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STUDY AREA

DIFFERENCES IN CROPPING SYSTEMS AND SOIL ORGANIC CARBON DUE TO CLIMATE CHANGE AND SOCIOECONOMIC FACTORS IN POTATO-BASED CROPPING SYSTEMS IN THE BOLIVIAN HIGHLANDS. Peter Motavalli, Jorge Cusicanqui, Javier Aguilera, Corinne Valdivia, Magali Garcia, Elizabeth Jiménez , and Roberto Miranda.

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STUDY AREA

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  1. DIFFERENCES IN CROPPING SYSTEMS AND SOIL ORGANIC CARBON DUE TO CLIMATE CHANGE AND SOCIOECONOMIC FACTORS IN POTATO-BASED CROPPING SYSTEMS IN THE BOLIVIAN HIGHLANDS Peter Motavalli, Jorge Cusicanqui, Javier Aguilera, Corinne Valdivia, Magali Garcia, Elizabeth Jiménez, and Roberto Miranda

  2. STUDY AREA • The Bolivian highland plateau region (Altiplano) is a semi-arid region in the Andes Mountains that occupies approximately 27% of the area of Bolivia and has a range in elevation of between 3600 and 4300 m above sea level. • Primarily potato-based cropping systems and livestock rearing of cows, sheep and camelids (e.g., alpaca and lama)

  3. SANREM STUDY AREA IN BOLIVIA A. B. Lake Titicaca Ancoraimes La Paz Umala Altiplano C. Ancoraimes D. Umala Chojňapata Kellhuiri Vinto Coopani Cohani Calahuancane Karkapata San Juan Cerca Chinchaya San José de Llanga Lake Titicaca

  4. CLIMATE CHANGE • The Altiplano 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). • The region will experience temperature increases of up to 6C by the end of the century (Bradley et al., 2006, IPCC, 2007). • A consequence of global climate change has and will be a higher incidence of extreme weather events (Haylock et al., 2006; Thibeault et al., 2008).

  5. STUDY AREA IN BOLIVIA Annual Rainfall Distribution Change in Minimum Temperature Average annual rainfall (mm yr-1) ºC yr-1 Garcia and Seth (in prep.)

  6. OBJECTIVES OF SOILS RESEARCH • To survey representative indigenous farming communities in the Altiplano of Bolivia to determine perceived changes in cropping practices in potato-based cropping systems due to global climate change and socio-economic factors. • To assess the effects of these changes on soil total organic C and other soil properties to determine if soil degradation has occurred.

  7. MATERIALS AND METHODS • Village-level surveys and participatory workshops were conducted in 4 to 5 villages situated at different relative altitudes in the communities of Umala and Ancoriames. • Replicated soil samples were collected in Umalato a 20 cm depth from agricultural fields of the same cropping system and sandy soil type (locally classified as “cha’lla” soil)to determine changes in soil properties with fallow length. • Replicate soil samples were collected to a 20 cm depth directly underneath or between “th’ola” (Parastrephialepidophylla), a common component of fallow vegetation, to determine its effects on soil properties during fallow.

  8. CHANGES IN SOIL MANAGEMENT PRACTICES 20 years ago in Chinchaya Present (Yucra and Gilles, unpublished)

  9. CHANGES IN SOIL MANAGEMENT PRACTICES • Increase in production of some cash crops (e.g. onion) and other income-generating activities (e.g. dairy production, day labor) • Decrease in the length of the fallow period in the crop rotation. • Reduction in planting of early season crops (e.g., fava beans and quinoa) due to early season rainfall uncertainty. • Greater tractor use for tillage in lower elevation communities. • Loss of native species (e.g., th’ola) that have multiple uses to restore soil fertility during fallow period and are a fuel source.

  10. COMMUNITY PERCEPTIONS OF SOIL RESOURCES AND SOIL-RELATED PROBLEMS • Soil-related problems are only one of several factors limiting crop production. • Soil management problems identified were: • Low soil quality and soil fertility(low soil nutrient content, high clay content and stoniness) • Excessive water and wind-induced soil erosion • Insufficient soil moisture due to lower rainfall • Inadequate soil management practices(Inappropriate tractor tillage practices, lack of a suitable crop rotation strategy, insufficient soil fertility inputs, and overgrazing by sheep)

  11. EXAMPLES OF LOCAL SOIL CLASSIFICATION SYSTEM AND PERCEIVED CHANGES IN SOIL PROPERTIES * Observed changes in use of soil over the last 10 years.

  12. EXAMPLES OF SOIL PROPERTIES OF SOIL TYPES BASED ON LOCAL SOIL CLASSIFICATION SYSTEM

  13. EFFECTS OF FALLOW AND CROPPING ON SOIL ORGANIC C IN UMALA

  14. EFFECTS OF TH’OLA AND CROPPING ON SOIL PROPERTIES Selected soil properties of sandy (ch’alla) soil collected directly underneath or between th’ola plants or in farm field during first year of cropping in San José de Llanga in Umala. “Th’ola” is an evergreen shrub (Parastrephialepidophylla) that re-grows during fallow periods

  15. CONCLUSIONS • Climate change and socioeconomic factors in the Altiplano region have led to changes in soil and management practices that have generally reduced soil fertility and soil organic matter. • The decreasing length of the fallow period and reduction in native vegetation (e.g. “th’ola”) caused by competing uses and mechanized tillage, may be removing an important mechanism by which soil fertility and soil organic matter are restored.

  16. CONCLUSIONS (CONT.) • Ongoing research is examining soil management practices that may increase soil fertility and soil organic matter by adding conventional and alternative organic soil amendments (e.g. compost, biofertilizers). • Additional research is needed to identify suitable plants that could be introduced for improved fallow management.

  17. QUESTIONS? COMMENTS? SUGGESTIONS?

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