One of the central to the concept of gardening is that you should know the types of soil in your garden, as well as how plants grow in the soil. Plants grow by extracting nutrients, minerals and other elements, not only from the soil, but also from the air and water, which they use to manufacture carbohydrates, fats and proteins, very much like a little food factory. Sticking to the factory analogy: the "mini-factory" gets its energy from the sun, then the chlorophyll in this mini-factory use a process called photosynthesis to convert carbon dioxide from the air and water from the soil to form carbohydrates and oxygen. The better the quality of the soil, the better mini-factory operates.
This is where fertilizer and the the different types of fertilizer enter the gardening scene. Fertilizer has become a necessity since the soil in which the plants must grow may not always supply the plant with sufficient nutrients that are required to manufacture the carbohydrates. Furthermore, plants need adequate nutrients so that they do not become susceptible to disease and attack by insects. However, while chemical fertilizer may work wonders for your plants, they tend to damage other areas of the ecosystem and the biosphere. Therefore, I would highly recommend that you practice organic gardening and use only organic fertilizer; but the choice is ultimately yours.
Soil is important, not only for water and nutrients, but also as a medium in which the plant can anchor itself by means of its roots. The roots also require air so the soil must have some level of aeration. In essence, soil is a composition of living and dead organic matter, mineral particles, water and air. The structure of the soil is determined by the size, chemical make-up and form of the mineral particles.
Due to its size, sand particles are largest and gritty and thus take longer to break down than the other particles in the soil and they usually have relatively larger spaces between them. The sand particles do not hold water and nutrients very well. On the other hand, they provide very good aeration and thus facilitate cultivation. Clay soil retains plant nutrients well, but do not facilitate cultivation very well as they have very poor aeration. Loam soil, the so-called in-between soil, is composed of clay, sand and silt particles and is an ideal gardening soil due to the fact that it drains without drying out too quickly and contains enough air pockets to provide adequate aeration for healthy root growth. In gardening it is also good to remember that soil pH might be alkaline or acidic. (Tip: Ask at your local nursery or garden center which plants do well in your type of soil.)
In the following pages we go into the finer details of soil, the types of soils, the types of fertilizer, especially organic fertilizer and fertilizing techniques, as well as soil amendments and organic gardening and their importance for all gardeners. We also discuss how to test the soil type, using the soil triangle, how to make soil amendments using fertilizer, how to test the soil pH, and how to make compost using a compost bin, but our main focus is on organic gardening.