Whether you have a farm, a garden or an allotment, the nutrients needed by plants are the same. Obviously all plants need water, carbon dioxide and oxygen, but there are others. These divide into macro and micro nutrients.Macronutrients are required in larger quantities than micronutrients, but all are important for plant health.
These are six of these. Many fertilisers contain a range of nutrients, though in different proportions. The three essentials are nitrogen, phosporus and potassium, which is why many fertilisers give you their N, P, K ratio, K being the chemical symbol for potassium
Nitrogen. This is essential for promoting green growth and it comes from manure to a great extent, though any kind of hair or feathers will also provide a good supply of this important element. This is why shoddy, wool waste from mills, is mulched over rhubarb, which requires a good nitrogen supply when in its early stages.
Phosporus. This element makes for strong flower and fruit development, so high phosphate feeds are known as bloom boosters. Do not overdo the phosporus, as excess can inhibit the uptake of other nutrients and lead to chlorosis, leaves going pale and dying. Cattle manure is good for phosphates, the form in which phosporus is absorbable by plants.
Potassium: This element makes for a good root system and is considered important for maintaining plant health. The best potassium feeds are woodash, which is high in potash, and banana skins, whose potassium level is very high.
Calcium. This is vital for bringing soils to neutral pH, but it is also important for building plant cells. Calcium deficiency makes leaves go white. Blossom end rot in tomatoes is due to calcium not reaching the tomatoes in the required quantity.Lime is a good source of calcium, as is bone meal, crushed seashells and eggshells
Magnesium: Calcium and magnesium work together. Lack of it produces symptoms similar to calcium. This element is often found in lime, particularly dolomite.
Sulphur. This element fosters green growth and maintains a healthy balance of nutrients in soil. It is rarely lacking in Britain, as much has been added to soil by burning fossil fuels, which have deposirted sulphur from the air, but if the soil has too high a pH, sulphur can be added to bring it down.
You rarely need to add a specific feed for micronutrients, as they are spread throughout a large number of different organic substances.A good seaweed meal is usually high in these micronutrients, and home made fertilisers, such as compost made from household waste, are high. Unless there is a specifically recognizable problem, a general addition of fertiliser will suffiice. Experts might design specific supplements based on chemical analysis.
Boron: Blackening and weakening of leaves and weakened root growth are deficiency symptoms. This deficiency is more common on sandy soils than on others.
Chlorine: Paling of the leaves is a sign of chlorine defiiciency
Copper: Deficiencies are most common on organic soils, derived from peat, and chalky soils. Mineral soils, those deriving from parent rock, but containing a good quantity of organic matter are generally not affected by deficiency of this element. Leaves go yellow and wither.
Iron: Deficiency symptoms are similar to calcium deficiency, but most British soils are not lacking, the ones most likely to suffer being those on limestone. High levels of organic matter generally ameliorate deficiency symptoms
Manganese. This substance works in conjunction with magnesium and the deficiencies are hard to tell apart.
Molybdenum. Rarely deficient, except in acidic soils on occasion, but whiptail is a molybdenum deficiency disorder fround in cauliflowers, in which the leaf blade is thin.
Zinc: Few cases of zinc deficiency are found in Brtitain. Weakening of leaves is a symptom.
Prevention is better than cure. Ideally growers will supply a good, well-balanced base dressing to the soil that includes a range of elements. They will use manure, compost derived form a number of sources and sea weed. This will prevent deficiency problems from arising. They will continue to supply soil supplements while the plants are growing.