Management of organic and inorganic soil fertility inputs in indigenous agricultural communities in the Bolivian Highlands

The Bolivian highland plateau region (Altiplano) is a semi-arid region in the Andes Mountains that has a range in elevation of between 3600 and 4300 m above sea level. The region's climate is characterized by high diurnal temperature variations, frost risks, low and irregular precipitation and high risks of drought during the growing season (Garcia et al., 2007). Recent research has indicated that the Andes region will experience temperature increases of up to 6 degrees C by the end of the century (Bradley et al., 2006, IPCC, 2007). In addition, a consequence of global climate change has been and will be a higher incidence of extreme weather events (Haylock et al., 2006; Thibeault et al., 2008). These climate changes may increase the risk of crop failure and food insecurity of local indigenous communities in the region. Other economic and social changes in the region, such as urban migration, have also impacted agricultural practices in this region, which are primarily potato-based cropping systems and livestock rearing of cows, sheep and camelids (e.g., alpaca and lama) (Valdivia et al., 2001). Research in the Altiplano has indicated that one consequence of climatic and socioeconomic changes has been increased soil degradation (Swinton and Quiroz, 2004; Motavalli et al., 2008). An important component of soils that may assist in mitigating this soil degradation is soil organic matter (SOM) or soil total organic carbon (SOC). Increased soil organic matter generally improves soil quality and the long-term sustainability of agroecosystems (Gupta et al., 1994). Improvements in existing soil management practices or the introduction of alternative practices that increase SOM may be needed for increased production and for reducing the negative consequences of climate change.