Soil is the top layer of the earth’s surface suitable for the growth of plant life. Soil preparation is vital to ensure plant productivity. Soil should be properly prepared to improve its water-holding capacity and to eliminate weeds. It must be tilted well for seed germination and seedling. Soil is tilted – the mechanical preparation of soil – so that it has the proper physical condition for planting. Soil is fertilized – the adding of nutrients to the soil. Aside from water, plants absorb from the soil 16 nutrients in order to grow normally. These nutrients are oxygen, carbon dioxide, copper, zinc, boron, molybdenum, sodium, and chlorine. Sodium and chlorine are always present in the soil and are not available.
All soil nutrients exist in two forms – available and unavailable. The available nutrients are those which are ready for plant absorption; the unavailable nutrients are those present in the soil but cannot be used by plants as food. Depending on soil conditions, very few of the existing nutrients are actually in a form available to plants.
The structure of the soil is changed and crop residue is managed by tilling so that the desired condition of the soil for planting is achieved. The soil is turned over to facilitate the drainage, storage, and transmission of water and to provide a good environment for the seeds and roots. Because weeds complete with the plants for the available supply of water, nutrients, and light, they have to be removed. Crop residue like dried stems and leaves on the surface of the soil are removed.
The desired soil texture and the size of soil particles dictate how a piece of land will be tilled. On a coarse-textured soil, the size of soil particles is increased 1 tillage provided it is done only when the pores are just filled with water. A fine-textured soil will have to be broken into smaller pieces or else, if not tilled, these will form lumps called clods. A fine-textured soil may be tilled only after a slow rain has moistened the clods and made them crumbly. When you till a fine-textured soil when it is very dry or very wet, tillage will be very difficult.
To prepare the land for planting, the following shall be done:
1. The area of the site is cleaned by pulling out weeds, grasses, and other rubbish.
2. The land is plowed. Plowing the land is the most important tillage operation in preparing the land. The main objective of plowing is to pulverize the soil, aerate it, and make the soil retentive.
3. The next step is harrowing. The purpose of harrowing plowed soil is to level it, make it fine, compact it, and destroy weeds. A native spike-toothed wooden harrow is the tool used for harrowing.
4. Beds are raised to provide drainage during rainy season. Plants like cabbage, radish, eggplant, and tomatoes are best planted on raised beds.