Plants do not need soil to grow. Plants can grow in many different media, including nutrient-rich water, peat- or bark-based growing mixes.

Hydroponics knowledge is ancient (think of the hanging Gardens of Babylon and The Floating Gardens of China), but there is a resurgence of interest today for hobbyists and commercial growers alike. It is a fun hobby for some, but the economic impact hydroponics can make is of greatest importance.
Reasons many choose hydroponic gardening:

* No weeds
* Fewer pests
* Fewer plant diseases
* Healthy, vigorous plants
* Faster maturing plants
* Yield earlier harvests
* Can grow plants year round
* Can grow indoors
* No fertilizer or pesticide runoff
* Conserves land, space, and water. Hydroponics also conserves greenhouse space for those who use greenhouses.
* Can be used in areas otherwise inhospitable to most plants, such as a hot, dry desert

Plant requirements are nutrients, water, air and sunlight (or some sort of light – see below for indoor gardening). When plants grow in the soil, they obtain nutrients and water through the soil. When plants grow in water or a soil less medium, you must add the nutrients in a steady diet to the plants.
You can even automate your hydroponics system with timers, further reducing the time spent on gardening. Today, hydroponic gardening kits and supplies are available online, with the systems ranging from small to elaborate.

The advantages of hydroponics for challenged land areas can be readily apparent: Through the use of hydroponic systems, a desert can produce as much food as any other place since precise water and nutrient application directly to the roots of plants conserves water and still allows the plants to thrive.

Indoor hydroponic gardening: You must provide adequate light and good air circulation for indoor gardening. Indoor hydroponics units often incorporate a small fan to circulate the air. Good air circulation allows photosynthesis to occur and also prevents fungus.
Indoor light sources:

* metal halide lamps
* sodium vapor lamps
* gro-lights
* fluorescent lights and incandescent light bulbs
* Natural sunlight from a South-facing window

About nutrient solutions:

There are 13 elements necessary for plant growth (nitrogen, phosphorus, potassium, magnesium, calcium, sulfur, iron, manganese, boron, copper, zinc, molybdenum and chlorine).

You will need a fertilizer or solution that is specially formulated for hydroponic gardening. You cannot use the fertilizers that are geared to amending the soil because they do not contain all the necessary nutrients. Ready-made solutions are easily purchased at hydroponics or organic gardening supply stores.

Then, too, there were great changes in temperature. First everything was heated to a high temperature, then gradually became cool. Just think of the cracking, the crumbling, the upheavals, that such changes must have caused! You know some of the effects in winter of sudden freezes and thaws. But the little examples of bursting water pipes and broken pitchers are as nothing to what was happening in the world during those days. The water and the gases in the atmosphere helped along this crumbling work.

From all this action of rubbing, which action we call mechanical, it is easy enough to understand how sand was formed. This represents one of the great divisions of soil sandy soil. The sea shores are great masses of pure sand. If soil were nothing but broken rock masses then indeed it would be very poor and unproductive. But the early forms of animal and vegetable life decaying became a part of the rock mass and a better soil resulted. So the soils we speak of as sandy soils have mixed with the sand other matter, sometimes clay, sometimes vegetable matter or humus, and often animal waste.

Clay brings us right to another class of soils clayey soils. It happens that certain portions of rock masses became dissolved when water trickled over them and heat was plenty and abundant. This dissolution took place largely because there is in the air a certain gas called carbon dioxide or carbonic acid gas. This gas attacks and changes certain substances in rocks. Sometimes you see great rocks with portions sticking up looking as if they had been eaten away. Carbonic acid did this. It changed this eaten part into something else which we call clay. A change like this is not mechanical but chemical. The difference in the two kinds of change is just this: in the one case of sand, where a mechanical change went on, you still have just what you started with, save that the size of the mass is smaller. You started with a big rock, and ended with little particles of sand. But you had no different kind of rock in the end. Mechanical action might be illustrated with a piece of lump sugar. Let the sugar represent a big mass of rock. Break up the sugar, and even the smallest bit is sugar. It is just so with the rock mass; but in the case of a chemical change you start with one thing and end with another. You started with a big mass of rock which had in it a portion that became changed by the acid acting on it. It ended in being an entirely different thing which we call clay. So in the case of chemical change a certain something is started with and in the end we have an entirely different thing. The clay soils are often called mud soils because of the amount of water used in their formation.

The third sort of soil which we farm people have to deal with is lime soil. Remember we are thinking of soils from the farm point of view. This soil of course ordinarily was formed from limestone. Just as soon as one thing is mentioned about which we know nothing, another comes up of which we are just as ignorant. And so a whole chain of questions follows. Now you are probably saying within yourselves, how was limestone first formed?

At one time ages ago the lower animal and plant forms picked from the water particles of lime. With the lime they formed skeletons or houses about themselves as protection from larger animals. Coral is representative of this class of skeleton-forming animal.

As the animal died the skeleton remained. Great masses of this living matter pressed all together, after ages, formed limestone. Some limestones are still in such shape that the shelly formation is still visible. Marble, another limestone, is somewhat crystalline in character. Another well-known limestone is chalk. Perhaps you’d like to know a way of always being able to tell limestone. Drop a little of this acid on some lime. See how it bubbles and fizzles. Then drop some on this chalk and on the marble, too. The same bubbling takes place. So lime must be in these three structures. One does not have to buy a special acid for this work, for even the household acids like vinegar will cause the same result.