Bacteria Enrich Soil Science Project

Science Project Idea - How bacteria on the roots of some plants may enrich the soil

Farmers have known for a long time that a crop of clover will improve the soil.But the reason for this has been known for only relatively a few years.It was found that in some fields clover plants did not have the power to improve the soil.A comparison of the plants showed that those which possessed this power all had little enlargements (called nodules) on their roots.

It was found also that if some of the soil from the field containing nodule-bearing clover plants was scattered over the other field, the clover plants in this field also developed nodules on their roots and gained the power to improve the soil.An examination of these nodules led to the discovery that they contained bacteria.It was found then that the soil could be inoculated with a culture of these bacteria either by mixing it with the clover seed before it was planted or by adding it directly to the soil.It has been found that the bacteria in these nodules

have the power of changing the nitrogen of the air, which cannot be used directly by plants, into a form which may be built up into the living matter of the plant.All of the plants of the clover family (legumes) may have these nod- ules containing nitrogen-fixing bacteria.Some of the principal members of the family are peas, beans, vetches, and alfalfa.If the soil does not contain the proper kind of bacteria, the nodules will not be formed and these plants will not be able to add to the fertility of the soil.There are other bacteria in the soil, not associated directly with plants as these nodule-inhabiting bacteria are, and these other bacteria have the power, under certain favorable conditions, of making the nitrogen of the air usable by plants.

Nitrogen-Fixing Bacteria Science Fair Project - Science Experiment

Grow beans from seed using two methods.

1) grow bean seeds in pots with regular soil.

2) grow bean seeds in pots with the same regular soil BUT add nitrogen-fixing bacteria (rhizobacterium) additive found in many gardening centre stores.

Examine and measure the growth of the bean seeds between the two different pots. Plot the growth on a spread sheet.

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