When do P-solubilizing bacteria need to be applied? XiteBio’s Phosphorus (P)-solubilizing technology needs to be applied early in the plant’s life cycle either at seeding or before the 6-leaf stage.
P-solubilizing bacteria are what is often termed Plant Growth Promoting Rhizobacteria or PGPR.
P-solubilizing bacteria:
- Are alive.
- Operate in the rhizosphere.
- Form relationships with plant roots.
XiteBio® Yield+ and XiteBio® Tuber+ are both based on XiteBio’s PGPR technology that uses the patented P-solubilizing bacteria Bacillus firmus. This blog will largely focus on application timing of this technology. Every ag-biological will have different specifications and you should always consult the label before using any product.
As with any other living thing certain conditions need to be met to ensure the health of your P-solubilizing bacteria. The first one is that you should not allow it to freeze. This means that while in the packaging your inoculant should always remain above freezing. But it also means that you should not apply these bacteria into frozen ground. PGPR technology should be applied into field conditions that are optimal for germination.
We recommend applying XiteBio® Yield+ in furrow or in the 0-6 leaf stage through the sprayer. XiteBio® Yield+ is compatible with many starter-fertilizer, herbicide, and pesticide products. The best results from ag-biological products often come when they are applied early and paired with an existing practice (1). Because of this a good PGPR technology needs to be tolerant of the products that are already used by the farmer. When PGPR is timed with an existing application it does not necessitate extra passes through the field. This saves time, money (fuel, wear-and-tear on the equipment) and compaction.
P-solubilizing bacteria operate in the rhizosphere, because of this they need to reach the soil to be effective. As we have seen in a previous blog post the rhizosphere (also known as the root zone) is the area within 4mm (1/8”) of the plant’s roots. Once they have reached the soil these bacteria colonize the rhizosphere and are nourished by the root exudates and sloughed off tissues of plant roots (2). When applying early post-emergent, the bacteria will move down into the soil and seek out plant roots to colonize. When applying in-furrow, bacteria will have to survive until germination before they can begin to establish themselves in a plant’s rhizosphere.
Because the bacteria rely on plant root exudates to survive it is important to apply your inoculant in concentrations that allow enough bacteria make it to your plant roots to establish viable colonies. Inoculant application also needs to be timed so that the bacteria can reach the soil. Once there they need to attach to the roots of your target crop and not any other plants or weeds that may be present in the field.
Farmers and agronomists should personalize their application timing to their field for maximum effectiveness. While some growers might opt for dual inoculation if they have found that the ROI is sufficient to justify this practice others might not. When applying through the sprayer it is important to keep and eye on ground cover both from plants but also from other obstructions like crop residue or cover crops. At XiteBio® we have found that certain crops tend to fill out quickly and that application before the 4-leaf stage can be beneficial. If you have a crop that is particularly full in the 6-leaf stage, it would be wise to attempt to spray earlier. In our experience XiteBio® Yield+ is effective at less than 25 per cent ground cover (3).
A good inoculant is one that works in tandem with the native microbes in the soil and does not overpower them or compete for resources. This type of inoculant may persist in the soil, but concentrations often return to normal levels year over year. This return to equilibrium can be seen as beneficial as the amount of naturally occurring bacteria returns to normal and the soil achieves balance. Because of this PGPR technology that operates in synergy with local native microflora should be applied every year to ensure that it colonizes the rhizosphere in viable concentrations to solubilize P (4).
When to apply P-solubilizing inoculants is a question of crop, application method and ROI. However, by understanding the basics of how PGPR technology works growers and agronomists can make informed decisions that will lead to P-solubilizing inoculants effectively colonizing the roots of their crops. Timing is very important in the ag-biological game and can make all the difference at harvest.
- https://www.realagriculture.com/2023/04/the-agronomists-ep-108-navigating-biological-products-with-mike-gretzinger-and-connor-sible/ Timestamp 16:01
- https://www.sciencedirect.com/science/article/pii/S1018364713000293
- https://xitebio.ca/inoculant-and-biological-faqs/
- https://cog.ca/article/promoting-growth-pgpr/