Soil phosphorus dynamics in a humid tropical silvopastoral system
In developing countries of the humid tropics, timber exploitation and agricultural expansion frequently result in deforestation. Extensive land management, coupled with inherently low soil fertility invariably produce declines in agricultural/livestock productivity which eventually lead to land abandonment and further deforestation. Phosphorus is often the major nutrient limiting plant growth in tropical soils. Agroforestry systems have been considered as viable alternatives to current land use practices. Several hypotheses suggest that combining trees with crops or pasture, especially leguminous species will improve soil nutrient cycling, soil structure and soil organic matter. In this experiment Erythrina berteroana (an arboreous legume) was grown in native grass pastures in Costa Rica to determine the effects of tree pruning and cattle grazing on soil P availability. I measured soil P fluxes as well as changes in pasture biomass over an 18-month period. In a separate field experiment, I determined decomposition rates and P release characteristics of Erythrina leaves, pasture grass clippings and cattle dung. Erythrina leaves decomposed faster than both pasture grass and cattle dung. Erythrina and pasture residues released 4-5 times less P than dung. Phosphorus fluxes after tree pruning and grazing were highly dynamic for all treatments. Tree pruning increased labile soil P over time when coupled with grazing. Pasture biomass production was greatest in the grazed tree treatment. Pasture biomass P production and concentration was greatest in the non-grazed treatment. Trees and grazing together tended to increase nutrient (P) turnover which stimulated biomass production. In contrast, trees without grazing promoted nutrient (P) accumulation in pasture biomass.
- Research Organization:
- The Ohio State Univ., Columbus, OH (United States)
- OSTI ID:
- 6117911
- Resource Relation:
- Other Information: Thesis (Ph.D.)
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
DEFORESTATION
ENVIRONMENTAL EFFECTS
SOILS
FERTILITY
TROPICAL REGIONS
BIOMASS
COSTA RICA
CROPS
DECOMPOSITION
DEVELOPING COUNTRIES
LAND USE
LEGUMINOSAE
NITROGEN
ORGANIC MATTER
PASTURES
PHOSPHORUS
PLANT GROWTH
PRODUCTIVITY
SOIL CHEMISTRY
TREES
CENTRAL AMERICA
CHEMICAL REACTIONS
CHEMISTRY
ELEMENTS
ENERGY SOURCES
GROWTH
LATIN AMERICA
MAGNOLIOPHYTA
MAGNOLIOPSIDA
MATTER
NONMETALS
PLANTS
RENEWABLE ENERGY SOURCES
095000* - Biomass Fuels- Environmental Aspects- (1990-)