I’ve recently taken up growing vegetables and herbs, tantalised by the idea of saving pennies at the Supermarket. Really, I had the desire come on slowly after looking up The Machinery of Life by David Goodsell, which features illustrations of molecules and cells. I haven’t picked myself up a copy just yet but looking into the organisation of these cells lead me to giving gardening, at least on the small scale, a go.

I picked up a book called Botany for Gardeners, a nice little pop-science book explaining some of the science behind plants, using examples of plants that most gardeners in the UK would be familiar with. The book features a section talking somewhat about the macronutrients and micronutrients for the plants. I wondered what the ideal profiles would be for the plants, leading me to do a small bit of searching to see what ratio of minerals within the soil would best help my plants to grow.

Botany for Gardeners recommends to only buy soil fertiliser that lists an N:P:K ratio on the label. N:P:K stands for Nitrogen, Phosphorus, and Potassium, three main macronutrients.

For reference, as a pizza appreciator, I am currently growing tomatoes, garlic, sweet peppers, oregano, and basil.


Nitrogen

“Nitrogen is an essential nutrient for plant growth, development and reproduction. Despite nitrogen being one of the most abundant elements on earth, nitrogen deficiency is probably the most common nutritional problem affecting plants.”

Nitrogen is an essential component of proteins and chlorophyll. Nitrogen can be derived from organic matter within the soil, when it is slowly broken down by micro-organisms.

Nitrogen is also highly soluble, and so watering the plants can end up washing away a significant amount of the macronutrient from the soil.

Good sources of nitrogen are manure, blood, and ammonium nitrate fertilisers.

Phosphorus

“Phosphorus is an essential nutrient both as a part of several key plant structure compounds and as a catalysis in the conversion of numerous key biochemical reactions in plants. Phosphorus is noted especially for its role in capturing and converting the sun’s energy into useful plant compounds.”

Phosphorus is important for cell division and commonly associated with healthy root growth. Legumes have a high demand for phosphorus.

Sources of phosphorus include rock phosphate, bonemeal, and fish, blood and bone.

Potassium

“Potassium is essential in nearly all processes needed to sustain plant growth and reproduction. Plants deficient in potassium are less resistant to drought, excess water, and high and low temperatures. They are also less resistant to pests, diseases and nematode attacks.”

Potassium controls water uptake by the roots and reduces water loss from the leaves. Potassium also promotes flowering and fruiting, making it very important for my needs growing tomatoes and peppers.

Sources of phosphorus include manure, and sulphate of potash.

Calcium

“Calcium is a low-key essential nutrient that carries a heavy load in plant growth. Too often, it takes a backseat as soil fertility programs are developed for many high-yield and high-quality crops. Peanut and tomato growers are probably exceptions in their emphasis on good calcium nutrition.”

Calcium regulates the transport of nutrients between cells and is involved in the activation of certain plants enzymes. Calcium concentration in the soil determines acidity and alkalinity. It also assists in nitrate-nitrogen conversion and improves resistance against diseases.

Calcium is commonly found as chalk, limestone and gypsum, and can be added to the soil.

Magnesium

“Wheat and other crops require magnesium to capture the sun’s energy for growth and production through photosynthesis. Magnesium is an essential component of the chlorophyll molecule, with each molecule containing 6.7 percent magnesium. Chlorophyll, the green pigment in plants, is the site where photosynthesis occurs. Without chlorophyll, plants could not manufacture food, and life on Earth would cease to exist.”

Deficiency in magnesium results in interveinal chlorosis (yellowing between the leaf veins) and is aggravetd by soil compaction and waterlogging.

A remedy for deficiency can be magnesium sulphate or Epsom salts.

Sulfur

“Sulfur is supplied to plants from the soil by organic matter and minerals, but it is often present in insufficient quantities and at inopportune times for the needs of many high- yielding crops. Most S in the soil is tied up in the organic matter and cannot be used by plants until it is converted to the sulfate (SO₄²⁻) form by soil bacteria. That process is known as mineralization.”

Sulphur is a structural component of many cell proteins and is essential in the manufacture of chloroplasts, making it vital in photosynthesis. Deficiency is rarely seen, luckily, because of the vast amounts in our atmosphere due to heavy industrialisation that causes it to rain down.

Micronutrients

There are several other minerals that are used by plants, however these are required in smaller amounts and the amount of easy-access literature on them is lesser than for the macronutrients displayed above.

  • Boron - one of the most important micronutrients affecting membrane stability
  • Copper - activates enzymes and catalyzes reactions in several plant-growth processes
  • Iron - essential for crop growth and food production
  • Manganese - primarily as part of enzyme systems in plants, it activates several important metabolic reactions
  • Molybdenum - required for the synthesis and activity of the enzyme nitrate reductase
  • Zinc - one of the first micronutrients recognized as essential for plants and the one most commonly limiting yields
  • Chlorine - active in energy reactions in the plant
  • Nickel - important in plant N metabolism because it is a component of the urease enzyme

If you’ve found this article interesting and would like to read more, I recommend the following websites:

References