V. Sabev, S. Raykov, V. Arnaudov
Abstract. The study was conducted in the experimental field of the Institute of Forage Crops Pleven, Pavlikeni branch during the 2005–2007 period. The objective of the study was to determine the effect of soil trampling by the wheels of the tractor unit on the structural elements of yield and productivity of soybean. It was found that soil trampling by the tractor unit tires had a negative effect on the ramification number, being most pronounced after three and four passages. The trampling influenced negatively also the pod number and grain yield per plant, the results being statistically significant. The single and two-fold passage decreased productivity 13 to 24% and after three and four passages over the area the yield was reduced to 40% and the yield was lower at very good statistical significance.