How much longer can we use fertilizers?

Phosphorus, Phosphates

Phosphorus, chemical symbol P, is one of several nutrients that are important in the production of food. It has atomic number 15. It is very reactive, so it never occurs as an element in nature; only as compounds. There are several naturally-occurring compounds that contain phosphorus. They have low solubility and volatility, so there is little naturally-occurring phosphorus dissolved in lakes, rivers and seas, and virtually none in the atmosphere. Most phosphorus is found in the Earth's crust. Phosphorus found in the soil tends to be bound up in particles and not available to plants. Water in soil can contain dissolved ions of phosphorus that plants can take up. It generally occurs as the negatively charged phosphate ion PO₄^3-; otherwise it forms insoluble chemical compounds with other elements that become part of the soil. Clay soil particles are negatively charged, so they repel phosphates which are easily leached out of the soil. These particles are carried along in rivers and end up as sediments at the bottom of lakes, so it is important to try and minimize erosion. Sediments with high concentrations of phosphorus can contribute to eutrophication, which can lead to algal blooms and fish deaths. Phosphorus is a starting material for photosynthesis.

Farmers often add phosphorus to fields in NPK fertilizers (N = nitrogen and K = potassium), and the absence of each nutrient can affect the take up of the others. Phosphorus compounds are also present in domestic sewage and some industrial waste. Detergents also used to be a major source (in the form of sodium tripolyphosphate (STPP)), but since the early 1980's have been replaced by non-phosphorous versions in many countries. Phosphorus compounds are not removed by normal sewage treatment.

Tropical rain forests appear very lush, and when they are burnt, phosphorus and potassium from the upper soil are released, which helps the first year's crops to be bountiful. The high levels of rainfall leach out the nutrients quickly, however.

Apart from the problems caused by the use of fertilizers, a lot of energy is needed to mine the raw materials, which usually entails fossil fuels. They are only mined in relatively few areas, including Canada, China, Morocco, the UK and the former USSR. In the United states there are deposits in Florida, Idaho, Tennessee, and Utah but these are likely to be depleted in 2035. Another risk is in the manufacture of phosphates: water is used in the processing of phosphate into the phosphoric acid that is used to make fertilizer. The ponds that hold the acidic water can be breached, particularly during hurricanes in the USA.

Phosphorus is found in the DNA and RNA of all living cells, and is essential for life. Adenosine triphosphate (ATP) is used to transport energy.

As well as being used for fertilizers and detergents, phosphorus is used for fireworks, explosives, friction matches, bombs, baking powder, methamphetamine and toothpaste. Calcium phosphate is used to make fine china.

Organic compounds containing phosphorus are called organophosphates, and they are used as part of insecticides (including sheep dips), herbicides, and nerve gases, etc. They are used against West Nile Virus, for example. They can damage people (for example farm workers) who are regularly exposed to them, and children.

Judge to Determine Next Step in Everglades

Phosphorus fertilizer runoff has polluted the Everglades, upsetting the balance of plants that grow there. An $8.4 billion court-ordered clean-up began a decade ago. Environmentalists and the local Miccosukee Tribe of Indians say that the government cannot meet its Dec. 31, 2006 targets, and a Miami U.S. District Judge has ordered hearings starting Monday.

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Study Says Ethanol Not Worth the Energy

A study by researchers at Cornell University and the University of California-Berkeley says that it takes more fossil energy to grow and turn crops into ethanol than is produced. They say that solar, wind and hydrogen energy would be better targets for investment. The study disagrees with other reports. Proponents say that ethanol produces less pollution, reduces dependence on foreign oil and benefits farmers by providing another market for their crops. Ethanol can replace the pollutant MTBE.

Channel Catfish Photo courtesy of U.S. Fish and Wildlife Service

Vietnamese Catfish Just Taste Better

There are 37 families of catfish in the world, varying from tiny ones to giants weighing up to 771 pounds. In the United States, only native fish can be labeled as catfish. Doubt has been cast on whether the basa catfish from Vietnam is an inferior product, however.

Stray Dogs Kill Birds at Indianapolis Zoo

A pack of stray dogs got into the Australian exhibit at the Indianapolis Zoo on Sunday and killed all the birds there, including black swans, emus and magpie geese. FOur of the dogs were killed.

Tiger numbers drop in India's showcase reserve

There has been a reduction from 47 to 26 in the count of the numbers of tigers in the Ranthambhore sanctuary, western India. The difference may be partly because better methods of counting have been used this time. Tiger numbers are between 5 and 10 percent of numbers a century ago.

Nile Hippopotamus Photo courtesy of Smithsonian

Hippo, Believed Among Oldest, Turns 54

Mesker Park Zoo & Botanic Garden, Ind. has been celebrating the 54th birthday of their resident Nile hippo, Donna, who weighs in at 3,500 pounds.

Rats invade central Hong Kong

This year rats have invaded the central business district of Hong Kong, where there are many fashionable bars

Panda Leads Chinese City on Pursuit

A wild Giant Panda wandered around the southwestern Chinese city of Dujiangyan in Sichuan province for several hours before being caught. It eluded captors for some time by scrambling across roofs. The animal, which is diseased and hurt its paws during the chase, is being cared for at Wolong giant panda research center, but hasn't eaten yet.

Tiny Tsunami Reveals Big Gaps in Readiness

The major earthquake off the far Northern California coast last month only generated a small tsunami, but it was enough to test the readiness of communities at risk from tsunamis. Some communities received no warning, others too little too late, and others had no evacuation plan. The states involved are working to solve the problems.

Report: No High Radiation Risk in S.C.

The Savannah River Site supplied the USA with plutonium for atomic weapons between the early 1950s and 1992. A federal study of records just completed found that people living nearby would not have been exposed to major doses of radiation, and very few would get cancer. There is concern because the people downstream use the river water.

How much longer can we use fertilizers?

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