MANGANESE

Manganese deficiency accurs most often on high organic matter soils, on soils with neutral to alkaline pH and soil that are naturally low in Manganese content.

Deficiency symptoms:

Plants show yellowing, veins remain green. Mature leaves may be 'mottled.' First signs of deficiency often show up as small pin-head sized brown specks on the leaves. Flower formation is reduced. In cotton the young leaves are yellow (lower leaves are less affected) sometimes grey to reddish-grey between veins. The veins remain green. Mn deficiency will delay maturity.

Functions in plant:

Aids in chlorophyll formation: serves as a catalyst in enzyme reactions such as breakdown of carbohydrates, formation of vitamins and nitrogen transformation.

Mobility in plant: Relatively immobile.
Mobility in soil: Relatively immobile (Soluble forms are usually fixed into insoluble forms within 1 year.)
Influence of soil pH: The availability of Mn drops off sharply as the pH goes from 5.0-7.0.
Factors affecting level: High pH; low organic matter usually will give low Mn levels; some sandy soils are low in Mn; poorly drained, calcareous silts and clays are often low.
Factors affecting utilisation: pH; high levels of Fe, Cu and Zn may reduce uptake of Mn; problems show up more during dry years-apparently because of better drainage, thus more oxidation and less solubility of Mn.
Adequate level in plant: 23 ppm in soybeans, 25-30 ppm in cotton, sugar cane 40-250 ppm, wheat 10-300 ppm.

Corecting deficiencies:

Broadcast 5-20 kg per hectare (rate depends on soil pH and particular crop sensitivity); spray- 0.5-0.75 kg in 2-400 litres water per hectare. Mn sulphate is preferred over Mn oxide unless the pH of the fertilizer is very low.

Remarks:

The more acid forming the fertilizer, the more available the Mn. Mn toxicity occurs quite often below pH 5.0 plants vary widely in their response to Mn.

 

ZINK

Zinc concentration in the soil can decrease 30 fold for every pH unit increase between 5.0 and 7.0..

Deficiency symptoms:

Bronzing and yellowing between the veins of the leaf, the leaf margins and midribs remain green. Growth is retarded, internodes are shortened, maturity is delayed. The leaves become small, thick and brittle with upturned margins. Plants are usually stunted.

Functions in plant:

Needed in protein formation. Influences consumption of sugar in the plant. Necessary for many enzyme reactions in plant, including the forming of one of the plant hormones.

Mobility in plant: Slightly mobile in plant and immobile in soil.
Influence of soil pH: The availability goes down as pH goes up; over liming can induce deficiencies.
Factors affecting level: High pH, some soils (sandy or peaty) have a low total Zn content; removing Zn in topsoil by levelling or erosion; higher organic matter (such as topsoil) soils are generally higher in Zn.
Factors affecting utilisation: pH; high phosphate or magnesium levels may depress Zn; cold root zones limit uptake; a P:Zn ratio of greater than 150:1 is likely to depress Zn.
Level in soil: 2-40 kg per hectare available; approx 20-600 kg per hectare total.
Adequate level in plant: Cotton 20-80 ppm, soybeans 20-70 ppm, rice 20-50 ppm, apricot 20-100 ppm.

Corecting deficiencies:

Broadcast and incorporate 20-40 kg Zn per hectare. Thorough distribution is essential because of poor mobility. Foliar - deficiencies can be often corrected early when sprays of a 0.25-1.0% solution of Zn are applied.

Remarks:

Zinc is closely related to the organic matter of the soil. Zinc problems often show up where NPK fertilization is at a high level.

 

 

CHLORIDE

The essential elements, Cloride, Molybdenum, Cobalt and Vanadium, are not as well known as the others. However, improved understanding of their roles in plants can increase productivity.

Deficiency symptoms:

Symptoms include wilting, stubby roots, chlorosis (yellowing) and bronzing. Odours in some plants may be decreased.

Functions in plant:

Chlorine is involved in osmosis (movement of water or solutes in cells), the ionic balance necessary for plants to take up mineral elements and in photosynthesis.

Mobility in plant: Chloride, the ionic form of chlorine used by plants, is usually found in soluble forms and is lost by leaching.
Level in soil: The soil chloride supply is interpreted as deficient for cereal grain crops when there are fewer than 60 lbs Cl/acre in the surface 24 inches of soil.
Adequate level in plants: In many plants the optimum levels of chloride concentration in plant tissue are unknown. Depending on the plant species and soil chloride supply, plant tissue concentrations can range from 0.1 to 2.0% Cl. Some species appear to be healthy with only 0.01% Cl in their plant tissue. Small grains and corn need a minimum of 0.4% Cl in their tissue to achieve their full yield potential. In some crops, concentrations greater than 0.5% Cl can lower crop yield and quality.

 

POTASSIUM

Potassium is known to interact with almost all the other essential plant food nutrients. It is important for enzyme activation, efficient use of water, photosynthesis, transport of sugars, water and nutrient movement, protein synthesis, starch formation and crop quality.

Deficiency symptoms:

Deficiencies result in low yields, mottled, spotted or curled leaves, scorched or burned look to leaves.

Functions in plant:

Potassium is necessary for formation of sugars, starches, carbohydrates, protein synthesis and cell division in roots and other parts of the plant. It helps to adjust water balance, improves stem rigidity and cold hardiness, enhances flavour and colour on fruit and vegetable crops, increases the oil content of fruits and is important for leafy crops.