We started into foliar N and K a few years ago, the initial interest came from our sandy soil not being able to hold onto potassium. No matter what we applied via fertiliser, fibrophos or manures soil indexes don't increase. Foliar is a part of our solution to this.If this form of treatment is just about cost savings then you should firstly explore what you are trying to achieve by putting fertiliser on in the first place.
Liquid application is very inefficient if you are trying to correct a macro element deficiency in either the plant or soil because;
So sort out what is the purpose of fertilising, what you are trying to achieve and use the best system to achieve your goals. Liquid application has a place, but is not an alternative for every reason to apply plant nutrition.
- each spray pass only puts on very small quantities, insufficient to correct deficiencies and imbalances. Therefore needs multiple applications.
- the mode of foliar absorption is via the leaf stomata, the plant's respiratory openings designed for gas exchange (oxygen and carbon dioxide), only small and simple molecules can pass through the cell walls within the stomata. Nitrogen molecules being small enough. However most macro element containing molecules in solution are too large for osmosis to occur. This is why plants have ROOTS. Such essential elements need washing off the leaves into the soil for the roots to do their designed thing.
- a short term N boost can be made efficiently via foliar fertilising.
- a short term trace element application can also work for plants and less successfully for grazing livestock as for the latter it is equivalent to drenching the animals. This is most pertinent with cobalt which rumen bugs needs a constant supply, not a short term hit for manufacturing vitamin B12.
We started into foliar N and K a few years ago, the initial interest came from our sandy soil not being able to hold onto potassium. No matter what we applied via fertiliser, fibrophos or manures soil indexes don't increase. Foliar is a part of our solution to this.
The efficiency of foliar urea applications make sense to me, we have also seen pasture quality improvements from both foliar N and K applications.
Current N prices are certainly increasing interest in foliar and we will continue to trial and use it this next year.
@daithi there have been a good few threads on this recently so I'll not repeat myself but the links and what we've done should all be in there