Identifying and Preventing Nutrient Deficiencies

Published: August 18, 2021

Timely identification of nutrient deficiencies in plants is key to proper yield management.
Mariposa Technology - Identifying and Preventing Nutrient Deficiencies
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Cultivating hemp can be a double-edged sword. On the one hand, it is amongst the most profitable ventures out there. On the other, it could be a tad frustrating dealing with the arduous task of identifying and fixing plant deficiencies, especially with the relatively minimal published research and several controversies surrounding the plant’s nutrition.

Thus, every true hemp expert will willfully admit that regardless of the amount of knowledge or successful harvests they have had, encountering problems with the relatively new plant is not uncommon, especially in nutrition.

Mobile vs. Immobile Nutrient Deficiency

Depending on essentiality, there are two primary nutrient types: mobile and immobile. Understanding this difference is the first step to making a proper diagnosis.

Simply put, mobile nutrients flow through the plant system to reach areas where they are most needed, and immobile nutrients tend to stay close to their initial deposition site.

Deficiency of mobile nutrients is often characterized by the yellowing of older leaves at the base of the plant, whereas that of immobile nutrients exhibits initial signs on newer growths at the top and outer branches of the plant.

Identifying Nutrient Deficiencies in Hemp

Proper nutrient deficiency diagnosis requires taking the right steps, and this includes crossing out whatever parameter might yield similar symptoms with a nutrient deficiency.

Plus, nutrient deficiency is not always the culprit in unhealthy plant growth. The signs might be because of nutrient lockout, in which case adding more nutrients is not the solution.

Thus, the following steps are functional in effectively diagnosing nutrient deficiencies in the hemp plant:

  • Daily Visual Inspection
    Admittedly, similar symptoms make it harder to diagnose plant conditions on-site/in-vivo. As a result, the plant is often beyond salvaging by the time there is a proper diagnosis. But with daily monitoring, this is avertable.

    With the hemp plant being a known bio-accumulator, performing as many level-based tests as possible coupled with daily visual assessment improves the probability of getting an accurate diagnosis early.

    It is needless to say, knowing what nutrients and conditions are imperative at each phase of the plant’s growth is key to maintaining healthy plants. Thus, to avoid nutrients canceling out, getting familiar with what nutrient is essential at that stage.

  • Early Intervention
    For better diagnostic accuracy, visual observation should be paired with tissue analysis and soil testing.

    Supposing the plant is assumed to have many deficiencies, it is advisable to set baselines by conducting several tests to establish theories and provide precise solutions.

PLANT TISSUE ANALYSIS

This category of analysis helps to detect nutritional imbalances long before visual symptoms appear. These tests can help determine the efficacy of the fertilizer programs, nutrient levels, and many more, making it ideal for early intervention.

Considering the advised frequency rate of this testing type, an effective device that enables in-vivo, rapid, DIY (do-it-yourself) testing is vital.

  • Make the necessary modifications:
    Confirming a nutrient deficiency as the problem, identifying the exact nutrient is next. Thus, understanding the different nutrient levels needed at each phase is the fine line between salvaging harvest and having no yield at all.

    Note #1: For pH in a hemp grow-medium:
    • In a soil system: 6.0 -7.0
    • In a hydro-system/coco-coir: 6.0 – 6.5

      Note #2: Nutrient deficiencies are not phase-restricted. Thus, each nutrient must be supplied in the required amount at each stage to avoid a deficiency case.

Nutrient Deficiencies at the Vegetative Stage

At the vegetative stage, some of the most common nutrient deficiencies include:

  • Note: For every deficiency, there is a somewhat equal but opposite toxicity.

Nitrogen

As one of the essential nutrients in the vegetative and flowering stage, hemp nitrogen requirement is considerably high. The mineral which leads plant metabolism; especially, photosynthesis, is a mobile nutrient. Thus, the inadequacy of this particular mineral can be cataclysmal to the yield.

Symptoms of nitrogen deficiency include:

  • Subsequent yellowing of older leaves, especially leaves close to the base of the plant.
  • Progressive yellowing of leaves. Plus, possible discoloration and brown spots at leaf
  • margins with eventual leaf curling and dropping.
  • Appearance of smaller budding sites in the plant and early efflorescence.

Note: Chlorinated water can convert nitrate into nitrogen gas.

Fixes:

  • A nitrogen-rich diet is an excellent solution for this deficiency. A premixed formula, nitrate of soda, or an organic fertilizer could suffice.
  • Check and adjust the conditions of the grow medium accordingly.
  • In adequate lighting, use a foliar spray of nitrogen on the underside of the leaves.

Note: Plants do not require nitrogen during the last three weeks of flowering. Therefore, yellowing and shedding are natural during this time.

Magnesium

The central atom in chlorophyll molecules, which means it is also essential to the plant’s survival. As a mobile, macro-nutrient, magnesium travels from older leaves to newer ones to support their metabolic activities.

Symptoms of magnesium deficiency include:

  • Progressive discoloration and interveinal chlorosis: Rust-colored spots on leaves and areas between veins of older leaves turn yellow. As the condition progresses, the patches become larger, developing on the tips and margins of leaves.
  • Curling, necrosis, and dropping: The entire plant, which looks sickly, begins to weaken as some leaves start to curl, die and fall.

Fixes:

  • Flush the entire system with fresh nutrients-infused water at a suitable pH level.
  • Using a foliar spray rich in magnesium on the plants.
  • Check and adjust growth medium factors accordingly.

Nutrient Deficiencies at the Flowering Stage

At the flowering stage, some of the most common nutrient deficiencies include:

Potassium

A member of the ‘big three.’ Potassium is a plant macronutrient involved in metabolic activities. This mobile nutrient factors in activities like; production and translocation of essential compounds, cell division, root growth, and transpiration. However, it is often the most minimal nutrient in N-P-K fertilizers.

Symptoms of potassium deficiency include:

  • Dull, overly green leaves with rusty brown tips, subsequent chlorosis, and brown spots, especially on older leaves.
  • Dehydration, leaf burn, and curling of younger leaves.
  • Plant deterioration

Note: Tall, healthy plants may also be potassium-deficient. Check the bottom leaves.
LED/Light burn has a similar effect on the leaves as potassium deficiency.

Fixes:

  • Flush the entire system with fresh nutrients-infused water at a suitable pH level.
  • Using a water-soluble fertilizer rich in potassium.

Phosphorus
As an essential mobile nutrient, phosphorus plays an active role in metabolic activities, like photosynthesis and protein synthesis, within the plant.

Although there is a higher chance of running into phosphorus toxicity (excess phosphorus) than deficiency, it does not overrule the devastating effect of this deficiency.

Symptoms of phosphorus deficiency include:

  • Purpling of older stems and blue-green hue on leaves.
  • Retarded growth and blackish purple or dark copper spots on leaves.
  • Dead spots on areas like petioles.
  • Curling and subsequent dropping of leaves.

Tip: The lower the lighting, the less the chances of a phosphorus deficiency.

Fixes:

  • Use solubilized phosphorus.
  • Check and adjust the conditions of the growth medium accordingly.
  • Flush the entire system with fresh nutrients-infused water at a suitable pH level.

AUTOMATION MAKES IT ALL EASY

Operating a small-scale system is much different from growing for commercial purposes. To effectively meet demands, growers must adapt and scale processes, which brings a barrage of hurdles and challenges.

For a labor-intensive and delicate plant like hemp, the system will need skilled, competent staff. But as Jim Belushi taught us, err is human, and one tiny mistake could lead to catastrophic outcomes.

Thus, with a crop where consistency is critical to separating good yield from excellent yield, the answer many commercial growers seek lies in automation technology. Automating nutrient application will eliminate the variable of human error and maximize harvests.

Author: Deborah Agboola, Content Editor at Mariposa Technology

About Mariposa Technology

Putting Power & Profits Into The Farmer’s Hands

At Mariposa Technology, we are developing a revolutionary protocol for rapid, in-field testing of industrial and pharmacological hemp. By utilizing a handheld Raman Spectroscopy device, paired with our proprietary database, we will provide affordable, accurate and immediate test results. Our technology will bring the power of self-testing to farmers at a fraction of the price of traditional laboratory testing while also guaranteeing their digital farming experience optimizes their profits. Moreover, our technology will drastically reduce the carbon footprint of the hemp industry at large.

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