Number of Microorganisms in the Soil Cultivated with Legume-Grass Mixtures Supplied with Phytohormones and Nitrogen

Jacek Sosnowski,Elżbieta Malinowska,Beata Wiśniewska-Kadżajan,Roxana Vidican,Anna Kaczorek,Kazimierz Jankowski

doi:10.15835/nsb649468

Abstract

The study concerned the number of microorganisms colonizing the humus layer and under plough soil from the cultivation of perennial ryegrass mixtures with red clover, which were fed by biostimulant based on the phytohormones and different doses of nitrogen. Nitrogen was applied at four levels-control (no nitrogen), 50, 100 and 150 kg N∙ha-1, biostimulant in two combinations - with and without preparation. Soil material to assess the size of individual groups of microorganisms was collected from each experimental plot in autumn 2010 from the humus (0-20 cm) and under plough layers (20-40 cm). The analysis of soil samples for a total number of bacteria, actinomycetes and fungi was conducted at the Department of Agricultural Microbiology IUNG-PIB in Pulawy. Results of studies have shown that more colonies of bacteria, actinomycetes and fungi were colonized the humus horizon. Biostimulant application in this cultivation led to a decrease of the total number of colonies of the all soil microorganisms groups but improved the ratio of bacteria to fungi. Increasing doses of mineral nitrogen by the limiting of the bacteria number and intensive development of soil fungi, helped to narrow the B/F ratio.

Highlights

The conventional system of crop production was conducted in order to maximize yield through the intensive fertilization and plant protection treatment that has a major influence on soil characteristics
The aim of this study was to determine the number of bacteria, actinomycetes and fungi located in the humus and under plough layer from the cultivation area of perennial ryegrass in combination with red clover supplied with phytohormones and different nitrogen dose
The assessment of the microorganisms number (Tabs. 2, 4) indicates that, the application of biopreparation in cultivation of perennial ryegrass with red clover, regardless of the nitrogen dose and sampling levels of soil resulted in more than 48% reduction in the number of soil bacteria, 16% of actinomycetes and over 26% of fungi

Summary

Introduction

The conventional system of crop production was conducted in order to maximize yield through the intensive fertilization and plant protection treatment that has a major influence on soil characteristics. These practices caused the deterioration of biological and physico-chemical properties of the soil. Among the organisms mentioned above, a specific group stated mycorrhizal fungi They create symbiotic systems with the roots of crop plants enabling them to take the available forms of phosphorus, and other components such as micronutrient, increasing the absorptive surface of roots and producing appropriate enzymes (phosphatases) (Alabouvette, 2000). Mycorrhizal fungi play an important role in creating a lumpy soil structure (Crecchio et al, 2007; Polyanskaya et al, 2012)

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