Foliar application of fertilizers
Considerations
- Several new considerations, such as cost of fertilizer materials, concern for ground water quality, availability of new formulations of compounds, newer surfactants that increase efficiency of foliar absorption, etc., are factors that give reason to consider this fertilization method.
- Foliar fertilizer materials can be one more tool, along with soil-applied fertilizers, soil tests, and petiole analyses, to fine-tunefertility programs to maximize both quantity and quality of potatoes produced.
- Nutrients can be applied effectively as foliar sprays, but only small quantities can be applied in any
single treatment, otherwise, "burning" of the foliage can take place.
- Foliar feeding is best used
with secondary or micronutrients where plant requirements are relatively small.
- For major
nutrients, such as nitrogen, it is often necessary to use several foliar applications in order to
supply enough of that nutrient to significantly improve crop yield or quality.
Application
A number of factors are to be considered in the application and use of foliar nutrients:
- Application rate:
Too much of certain nutrient elements can cause leafburn, be wasted, or be toxic.
- Time of day:
For optimum absorptionby plants, it is generally recommended that application take place early in the morning or late in the evening. It is further recommended that application not be made during midday, except during cool and cloudy weather.
- Growth stage:
It is generally agreed that these compounds should be applied early in the growing season.However, there is now information to show possible benefits of later applications during the tuber-bulking or tuber-maturing stages.
- Droplet size:
Droplet should be as fine as possible and achieve uniform wetting of leaf surfaces during application.
- Weather:
Apply foliar sprays only when there is adequate soil moisture. Do not apply to plants in a moisture-stressed condition.
- Balance:
Apply only what the plant needs. If there is not a low level on anyone nutrient, a balanced formulation would be preferred.
- Minimum water volume:
Foliar nutrients can be applied with most insecticides or fungicides, provided a minimum water volume of 200 litre/hectare is being used.