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Chelated Nutrients & Micronutrients for Better Crops

Just as people need a range of vitamins and minerals in addition to protein and carbohydrates, our plants need a range of major and minor nutrients to thrive and grow to their full potential.

Even if the soil has a high level of the main nutrients – Nitrogen (N) Phosphorus (P) and Potassium (K) – a lack of Manganese will hamper photosynthesis. Calcium is particularly critical for cell wall development and crop shelf life and Boron is needed to enable the uptake of Calcium.


Manganese plays a key role in several physiological processes, particularly photosynthesis. Manganese deficiency is a widespread problem, most often occurring in sandy soils, organic soils with a pH above 6 and heavily weathered tropical soils. It is typically worsened by cool and wet conditions.

Numerous crop species have been reported to show high susceptibility to Mn deficiency in soils, or a very positive response to Manganese fertilisation including cereal crops (wheat, barley and oats), legumes (common beans, peas and soybean), palm crops , citrus, potatoes, sugar beets and canola.

Iron, Magnesium and Zinc

Chlorosis is commonly caused by an inability to synthesise sufficient chlorophyll which can be caused by poor nutrition including a deficiency of Iron, Magnesium and Zinc.

Which soils are likely to need micronutrient supplements?

Generally soils organically fertilised with a mix of manures and composts are less likely to suffer from deficiency problems although they can occur. It depends on how the compost was made and what was in it. Soils that are just fertilised with basic commercial fertiliser like Growmore are most likely to suffer from micro-nutrient deficiencies.

Soil Acidity

Another factor that can limit nutrient availability is the soil acidity. Most vegetables like a pH level around 6.5 which is the level at which the main NPK macro-nutrients are most available but most soils naturally fall outside of this range.

Locked Up Nutrients

Nutrients in composts or occurring in soil from organic materials naturally decomposing can be unavailable to plants because they are insoluble in water. The nutrients are said to be ‘locked up’. Healthy soil will contain biological systems, usually fungi based, which produce natural chemicals like chelates. Over time these change the nutrients making them more available to the plants.

Imbalances in nutrients can cause other nutrients to become locked up. A good example most tomato growers will know is applying too much high-potash and phosphorus fertiliser causing magnesium deficiencies.

Remember, just one micro-nutrient in short supply will limit growth even if all the other nutrients are available.

Benefit of Chelated Nutrients

Chelated nutrients combine the nutrients with other chemicals in a process which enables them to be available to plants across a wide pH range. This makes them more easily assimilated by the plants than non-chelated minerals. Because they are safe and biologically friendly, they have been found to work with the soil biology not against it, so effectively feeding the soil which then continues to feed the plant.

Soil Association Approved

Soil Association ApprovedUnlike many micronutrient supplements, S-Chelate products are non bio-accumulative. They do not build up in the soil and cause other nutrients to become locked up. The S-Chelate chelating agent has Soil Association approval so all of their micronutrient-only products are approved for organic growers.

Established chelating agents like EDTA, DPTA and EDDHA are bio-accumulative so are not so biologically friendly.

What crops benefit from Chelated Micronutrients?

Different crops are more sensitive to lack of some micronutrients than others – as the examples below show:

  • Lettuce is particularly sensitive to lack of magnesium and copper as are onions and strawberries
  • Leafy brassicas need a good level of iron with cauliflowers showing brown curds being a problem of low boron availability.
  • Sweetcorn reacts badly to low levels of zinc.

S-Chelate produce chelated nutrients in bulk for the horticultural and agricultural markets. Realising the need small scale home growers have for micronutrient supplements they have produced two new products.

S-Chelate-O Cultiv-8

s-chelate-o cutiv-8S-Chelate-O Cultiv-8 is a concentrated Plant Health and Growth Booster. Supplied in completely water-soluble powder form, it contains 8 of the most important micronutrients and is Soil Association approved for Organic Growing. It is designed to work with organic composts or on established plants by enhancing and unlocking available naturally occurring nutrition.

A 350gram pack of S-Chelate-O Cultiv-8 will produce 100 x 4.5 litres (1 gallon)  watering cans of ready to use plant food

S-Chelate 12 Star

12-Star Fertiliser PackThis is a complete feed that contains all the micronutrients in S-Chelate-O Cultiv-8 plus the 4 most important macronutrients.NPK and Calcium. Ideal for container growing, greenhouse borders and general garden use.

A 500gram pack of S-Chelate 12 Star will produce 50 x 4.5 litres (1 gallon)  watering cans of ready to use complete plant food

Case Studies

S-Chelate have seen great performance from S-Chelate-O Cultiv-8 over a number of years in informal trials. Recently they have conducted controlled trials comparing market leading plant foods with S-Chelate 12 Star which incorporates the other major nutrients of Nitrogen, Phosphorus, Potassium and Calcium.

The Avocado trials detailed on their website show the results of a controlled comparison of S-Chelate 12 Star against two long established competitive feeds.

There are also case studies of the following plants:

  • Fruits – Avocados, Figs, blackcurrants and plums
  • Flowering plants – Orchids, Agapanthus, Ceanothus, Amaryllis and Iris
  • Field & Food Crops – Winter Linseed, Potatoes, Beetroot, courgettes
  • Cacti and Succulents – Christmas Cactus-Schlumbergera x buckleyi, Schlumbergera truncate, Trichocereus pachanoi
  • Herb – Basil
  • Aquarium plants – plants and tropical fish all thrived

Further Information

S-Chelate Fertilisers

Understanding and Applying Chelated Fertilizers Effectively Based on Soil pH, Guodong Liu, Edward Hanlon, and Yuncong L – publication University of Florida (pdf)

What Are NPK – Basic Components of Fertiliser Explained

Effects of pH on Nutrient Availability

Elements of Plant Nutrition: Calcium, Sulphur, Magnesium

Trace Elements in Plant Nutrition

This article was produced in conjunction with Barry Langdon of S-Chelate. If you have any questions regarding chelated nutrients you can contact him here

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