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A short report about the work being done

During October-November the following work was done by the united team of schools ¹45 and ¹157:

  1. The samples of plants were selected from 4 districts of Saint-Petersburg.
  2. Species of plants were determined.
  3. The experiment of determining the content of some elements in the chosen plants was held with the help of a set of tests Plant tissue.
  4. The standard scale for valuation was worked out for the quantitative valuing.
  5. All the facts were brought together in the table 1.

For the determination of important elements (nitrogen, phosphorus, potassium) contents for the plants in soil we took the samples for the experiment in different parts of Saint-Petersburg: 2 samples were taken in the centre of Saint-Petersburg, 2 – in the outskirts. The samples of central districts were taken from the parks (Tavricheskiy garden, public garden of NII Morphyspribor), one sample – from the forest-park zone (South-Seaside park), one – from the Komendantskiy aerodrome district. The grasses, that are widespread in our city, were studied: the dandelion (Taraxacum officinale), the stinning-nettle (Vitica dioica), usual buttercut (Ranuncula), meadow clover (Trifolium pratense), bubble sedge (Carex vesicaria), coltsfoot (Tussilago farfara). The end of October-the beginning of November is a time of the formation of winter. This autumn was significantly warmer ( average daily temperature was 9,5 C. That is 2 degrees warmer than normal) than average ones and humid enough. Thats why the plants kept their land parts. Stems and leaves were light-green.

The determination of the qualitative (N, P, K) and comparative (the samples were compared with each other) quantitative content (P, K) was done according to the methods of the set of tests Plant tissue. The standard solution containing the certain amount of nitrogen (50 mg) was prepared to determine the absolute quantitative nitrogen content. This let us receive the numerical expression of the experimental facts. The nitrogen content was high enough, so we had to dilute the extracts with water: we diluted the sample ¹ 1 10 times, ¹ 3 – 5 times, ¹ 2 and ¹ 4 were left without any changes.

Table 1. The results of the experiments

# of the sample

Place of the selection

Mass of the sample g

Phosphorus content

Nitrogen content mg/l

Potassium content
1 Tavricheskiy garden 4,1 The richest with phosphorus 250 Rich
2 Komendantskiy aerodrome 4,5 Not enough Not fixed Average
3 Garden of NII Morphyspribor 3,2 Rich 150 Rich
4 South-Seaside garden 2,37 Rich 1 Average.

  • The discussion of the results

    The analysis of facts shows, that the soils of Komendantskiy aerodrome only are poor with such important for plants elements like N, Ph, K. All the other samples have enough Ph and K. It can be noticed, that nitrogen content in the samples ## 1 and 3 is high. This can be caused by the following reasons:

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