Why inoculation is important for your crops.
Nitrogenous fertilizer is the most expensive of plant fertilizer.
The reduction of elemental nitrogen to ammonia is an energy intensive reaction. In the Haber-Bosch reactor nitrogen and hydrogen react at high temperature (350⁰C) and great pressure (300-500 atm) and a catalyst as follows:
N2 + 3H2 = 2NH3
For every kilogram of NH3 formed 2 to 2,5kg diesel is consumed.
Likewise biological nitrogen fixation is an energy intensive process involving 2 to 2,5kg of photosynthate (glucose) for the formation of 1kg NH3. If nitrogenous fertilizer is available, the plant would rather use this than fixing nitrogen from the atmosphere.
In biological nitrogen fixation, 2,2 to 2,5kg of glucose is needed to produce 1kg of NH3 (this is also expensive, but these costs are not covered by the farmer).
Furthermore, this process takes place under normal temperatures and pressures, by means of an enzyme system that includes molybdenum, iron and sulphur (therefore, molybdenum is essential for nitrogen fixation).
Large quantities of nitrogen are fixed annually through effective symbiosis between legume and rhizobia.
The correct, selected bacteria are then either applied directly to the seed before planting or added in a liquid form to the seeds in the plant furrow during planting.
In order for this symbiosis to be effective, the correct bacterial symbiont is essential.
Was inoculation successful?
The effectiveness of inoculation can be evaluated by looking at the number, position and colour of the nodules.
Number and size of nodules:
It is determined by the size of the plant and the nitrogen requirements of the host at the time.
Position of the nodules:
The position of the nodules on the roots indicates when nodulation took place. A few large pink nodules high on the root crown indicate early and effective nodulation. The lower the nodules are on the root system, indicates later nodulation.
The colour of a nodule that is cut open also indicates effectiveness and activity. Pink nodules indicate an effective strain of rhizobia that nodulated the plant. Later in the season the nodules turn green, indicating nitrogen fixation had stopped. A large number of small, white nodules over the whole root system indicate an ineffective strain was used to inoculate the plant or that resident rhizobia have nodulated the plant.