Bush Fallow Farming

Bush fallow farming currently occurs mainly in the humid tropics of Africa, South and Central America, southeast Asia, and parts of Oceania. In these regions, average temperatures for the coolest month are above 18 °C and annual precipitation exceeds potential evapotranspiration. Temperatures and moisture conditions in turn affect soil and vegetation characteristics. Soils are generally heavily weathered and lacking in basic nutrients, but on these soils grow a great biodiversity of plants in forest and savanna biomes. Bush fallow farming is a response and adaptation of farmers to this environment. It can be defined as an agricultural land use system and set of practices that is based on the rotation of land between different uses rather than a single permanent use, to achieve several agronomic goals. It involves the rotation of land between cultivation and fallow to create favorable agroecological conditions, such as regenerating soils through a vegetation-soil nutrient cycling. Following widely varying periods of cultivation of different crops, a farm plot is allowed to rest or remain fallow, and for soils, in particular, to regenerate as vegetation grows and returns large quantities of biomass to the soil—all this while another plot is brought into cultivation. Some authors have used the term shifting cultivation as a synonym for this type of farming, while others have suggested that shifting cultivation be limited to situations of land rotation that involve the shifting of homes of farmers when cultivation shifts to a new land patch.

A key to understanding all farming systems is to be conscious of variety within them and the changes they undergo over time. With the exception of the land rotation criterion, there are many varieties of bush fallow farming, as the ecological, social, economic, cultural, demographic, and technological conditions in which they occur vary. Tropical crops cultivated in bush fallow farming vary greatly in number and biodiversity. They include rice, maize, millet, sorghum, groundnuts, yams, taro/cocoyam, cassava/manioc, plantain, and a wide variety of vegetables and fruits, often intercropped in various combinations. Bush fallow farming occurs in areas of land abundance and those with less abundant land, in areas of low to medium population densities to those with high population densities, and in areas of varying cropping-fallow regimes, ranging from a few months of fallow to many years of fallow. Fallow periods may be shorter, the same length, or longer than the period of cultivation. Human-assisted fallow regeneration occurs in some practices, while greater reliance is placed on natural successional fallow growth for restoring soil fertility in others. The fallow vegetation is varied. Some bush fallow farming involves heavy tillage of soils, while others have minimum tillage. As commercialization and markets have expanded, the sizes of fields and farms, the land titles and rights, the types of labor arrangements, the technologies and inputs employed, and the proportion of output sold on markets have evolved. Given such complexity and variety, considerable caution is warranted when generalizations are made about such a varied system of farming.

Yet in spite of such complex variations in bush fallow farming, there is a dominant discourse that derides it as the preeminent threat to tropical forests and their massive biodiversity. Bush fallow farming is viewed as synonymous with swidden cultivation/slash-and-burn cultivation, where following a fallow period, temporary agricultural fields are cleared and prepared for cultivation by burning the vegetation. This burning, it is argued, destroys tree seeds, seedlings, [Page 302]saplings, and leads to the loss of many soil nutrients, such as carbon and nitrogen. Soil erosion and leaching exacerbates nutrient loss. Soil fertility thus declines rapidly with cultivation, leading farmers to abandon plots and clear forests for more fertile plots. Unfortunately, forest and soils are not allowed to regenerate long enough before land is put to cultivation, leading to detrimental ecological change. The loss of forest and their biodiversity is said to accelerate with the high rates of population growth and rising population densities in the tropical developing world. The loss of forest carbon sinks and their biodiversity, increasing carbon dioxide, and global warming lead to the verdict that the ecological impact of bush fallow farming is negative and that modernization is needed. Agronomic shortcomings in terms of the low productivity of bush fallow farming are also given as further justification for change.

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