|Soil Conservation Techniques for Hillside Farms (Peace Corps, 1986, 96 p.)|
Traditional hillside land-use patterns in much of Honduras are based roughly cr. the following series of events:
Fig. 1. A forested lot is clearcut and residues are burned
Fig. 2. Crops are planted with rows oriented up and down the hillside
Fig. 3. Crop yields decline each year as soil erodes
Fig. 4. The land is planted in perennial pasture grasses or abandoned after having been cultivated for a relatively short time (often only 1-20 years, depending on site-specific factors).
This pattern of land use may avoid some problems with crop pests and the need for supplemental fertilizer. However, in a densely settled area land soon becomes scarce, and matureforested, fertile plots are not always available to be cleared and cultivated. In such densely settled areas, a land use pattern which results in a permanent cultivation of the same plots is desired.
There are three related problems associated with this traditional land use patterns which must be corrected if permanent cultivation practices are to be successful!: soil erosion, rapid water runoff, and decreased soil fertility. As the native vegetation is cut and burned, the soil surface is exposed to the impact of raindrops. The force of the raindrop impact dislodges soil particles. These soil particles and the valuable nutrients they contain can then be carried out of the area by the water flowing over the soil surface. This rapid rainfall runoff means that less water infiltrates into the soil to be available later, exagerating any natural flood/ drought cycles.
When the native vegetation is intact, the force of falling raindrops is mostly absorbed by the vegetation, as there is much less bare ground surface exposed. The decaying leaf litter on the ground and in the upper soil layers also protects the soil, acting as a sponge, absorbing much of the rainfall and decreasing the amount that can freely run over the land surface. Since more of the rainfall remains in the soil rather than running off, the soil retains its moisture . longer in the absence of rainfall. Since fewer soil nutrients are lost in runoff water, soil fertility is maintained.
A comparison of these two scenarios illustrates how in the traditionally farmed field, characterized by the absence of protecting vegetation, the rainfall impact and the loss of soil particles, dissolved nutrients, and water are all increased. The rest of this guide focuses on techniques for reducing the soil erosion and water runoff associated with agricultural activities, techniques of maintaining or increasing the soil fertility necessary for permanent cultivation of the same plots, and extension methods useful in promoting the adoption of these different farming techniques.