Nutrient deficiency: Phosphorus (P)

7 09 2010

Phosphorus summary

Phosphorus plays an important role in all living organisms and forms an essential element in plant and animal foodstuffs. It has a key position in cell metabolism and the plant’s total energy transfer. It is also a building block for the cell walls, DNA and all sorts of proteins and enzymes. The availability of phosphate is essential for young plants since approximately three-quarters of the total amount of phosphorus absorbed by the plant occurs before it is a quarter of the way through its life cycle! The biggest concentrations of phosphorus are also found in the self-developing plant parts such as the roots, side shoots and vascular tissue.

Phosphorus is a non-metal, chemical element which, because of its nature, is not found in its pure form because it is extremely reactive. It was discovered in 1669 by an alchemist who was condensing urine in an attempt to make gold. Phosphate compounds are rarely found in nature in the form that plants can utilise. Ground bones (bone meal) were previously used as fertilizer and they were later treated with sulphuric acid which made the phosphates a lot easier to absorb. In the second half of the 19th century, guano, a natural phosphate fertilizer, was dug up on a large scale and used in farming. These raw materials are currently obtained from rock phosphates which are phosphate rich ores. Some of the locations where this is mined include Morocco, Algeria and North and South America. In order to make rock phosphates suitable for use in agriculture and market gardening they are first acidified and purified. In alternative agriculture they are first finely ground or heated and are then available to the trade as expanded granules.

  • In the beginning the plant has a dark green color but it’s a different dark green (blue-green) from that of a K deficiency.
  • Growth in height and the development of side shoots are inhibited.
  • After 2 to 3 weeks dark purple/black necrotic spots form on the older and middle-aged leaves causing them to deform.
  • The purple/black necrosis later spreads out to the leaf stalks. The leaves turn, curl badly and die.

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Nutrient deficiency: Potassium (K)

23 07 2010

Summary

Potassium is present throughout plants and is required for all water-related transport activities in plants including opening and closing the stomas. Potassium is also responsible for the plants’ strength and quality and it controls countless other processes such as carbohydrate management.
The Romans and Etruscans improved the soil with potassium by burning down the local vegetation and this form of slash-and-burn has been employed throughout the world during the last centuries and has resulted in enormous soil erosion. In the thirties, wood ash mixed with stable manure was frequently used in the Netherlands.
Potassium is a soft, silver-white metal that reacts very violently with water and light in its pure form. 300 million years ago minerals such as potassium, sodium and magnesium became dissolved in the sea due to soil erosion. The seawater evaporated in large sea basins and the salts crystallised. This created the salt formations in Alsace in south-western Germany. Around the turn of the century only table salt was extracted from these formations and the excess potassium salt was discharged into the Rhine. Because of the increasing use of inorganic fertilizers, other minerals such as magnesium, sulphur (Epsom salts), phosphorus and boron are now extracted from these mines as well as table salt and potassium.

  • In the beginning you see a healthy looking, dark green plant with semi-shiny leaves that later become dull.
  • Plants often have more side shoots than is normal and stems remain thinner.
  • The points of the young leaves get grey edges, later turning rust brown, necrotic and they shrivel and curl up.
  • The leaves turn yellow progressing from the edge towards the veins and necrotic, rust brown spots appear in the leaf.
  • The leaves often turn or curl radially in the top, entire leaves become necrotic and they continue to curl and then fall off (old leaves).
  • If it is a severe deficiency the plant will look dull and unhealthy and flowering will be severely inhibited Read the rest of this entry »




Medicinal Cannabis in the USA

26 11 2008

medusaAs of 2008, thirteen states have passed laws allowing the medicinal use of cannabis.
In most cases, the changes in state law were made through ballot initiatives – where voters can petition proposed law changes to be included on state and local ballots, allowing the public to vote for or against them.

Interestingly, where figures on such ballot initiatives are available, they show that laws in favour of medicinal cannabis laws are approved by more voters and receive a greater percentage of the vote than any successful Presidential candidate in recent memory!

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