Micronutrients for Plants

7 Most Important Micronutrients for Plants

As micronutrients, there are seven important elements for plants: Boron (B), Zinc (Zn), Manganese (Mn), Iron (Fe), Copper (Cu), Molybdenum (Mo), and Chlorine (Cl).


Overall, they make up less than 1% of the dry weight of the majority of plants. The discussion that follows mostly focuses on the soil properties for the micronutrients.

micronutrients for plants growth
micronutrients for plants growth


The Standard Soil Test includes boron. When extractable boron is less than 0.1 pounds per acre, the level of soil boron is considered “insufficient” or “low.” When boron-containing minerals dissolve or when soil organic matter decomposes, both organic and inorganic forms of boron in the soil become available to plants.

The availability of boron and plant function can be influenced by soil and plant concentrations of calcium, potassium, and nitrogen, with the calcium:boron (Ca:B) ratio connection being the most significant. Soils with higher calcium will therefore need more boron than those with less calcium.
Boron poisoning is more likely in soils with low calcium contents.

Crop requirements and soil boron test levels are used to assess if boron should be included in fertiliser recommendations.

When boron is suggested for a crop, it may be necessary to apply a high rate of boron to the following soil types: clay-type soils; soils with high calcium and/or pH levels; soils with high levels of organic matter; and soils where boron is broadcast rather than banded or applied foliarly.

Micronutrients for Plants Growth

For the crops cotton, peanut, alfalfa, apple, root crops, cabbage, broccoli, and cauliflower, as well as when reseeding clover or when clover seeds are to be gathered, borax is frequently recommended as a fertiliser.

Many kinds of animal manures, superphosphate (0-20-0), and liming products may contain enough boron when used as part of a soil fertility programme to satisfy the boron need for particular crops.

Crops vary in their sensitivity to or tolerance of boron, with peaches, strawberries, and soybeans being the most sensitive; corn, tobacco, tomato, and small grains being moderately tolerant; and cotton, sunflower, and alfalfa being the most tolerant.

When signs of boron deficiency appear, boron application rates based on the crop are advised as follows:

Boron application rates Recommendations for Correcting Crop Boron Deficiency

Boron Recommendation for Plants

It is important to take precautions not to go over the suggested boron soil and foliar application rates because boron poisoning is undoubtedly a possibility. The best way to determine when boron is actually required is through a plant analysis. When extractable boron exceeds 3.0 pounds per acre, soil test boron is considered to be “high”.

micronutrients fertilizers

2. ZINC(Zn)

The Standard Soil Test includes zinc. When extractable zinc is less than 2.0 pounds per acre and the soil pH is less than 6.1, as well as when extractable zinc is less than 2.5 pounds per acre and the soil pH is greater than 6.0, the level of soil zinc is “insufficient” or “low.”

During cool, wet seasons, zinc shortage in early-planted maize has been noted; however, plants often recover as the soil warms and dries. When the soil pH is more than 6.5 and the soil is sandy (Soil Groups 1 and 2), zinc is frequently advised for maize cultivation. 



Unless a plant analysis shows that zinc is not required, a zinc application is typically advised for pecan. For peach and apple, a zinc advice is typically not given until a deficiency is proven through a leaf study. If a zinc deficit is present, it should be identified using both soil and plant studies. Certain crops should be treated with zinc at a rate of 3 to 5 pounds per acre when the zinc content of the soil is “insufficient”.


Due to their high sensitivity to zinc, peanuts can become poisonous when extractable zinc and soil pH are combined:

These soil pH and zinc extractability ratios indicate that another crop should not be grown on the soil.
Other crops may become poisonous to zinc at concentrations more than 40 pounds per acre.
The zinc (Zn2+) cation is present as zinc in the soil solution.

List of Commercial Fertilizers Containing Zinc:


The Standard Soil Test includes manganese. When the soil pH is high (>6.0 or 6.5, depending on the type of soil), manganese deficiency is more likely to occur in soybean, peanut, oat, wheat, and cotton cultivated on soils in Soil Groups 1, 2, and 3 in Area 5 and on some poorly drained soils in Area 4.

Soil factors that contribute to manganese deficiency include: • waterlogged conditions that occur for a portion of the crop year; • poorly drained soils that are naturally low in manganese; and • high soil pH (>6.0 or 6.5, depending on soil type).

Soil manganese levels are “insufficient” or “low” when the soil pH and extractable manganese are:

Manganese deficiency can be remedied through soil or foliar manganese applications. When the soil pH is greater than 6.4, 15 to 75 pounds manganese sulphate (MnSO4.H2O – 26 to 28 percent manganese) or its equivalent per acre is recommended for optimum yield.
However, in high pH soils (>7.0), correcting a manganese deficiency with a soil manganese application may not be sufficient because the majority of the applied manganese will most likely be converted to an unavailable form.

Manganese toxicity is unlikely in most soils, except those that are extremely acidic (pH less than 5.0). In general, crops that are susceptible to manganese deficiency are also susceptible to high levels of soil-available manganese. High soil test manganese levels can be easily reduced by adjusting the soil pH to the crop’s recommended level.

Commercial Fertilizers Containing Manganese:

4. IRON(Fe)

Plant iron insufficiency is typically not caused by a lack of iron in the soil, but rather by factors in the soil that make it less available to plants, such as:
High temperatures, prolonged periods of excessive soil moisture, high soil pH, low soil oxygen levels brought on by either soil compaction or water logging, and low oxygen levels in the soil
• elevated quantities of zinc, copper, manganese, and phosphorus in the soil
The extractable-iron concentration in the soil is not given due to these soil-influencing factors and the lack of a relationship between Mehlich No. 1-extractable iron and plant response.

Some plants have been called “iron sufficient” because their roots can make the rhizosphere more acidic or release phytosiderophores that bind iron at the root-soil interface and make it easier for the plant to take it up.

List of commercial fertilisers that contain iron:

5. Copper (Cu)

Copper deficiency is common in organic soils, mineral soils with a high amount of organic matter (>5%), and very sandy soils that have been over-limed and have a high pH (>6.0 or 6.5, depending on the type of soil).

Copper has a very narrow range between deficiency and toxicity, and recommendations for either soil or foliar application should be based on a plant tissue analysis that shows a deficiency.

List of commercial fertilisers that contain copper:


When a deficit is indicated in legumes growing on acidic soils, molybdenum is advised. It is not advised to apply molybdenum to non-legume crops.

The main soil element regulating the availability of molybdenum to plants is soil pH. In general, a deficiency is unlikely to happen if the soil pH is higher than 6.0. The suggested application dosage for the majority of legume crops is 2 to 8 ounces of molybdenum per acre delivered as either a seed treatment or foliar spray if the soil pH is below 6.0 and molybdenum shortage is suspected.

List of Commercial Fertilizers Containing Molybdenum:


Chlorine, which is found in soil as the chloride (Cl-) anion, is a crucial component of plant nutrition.
The abundance of this anion makes chloride excesses more frequent than its lack.
The application of fertilisers containing chlorides can have an impact on crop quality. Instead of potassium chloride (muriate of potash, KCl), potassium sulphate (K2SO4) or potassium nitrate (KNO3) are the preferred potassium fertiliser sources for tobacco, potato, and tomato.

List of Commercial Fertilizers Containing Chlorides:

micronutrients and macronutrients

Good New!

Micronutrients Manufacturers can avail IMMA Memberships now

The Indian Micro Fertilizers Manufacturers Association (IMMA) assists in policy advocacy with the government and also provides guidance on fertiliser laws and acts. Members are also trained on various technical aspects through training sessions/seminars, etc.

IMMA new membership registrations are open now click here to become a member and take its benefit.

Leave a Comment

Your email address will not be published. Required fields are marked *

Enquire Here
IMMA Exclusive Membership Enquiry
Seraphinite AcceleratorOptimized by Seraphinite Accelerator
Turns on site high speed to be attractive for people and search engines.