NPK-fertilization influences on proteinase activity in alluvial soil

Abstract

During the period of 2003-2005 the effect of different NPK fertiliser rates oil the proteinase activity of alluvium planted to plum was examined. The trial was carried out in a trial plum plantation of the Fruit Research Institute and at the Microbiology Department of the Faculty of Agronomy in Cacak. The soil was treated with mineral fertilisers having a 8:16:24 + 3 % MgO formulation, as follows: variant I (control) - non-fertilised soil; variant 2 - 400 kg ha(-1); variant 3 - 600 kg ha(-1); variant 4 - 800 kg ha(-1); variant 5 - 1000 kg ha(-1). The fertiliser effect was determined three times during the growing season and was observed by identifying the proteinase activity. Determination of the enzyme activity was made using standard microbiological methods. The investigation results showed that the soil proteinase activity was affected by the fertilisation variants employed, sampling period and research years. High mineral fertiliser rates used caused a reduction in the soil proteinase activity. Of all the fertiliser variants examined the most pronounced inhibitory effect was exhibited by the variant 5 (the variant with the highest nitrogen rate used). Conversely, lower mineral nitrogen rates had a stimulatory effect oil the activity of this enzyme. The fertiliser effects mentioned were most pronounced in the third sampling period. Furthermore, a more marked effect was recorded in 2003.