Changes of contents and quality of humus in dependence on different tillage

The object of the study was to check an influence of ways of tillage on the changes of humus contents, humus substances and qualitative parameters of humus. The trial was established in the years 1998-2005 in Milhostov on gleyic Fluvisol. This experimental place is situated in central part of the East-Slovak Lowland, approximately 106 m above sea level. The territory has continental character of climate with average year temperature 8.9 degree C, during vegetation period 16.0 degree C, with average annual precipitation 560 mm, during vegetation period 350 mm. Changes of humus content in the soil and its quality were studied in the years 1998-2005 at the following crops: clover-grass mixture in 3rd crop year (1998), grain maize (1999), field bean (2000), winter wheat (2001), English pea (2002), grain maize (2003), spring barley (2004), sunflower (2005). Two tillage technologies were examined: conv. - conventional tillage (current way of soil by ploughing), it was made a stubble breaking and mean or deep ploughing in dependence on the grown crops, pre-sowing soil treatment was made using block of machines (smoothing harrow and heavy-duty harrow), sowing was done with the sowing machine Kinze 2000 or Great Plains, dir. -direct sowing without tillage (for direct sowing of maize and sunflower the sowing machine Kinze 2000 was used, for direct sowing of bean, pea, wheat and barley the sowing machine Great Plains was applied). All variants were made in four replications, field area was 414 square m (18 x 23 m). Taking of soil samples from the depth of 0-0.3 m was carried out in the 1st decade of October. The following chemical soil characteristics were observed: humus content, humus substances, humic acids, fulvic acids and qualitative parameters of humus. Obtained data were compared with the soil characteristics found in the experimental year 1998. Data were processed by mathematics-statistical methods. Multifactor variance analysis, multiplied test comparison and simple regression linear analysis were used. On the basis of the obtained results it can be stated that the influence of tillage technology on humus content in the soil was not significant. Tillage technology significantly influenced the humus substances in the soil. Higher content of humus substances was found in variant with conventional tillage in comparison with no-tillage. Higher humus substances content, which was found at conventional tillage, was related to higher contents of humic acids and fulvic acids. Humus contents and contents of both components of humus substances were significantly influenced by the grown crop. Significant increase of humus content in the soil at the studied tillage systems was found out in the end of research period as compared to initial state. At the same time, the content of more stabile humic acids decreased and labile fulvic acids content increased. The observed parameters of humus quality (ratio of humic acids to fulvic acids, percentage ratio of humic acids to carbon) were significantly influenced by the grown crop. After the eight year crop cultivation there appeared a decline of the studied parameters of humus quality in both variants of tillage.