- OTHER IMPORTANT ELEMENTS
Some of the other elements which are important in plant nutrition and which have to be present in the soil to ensure maximum plant growth are:
Calcium is used by the plant for the continuous formation and division of cells and is an important part in the cell wall structure. It provides strength and helps the transportation of all the other elements around the plant. It can also act against alkaline salts and/or organic acids. It helps with reducing plant transpiration and the translocation of photosynthesis. This goes from the leaves to the fruits that are developing and increases fruit set. Calcium is involved with metabolising nitrogen and also stimulates microbial activity. Some sources of calcium are from dolomitic lime, gypsum and superphosphates.
Figure 1: Blossom-end rot in tomatoes which derives from a calcium imbalance (left).
Figure 2 Shows calcium deficiency in maize, the leaf stays rolled up and joined together on the younger leaves (right).
Source: hotpepperwax.blogspot Source: extension.uidaho
Magnesium is essential for the formation of Chlorophyll in the plant. This is the green pigment without which the plant cannot photosynthesise. Deficiency of Mg causes blotches on the leaves which then turn black and die. Acid sandy soils can be deficient in Mg, and a deficiency can also be caused by over-liming, when the plant takes up Calcium Ions (Ca++) instead of Magnesium Ions (Mg++). Magnesium is held in the soil as Magnesium Ions (Mg++) attached to the clay particles (clay colloids). Sources of Magnesium are Dolomitic Limestone which contains 12% Magnesium, and Epsom Salts (Magnesium Sulphate) which contains 16% Magnesium. Where a severe deficiency occurs, a weak solution of Epsom Salts can be sprayed onto the crop.
In the U.K. magnesium deficiency can occur in pastures and cause a deficiency in the grazing animal, particularly in milking cows. This causes brain fever which unless treated quickly leads to the death of the animal. It can be treated by injecting the animal with a solution of Magnesium.
Figures 3 and 4: Show magnesium deficiency in both maize (left) and in soya beans (right).
Source: nkcropbarometer.wordpress Source: soybeansoilfertility.blogspot
Sulphur is a constituent of all proteins and important in plant growth. It also helps with chlorophyll formation, root growth and seed production. It is an essential nutrient for protein production and development of enzymes and vitamins. However, it is seldom deficient in soils and is supplied by the fertilisers Sulphate of Ammonia and Sulphate of Potash, Gypsum and rain water which often contains some Sulphur, particularly around industrial areas.
Sodium is an important constituent of all plants and normally there is no deficiency in the soil. It is held on the clay colloids as Sodium Ions (Na+).
Figures 5 and 6: Show sulphur deficiencies in maize plants which have been grown under experimentation (left).
Source: agdev.anr.udel Source: agritech.tnau
- 2. TRACE ELEMENTS
These are elements which are essential to plant growth but are taken up by the plant in very small quantities.
Boron aids in the uptake of nutrients and regulates other nutrients. It helps in the production of sugars and carbohydrates as well as seed and fruit development. Deficiency causes rots in brassicas (cabbage, kale, etc.), hard fruit disease in citrus fruit.
Boron is essential for Legumes. It is supplied in some fertiliser compounds (see Fertiliser List) in amounts from 0.04% – 0.1%. An excess of Boron can cause the poisoning of plants.
Figures 6 and 7: Shows boron deficiencies in the fruit of a guava tree, notice the nodule like formations giving it a hard feel and appearance (left). The cauliflower head shows a dark colour resembling a rot (right).
Source: agritech.tnau Source: nchuntandfish
Figures 8 and 9: Shows boron deficiency on the inside of a cauliflower causing the rot.
Source: extension.umn Source: quantumagriculture
Manganese is involved with enzymes in the breakdown of carbohydrates and aids in nitrogen metabolism. Deficiency occurs in organic and sandy calcareous soils and can be caused by over- liming in any soil. Deficiency affects yields in potatoes and cereals and causes disease in oats and peas.
Cattle dung contains Manganese and this can he applied to the soil. In cases of severe deficiency a solution of Manganese can be sprayed onto the crop. Manganese is held in the soil as Manganese Ions (Mn++).
Figures 10 and 11: Show manganese deficiency in soya beans, the leaves of the plant showing yellowing of the leaf.
Source: soybeansoilfertility.blogspot Source: soybeansoilfertility.blogspot
IRON (Fe++ or Fe+++)
Iron is another element which is essential for the formation of Chlorophyll. Deficiency in the soil is rare but may occur after the soil has been limed. This is because the Iron in the soil has been made insoluble. It is held in the soil as Ions.
Figures 12 and 13: Show iron deficiencies, normally leading to a bleached appearance in severe
Source: httpthebestgardening Source: agritech.tnau.ac.in
Copper aids in the utilisation of proteins and root metabolism and is essential for reproductive growth. Deficiency can occur on some light, sandy soils and a shortage in grazing pastures can affect stock. One disease caused by Copper shortage is Swayback in lambs. Deficient pastures can be sprayed with Copper Sulphate but an excess is poisonous. Copper is held in the soil as Copper Ions (Cu++).
Figures 14 and 15: Show symptoms of copper deficiencies in which the leaves start curling upwards which is the case in tomatoes (left) and potatoes (right).
Source: grk142praktiesmetingvanplantjies Source: yara
Zinc regulates the consumption of sugars and the part of enzymes which adjusts plant growth. It is also important in the transformation of carbohydrates. Deficiency causes poor growth in fruit trees and maize caused by poor root development. Some soils are deficient in Zinc and fertilisers which contain zinc should be applied.
Figures 16 and 17: Symptoms of zinc deficiencies on citrus; oranges (left) and on tomato leaves
Source: plantali.blogspot Source: 4e.plantphys
It is essential for the bacteria living in the root nodules of legumes and aids in the uptake of nitrogen. The availability of Molybdenum rises as the soil pH rises which is one reason why legumes like lime. On some pastures in the U.K. excess molybdenum causes a deficiency of copper and this affects grazing stock.
Figure 18: Shows molybdenum deficiencies in butternut.
Chlorine helps with plant metabolism and is taken up by the growing plant in fairly large quantities therefore deficiency seldom occurs.
Cobalt is essential for animals and is thought to be essential for Plants although the reason is not known. It is held on the soil colloids as Cobalt Ions (Co+).