Alluring Roses FROM AFRICA

Roses, including both those that grow wild and those cultivated by man, perhaps none has acquired more international acclaim than the rose. It has captured man’s imagination for centuries. Poets have written about it, while artists have often depicted it. Shakespeare extolled it with the famous line from Romeo and Juliet: “What’s in a name? That which we call a rose by any other name would smell as sweet.” Thanks to the rose, new friendships have been established and cemented, strained relationships have been restored, and many a sick person has been encouraged.

In addition to all of that, the rose has great economic value. In many countries where climatic conditions favor flower farming, the rose is a major earner of foreign exchange. In Kenya, for example, out of the millions of flowers exported during one recent year, over 70 percent were roses, making the country one of the leading producers in the world.
In times past, before man discovered the flower’s alluring qualities, the rosebush grew freely in the wild. Today, through the use of carefully controlled methods of crossbreeding, some of the more than 100 species of wild roses have been bred to produce the thousands of varieties of roses known today. As a result, the flower has become known worldwide and is found in almost every country on earth. The most popular and widely cultivated is the hybrid tea rose.

 From the farms to your flower vases at home
 Mostly, people buy their roses either from a florist or at a supermarket. These flowers are grown commercially on large farms and require much more attention than the backyard variety. A visit to one such farm located near Nairobi revealed to us the extra care that goes into preparing the flowers for market.
Here, as elsewhere in Kenya, elaborate polyethylene greenhouses readily identify the commercial rose farm. These structures serve several purposes. The newly grafted roses are delicate and require protection from harsh weather. Heavy rain, wind, or direct sunlight can wreak havoc on them. To maintain a constant temperature, it is necessary that cool air enter the greenhouse easily and hotter air be expelled.
Inside the greenhouses there are rows of young flowers in different stages of growth. At this farm several types of roses are cultivated, ranging from the popular hybrid tea rose, cut at a little longer than 27 inches, to the 14-inch-long sweetheart rose, a particular type of hybrid tea rose. The two and a half acres here may contain up to 70,000 plants.
How do the plants receive their nutrients? Ordinary soil is not used. The flower bed is made up of pumice (volcanic rocks) laid on polyethylene sheets. This is a preferred method, as the rocks are free from many soilborne diseases. The drip-irrigation concept is employed to water the plants. In this method small pipes are directed to the flower bed, discharging the water and other nutrients in well-regulated quantities. Being porous, the volcanic material allows water to drain from the plastic bed. Then it is collected and reused.
Despite the specialized care provided, roses can become infected by a number of diseases, mainly caused by funguses. These include botrytis and powdery mildew, which attack the leaves and stems of the plants. Left unchecked, these diseases can adversely affect the flower quality. Applying fungicides helps control the problem.
As time passes, some bright colors begin to show up, a clear indication that the roses are ready for harvesting. The flowers are carefully cut at the tight-bud stage. At this point the petals have yet to unfold. Harvesting at this time enhances the life span of the cut flowers as well as their color retention. However, the harvesting stage may vary slightly from variety to variety. It is vital to cut the flowers in either the morning or the late afternoon, when humidity is high and wilting is slower. Harvested flowers are then taken to the cold room for precooling. This too ensures that the roses remain fresh for a longer period of time.
The flowers will pass through another vital phase—the grading stage. Here they are separated according to color and size. Packaging is done according to customer requirements. Finally, the flowers are ready for market. From this farm they are transported to the main airport in Nairobi, and from there they will be exported to Europe, thousands of miles away. Because they are highly perishable, the flowers should reach the market, local or international, within 24 hours of harvesting.
The next time you receive a bouquet of roses as a gift or buy them from a supermarket or a florist, pause and think of the long journey they may have made, possibly even from Africa. Possibly it will enhance your appreciation for this beautiful plant.

ENERGY FOR YOUR HOME: NATURAL GAS

NATURAL GAS supplies more than 20% of the world’s total energy requirements. What is the source of natural gas? How clean is it? And how much is left?

Many scientists believe that eons ago natural gas was formed from the decay of plant and animal remains, including plankton. According to this theory, over long periods of time, microbes, together with pressure from the accumulating sediment above and heat from deep in the earth below, converted the organic debris into fossil fuels – coal, gas, and petroleum. In time, much of the gas found its way into porous rocks, sometimes forming vast reservoirs, or gas fields, that were sealed beneath a layer of impermeable rock. Some gas fields are huge, containing trillions of cubic meters of gas. How are gas deposits found?

Remote sensing satellites, global positioning systems, reflection seismology, and computers have taken some of the guesswork out of gas exploration.  Reflection seismology is based on the principle that sound reflects from layers of rock within the earth, thus giving scientists an acoustic picture of what lies below. The sound sources are man-made, usually involving small explosives or vibrators fitted to special trucks. The resulting shock waves travel into the earth’s crust and are reflected back to waiting instruments, which help scientists generate three-dimensional computer models of rock formations. These models in turn, may indicate potential gas deposits.

In offshore exploration, sound waves are made by special guns that shoot compressed air, steam, or water into the sea. The resulting pressure waves penetrate the seabed and reflect back to hydrophones attached to a long cable towed behind the survey ship. Here, too, researchers use the signals to form computer models for analysis.

To justify the cost of extraction, a field must have sufficient gas. Hence, geologists have to ascertain both the pressure and the volume of a reservoir. The pressure can be measured quite accurately with gauges. The precise volume, however, is harder to determine. One method involves reading the initial pressure, releasing a measured amount of gas, and then taking another pressure reading. A small drop in pressure indicates a large reservoir; a large drop, a small reservoir.

After being extracted, natural gas is piped to refineries for the removal of unwanted chemicals, such as carbon dioxide, hydrogen sulfide, and sulfur dioxide, as well as water vapor, which can corrode pipelines. Natural gas is then distilled at very low temperatures to remove incombustible nitrogen and to recover valuable helium, butane, ethane, and propane. The final product is essentially pure methane, which is colorless, odorless, and highly combustible. Because the methane is a natural product, it is also called natural gas.

To make natural gas safe for domestic use, manufacturers add tiny amounts of pungent sulfur-containing compounds so that leaks can be readily detected and safely stopped before an explosion occurs. Nevertheless, natural gas is a much cleaner fuel than other fossil fuels, such as coal and oil.

To facilitate transport, some natural gas is chilled to very low temperatures and converted into liquefied natural gas. Butane and propane often end up as liquefied petroleum gas (LPG), which is well-known to those who like to cook on gas barbecues with bottled gas. LPG is also commonly used as fuel for buses, tractors, trucks, and other vehicles. On the chemical front, butane and propane have found their way into plastic, solvents, synthetic fibers, and other organic products.

Like all other fossil fuels, natural gas is also a finite resource. According to estimates, about 45% of the world’s recoverable gas remains to be found. If the estimate is correct, with the present rate of usage, the supply may last about 60 years. But in many land, energy consumption is increasing, so present predictions may be highly inaccurate.

To be sure, the almost frenetic rate of industrialization in some lands could lead people to believe that the earth’s resources are infinite. Granted there is also nuclear power as well as renewable energy sources, such as solar and wind power. But will these meet the growing energy needs? And will they prove to be environmentally clean and safe? Only time will tell.