Erosion – steps to prevent it

GOOD morning once again to you all. Did you have a good week. How could we forget, how could we be so much like job, how could we forget, how could we be so much like job, how could we fail to be awestruck by Gods majesty. Jobs sufferings led him to doubt God, sometimes we do also. But our heavenly father is always there to remind us of his unfathomable ways. He laid the earth's foundations, he set the boundaries of the ocean, he sends the morning sun, he controls like and death, he sends the snow, rain and hail, he imprints knowledge on our hearts, he sets the time for the birth of animals, he instills the horse with great power, he directs the hawk and eagle. Each day, this earth shoots aloud a song of recognition of the creator, let take some time today to echo that tune, and pour out our praises to our mighty Creator-God Let us pause for a moment: May we never forget Gods awesome majesty, wind, water, light and God, Let us give to him our praise, For the goodness he displays. God work of creating is done our work of praising has just begun.

OUR TOPIC: Erosion can be controlled by reducing the impact of raindrops and slowing down run-off water. RUN-OFF is the vehicle of erosion and it is determined by a) the amount and intensity of the rainfall b) the soil cover from crops and mulch c) the receptivity and erodability of the soil d) the scope of the land e) the land usage f) the barriers to run off. The intensity of the rainstorms of the tropics, often accompanied by strong winds, and the size and speed of the raindrops, beating on the exposed soil, are the origins of erosion. The large amount of kinetic energy is dissipated in moving the soil or in breaking down the soil crumbs and sealing the surface. If the impact is broken either by natural cover, a crop, or mulch, the kinetic energy is reduced and the effect on the soil surface minimized. If the soil structure is poor or this surface capped, due to overcropping or trampling by animal feet, erosion, beating by the rain then the receptivity of the soil to rain will be reduced and run-off increased.

Receptivity is better where worms, ants and some termites are active, this applies particularly to forest soils. As in many parts of the tropics, rainfall is marginal for crops, the loss of rainfall by run-off could be critical. The velocity of the run-off is determined by the scouring capacity and can carry particles 64 times as large.

Erosion is lessened by reducing the influence of these factors which increase run-off. The soil must be protected from the beating rain by plant cover from either crops, cover crops or mulch, and left bare as short a time as possible during the year. This is one benefit from inter-cropping and relay cropping. The receptivity of the soil should be increased by breaking up any cap which forms either in cultivated or grazed land, by improving the soil structure by crop rotations, adequate resting follows, and maintaining the organic matter by manuring or mulching.

The hilltops which receive most rain and are steep should be kept as forest reserves. Much of the flooding and serious erosion caused by the typhoons can be avoided if the slopes are not deforested. The steeper cultivated slopes should be used for crazing or planted to permanent crops, with cover crops or mulched, but not clean weeded. Annual crops would be better planted on the more gentle slopes in strips. Wherever possible all cultivation's, ridging, planting and weeding should be carried out along the contour and not up and down the slope.

Planting crops on tied ridges, provided that the ridges are well maintained. Prevents both erosion and the loss of available rainfall by run-off. Research has shown that yields have been increased under certain rainfall and soil conditions on annual crops by planting on tied ridges. Ridging however increases the soil surface from which rainfall is evaporated, and in some cases this extra evaporation loss may be greater than the extra rainfall conserved.

As water flows down a slope it tends to take into suspension first the fine material, the clay, and as it speeds up so it picks up progressively silt and then fine sand. Three more or less distinct types of erosion are recognized, known as sheet, rill and gully erosion. In sheet erosion soil is removed fairly uniformly all over the slope, in rill erosion numerous shallow gully's or “rills” are formed, when the water is concentrated into narrow streams deep gully's are formed. Crops planted up and down the slope can aggravate the risk of erosion by providing ready made channels for water to run down. I have said this many times before. Well farmers, I hope this has been of value to you. Take care, see you next week.