Microbiological Characteristics of the Soil under the 'Cacanska Lepotica' Plum Cultivar in Mineral Fertilisation Conditions

Abstract

Over the 2003-2005 period, the effect of different mineral fertiliser rates on the number of actinomycetes in alluvium under the 'Cacanska Lepotica' plum cultivar was monitored. The investigations were conducted in an experimental plum plantation of the Fruit Research Institute and at the Microbiology Department of the Faculty of Agronomy in Cacak. The soil was treated with different 8:16:24 + 3% MgO mineral fertiliser rates, as follows: the N-1 variant - 400 kg/ha; the N-2 variant - 600 kg/ha; the N-3 variant - 800 kg/ha; the N-4 variant - 1,000 kg/ha and the N-5 variant (the control - non-fertilised soil). The effect of the fertilisers used was monitored through determinations of the number of actinomycetes made three times during the growing period by an indirect dilution method on Krasilnikov's synthetic medium. The development of the actinomycetes in the soil was dependent on the fertilisation variant applied, the sampling period and the research year. The use of high mineral fertiliser rates induced a decrease in the number of actinomycetes, which was particularly pronounced with the N-4 rate used. The use of lower rates brought about an increase in the number of actinomycetes. Of all the fertiliser variants examined, the most stimulatory effect was expressed by the N-2 variant. The most pronounced effect of the applied fertiliser was recorded in the second sampling period and in 2003. The most important increase in the plum yield was achieved by the use of mineral fertilisers at the rate of 600 kg/ha.