Shifting cultivation

Shifting cultivation, one of the first agricultural practices developed, is still widely used. In the early 1970s, about 36 million square kilometers of land were farmed under this system, producing food for about 250 million people. Each hectare (2.47 acres or... 

Negligible quantities of wood may be removed when tropical forests are cut for shifting cultivation or pasture conversion. In contrast to the temperate coniferous forests of the Northwest USA, only small quantities of wood are usually exported as a result of timber operations in tropical evergreen forests. In... 

Much of the surface soil erosion and hence nutrient loss occurs when deforestation and biomass burning removes and/or consumes the organic materials that protect the soil surface. Significant losses may occur by dry ravel or overland water erosion associated with precipitation events. Under a shifting cultivation system in a tropical deciduous forest ecosystem in Mexico, Maass et al. 61) reported first year losses of N, P, K, and Ca were 187, 27, 31, and 378 kg ha" respectively. In contrast, losses in adjacent undisturbed forests were less than 0.1 kg ha for all nutrients except Ca (losses were 0.1-0.5 kg ha for Ca). 

Nye, P.H. Greenland, DJ. The Soil Under Shifting Cultivation. Tech. Commuru 51 Famham Royal, England Commonwealth Bur. Soils, Commonwealth Agric. Bur., 1960. 

Yang CH, Crowley DE, Menge JA (2001) 16S rDNA fingerprinting of rhizosphere bacterial communities associated with healthy and phytophthora infected avocado roots. FEMS Microbiol Ecol 35 129-136 Yemefack M, Jetten VG, Rossiter DG (2006) Developing a minimum data set for characterizing soil dynamics in shifting cultivation systems. Soil Tillage Res 86 84-98... 

At any rate, boosting African crop production will require increased use of soil amendments. Natural soil fertility restoration during long fallow periods, as practised in traditional shifting cultivation systems, becomes less and less feasible with rising population pressure. Mineral fertilisers have been key components of strategies to increase crop yields and restore soil fertility (e.g. Quinones et al., 1997), yet their availability and use in SSA remain very low due to lack of production, transport and market infrastructures (Larson and Frisvold, 1996 Dudal, 2002). Nutrient imbalances have resulted in the loss of an estimated 700 kg N, 100 kg P and 450 kg K ha 1 from SSA cropland during the last 30 years, while... 

Sanchez, P. A. 1976. "Soil management in shifting cultivation areas." In Properties and Management of soils in the tropic, ed. P. A. Sanchez (John Wiley Sons, New York), pp. 347-412. 

Shang, C., and H. Tiessen. 1997. Organic matter lability In a tropical Oxisol evidence from shifting cultivation, chemical oxidation, particle size, density, and magnetic fractionations. Soil Science. 162 795-807. 

Only the net effect of shifting cultivation is included here. The gross fluxes from repeated clearing and abandonment are not included. 

The ecological caution of shifting cultivation, in other words, was the reason behind the appearances that so offended development officials. 

Shifting cultivation is also common throughout much of Southeast Asia and Latin America. 

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