| Soils, Crops and Fertilizer Use |
|Chapter 4: Seedbed preparation|
NOTE: For a more detailed description of tillage equipment, see the PC/ICE Traditional Field Crops Manual.
Hand Implements: Digging hoes, shovels, turning forks, and rakes are very effective for smaller areas. By using the double-digging method (described later in this chapter), the subsoil can be loosened too.
Wooden Plow: Designs date back many centuries; they're animal drawn, and some have a metal tip. They do not invert (turn over) the soil or bury crop residues like a moldboard plow but basically make grooves through the soil. Wooden plows penetrate about 15-20 cm deep.
Moldboard Plow: Depending on its size and the condition of the soil, it penetrates 15-25 cm deep and inverts the furrow slice, making it very effective for burying weeds and crop residues. (Bulky residues like maize stalks must be chopped up first.) Both animal- and tractor-drawn models are used. Moldboard plows aren't as well suited to dry soils, as disk plows and don't handle rocky soils as well. They also don't work well in sticky, clayey soils.
Disk Plow: Better suited than the moldboard to hard, clayey, rocky, or sticky ground but won't bury residues as well; however, this is an advantage in drier areas where leaving residues on the surface cuts down wind and water erosion and reduces moisture evaporation. Nearly all disk plows are tractor drawn.
Rototillers (rotovators) are available in self-powered and tractor-drawn models. They thoroughly pulverize the soil and partially bury crop residues. Heavy duty models can be used for a once-over tillage job. However, their power and fuel requirements are high, and they can easily over-pulverize a soil and destroy its beneficial crumb structure.
Disk Harrow: These are available in animal- or tractor-drawn models and are commonly used after plowing to break up clods, control weeds, and smooth the soil before planting. They are also useful for chopping up coarse crop residues before plowing, but heavier models with scalloped (notched) disks are best for this purpose. Disk harrows are expensive and prone to frequent bearing failure unless regularly greased. Large, heavy duty versions called Rome plows, which are drawn behind big tractors, can sometimes substitute for plowing. Disk harrows cut, throw, and loosen the top 8-15 cm of soil but pack down the soil immediately below that. Repeated harrowing, especially when the soil is moist, can cause compaction in the lower topsoil.