ABSTRACT
This chapter discusses the flow of energy and nutrients within and through the soil system and between different trophic levels, which are reviewed in the preceding chapter. Organic energy, once it has been fixed by plants into compounds, moves within soil systems through the consumption of organic matter, living or dead, by uncountable numbers of organisms that travel through the soil and above it. Losses of nutrients from soil systems are by leaching, soil erosion, gaseous losses like the loss of N through denitrification, and plant uptake. This complex reserve of organic molecules has physical properties that are very beneficial in soil systems, such as increasing their cation exchange capacity, a key parameter for soil system functioning. While the complex OM fraction in soil is decomposing slowly, releasing nutrients, more is continuously being created within functioning soil systems.
