Pros and cons of foliar feeding with micronutrients
Foliar nutrient applications to corn and soybean plants have become a normal practice in production agriculture during the past 20 years—by definition, foliar feeding is the application of crop nutrients in a liquid form onto the plant’s leaf surface. The nutrients are then absorbed through the leaf’s stomata (or the pores on a plant’s leaves and stems that facilitate gas exchange and help them absorb essential elements).
On many farms, foliar applications are a reliable method to correct crop nutrient deficiencies and provide micronutrients to crops during critical growth stages, but they are not typically used to replace large quantities of macronutrients, such as phosphorus or nitrogen requirements.
Like many farming practices, as foliar feeding has become more common, agronomists and researchers have debated the value of foliar feeding various crops versus soil-applied fertilizer to maximize crop yield.
Here are a few of the possible benefits and concerns around foliar feeding.
Benefits of foliar feeding
- Nutrient efficiency with foliar applications can be higher than soil-applied fertilizer (due to insect root damage, soil drainage, drought conditions, soil pH and other soil stresses)
- Eliminates soil interaction with the nutrients being applied—foliar feeding is not affected by soil pH
- Convenient way to apply small amounts of certain micronutrients that roots cannot supply from the soil
- Speed of reaction time to correct deficiencies—plant response time is quick to address symptoms
- Return on investment potential from increased yield—relatively inexpensive as small rates of nutrients are typically applied
- Corrects nutrient shortages for maximum production after plant growth has begun
- Can be used as a supplemental fertility program following a regular soil and/or tissue test
Concerns about foliar feeding
- Can be difficult to align plant and environmental conditions with proper timing of the application to allow nutrient uptake efficiently
- Possible leaf burn or plant damage can occur from the nutrient being applied
- Only small amounts of nutrients can be applied per application—may take several applications to correct the deficiency
- Correction may be only a quick or temporary fix that is not lasting
- Possible added expense of several tissue tests throughout growing season—labor involved in collecting the tissue test during busy times of year
- Difficult to determine return on investment
- Foliar feeding is not a substitute for a soil test and a sound fertility plan
Tissue testing helps ID nutrient deficiencies
Tissue tests taken on a growing crop can identify nutrient deficiencies before you see them, and help determine if your crop might benefit from a foliar fertilizer application. Most tissue tests are not taken until some type of deficiency has been seen—tissue tests are sometimes used as a follow-up step to confirm results of soil test results—but it is more effective to conduct tissue tests proactively to find out if your crop is experiencing a micronutrient shortage.
Generally speaking, chelated nutrient products (used for nutrient uptake and efficiency) do not work well in foliar feeding due to molecule size. Chelated molecules are larger than other liquid forms of nutrients and have difficulty entering the leaf’s stomata. Instead, consider using a sulfate nutrient source, or adding a low rate of nitrogen to the spray solution to increases nutrient efficacy.
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- 6 Factors That Are Affecting Your N Strategy
- Yield Goals vs. Profit Goals: Determining Your N Rate
- Network Trends: Nitrogen Use Across the United States
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