Great questions. It would be great to know frequency of application for liquid fertilizers! Are you using compost tea as a liquid fertilizer or manure? An article published from ECHO’s West Africa Regional Impact Center says the following about the use of manure liquid fertilizer:
"After 14 days, the liquid fertilizer is ready to use. Liquid fertilizer can be used for nurseries, gardens, fruit trees, and other large crops.
Before using it, it is necessary to extract the liquid portion out of the mixture. This is the liquid fertilizer. Dilute a volume of this liquid in fifteen to twenty volumes of water (1 for 15 to 20) and finally to use this diluted solution by spraying the base of the plants once or twice a week. It is strongly advised to mulch the plant base before using the liquid fertilizer.
- When mature, undiluted liquid fertilizer can be stored in a container of any size for a long time.
- Undiluted liquid fertilizer can burn plants.
- Even if diluted, if applied directly to plant leaves, liquid fertilizer can burn plants.
- Liquid fertilizer can be applied 7 to 10 days after germination of the plants and is continued if necessary."
As far as when to stop fertilizing, it depends a lot on the crop! Here’s a link to a University website that explains N uptake and partitioning over time in general for crops. On the left-hand side, you will see where you can click to see the N uptake curves for different types of crops (they differ). Once flowering starts, most plants taper off in N uptake. If you are mostly interested in the liquid fertilizer for supplying Nitrogen requirements, I hope this is helpful!