The Effect of Mineral Fertiliser Use on the Microbiological Activity and Productivity of Alluvim under Plum

Abstract

Over a three-year examination period (2003-2005), the effect of different NPK fertiliser rates on the microbiological activity of alluvium under plum was monitored. The trial was set up in a trial plum plantation of the Field and Grape Research Institute and at the Microbiology Department of the Faculty of Agronomy in Cacak according to a randomised block design with three replications. The soil was treated with a 8:16:24 + 3% MgO mineral fertiliser, 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 - 1000 kg/ha and the N-5 variant (control - non-fertilised soil). The applied fertiliser effect on soil microorganisms was determined three times during the growing season and was monitored by determining the total number of microorganisms and the number of ammonifiers. The high fertiliser rates used brought about a decrease in the total number of microorganisms, as well as in the number of ammonifiers (the most pronounced one in the N-4 variants), while lower and medium rates induced an increase in the number of the examined groups of microorganisms (the most pronounced one in the N-2 variants). The applied fertiliser effect was most marked in the second sampling period, during 2003. The most significant plum yield increase was achieved by the mineral fertiliser application rate of 600 kg/ha. Considering the above mentioned and based on the plum yields achieved, as well as on the chemical and biological characteristics of the soil and economic and ecological indicators of the results of the fertiliser treatments mentioned, it can be concluded that the 600 kg/ha rate can be recommended for plum cultivation under the said agro-environmental conditions.