|Amaranth to Zai Holes, Ideas for Growing Food under Difficult Conditions (ECHO, 1996, 397 p.)|
|28 additional technical notes about tropical agriculture|
A. PREVENT A WATER SEAL AT SURFACE. Probably the greatest deterrent to a high rate of water absorbtion is the tendency for soils to puddle at the surface and form a seal against water intake. The beating action of raindrops tends to break down cloddiness and disperse the soil.
1. By tillage, create a rough, cloddy surface which lengthens the time necessary for the rain to break down the clods and seal the surface. For seed bed preparation in general, small seeds should have a finer, mellower bed than large seeds.
2. After harvest, create a stubble mulch on the surface. Such material not only prevents raindrops from inpinging directly on the soil, but impedes the flow of water down the slope, increasing absorbtion time.
B. REDUCE THE RUNOFF OF WATER. To the extent that waterlogging is not a problem, the runoff of water and its attendant erosion must be stopped.
1. Cropland should be as level as possible.
2. All tillage and plantings must run across (or perpendicular to) the slope of the land. Such ridges will impede the downward movement of water.
3. For every two feet of vertical drop or 250 feet of horizontal run, the field should either have bunds or contour strips (details of these practices are discussed later).