Vegetation experiments

Vegetation experiment is carried out for the assessment of the impact of various factors, such as mineral fertilisers, chemicals used in plant protection and/or other factors affecting the growth and development of plant under study.

Vegetation experiments can be divided into two types:

field vegetation experiment

pot vegetation experiment.

In both types of experiments the effect of the investigated factor (factors) is being evaluated by comparing the results from the objects subject to a certain factor with those collected from the control objects without the studied factor.

Field vegetation experiments are carried out under field conditions on experimental plots of the area depending on the factor under study as well on technology of cultivation and harvest of the specific plant. This area usually varies between 20 m 2 and 0.5- 1.0 ha, while their number is related to the statistical model assumed for the experiment. The results recorded over the experiment and after it must be analysed statistically to draw correct conclusions. In order to get rid of mistakes resulting from changing vegetation conditions of plants connected with agrotechnology and weather conditions field experiments should be run over three successive vegetation seasons.

The same site and agrotechnical conditions, such as cultivation on the same type and kind of soil, the same forecrop and fertilisation, should be maintained. Therefore the experiment carried out in a correct way is costly. The results after statistical analysis allow drawing conclusions which in the case of a positive effect of the factor (factors) under study can be introduced to the widely and well-understood agricultural practise.

Pot vegetation experiments require by far less financial support. In this case the plants are cultivated in vegetation pots filled up with liquid medium, gravel or soil. The use of soil in such experiments is most recommended because the results are most close to those potentially obtained after cultivation of plants directly on the field. The soil applied in the pot experiment must be analysed for physico-chemical and chemical properties.

In order to secure conditions the best for indicator plant development used in the experiment the pots are filled up with the solum and than the seeding or planting takes place. The pots are kept in a vegetation hall or a glasshouse. The growing plants are watered according to their needs, i.e. when the soil moisture level drops below certain value and the pressure binding water in the soil is higher than pF 4.2 (pF - soil sucking power meaning logarithm of the water pressure column height [in cm] corresponding with the pressure under which water is bound by the soil). It is measured with the soil moisture meter or soil tensionmeter.

Various pots can be used in such pot experiments. One of those is the vegetation pot worked out by Dr. Piotr Szulc (.......), in which technical solutions allowing the plants to grow under the most optimum conditions for their growth and development. This type of pot prevents the plants from freezing (temperature below -5 o C) and insufficient oxidation (the use of aerating filter). The application of vegetation pots ... makes the assay of soil moisture (optional soil tensometer) and the amount of water leaking through the soil possible. The composition of this water fraction can be determined by gas chromatography (GC), high performance liquid chromatography (HPLC) or emission atomic spectrometry with plasma agitation (IPC).

One-year-long pot experiment allows doing statistical analysis of the results and drawing conclusions because the soil moisture controlled over the experimental period is one of the most important factors causing the changing of the results. In contrary to the field vegetation experiment it is not necessary to repeat this kind of the experiment over the successive vegetation seasons. In the case of a beneficial effect of the factor under study on the growth and development of plants as well as the yield the results can be transferred to the field cultivation.

The pot vegetation experiments are worth to run because:

the costs of starting the experiment and its carrying out are reasonable,

there is a possibility for drawing conclusions after one-year-long experiment after statistical analysis,

there is a possibility for analysing various factors affecting vegetation of a plant without evaluating their effects on the natural environment. This is possible because of the tightness of the pots; the factors under study do not penetrate to the natural environment and do not cause its degradation,

there is a possibility for thermal, chemical and/or phytoremediation utilisation of the soil used in a pot vegetation experiment.

The sealed system of the pot experiment prevents penetration of the factor under study, such as heavy metals, plant protection chemicals, etc.) to the soil environment. Therefore no threat of pollution and the following chemical degradation of large soil surfaces exists. This hazard exists in case of field vegetation experiments.

The final conclusion is that the pot experiments are cheaper, more effective and safe to the soil environment. The model vegetation pot fulfils all the above requirements.

Mailing address:

Szulc Piotr
Skrytka pocztowa 75
85-959 Bydgoszcz 2
Poland

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