School Science Lessons
2024-6-22
(Soils3)
Soil Science 3
Contents
6.15.0 Soil mineral deficiencies
6.11.0 Mineral deficiency symptoms
6.12.0 Macronutrients in soils
6.13.0 Micronutrients in soils
6.12.0 Macronutrients in soils
6.12.1 Calcium deficiency in soils
6.12.2 Magnesium deficiency in soils
6.12.3 Nitrogen deficiency in soils
6.12.4 Phosphorus deficiency in soils
6.12.5 Potassium deficiency in soils
6.12.6 Sulfur deficiency in soils
6.13.0 Micronutrients in soils
6.13.1 Boron deficiency in soils
6.13.2 Chlorine deficiency in soils
6.13.3 Cobalt deficiency in soils
6.13.4 Copper deficiency in soils
6.13.5 Iron deficiency in soils
6.13.6 Manganese deficiency in soils
6.13.7 Molybdenum deficiency in soils
6.13.8 Nickel deficiency in soils
6.13.9 Zinc deficiency in soils
6.11.0 Mineral deficiency symptoms
A mineral element is essential if it is necessary for the reproduction of the plant.
The sixteen essential elements are as follows: carbon, hydrogen, oxygen, nitrogen, phosphorus, potassium, calcium, magnesium, sulfur, iron, manganese, zinc, copper, boron, molybdenum and chlorine.
The 7 macronutrients, 1 to 150 g per kg of plant dry matter required, are N, P, K, Ca, Mg, Na, and S.
The 9 micro nutrients, 1 to 1.00 mg per kg of plant dry matter required, are Fe, Zn, Mn, Cu, B, Mo, Cl, Ni, Co.
The main function of micronutrients is as catalysts for chemical reactions in the plant.
Chloride is a micro nutrient, but it can accumulate in the plant if present in high concentrations in the soil solution.
Mineral deficiency symptoms are sometimes confused with damage caused by insect pests, disease, salt stress, pollution, light and temperature injury and herbicide damage.
Also, toxicity of Mo or Se is similar to P deficiency and Fe deficiency in a mango is similar to chloride toxicity.
Interrelationships in mineral nutrition
Excess potash can reduce magnesium uptake.
Excess potassium can replace calcium in the plant, creating problems
Excess sodium can replace potassium, creating problems.
1. calcium / magnesium ratio
Excess lime can cause magnesium deficiency
2. Iron / manganese ratio
Iron should always be higher than manganese.
Iron chlorosis may occur when iron levels on leaf analysis fall below 50 ppm, or when manganese exceeds iron levels by two times or more.
3. Calcium / boron ratio
Boron may be toxic in the absence of sufficient calcium.
4. Phosphorus / magnesium ratio
Phosphorus is often taken up by plants as a magnesium compound, so magnesium may alleviate phosphate deficiency more efficiently than applied phosphate.
5. Phosphorus / zinc ratio
The ideal phosphorus / zinc ratio is 10:1.
Excess phosphorus will reduce zinc uptake, and excess zinc will reduce phosphorus uptake.
6. Molybdenum / nitrogen ratio
Nitrogen-fixing bacteria cannot fix atmospheric nitrogen to the soil without molybdenum.
6.12.1 Calcium deficiency in soils
The plants are small with unusually shaped leaves.
The shoot tips may die.
Chlorosis of young leaves along the veins, in birdsfoot trefoil and blueberry.
Bleaching of upper half leaf, then leaf tip curling, in black pepper and sugarcane.
Growing bud leaf chlorotic white, but leaf base remains green, and distortion of the tips of shoots, i.e. dieback, in peach seedlings.
Brown spots on leaves, reduced expansion and premature leaf senescence, in soybean.
Calcium stress during fruiting increases susceptibility to blossom end rot, in tomato.
Symptoms: bitter pit in apple, leaf tip burn in cabbage and lettuce, black heart of celery, cavity spot of carrots, vitrescence in melons.
Lime applications are used to prevent root rot, depending on the buffering capacity of the soil.
6.12.2 Magnesium deficiency in soils
Magnesium deficiency causes yellowing, but it is unlike the yellowing of leaves caused by nitrogen deficiency.
The yellowing occurs between veins of older leaves and veins remain green, leaf curl may occur, followed by necrosis of tissues
in bird's foot trefoil, melons, black pepper and blueberry.
Magnesium deficiency may be caused in tomatoes by high levels of ammonium ion in a nutrient solution.
Magnesium deficiency of citrus causes yellow areas near the midrib.
6.12.3 Nitrogen deficiency in soils
The plants are small with few leaves that are pale green or yellow.
The lower leaves look burnt and die early.
Nitrogen deficiency symptoms are the appearance of uniform yellowing of leaves including the veins, in older leaves of blueberry, fescue, chilli and sugarcane.
The leaves become stiff and erect.
In dicotyledons the leaves detach easily under extreme nitrogen deficiency.
Cereal crops show characteristic V-shaped yellowing at the tip of the lower leaves.
Small and pale green leaves with dull appearance occur in sweet potato.
If nitrogen deficiency persists, decreased foliage and shoot growth occurs in black pepper and sapota.
6.12.4 Phosphorus deficiency in soils
Plants are small, take a long time to produce fruit which are small and badly-shaped.
Leaves are a blue-green colour and are usually purple underneath, with lower leaves dying early.
Leaves remain small, erect, and unusually dark green with greenish red in sweet potato, blue-green in chilli, brown in bird's foot trefoil
and with purple tinge in sugar maple, blueberry and sugar cane.
Under side of the leaves develop a bronze appearance.
Restriction of root growth in black pepper and increase of anthocyanin pigment in leaves of barley and thale cress (mouse-ear cress),.
6.12.5 Potassium deficiency in soils
The plants have small main shoots, but many side shoots.
The leaves have dead white areas on the leaf edges and later die.
Potassium deficiency causes yellowing of leaves starting from the tips or margins of leaves extending towards the centre of leaf base.
The yellowing is interveinal and irregular in the leaves of tomato and blueberry.
These yellow parts become necrotic (dead spots), with leaf curling in tobacco, sugar maple, sapota and sugarcane.
There is a sharp difference between green, yellow and necrotic parts.
6.12.6 Sulfur deficiency in soils
Plants are small with pale green upper leaves.
Leaves yellow in black pepper, potato, and wild cabbage, and so appear similar to nitrogen deficiency.
Symptoms are first visible on younger leaves.
Affected leaves are narrow and the veins are paler and chlorotic than in the interveinal portions, especially towards the base with marginal necrosis in sugarcane.
6.13.1 Boron deficiency in soils
1. Boron is associated with several of the functions of calcium.
Boron improves calcium efficiency and vice-versa.
However, if calcium levels are low, boron may become toxic.
So calcium and boron deficiency must always be addressed together.
Boron is the most leachable of micronutrients, so in light soils it is difficult to maintain good levels in wet conditions.
Also, boron availability declines just as rapidly in very dry conditions.
Boron is not readily mobile within the plant.
I ppm of boron is considered an ideal level within the NTS Soil TherapyTM approach, but this level is hard to maintain.
Foliar applications immediately before flowering is recommended.
2. Functions of boron
* Synthesis of cell wall components.
* Germination of pollen, growth of pollen tubes, fruit set.
* Cell division and elongation of cells near the tips of shoots and roots.
* Pollen viability and good seed set.
* Nitrogen availability to the plant.
* Calcium efficiency within the plant.
* Nodulation of legumes.
* Carries starch from the leaf to the grain or fruit.
3. Causes of boron deficiency
Sensitivity to boron deficiency varies between different plant species.
* Leached, acidic soils
* Calcareous or over-limed soils
* Light, sandy soils
* Excessive usage of potassium and nitrogen
* Drought conditions
* Soils low in organic matter
* Soils with high pH
* Low phosphate levels, e.g. maize
4. Boron deficiency symptoms
Boron deficiency is uncommon, but may occur in areas of high rainfall and leached soils.
Also, boron may be present in the soil, but is not available in soils with a high pH especially in wet seasons.
The primary role of boron is its involvement in the stabilization of the primary cell walls in plant cells.
Boron is also involved in the carbohydrate metabolism in plants, protein synthesis, seed and cell wall formation, germination of pollen
grains and growth of pollen tubes and sugar translocation.
Boron is important for cell division and for development in the growth regions of the plant near the tips of shoots and roots.
It also affects sugar transport and aids the assimilation of calcium.
Boron affects pollination and the development of viable seeds that, in turn, affect the normal development of fruit.
Some boron is needed for the plant to use calcium.
Boron is more readily leached than other micronutrients especially from acid sandy soils or the highly weathered red basaltic soils.
Heavy leaching rainfall can remove much of the available boron from the surface soil.
Drought or cool spring or autumn soil temperatures can reduce the root's access to boron and capacity to absorb soil boron.
Fruit crops require a small, but continuous supply from the soil for growth, pollination and fruit development, so a deficiency of boron can be induced by fluctuating seasonal conditions and symptoms may suddenly appear although the problem has not been seen for years.
5. High levels of exchangeable aluminium, over-liming, excessive irrigation, heavy application of potassium or nitrate fertilizers, and practices that lead to root damage or soil compaction can induce boron deficiency.
6. Loss of soil organic matter under orchard culture also reduces the capacity of soils to retain boron in older orchards.
7 Symptoms may affect fruit, shoots, and leaf growth, but unless the deficiency is severe the symptoms in the fruit are usually noticed first.
The effects of deficiency appear first in young tissues, growing points, root tips, young leaves and developing fruit.
Boron is more readily leached than other trace elements especially from acid sandy soils or the highly weathered red basaltic soils.
Heavy leaching rainfall can remove much of the available boron from the surface soil.
Drought or cool spring or autumn soil temperatures can reduce the root's access to boron and capacity to absorb soil boron.
Since fruit crops require a small, but continuous supply from the soil for growth, pollination and fruit development, a deficiency of boron can be induced by fluctuating seasonal conditions.
So symptoms may suddenly appear in one season though the problem has not been seen for some years.
High levels of exchangeable aluminium, over-liming, excessive irrigation, heavy application of potassium or nitrate fertilizers, and practices that lead to root damage or soil compaction can induce boron deficiency.
Loss of soil organic matter under orchard culture also reduces the capacity of soils to retain boron in older orchards.
Symptoms may affect fruit, shoots, and leaf growth, but unless the deficiency is severe the symptoms in the fruit are usually noticed first.
The youngest leaves and stem show a yellowing or chlorosis, starting from the base to the tip, dieback and distortion of the growing point.
Symptoms include rosettes of terminal shoots in potato, browns heart in radish, crown choking in coconut, lumpy flesh and bad taste in papaya fruit, and leaf tip burn that elongates and become white-brown in rice.
In extreme cases, the terminal bud dies.
In small crops brittle tissue may crack or split.
The surface of petiole stems and leaves develop many transverse cracks or corkiness.
Storage roots split, and stems develop hollow sections.
The growing point may die, creating multiple shoots.
In fruit crops, symptoms can be found in fruit shoots and then leaf growth.
Trees with severe boron deficiency can suffer from die-back in spring, because buds fail to develop.
Fruit may be misshapen, with irregular depressions developing as it ripens.
Uneven development of berries and seedless berries within the bunch, in grapes.
Burning and crinkling of the edge of young leaves, stunting of the growing part and deformed fruit, in strawberries.
Stunting of young plants, shortened, bent ears, tip kernels aborted and leaves fail to emerge and unfurl, in cereals.
Upper leaves become rosetted and turn yellow, in lucerne.
Dark depressions in the centre of the nut, in peanuts.
Shortened internodes, death of the growing bud, and tuber stem-end browning, in potatoes.
Examples of boron deficiency include "beetroot cancer", "cauliflower hollow stem", "water core" of turnip, "internal cork" in pome fruit.
8. Sources of boron
* Borax, sodium tetraborate, Na2B4O7.10H2O, white powder, colourless crystals, easily dissolves in water, contains l% boron, is
useful in maintaining soil levels.
However, borax is too soluble and excess boron is highly toxic to plants, so when applying the borax to the soil spread it evenly over the area and crush all lumps to avoid high concentration places.
Polyborate fertilizer at half the borax rate can be dissolved in water and sprayed onto the soil.
A spray of 1 g borax dissolved in a cup of hot water and 1 g urea or urine in 1 litre of water sprayed at early flower bud stage increases fruit set.
* Inkabor/Solubor, Peruvian boron-based organic fertilizer, is a more soluble boron source, containing 21% boron.
* Ulexite mineral, hydrated sodium calcium borate hydroxide, NaCaB5O6.5H2O, contains 14% boron, is naturally fused with a calcium
synergist.
* NTS Stabilized Boron HumatesTM, stabilized boron product with leachability not a problem, because boron is complexed by humates.
* Nutri-Key Boron ShuttlerTM, 4.7% liquid boron with 14 elements of background nutrition and organic additives, including fulvic acid.
9. Recommended foliar spray is 150 g / 100 L polyborate powder (20.5% Boron).
Soil application of 20 - 30 kg / hectare suit most crops and soils including bananas and pineapples, but the rate for papaya should be < 20 kg / hectare.
Borax is too soluble.
Excess boron is highly toxic to plants so when applying the borax to the soil spread it evenly over the area and crush all lumps to avoid high concentration hot spots.
Polyborate fertilizer at half the borax rate can be dissolved in water and sprayed onto the soil.
A spray of 1 g borax dissolved in a cup of hot water and 1 g urea or urine in 1 litre of water sprayed at early flower bud stage increase fruit set.
10. "OrganiBOR", CaO.MgO.3B2O3.6H2O, is a naturally occurring, certified for organic use, magnesium/calcium borate that replenishes the boron levels in the soil.
It can be applied once every 2-5 years depending on the crop, climatic and soil conditions.
It will continually release boron over that period of time so the plants, vines or trees will have a continual supply of boron right through all of their growing phases.
The effect on the tree is the same as if it was grown in boron rich soils.
11. Using boron to speed up natural maturity and senescence, by John Kempf, Sub-Tropical Fruit Club of Qld. Inc, April-May 2020
One of the characteristics boron is known for is to facilitate rapid nutrient transport to the sugar sinks.
This effect can be very valuable to speed up crop maturity and senescence while also increasing harvest quality.
When an alfalfa crop is growing rapidly and still very vegetative in late fall as we approach winter dormancy, it is possible to quickly
trigger senescence and rapidly move the sugars contained in the plant down into the crown with a generous foliar application of boron.
A treated section can turn brown within a few days to a week (depending on weather and time of year), as all the sugars move down into the crown and the plants begin to senesce.
The following spring, the section treated with boron in the fall will emerge from winter dormancy much faster and with many more shoots than an untreated section, because the crowns have much more energy from the stored sugars.
Any perennial crop with a similar growth pattern will show this effect.
This effect can also be used to speed up the natural maturity process of other crops.
A generous foliar application of boron on fruit such as tomatoes or apples will speed up the natural sugar transport into the fruit.
This can help the fruit colour and mature quickly and evenly days to weeks earlier than plants without a generous supply of boron.
This effect of boron on speeding up maturity and natural ripening can also be used on small grains in place of a desiccant or harvesting aid.
Wheat that receives a foliar application of boron can mature rapidly and dry down as much as five to ten days faster than plants without adequate boron.
The upside is that there is often a gain in test wheat and protein content, since boron produces this effect by increasing photosynthesis
and protein transport into the grain rather than reducing transport to the grain as a desiccant might.
Boron does not produce these effects if the crop is not at the right stage of growth.
It can only speed up the plant processes which are occurring naturally.
Managed well, boron applications can speed up these natural processes dramatically, and produce a higher quality grain or fruit, with an improved nutritional content.
How much boron is required?
It varies based on the existing boron content of the soil and the crop.
Many crops and soils are deficient, which is why crops are not maturing well in the first place.
Often, the upper end of label rates are required if this is the only application being applied in the season.
It is better to supply the crops foundational boron requirements during the growing season, and then top off the requirements with a lighter application a few weeks before maturity to produce the optimal effects we are looking for.
6.2,2 Chlorine deficiency in soils
Discrete patches of pale green chlorotic tissue between the main vein near the tip of the leaf, first on older leaves, and downward upping of older leaves of kiwi fruit.
Leaflets of the youngest leaves shrivel completely.
Older leaflets develop brown necrosis that starts near the tip and extend backwards, particularly at the margins in red clover.
6.13.3 Cobalt deficiency in soils
1. Cobalt is rarely measured in soil tests, but it plays a significant role in the support of Rhizobium and other soil bacteria.
0.5 ppm is considered ideal concentration.
2. Functions of cobalt
* Involved with atmospheric nitrogen fixation by Rhizobium bacteria on legume plants.
* Promotes soil bacteria.
3. Symptoms of cobalt deficiency
* Limited Rhizobium colonization on legume roots.
* Nitrogen deficiency in legumes, i.e. chlorosis and poor growth.
4. Sources of cobalt
* Cobalt sulfate: A soluble powder, useful for adding to irrigation or foliar feeding.
* Vitamin Bl2 is a good natural source of cobalt.
* Nutri-Key Cobalt ShuttlerTM, cobalt-based liquid fertilizer.
6.13.4 Copper deficiency in soils
1. Copper deficiency causes visible foliar symptoms appear on young leaves as chlorosis changing to necrosis, the rolling, wilting and twisting of leaves in wheat and the later affected leaves appearing papery and twisted in rice.
The stem may have an s-shape between internodes.
Copper is involved in the formation of lignin for strong shoots and stems.
The ideal range in the soil is 5-10 ppm canola.
Copper inhibits the growth many species of fungi, but copper levels in the soil become too high (above 15 ppm), it may affect beneficial fungi
Excess copper may affect phosphate, zinc and iron uptake, and may limit wheat, maize, pasture, orchard crops, onion, spinach and canola.
2. Functions of copper
* Essential in many enzyme systems, particularly those associated with grain, seed and fruit formation.
* Important for water movement within the plant.
* Copper is a key component in many proteins.
* Essential for chlorophyll formation and associated photosynthesis.
* Regulates elasticity, i.e. it has a marked effect on the formation and composition of cell walls.
Important for strong, flexible stems.
* Vitally important for root metabolism.
* Helps prevent development of chlorosis, rosetting and die-back.
* Provides a natural fungicide effect.
3. Causes of copper deficiency
* Light, sandy, coastal soils are invariably deficient.
* Peaty, high-organic matter soils tend to hold copper, strongly reducing plant availability.
* Excessive phosphate and nitrogen can limit copper availability.
* Over-liming can create deficiency.
* High zinc levels can reduce copper uptake.
* High soil pH.
* Drought conditions can intensify any copper problems.
4. Copper deficiency symptoms
Copper deficiency causes visible foliar symptoms appear on young leaves as chlorosis changing to necrosis, the rolling, wilting and twisting of leaves in wheat and the later affected leaves appearing papery and twisted in rice.
The stem may have an S-shape between internodes.
Deficiency symptoms normally occur on new growth.
In small crops, symptoms vary between crops, but there are some common symptoms:
* Crops are usually patchy, stunted and yield poorly.
* Youngest leaves are worst affected.
* Plant is often wilted and lacks firmness.
* Leaf rolling, bending or crinkling is common.
In fruit crops, young shoots may be vigorous, but are weak and become S-shaped as they bend and continue to grow.
* The leaves on these shoots are usually large, but pockets of browned gum form on the stems, and affected twigs often die back.
Fruit peel on citrus often develops gum-impregnated browning.
* Leaf tips die and curl like pigs tails in maize and small grains:
* Youngest tissue turns faded green with a greyish cast, and plants appear bushy and drought stricken, in lucerne.
5. Sources of copper
* Copper sulfate, CuSO4.5H2O, "bluestone", a soluble powder containing 23% copper, is the best material to build soil levels.
Maximum application at any one time is 20 kg per hectare, because copper applications can affect soil life.
Copper sulfate can be used as a foliar application and may be more effective than the more expensive hydroxides and oxychlorides.
* Copper Chelates (EDTA), should be avoided in favour of naturally chelated products.
* Nutri-Key Copper ShuttlerTM contains 7.68% copper and background nutrition, including molybdenum, a copper promotant.
6.13.5 Iron deficiency in soils
1. The younger leaves look yellow, called chlorosis.
The yellowing of leaves caused by lack of chlorophyll is called chlorosis and this may be due to a deficiency in one or more plant nutrients.
The symptoms of yellowing of the young leaves, with green veins, scorched leaf edges and leaf fall, called "lime-induced chlorosis", occurs in azaleas, camellias, gardenias, hydrangeas, and some native Australian plants, when the soil is too alkaline for sufficient takeup of iron.
Iron is the most abundant element in the known universe, and yet the lack of plant-available iron can limit yield.
Most soils contain 20 - 2O0 tonnes of iron per hectare, but very little of this reserve is in plant-available form.
The problems is magnified, because iron does not move easily within the plant.
Ideal soil analysis figures for iron, listed in the NTS Soil TherapyTM format, range between 40 to 200 ppm, but levels exceeding these figures do not appear to cause problems.
Iron is the only element where deficiency are not reliably detected with leaf analysis data.
If the test figures are low, then there will definitely be a deficiency, but a deficiency may be present that is not reflected in the data.
2. Functions of iron
* Biological nitrogen fixation, protein synthesis, oxygen carrier for chlorophyll production, respiratory enzyme systems.
* Increases leaf thickness to improve nutrient flow and increase yield.
* Makes the leaf darker so increases greater capacity to absorb solar energy.
3. Causes of iron deficiency
* Excess phosphate applications or high phosphate levels in the soil.
* Excess manganese, copper or molybdenum reduces iron uptake.
* Cold, wet conditions may limit iron uptake in the early growth stages.
* Excess lime applications reduces iron availability.
* Inadequate soil aeration reduces iron mobility.
* pH 7.5 or higher.
* Low organic matter in the soil.
4. Iron deficiency symptoms
The younger leaves look yellow while the older leaves remain green.
The light green colour of tissues between the veins (chlorosis), with the veins remaining dark green.
However, chlorosis may indicate lack of one or more plant nutrient deficiency
In small grains, the leaf blades develop yellow stripes.
5. Sources of iron
* Use ferrous sulfate, [iron (II), sulfate, FeSO4], NOT ferric sulfate, [iron (III), sulfate, Fe2(SO4),3]
* Fine crusher dust.
* Molasses, but not more than 50 L per crop cycle.
* Nutri-Phos Soft RockTM, 2% iron in colloidal form.
* Nutri-Key Iron ShuttleTM, high analysis chelated iron.
6.13.6 Manganese deficiency in soils
1. The principal veins and smaller leaf veins to remain green, but the interveinal portion becomes chlorotic, followed by necrosis and browning of interveinal tissue in melons.
The affected young leaves remain small and abscise before older leaves in birdsfoot trefoil.
Manganese deficiency of citrus causes light yellow-green between veins.
Manganese is essential for seed formation, seed germination and early establishment of the seedling.
Early maturity in all crops is also linked to manganese.
The requirement for manganese is 30 to 100 ppm
If serious manganese deficit, it is not cost-effective to build soil levels with manganese sulfate, so use foliar supplementation.
2. Functions of manganese
* Hastens the fruiting and ripening of crops.
* Accelerates and improves germination.
* Required for chlorophyll production.
* Critical enzyme activator.
* Essential for carbohydrate and nitrogen metabolism.
* Required for the assimilation of carbon dioxide in photosynthesis.
* Directly involved in plant uptake of iron, carotene and Vitamin C.
* Necessary for optimal seed formation.
3. Causes of manganese deficiency
* High soil pH - manganese solubility increases 100-fold per unit drop in pH.
Manganese can be toxic in low pH soils.
* Soils with very high levels of organic matter.
* Cool, wet conditions.
* Excessive calcium can tie up manganese.
Overliming can cause problems and even moderate applications of lime will increase manganese deficiency.
* High phosphorus and iron can limit manganese uptake.
* Light, sandy soils.
* Heavy cuts on graded paddocks and heavy erosion may cause manganese deficiency.
* Excess use of potassium and magnesium may reduce manganese uptake, because of soil pH increase.
* In lighter soils, if sodium and potassium base saturation percentages total over 10%, manganese uptake will be limited.
4. Manganese deficiency symptoms
The principal veins and smaller leaf veins to remain green, but the interveinal portion becomes chlorotic, followed by necrosis and browning of interveinal tissue in melons.
The affected young leaves remain small and abscise before older leaves in birdsfoot trefoil.
Manganese deficiency of citrus causes light yellow-green between veins.
* Small crops and soybeans may have interveinal yellowing of recently matured leaves
* Crops may progression from pale green to yellow, unlike the whitish cream colour associated with severe iron deficiency.
Also, in contrast to iron deficiency, the veins remain darker.
* Fruit crops: Bands of dark green surround the main veins, and a light green mottle develops on the area between the veins.
Symptoms are most common in early summer growth on recently mature leaves (as opposed to very young leaves with iron deficiency),.
Leaf shape, size and shoot length remain normal, and chlorosis symptoms are more pronounced on the shady side of the tree.
* Maize and grain sorghum: Interveinal chlorosis with general stunting.
* Small grains have marginal grey and brown necrotic spots and streaks appearing on the basal portion of the leaves.
On older affected leaves, the spots are oval and grey brown.
5. Sources of Manganese
* Manganese (II), sulfate contains 25% manganese and is used as a soil supplement or injection into irrigation when deficiency within 10 ppm of minimum acceptable levels.
In more seriously deficient soils, use the foliar manganese (II), sulfate or the more effective chelated Nutri-Tech Solutions.
* Royal Jelly is the best natural source, but it is very expensive.
* Manganese Chelate (EDTA ),is more efficient than manganese (II), sulfate as a foliar application.
* Nutri-Key Manganese ShuttlerTM is a better chelated product, containing high analysis over 13% manganese, and background nutrition of other elements and natural plant growth promotants, including liquid vermicast and fulvic acid.
6.13.7 Molybdenum deficiency in soils
1. There is a general yellowing, marginal and interveinal chlorosis, marginal necrosis, rolling, scorching and downward curling of margins
in poinsettia cultivar and in various field, horticulture and forage crops.
The deficiency of molybdenum in cauliflower causes the "whiptail" disorder.
Molybdenum is the least abundant of all the recognized micro-nutrients in the soil, but it plays a critical role in one of the most significant soil life functions - the fixation of nitrogen from the atmosphere to the soil.
Both free-living nitrogen-fixing bacteria, like Azotobacter, and symbiotic species like Rhizobium cannot fix nitrogen in the absence of molybdenum.
Molybdenum is the only trace element where availability increases as pH rises.
2. Functions of molybdenum
* Essential for nitrogen fixation.
* Required for the synthesis and activity of the enzyme nitrate reductase (reduces nitrates to ammonium in the plant),.
* Involved in electron transport in plant metabolism.
* Linked to organically-bound phosphorus uptake in the plant.
3. Causes of molybdenum deficiency
* Acidic soils that are highly leached.
* Timber soils.
* Acidic, sandy soils.
* Soils that are high in other metal oxides.
3. Symptoms of molybdenum deficiency
* Few symptoms are ever obviously apparent in fruit crops, but in vegetable crops and legumes the nitrogen connection results in deficiency, which look very much like nitrogen deficiency (paleness and stunting.
* The leaf edges also tend to burn, because of the accumulation of unused nitrates.
* There is a general yellowing, marginal and interveinal chlorosis, marginal necrosis, rolling, scorching and downward curling of margins in poinsettia cultivar and in various field, horticulture and forage crops.
The deficiency of molybdenum in cauliflower causes the "whiptail" disorder.
4. Sources of molybdenum
Sodium Molybdate: A soluble powder containing 4lYo molybdenum.
Nutri-Kelv Molu ShuttlerTM: A complete molybdenum-based liquid fertilizer.
6.13.8 Nickel deficiency in soils
There is a reduced plant growth and older leaves turn chlorotic similar to nitrogen deficiency.
Similar symptoms appear in tomato, soybean oilseed rape, zucchini when grown on urea-based nutrient solutions not supplemented with nickel.
Reduced plant growth and older leaves turn chlorotic, similar to nitrogen deficiency.
Similar symptoms appear in tomato, soybean, oilseed, rape, zucchini, when grown on urea-based nutrient solutions.
6.13.9 Zinc deficiency in soils
1. The leaves become narrow and small in chilli, the lamina becomes chlorotic in sweet potato, sour orange seedlings and chickpea, while veins remain green.
Subsequently, dead spots develop all over the leaf including veins, tips and margins under severe deficiency, shoot growth is reduced, so decrease in stem length.
Khaira disease in rice is caused by zinc deficiency.
Shoot elongation is reduced and a tuft or rosette of distinctly narrow leaves is produced at the shoot terminal in apple and pear, called "little leaf" or "rosette".
Zinc governs production of the natural growth hormone auxin.
If lack of auxin, plants become stunted and distorted.
Ideal soil analysis figures for zinc are 5 ppm to 10 ppm, but at least 3 ppm for cereal crops.
Zinc is the second most abundant trace element found in our body after iron.
2. Functions of zinc
* An essential component in many enzymes.
* Linked to the growth hormone auxin - low auxin levels cause stunting of leaves and shoots.
* Plays an important role in the formation and activity of chlorophyll.
* Involved in protein synthesis.
* Important for carbohydrate metabolism.
* .Zinc plays a major role in the absorption of moisture.
Plants with adequate zinc nutrition have enhanced drought-handling capacity.
2. Causes of zinc deficiency
* High pH soils - solubility increases 1O0-fold for each pH unit lowered.
* Soils lacking mycorrhizal fungi.
* Calcareous soils.
* Over-limed soils.
* Light, sandy soils.
* High phosphorus levels - phosphate ties up zinc.
* Cold, wet soils.
* Soils featuring anaerobic decomposition, i.e. zinc bonds with sulfides and becomes insoluble.
3. Zinc deficiency symptoms
* In small crops, shortened shoots produce clusters of small, distorted leaves near the growing tip, interveinal yellowing and overall leaf paleness, flowers and pods drop off and yields are reduced.
The leaves become narrow and small in chilli, the lamina becomes chlorotic in sweet potato, sour orange seedlings and chickpea, while veins remain green.
Subsequently, dead spots develop all over the leaf including veins, tips and margins under severe deficiency, shoot growth is reduced so decrease in stem length.
* In fruit crops, interveinal chlorosis in small, narrow, often distorted leaves at ends of shortened shoots.
Shoot elongation is reduced and a tuft or rosette of distinctly narrow leaves is produced at the shoot terminal in apple and pear, called "little leaf" or "rosette".
Chlorosis varies with the crop, less in apples, severe in citrus, stone fruit and grapes.
Blossoming and fruiting declines rapidly as a zinc deficiency develops.
* In cereal crops, within two weeks of emergence a broad stripe of chlorosis, mostly at the base of young leaves, delayed maturity and reduced yields.
Khaira disease in rice is caused by zinc deficiency.
4. Sources of zinc
* Zinc sulfate heptahydrate, ZnSO4.7H2O contains 23% zinc
Zinc sulfate monohydrate, ZnSO4.H2O contains 35% zinc, so is a more economical choice.
* Zinc Oxide, ZnO, is used to build soil levels, because it contains 80% zinc, but it is usually a slow release product effective only towards the end of the crop.
* Zinc Chelates (EDTA), are not recommended, because the EDTA chelating agent competes with the plant for nutrients.
* Nutri-Keyz Zinc ShuttlerTM contains chelated zinc component of 9.86%, and background nutrition of other elements and natural plant growth promotants and Saponins.