Overview of Inoculants

Biological Nitrogen Fixation
There is great potential to increase the yield and protein content of crops through biological fixation of atmospheric nitrogen (N2). There are free living microorganisms with the ability to “fix” atmospheric N2 into bio-available nitrogen. However, the best known, and agronomically most important N2 fixation process is performed by mutually beneficial associations between the group of soil bacteria, Rhizobium/ Bradyrhizobium, and legume crops. This symbiosis results in the formation of root nodules that can fix N2 by converting it to ammonium. The ammonium is subsequently converted to amino acids which form the building blocks of protein. The energy for the fixation process is derived from carbohydrates which are produced in the leaves by photosynthesis. These carbohydrates are translocated to the root nodules where they serve as an energy source which drives the nitrogen fixing enzyme, nitrogenase. This enzyme is extremely sensitive to oxygen and can be deactivated unless the oxygen level within the nodules is lowered. This is achieved by the substance, leghaemoglobin, which absorbs oxygen and gives the interior of the nodule a red/pink colour. Although a pink/red coloration of the nodule cortex is an indication of activity, the level of effectiveness of such nodules cannot be determined visually. Although this visual inspection cannot give a definitive assessment of nitrogen supply, it is true that nodules that are green or white inside are inactive.

Nodulation
Nodulation is initiated by invasion of the root hairs, followed by bacterial multiplication within the root tissue. This process stimulates root cell division to form the nodule with rhizobial cells as a central core. The association is highly specific, each legume forming nodules with a particular species of Rhizobium/ Bradyrhizobium, and is symbiotic - the plant benefiting by improvement in its nitrogen status, and the bacterium benefiting by receiving a carbohydrate energy source from the plant. Nodule shape varies from spherical, as on soybeans and peanut roots, to elongate as on clover and alfalfa roots. Once the seed germinates, the rhizobial cells infect the young root hairs and form nodules 2-4 weeks after planting, depending on field conditions and growth of the seedlings.

The Need for Crop Inoculation
Nodulation and N2 - fixation occurs naturally in soils containing a native population of Rhizobium/ Bradyrhizobium specific for the crop. However, native rhizobial strains are generally poor N2 - fixers compared to the selected strains used in high quality inoculants. In many soils the specific strains necessary for certain crops such as soya and lupin are absent or present in insufficient numbers to guarantee effective nodulation and high N2 - fixation rates.

To ensure maximum biological N2 - fixation, and hence maximum crop yields, it is therefore essential to assure the participation of highly effective Rhizobium/ Bradyrhizobium cells, and this can only be achieved by inoculation.

Frequently Asked Questions
Why are Legume Technology’s Legume Fix Inoculants the best product choice?

Do I still need an inoculant where I have grown these crops before?
Yes. Although you may have grown an inoculated crop in the previous year(s), planting seed in that field without inoculant will mean you only achieve a partial, low vigour root nodulation. In many parts of the world crops in long-term short rotation patterns still show benefits from using a high quality inoculant.

What are the differences between a sterile and a non-sterile product?
Sterile inoculants (peat and liquids) have higher concentrations of pure viable rhizobia. Contaminants are unavoidably high in non-sterile products. Thus, rhizobial numbers are quickly depleted during storage. For this reason, sterile inoculants can be stored for longer periods, and deliver higher numbers of pure (not contaminated) viable Rhizobium cells to the bean crop.

What does the polymer adhesive do?
The polymer significantly increases the adhesion of peat based inoculant to the seed surface. Without this gluing agent the product will fail to stick to the seed. This leads to less inoculant reaching the seed bed with the seed and consequently less beneficial bacteria are delivered where they are needed – with the seed. The most convenient sticker is one that is integral or actually a part of the product, allowing a quick, clean and easy inoculation.

How does Legume Fix work?
Legume Fix inoculants are simply applied between seed layers or onto augered seed. The sticker helps attach the product to the seed, so minimal mixing is required. Once the inoculated seed are planted and start to germinate, the high concentration of inoculant Rhizobium cells on the seed surface are able to quickly form effective nodules on the developing root hairs. Nodules that actively fix nitrogen are dark red in color. Effective nodulation results in maximum nitrogen fixation, which has a direct positive benefit on yield.

Do I need special equipment to apply Legume Fix?
No. Legume Fix inoculants are compatible with all standard farm machinery.

How much mixing is required with Legume Fix?
Legume Fix has an integral sticker, which maximizes adhesion of rhizobia to the seed surface with minimal mixing. The inoculant should be added to the seed and mixed in layers in the seed drill.

Can I use Legume Fix in my air planter?
Yes. Legume Fix contains an integral sticker that maximizes product adhesion to the seed. It well in both positive pressure or negative pressure (vacuum) planters.

Can I use Legume Fix with bulk seed?
Yes, it can be applied and mixed quickly and conveniently in bulk systems. Either mechanically or manually mix inoculant into the seed flow while filling, usually into the hopper as it feeds into the auger or conveyor. Using this method, Legume Fix works very well with brush auger, belt conveyor or pneumatic systems.

Will it slow down my planting?
No. Once the seeds have been inoculated, planting can be carried out as normal. Application is fast.

Is Legume Fix safe to use?
Legume Fix is a natural product. All ingredients are considered non-hazardous to the manufacturer, farmer and the environment.

Will extreme heat or cold affect Legume Fix?
Extreme heat can effect all inoculants during storage (see below). It is important that the product is stored correctly until used in the field. Very rarely will soil temperature reach a level that can affect Legume Fix inoculants.

How should I store Legume Fix?
Out of direct sunlight in a shady, cool part of the store. Do not allow product to be stored above 86 F. for extended periods of time.

Will freezing damage Legume Fix?
Unlike a liquid inoculant, freezing will not damage the Rhizobium in the sterile peat based Legume Fix product. For best performance, though, Legume Fix should be stored without freezing.

Does soil type affect Legume Fix performance?
Legume Fix is effective in all soil types. Both heavy and dry light soils tend to have lower levels of natural rhizobia. Legume Fix inoculation is essential on these soil types.

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