Effect of soil deep ploughing on winter wheat depending on soil conditions.

Abstract. Soil deep ploughing has a significant role on packing prevention technologies of soil layer beneath topsoil. It demands high energy consumption. This investigation was intended to clarify the effectiveness of deep ploughing in various field relief conditions. The experiments were arranged in LUA RFS Vecauce Ltd during the years 2001- 2007. Field trials were settled in loamy sand sod-podzolic soils with equalized micro-relief during the years 2001-2004. Winter wheat was grown after clover- timothy mixture. The field was treated with glyphosate herbicide after harvesting of fore-crop. Soil tillage included soil deep ploughing in the following treatments: untreated (without tillage), deep ploughing at 0.25, 0.35 and 0.50 m depth. Subsequent soil treatment included soil ploughing at 0.22 – 0.25 m depth and direct sowing. Field trials in production fields were carried out in the years 2004-2007. Soil tillage included soil deep ploughing at the depth of 0.35 and 0.50 m. All observations were carried out in certain field points detected by GPS. The chosen fields had wavy meso-relief. Grain yield was determined by CLASS LEXION 420 GPS-established harvest maps. Soil deep ploughing at the depth of 0.50 m gave the winter wheat yield increase by 7.3 % or 0.4 t ha-1 on average of three year field trials in 2001-2004. A significant positive effect of soil deep ploughing at the depth of 0.35 and 0.50 m on yield of winter wheat in the next year was determined. The impact on soil resistance from soil deep ploughing was significant only on the trail of tine and 0.10 m away from it. Significant increase of soil resistance was determined at the