An introduction to plant nutrient deficiency and how to avoid it
Nutrients are an essential food source for plants, helping them to grow, develop, and reproduce. All plants will require a balanced nutrient source to help them grow. A lack of nutrients can cause your plants to suffer. Here’s an introduction to plant nutrient deficiency and how to avoid it.
What is plant nutrient deficiency?
Plants require nutrients as an essential food source. In the same way humans require vitamins and minerals for bodily functions, plants need nutrients for growth. Nutrients are crucial in a plant's lifecycle, giving it food for growth, development, and reproduction.
Plants absorb nutrients from the soil using their roots. As a result, certain conditions need to be present to increase the nutrient absorbency. Soil must be moist, at an appropriate temperature, and within a specific pH range.
Plant nutrients can be split into two categories: macronutrients and micronutrients. Macronutrients are those essential for plant growth and are consumed in large quantities. You should avoid micronutrient deficiency at all times.
Examples of macronutrients include:
- - Nitrogen (N)
- - Phosphorous (P)
- - Potassium (K)
- - Calcium (Ca)
- - Magnesium (Mg)
- - Sulphur (S)
Micronutrients are also crucial for plant growth but are consumed in much smaller quantities and less frequently. It’s also important to ensure plant roots can absorb micronutrients, such as:
- - Boron (B)
- - Copper (Cu)
- - Iron (Fe)
- - Manganese (Mn)
- - Molybdenum (Mo)
- - Zinc (Zn)
- - Chlorine (Cl)
- - Nickel (Ni)
While the optimum balance of these three factors will differ from species to species, it indicates the importance soil conditions play in allowing plants to use nutrients. Soil pH, in particular, can affect which nutrients are absorbed from soil.
The chart below indicates the optimal pH levels for each nutrient plant roots can absorb from soil:
Understanding pH levels
Soil pH is measured using a logarithmic scale ranging from 0-14. A pH reading between 0 and 6 is acidic, while 8-14 is alkaline. The middle number on the scale, 7, is neutral. The lower the number, the greater the acidity, while the higher the number, the greater the alkalinity.
pH stands for potential hydrogen and measures the number of hydrogen ions in the soil. It is important to monitor soil pH levels to ensure plants can absorb various nutrients that support different growth functions.
An incorrect soil pH causes the nutrients to become bound up in a form that plant roots cannot absorb. As a result, plants struggle to grow healthy due to a lack of food sources to support growth functions. For example, low soil pH limits the magnesium absorbency necessary for photosynthesis.
What causes plant nutrient deficiency?
Several factors can cause plant nutrient deficiency. However, predicting whether plants will experience nutrient deficiency can be difficult unless you monitor soil conditions and pH levels. Here are some of the common causes of plant nutrient deficiency:
- - Lack of nutrients in the soil.
- - Poor growing conditions, such as temperature.
- - Incorrect soil pH, high alkaline or acidic levels.
- - Dry or waterlogged soil.
- - Weathering effects on the soil, such as heavy rainfall.
- - Soil type, e.g. clay or sandy soils.
- - Using certain fertilisers.
The soil type is a significant factor affecting nutrients present in the soil and how easily plant roots can absorb them. Here’s an overview of how soil types affect nutrient absorption:
- - Clay soils are more likely to hold potassium but can suffer from phosphorous shortages.
- - Sandy soils are likelier to experience magnesium shortages, and potassium is more easily washed away.
- - Chalky soils are more likely to experience potassium washing away.
What are the different types of nutrient deficiency?
Nutrient deficiency can affect plants in many ways, depending on the nutrient lacking. Here is a breakdown of how some nutrient deficiency for the most crucial nutrients affects plants:
Nitrogen
- - Absorbed by plants in an ammonium of nitrate form readily dissolved In water.
- - Necessary for rapid plant growth, alongside increasing leaf size and quality.
- - Symptoms of nitrogen deficiency include yellowing of leaves, plant chlorosis, or spindly plants (flopping).
Potassium
- - Absorbed by plants as an ion that can be readily leached.
- - Necessary for sugar formation needed for protein synthesis, root development, and cell division. It also builds plants' resistance to diseases.
- - Symptoms of potassium deficiency include chlorosis on leaf edges, scorches from leaf edges, and necrosis (cell death).
Phosphorous
- - Absorbed by plants in a phosphate form.
- - Necessary for photosynthesis, seed germination, bloom stimulation, and protein formation.
- - Symptoms of phosphorous deficiency include the underside of leaves turning purple or bronze. Plant growth is also stunted.
Magnesium
- - Forms a structural element of chlorophyll modules.
- - Necessary for plant enzyme function, nutrient absorption regulation, and production of carbohydrates, fats, and sugars.
- - Symptoms of magnesium deficiency include interveinal chlorosis, slow plant growth, small leaf size, and shedding of lower leaves.
Manganese
- - Used as an enzyme activator for assimilating nitrogen.
- - Necessary for respiration, photosynthesis, and enzyme reactions.
- - Symptoms of manganese deficiency include interveinal chlorosis, light green areas around veins, small new leaf growth, and tip dieback.
Calcium
- - Calcium provides cell wall structural support.
- - Necessary for producing new root tips and growing points.
- - Symptoms of calcium deficiency include stunted growth of new roots and foliage, new leaves curling downwards, browning leaf edges, tip burn, or short, stubby roots.
Iron
- - Important for several plant functions within a plant’s metabolism.
- - Necessary for synthesising chloroplast proteins and other enzymes.
- - Symptoms of iron deficiency include interveinal chlorosis on new leaves, shoots dying from the inside, reduced leaf growth, and paler colouring of new leaves with necrotic spots.
Zinc
- - Used in triggering auxin and indole acetic acid.
- - Necessary for activating growth regulators.
- - Symptoms of zinc deficiency include chlorosis, mottling or browning of new leaves, reduced shoot growth, interveinal chlorosis, and a rosette-like discolouration of leaves.
Boron
- - Absorbed by plants as borate.
- - Necessary for cell differentiation.
- - Symptoms of boron deficiency symptoms include stunted or deformed growth, loss of apical dominance, new dark green growth, and small brittle leaves with short internodes.
How can you avoid nutrient deficiency?
There are several ways you can avoid nutrient deficiency for your plants, including:
- - Monitor pH using a soil pH meter and adjust the pH level as necessary.
- - Check your soil type and feed certain nutrients more easily washed away into the soil.
- - Regularly water plants when dry and avoid overwatering. Check if the soil is moist at finger depth is an excellent way to check.
- - Ensure soil doesn’t become too hot or cold during extreme weather.
- - Limit the use of certain fertilisers, such as potassium-rich fertilisers.
While many people are unaware, soil pH is crucial in preventing plant nutrient deficiency. If you spot any of the symptoms outlined above, you should begin testing the pH levels of the soil. Typically, this is the most significant cause of nutrient deficiency.