Crop Nutrition 101: Everything Growers Need to Know About Crop Nutrition

FBN Network

Sep 01, 2023

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This guide includes the following sections:

What Is Crop Nutrition?

Crop nutrition, or crop fertility, refers to the programmed approach of evaluating, supplementing and monitoring crop nutrients to maximize in-field success.  

Crops need balanced nutrition to: 

  • Optimize growth and development

  • Enhance physiological efficiency 

  • Maximize yield potential

By supplying essential crop nutrients at the correct time, using sufficient rates and optimal sources, farmers can improve the yield and quality of their crops. 

[Related: Why Does Soil Type Matter When Buying Farmland? ]

What Essential Nutrients Do Crops Need?

All plants require 17 essential nutrients in balanced ratios for proper growth and development. If just one of these essential nutrients is deficient, yield potential and crop quality can be reduced. 

Liebig’s Law of the Minimum states that the most limiting resource dictates yield potential in crop production. Often, the most limiting resource is a crop nutrient that hasn’t been adequately replenished in the soil. 

Fortunately, a balanced fertility program can ensure a crop has the essential nutrients it needs throughout the season to maximize yield potential.

Crops need three main types of nutrients: 

  1. Macronutrients

  2. Secondary nutrients

  3. Micronutrients

Source: University of Minnesota

Macronutrients are nutrients that plants need in large quantities, often hundreds of pounds per acre, depending on the crop. They include:

  • Nitrogen (N)

  • Phosphorus (P)

  • Potassium (K)

For more information about essential crop macronutrients, read “What’s In Your Soil: Making Sense Out of Macronutrients.”

Secondary nutrients are needed in smaller quantities than macronutrients, often tens of pounds per acre, depending on the crop. They include:

  • Calcium (Ca)

  • Magnesium (Mg)

  • Sulfur (S)

Micronutrients are nutrients that plants require in small quantities, but they are just as important for yield production as macronutrients and secondary nutrients. Essential micronutrients include:

  • Iron (Fe)

  • Manganese (Mn)

  • Zinc (Zn)

  • Copper (Cu)

  • Boron (B)

  • Molybdenum (Mo)

  • Chlorine (Cl)

  • Nickel (Ni)

Each nutrient plays a specific role in plant growth and development; therefore, it’s critical to have a balanced fertility program to support efficient plant physiology. 

To learn more about the importance of micronutrients for crop fertility, review “What Are Micronutrients and Why Are They Essential to Plant Growth?”. 

Nutrient Uptake From Soil

Plants generally uptake nutrients from the soil or other growing medium using a well-developed root system.

Three main processes help soil nutrients in solution reach the root system for plant assimilation: 

  1. Mass flow, which moves dissolved nutrients into a plant as the plant absorbs water for transpiration. Nitrate, sulfate, calcium and magnesium are mostly absorbed via mass flow.

  2. Diffusion, which moves nutrients to the roots in response to a concentration gradient. If the soil solution contains a high nutrient concentration, diffusion moves those nutrients toward the roots where nutrient concentration is lower. Phosphorus and potassium are absorbed via diffusion. 

  3. Root interception, which moves nutrients into a plant via direct root contact with nutrient-rich soil colloids. It is a minor pathway for nutrient transfer, although some secondary nutrients and micronutrients, including calcium, magnesium, iron and zinc, can be taken up via root interception. 

Nutrient uptake may happen passively (no energy required) with water or actively (energy required) with the help of a carrier molecule or ion.  

Factors Affecting Soil Nutrient Uptake

Several variables can limit plant nutrient uptake from the soil, including 

  • Soil water content

  • Soil temperature

  • Soil aeration

  • Soil pH

  • Nutrient source 

  • Root development

That’s one reason it’s critical to take plant tissue tests in conjunction with soil nutrient tests

Even if soil tests indicate adequate nutrient levels, the factors above may inhibit plant uptake. Plant tissue samples provide a real-time snapshot of a crop’s nutritional status and can help identify nutrient uptake challenges that may need remediating to maximize yield potential.

[READ NEXT - How To: Post-Harvest Soil Sampling is Easier Than You Might Think]

Achieving Optimal Crop Fertility

Achieving optimal crop fertility starts with assessing soil nutrient levels using an effective soil sampling method. Soil samples are often taken in the fall after crop harvest to establish a nutrient baseline for the subsequent growing season. Based on the soil test results, a fertility program can be designed based on the crop yield goals for the following season. 

Nutrient Sources

To maximize the return on investment of fertility costs, plants must have the nutrients they need when they need them most. It’s important to consider the nutrient source, as some nutrients may not be immediately plant-available and may need time to mineralize in the soil before plants can take them up. 

For example, plants only take up sulfur from the soil in the sulfate form. Elemental sulfur applications require sufficient time for soil microbes to convert sulfur into a plant-available form. Therefore, crops may need a sulfate sulfur fertilizer like AMS at planting for immediate uptake, while an elemental sulfur source can continue to provide sulfur throughout the growing season. 

Application Timing

Proper application timing is another way to maximize the return on investment of nutrient applications. Nutrients must be available for plant uptake before peak nutrient demand periods, which vary depending on the crop. 

For example, a corn crop takes up nearly two-thirds of its nitrogen demand during the vegetative growth stages. Applying nutrients as close to peak demand periods as possible helps ensure crops have sufficient nutrients when they need them.

If nutrients are applied too soon, they can be lost from the soil through leaching, vaporization or runoff. If nutrients are applied too late, they aren’t available when the crop demands them for proper growth and development. 

Both scenarios can result in lost profitability through lower yields and less effective crop nutrition.

Split fertility applications are often the most effective as they are generally timed to meet a crop’s peak nutrient demands, thus maximizing crop nutrient availability and uptake. However, split fertilizer applications aren’t always feasible due to workloads and weather conditions. 

In situations where nitrogen is applied well ahead of the crop’s demand, nitrogen stabilizers can be a wise investment. Nitrogen stabilizers help minimize nitrogen loss by leaching and volatilization.

Application Rates

An effective fertility program matches crop nutrient rates with the expected crop yield. Fields with higher yield potential require more fertility; therefore, it’s important to customize crop nutrient rates for every field.

Overapplying crop nutrients is expensive, doesn’t increase yield potential and pollutes the environment. On the other hand, underapplying nutrients means the crop won’t have the nutrition it needs to maximize its yield potential. 

Crop Monitoring

Scouting the crop in season is one way to identify and mitigate nutrient deficiencies. Crops that appear discolored, streaked or stunted may have a nutrient deficiency. In some cases, there may be time for an in-season nutrient application to reduce yield loss. 

Timely plant tissue sampling can also help identify hidden crop hungers and is a diagnostic tool for fine-tuning in-season fertility applications. 

For more crop nutrient best practices, review Crop Nutrition & Biology: Where (And When) to Start?.”

Types of Crop Nutrition Products

Crop nutrients come in a variety of sources and formulations and can be applied in many different ways. To choose the most suitable option for your operation, consider: 

  • Product performance

  • Cost

  • Availability

  • Management preferences

Soil-applied Nutrients

Soil-applied nutrients are applied directly to the soil using equipment like ground sprayers, planter fertilizer attachments or irrigation lines. Soil-applied nutrients may come in liquid or dry (granular) formulations and are the foundation of a well-balanced crop nutrition program. 

Dry fertilizers can be: 

  • Broadcast

  • Banded in a 2” x 2” pattern at planting

  • Side-dressed and cultivated shallowly into the soil 

Benefits of using soil-applied dry fertilizers include:

  • Cost savings when purchased in bulk volumes

  • More storage flexibility (no settling or “salting out” under cold temperatures)

  • More efficient for heavy pre-plant applications

  • Extended-release formulation options for season-long nutrient availability

Soil-applied liquid fertilizers can be:

  • Broadcast

  • Used in a band application at planting 

  • Applied mid-season as a side-dress

Benefits of liquid fertilizers include:

  • Convenient handling and application 

  • Ease of blending with crop protection products for added field efficiencies

  • Increased consistency and uniform coverage compared to dry fertilizers

  • Application flexibility as a starter fertilizer and with in-season options

Foliar-applied Nutrients

Foliar-applied nutrients are liquid fertilizers that are applied to a growing crop. The plant absorbs nutrients through the foliar cuticle and leaf stomata.  

Benefits of foliar nutrients include:

  • Quick plant nutrient absorption

  • Convenience in correcting mid-season deficiencies or spoon-feed micronutrients

  • Support for plant health during times of environmental stress

Foliar nutrient applications can supplement a well-balanced soil-applied fertility program, especially for supplying in-season micronutrients. Generally, foliar-applied nutrient availability is short-lived, and some nutrients applied via foliar application don’t translocate well within the plant. 

Be sure to understand the limitations of foliar-applied nutrients and choose nutrient formulations more readily absorbed by plants, such as chelated micronutrients or amino acid complexed products like the Nourish line of foliar nutrients.


Biostimulants are substances or microorganisms that can be applied to plants or soil to elicit positive agronomic responses and enhance: 

  • Nutrient uptake

  • Nutrient use efficiency

  • Tolerance to abiotic stress

  • Crop quality

There are many classes of biostimulants, and crop response can be highly variable depending on the weather, soil type, organic matter content, tillage system, and the type of crop rotation. 

Common biostimulants used in agricultural production include:

  • Humic and fulvic acids – Soil organic matter from decayed plant, animal, and microbial residues. Peat, leonardite and soft coal are examples. Products like Inhabit Boost can boost root mass, improve soil structure and prevent soil nutrient loss.

  • Seaweed extracts – Soluble powders or liquids that contain growth-promoting compounds such as plant hormones (auxins, cytokinins), trace minerals and amino acids.  

  • Amino acids – Amino acid-based biostimulants can support plant metabolism, photosynthesis, and stress response. Products like Attarus can be tank-mixed with postemergence herbicide applications to mitigate in-season stress and promote overall plant health.  

  • Beneficial microorganisms – Beneficial bacteria, fungi and yeasts that live in soil and establish symbiotic relationships with plants to enhance nutrient uptake, disease resistance, and overall plant performance. Examples include Bacillus bacteria and Rhizobium mycorrhizal fungi. 

For more guidance on how to use biostimulants effectively, read “Use Biostimulants to Help Your Planted Crop Take Important Next Steps.”

What Are Soil Prebiotics?

Soil prebiotics increase soil microbial diversity and health by promoting the growth of microorganisms already present in the soil-plant system. Prebiotics do not contain live microbes, so they have a longer shelf life than products that contain microorganisms, including inoculants, probiotics and some biostimulants. 

Natural products, including biochar, compost and animal manure, are examples of prebiotics that enhance soil structure and promote soil biological activity.

Benefits of prebiotics include:

  • Versatility and compatibility with other agricultural inputs to enhance application efficiency

  • Ability to improve soil health and microbial diversity

  • Enhancement of soil structure

Liquid prebiotic products, including Catalyst 1-0-1, can be applied with other fertilizers as a broadcast application in the spring or fall, or in-furrow or 2x2 at planting with starter fertilizers.

Catalyst stimulates beneficial bacteria in the soil, improves plant germination and supports early plant development and health. 

What Are Soil Probiotics?

Soil probiotics are biological agricultural inputs containing living microbes that benefit soil health and plant growth. Probiotic fertilizers promote nutrient-mobilizing properties and enhance root development and natural biocontrol to improve yield and resilience to stress and climate change.

Probiotic fertilizers come in many formulations, including solid, liquid, and gel. They can be applied directly to the seed as a seed treatment or in-furrow, banded, side-dressed or broadcast to the soil. Soil probiotics typically perform best when applied in-furrow at planting but can also be effective when applied pre-emergence or during early vegetative growth stages. 

Soil probiotics can be more challenging to manage than soil prebiotics because they contain live organisms sensitive to weather extremes, handling, storage and mixing. Shelf life may be short for probiotic fertilizers, so it’s important to plan appropriately for the most effective performance. 

Unlike prebiotics, probiotics don’t necessarily feed existing native soil microbial populations. They can generally be mixed with other fertilizers but may not be compatible with crop protection products.   

Examples of probiotics include Inject-N™ ADV and Inject-Myco ADV™

Inject-N™ ADV is a liquid soil probiotic product that contains Azospirillum brasilense, a nitrogen-fixing soil bacteria. It helps promote nitrogen use efficiency and improves water and nutrient uptake in plants. 

Inject-Myco ADV™ is a gel-based formulation that contains mycorrhiza spores and hyphae that increase the size and establishment of a crop’s root system. Crop benefits include increased nutrient and water uptake and tolerance to environmental stressors like drought. 

[Related: How Does Soil Productivity Determine Land Value?]

What Are High-Uptake Nutrients?

High-uptake nutrients balance the plant diet by supplementing nutrients available in the soil and mitigating in-season nutrient deficiencies. They can be soil- or foliar-applied and delivered to crops in a very efficient, plant-available form.

High-Uptake Nutrient Application Timing

High-uptake nutrients are ideal for foliar-applied applications. Adding high-uptake nutrient products to a fungicide tank mix is an efficient way to support late-season plant health and boost crop nutrition ahead of reproductive growth. 

High-uptake nutrients also help mitigate in-season nutrient deficiencies visually observed or confirmed with tissue testing. Common visual symptoms of nutrient deficiencies may include:

  • Leaf discoloration (light yellow, purple, bronze, striping)

  • Stunted plants

  • Poor flowering or fruiting

  • Necrotic leaves

  • Shortened plant internodes (bushy appearance)

Foliar high-uptake nutrient products, including Nourish Vitals™, can supplement a soil-applied fertility program and provide a late-season nutrient bump to finish the season.

Nourish Vitals provides an optimal balance of nitrogen, phosphorus, potassium, micronutrients, and amino acids that support more efficient nutrient delivery in the plant. It is an ideal tank mix partner with late vegetative to early reproductive stage fungicide applications. 

For an early-season crop nutrient boost, Inhabit Start™ is a soil-applied starter blend complexed with micronized carbon to increase nutrient uptake. It has a low use rate and salt content to protect emerging crops and improves soil health and function.

To view all FBN crop nutrition products, review the FBN Crop Nutrition Product Glossary.

Buy Crop Nutrition Products from FBN Direct

FBN Direct has a comprehensive selection of crop nutrition products to maximize every crop’s yield and quality potential.

Our solutions span the entire growing season and include starter fertilizers, in-season foliar micronutrients and soil amendments, including prebiotics and probiotics to support plant health. Mix and match products to meet your crop’s unique nutritional demands. 

With 24/7 digital shopping access, direct-to-farm delivery, transparent pricing and savings opportunities, and detailed label information for each product, FBN Direct offers the information and crop nutrition products you need to maximize your crop’s potential this season.

Popular Crop Nutrition Products Available from FBN Direct

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FBN Network

Sep 01, 2023

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