units in the tilled soil was identified compared with the ploughless tillage soil