Influence of bulk density on soil resistance and yield of tobacco.

Influence of soil compaction on the growth and development of flue-cured tobacco was investigated at the experimental station of the Tobacco institute Zagreb. Research was carried out in model trials, in Mitscherlich's pots. Three soil compaction levels (1.2, 1.4 and 1.6 gcm -3 ) were randomized according to the block method with four replications. The soil used in the trials was the plough Iayer of Luvisol, the soil typical of the area in which flue-cured tobacco is grown in Croatia. Tobacco was picked in six harvests, and after the sixth harvest the tobacco root yield was determined by washing it out in a sieve. The soil resistance to penetration was measured during tobacco flowering, and a statistically significant increase of soil resistance (compaction) was recorded in the soil with medium and the highest bulk density compared to that with the Iowest density, increased soil compaction considerably reduced leaf yields and root development of tobacco. Tobacco leaf and root yields were significantly increased by intensified fertilization. The highest leaf and root yields were obtained in the lowest soil compaction.