Variations of maize yield and some quality indices of grain depending on the type of main soil tillage

P. Yankov*, M. Drumeva, D. Plamenov

Abstract. The investigation was carried out during 2008 – 2010 on the trial field of Dobrudzha Agricultural Institute, General Toshevo, Bulgaria, on slightly leached chernozem. To clarify the effect of different types of main soil tillage on the vertical distribution of maize seeds in the soil layer and the development of the plants, the following variants of a stationary field trial were analyzed: plowing at 24 –26 cm, disking in autumn and double cultivation in spring (check); double disking at depth 10 –12 cm accompanied by autumn disking and double spring cultivation; cutting at 24 –26 cm, disking in autumn and double cultivation in spring; direct sowing – pre-sowing treatment of the area with total herbicides. Hybrid Anasta was sown at crop density 55000 plants/ha. The brief replacement of the deep plowing with cutting without turning of the surface layer and adapted direct sowing led to slight increase of grain yield by 1.0 and 2.8 %, respectively. Lowest and with the highest variation were the yields from maize over years after main soil tillage performed as disking. The highest absolute grain weight was obtained after adapted direct sowing and constant cutting in comparison to conventional plowing, and the lowest absolute grain weigh was measured after annual disking. The replacement of annual plowing before planting maize with minimal tillage or tillage without turning of the soil layer did not cause statistically significant variations in the content of raw protein and oils in grain