|Traditional Field Crops (Peace Corps, 1981, 283 p.)|
|Planning and preparation|
Land preparation is a very location-specific practice varying with climate, soil type, crop, management level, and available equipment. The following is a summary of the principal factors involved in choosing the most feasible and appropriate land preparation method and seedbed shape for the reference crops:
1. Seedbed Fineness (thoroughness of preparation)
· Maize's large seeds and spikelike emergence gives it the best clod-handling ability of the reference crops.
· Rough (cloddy) seedbeds discourage weed growth and reduce erosion caused by rain or wind; they also increase water retention by cutting down water runoff.
· The reference crops can tolerate a rougher seedbed when planted by hand than when typical mechnical planters are used.
· To cut down on soil compaction and other effects of overworking the soil as well as to reduce labor, machinery and fuel costs, it is best to use the minimum amount of tillage consistent with adequate seedbed preparation.
2. Tillage Depth
· There is seldom any advantage to plowing deeper than 15-20 cm.
· Shallower plowing may be advisable in drier areas to reduce wind erosion and moisture losses.
3. Crop Residue Management
· Leaving crop residues on the soil surface is especially advantageous in drier areas since it reduces moisture losses and wind erosion. It also reduces erosion due to rainfall and increases water retention.
· When growing peanuts (and sometimes beans), complete residue burial is usually recommended where Southern stem rot (Sclerotium) is a problem, since the disease can incubate on surface plant residues.
· With the other reference crops, surface residues may sometimes aggravate certain insect and disease problems.
4. Suitability of Equipment
· The moldboard plow is the most effective implement for burying crop residues and grass sod.
· A disk plow is better suited than the moldboard to hard, clayey, rocky or sticky ground but does not bury residues or grass sod effectively.
· Chisel plows are best suited to lower rainfall areas and leave trash on top of the soil. They are fairly ineffective on wet soils.
· Disk harrows handle clods better than spike- (peg) tooth and spring-tooth harrows but are more costly and prone to repair problems.
5. Seedbed Shape
· Ridge planting is recommended for all the reference crops under high rainfall or poor drainage.
· Flat planting is best suited to soils with good drainage. However, soil can be mounded into the crop row as growth progresses to control weeds and improve drainage if rainfall increases.
· Furrow planting is best suited to low rainfall areas since it conserves moisture.
· Peanuts and beans are especially susceptible to root rots favored by excess moisture. They should be either flat-planted or ridgeplanted.