Fertilizer Types and What They Contain
Fertilizer Types and Their Contents
Each one of the essential nutrients — nitrogen, phosphorus (in phosphate) and potassium (in potash) —can be purchased separately as so-called ‘straight’ fertilizers, or in balanced mixtures known as ‘compound’ or ‘general’ fertilizers. The latter type generally include the most important trace elements.
Below is a table detailing the nutrient content of each one, together with application method and special features.
|APPLICATION METHOD||SPECIAL FEATURES|
|10% magnesium sulphur||Top dressing||Effective against chlorosis|
|Nitrate of Ammonia||35% nitrogen||Liquid feed||Do not mix with lime|
|Nitrate of soda
|16% nitrogen; trace elements||Top dressing||Fast acting but quickly washed out of the. Keep off foliage|
|Nitro chalk||16% nitrogen; calcium||Top dressing||Contains 48% lime. Long lasting, fast-acting; useful on acid soils. Can be used to aid rotting of compost.|
|Potassium nitrate||12-14% nitrogen; 44-46% potash||Top dressing / liquid feed||A general spring fertilizer. Impure Chilean potash nitrate contains only 15% K2O|
|Sulphate of ammonia||21% nitrogen; sulphur||Top dressing||Best source of N, but makes soil more acid. Do not mix with lime. Fast-acting.|
|Sulphate of iron||Iron; sulphur||Top dressing||Effective against iron-induced chlorosis. Acidifies the soil|
|Sulphate of potash||48% potash||Base or top dressing||Best general source of potash. Fast-acting forand fruit. Acidifies the soil|
|Superphosphate||13-20% phosphate||Base dressing||Best source of phosphates. Keep off delicate leaves. Do not mix with sodium nitrate|
|Urea||46% nitrogen||Liquid / foliar feed||Very rich source of N. Apply in spring|
2-5% nitrogen; 20-30% phosphate; calcium
Base or top dressing
Slow-release fertilizer; apply in spring or autumn. Contains lime. Ensure it is sterilized
|Dried blood||10-13% nitrogen||Top dressing / liquid feed||Fairly fast-acting. Apply in late spring or summer. Ideal for leaf vegetables|
|Fish meal||6-10% nitrogen; 5-12% phosphate; 1-2% potash||Base dressing||Fairly slow-release; apply during spring cultivation, one spade’s depth.|
|Hoof and horn||7-15% nitrogen; 1-10% phosphate; calcium||Base dressing||Fairly slow-release, though speed depends on fineness of grinding. Apply in spring|
|Wood ash||2-9% potash||Top dressing||Must be kept dry to retain potash. Young wood produces the richest ash. Not for chalky soil|
|7% nitrogen; 7% phosphate; 7% potash||Base or top dressing||Good general-purpose fertilizer. Apply in spring. Now available also in liquid form|
|John Innes base||5% nitrogen; 7% phosphate; 10% potash||Base or top dressing||Contains hoof and horn; slow-release of N. Used mainly in potting mixtures|
|Rose fertilizer||5% nitrogen; 6% phosphate; 12% potash; iron; magnesium||Top dressing||Fairly fast-acting. apply in summer. Specially formulated for, but suitable for others|
|Sequestine tonic||Magnesium; manganese; iron||Top dressing||Cures yellowing. May include other trace elements|
|Tomato fertilizer||6% nitrogen; 5% phosphate; 9% potash||Liquid feed||Used as weekly feed throughout the growing period to promote a high yield. Ideal for growing bags.|
Nutrient Deficiency Symptoms
Use the above table to assist with correcting the following plant deficiency symptoms:
Nitrogen deficiency is indicated by poor, stunted growth with pale leaves and weak stems. Leaves often turn orange, red or purplish and may fall prematurely. Fruit trees and vegetables are most commonly affected.
Potassium deficiency is indicated by brown scorching around the edges of the leaves. Flowers may be dull and sparse, and fruit yield may be low and of poor quality. Tissues are soft and more prone to pests and diseases.
Magnesium deficiency is indicated by yellow patches between the leaf veins which later turn brown. The affected leaves may wither. Roses andare often affected. Magnesium sulphate (Epsom salts) spray is the best cure.
Manganese deficiency is indicated by yellowing between the veins of older leaves. Leaf edges may become slightly in-curled and brown. Many types of plant may be affected occasionally. Apply a sequestrine plant tonic.