Appraisal of Shifting and Continuous Cultivation
Shifting cultivation is a cropping system whereby a piece of farmland under forest is opened up and used for cropping (usually arable crop such as yam, maize, rice, sorghum, or cassava) for two or more years before moving to another site.
The fresh land under forest or bush is cleared by the slash-and-burn method which involves the cutting down and burning the existing vegetation.
The system comprises a cropping period when food crops are produced for a few years until there is nutrient depletion, reduction in yields and infestation of weeds; the piece of farmland is then abandoned for a fallow period (ranging from 2 to 10 years) for the regrowth of the vegetation and the rejuvenation of the soil fertility.
Read Also: The Different Types of Cropping Systems
There is usually a yearly or bi-annual movement from one piece of land to another.
The practice had been carried out over a wide variety of soils over about 30% of total worldwide arable land. About 300 million people, mainly in the tropics, feed on this shifting cultivation system which also accounts for about 70% of tropical deforestation.
For centuries, shifting cultivation was able to maintain soil fertility because the land could be abandoned for more than 10 to 20 persons/km2.
However, even in Nigeria today for instance, population has exceeded this figure by 10 to 25 times. Hence shifting cultivation cannot support the present population pressure on arable land to the extent that the fallow period is now either equal to or even shorter than the cropping period.
The system must therefore be modified and improved upon if food production is to cope with population growth rate.
Read Also: Shifting Cultivation: Features, Advantages and Disadvantages