Soil is a rich but fragile ecosystem. Erosion can be described as the loss of the fertile topsoil due to natural causes or through human intervention. Millions of acres of farmland are lost each year in this way.

One of the major causes of erosion is of course deforestation. With the felling of trees on a massive scale, there is little or no chance of any plant regeneration and the soil that was once anchored by the roots of trees and bushes simply slides away under its own weight and this process is evidently exacerbated by the action of wind and rain.

Erosion is also caused by the weathering process, that is, the effect of rain, wind or ice on the ground over a long period of time. This process is obviously much slower and can even be considered as natural, but the end result remains the same. And sometimes, the weathering process can be speeded up as unusually heavy rain can cause landslides due to water-logging.

Another cause of erosion is over-grazing by cattle especially in certain susceptible areas such as steep or hilly terrain. This can be seen in many regions of Africa or Australia. Cattle or animals such as sheep have a tendency to uproot the grass they eat and thus leave big patches of unprotected ground, unlike wild herbivores, which simply clip off the ends of the grass they feed on.

One of the major consequences of erosion is the loss of fertile soil in which plants can grow and this ultimately leads to desertification, where land becomes arid and cannot support much life. This has disastrous effects on the people living on such land. Nomadic tribes move around looking for new fertile patches to live on,and so the problem spreads over an ever-widening area. The case of the Sahara Desert, growing year by year, is probably the best known in the world.

Floods are another consequence of erosion as eroded soil tends to collect in riverbeds, silting them up and thus making them shallower.Then when heavy rains fall, there is much less space for water in dams and rivers and they may burst their banks. The present flooding in Bangla Desh is the worst in living memory.

As for preventive measures, in cases where forests have already been damaged, re-forestation is the only solution. Specific tree varieties which have rapid growth rates and wide rooting habits should be planted in order to hold the soil. Another method which can be used in hilly areas is terracing of crops. That is, instead of making furrows straight up and down, planting should be done across the slopes so as to hold the soil more effectively.

Erosion is not a huge problem in Mauritius, in spite of our heavy downpours. This is because sugar cane, which is planted throughout the island, has, like any other member of the grass family, a very extensive system of roots which hold the soil well. We do however see some evidence of erosion in the reddish muddy water of rivers and estuaries, in the rainy season and especially after cyclones.