ABSTRACT
Ecosystem ecology is concerned principally with biogeochemistry and energetics of ecosystems, and with processes, such as primary production and decomposition, involved in fluxes of matter and energy through ecosystem components. Three classes of ecosystem processes are particularly relevant to agricultural sustainability and environmental quality: those involved in nutrient transformations; those affecting soil structure and hydrology; and those involving biological interactions. Current models of nutrient cycling in soil suggest that active or readily mineralizable fractions of soil organic matter are coupled to plant-available nutrient pools through the processes of mineralization and immobilization. Factors that control these processes are influenced by management practices and represent potential controlling points for managing nutrient cycles in agroecosystems. Inorganic fertilizers will undoubtedly remain an important source of nutrients in sustainable agriculture. Excess inorganic nitrogen in soil is highly susceptible to leaching and denitrification loss in humid climates.
