We offer a wide range of laboratory and field exercises in soil ecology. First, we consider root-related studies, including rhizotrons and mini-rhizotrons, sequential sampling of root cores, and root ingrowth. Process-related studies are consider next, including soil respiration, and litter decomposition. Soil microbe and protozoan exercises are considered next: quantifying mycorrhizal fungal colonization of roots, analyses for soil microbial biomass, and field exercises for soil protozoan activity and biodiversity. We then consider nematode sampling and extraction. This is followed by sampling and enumeration of microarthropods (mites and collembola). This is followed by quantifying the numbers and biomass of microarthropods. Sampling and enumeration of enchytraeids is presented next. This is concluded with methods for sampling and quantifying earthworms, followed by an exercise for conjoint sampling of macroinvertebrates, namely arthropods and earthworms.

We focus on the future effects of soil biotas and soil processes on Global Climate Change. This includes changes in evolution and uptake of the principal greenhouse gases and their interplay with pools of labile and resistant soil organic matter. The full costs of ecosystem services, as human population pressure increases, require innovative thinking and research. Simulation models provide insights and uncertainties in soil-atmosphere-biosphere fluxes. Soil biodiversity changes driven by global change are the result of direct impacts (changes in temperature and moisture), and indirectly, through shifts in nutrient supply from plants. Invasive plants and animals add to the complexity of these long-term processes. Future studies of land-use management will encompass the fact that soil biota act in concert to provide multiple benefits. Increasing food web complexity in soils should provide improved “health” (i.e., enhanced recycling of nutrients) in agro-ecosystems. We conclude with a critique of the interfaces between soil food webs, ecosystem engineers, and enhanced provision of ecosystem services over landscapes at millennial time scales.

Inputs from primary production in soils are from two principal sources: aboveground and belowground. We focus on inputs from roots and their rhizosphere associates, including mycorrhiza and rhizobia. Input measurement techniques include various nondestructive techniques, including rhizotrons and minirhizotrons, and destructive techniques, including soil coring, and isotopic-labeling of roots, followed by destructive sampling at specified time intervals to determine dynamics, e.g., over an entire growing season. Of equal importance to roots themselves are their generally more efficient physiological extensions, the root-fungus mutualistic association, mycorrhiza. At a cost of 5%–30% of the total photosynthate translocated belowground, mycorrhiza assists in obtaining inorganic nutrients, water, and in some cases, organic nutrients over a much wider range of the soil volume than roots alone. This symbiotic association has a significant effect on other biota, namely microbes and fauna, which inhabit all soil systems. Long-term Free Air Carbon Enrichment (FACE) studies have yielded information on flows to roots and their species-rich grazers and microbial and faunal associates.

Food web ecology has the potential as an integrating concept to unify perspectives in above-ground and below-ground ecology. A typical food web, particularly in arid lands, has 7–8 membered food chains embedded in the food web. By viewing soil systems holistically, including such microfauna as protists, and mesofauna (nematodes), there are ample supplies of biota (food) to enable longer food chains to exist. Thus production efficiencies can be up to 70%. Trophic transfer efficiencies, often thought of as maximal at 10%, can be up to 20%, particularly in such soil “hot spots” as rhizospheres and drilospheres. The future of food web ecology research is bright, with conjoint studies of biodiversity and including a wide range of innovative isotopic tracer techniques.

We set the stage by giving four main reasons to study soils: (1) humanity depends upon soils for their livelihood and ecosystem services; (2) as a last frontier in biodiversity research, soils teem with common and rare organisms; (3) soils are an excellent medium to study ecology ranging from organisms to ecosystems and entire regions; (4) more importantly, soils are exciting, challenging, and fun! We present a historical background of soil concepts, extending from early Chinese and Mesopotamian cultures, through Greco-Roman, into modern times. Much modern research focuses at the interface between soil–water–gases and organisms. Soils have texture and structure, arising via a range of mechanisms, mediated by the production of soil organic matter. The hierarchical nature of soil structure leads to characteristic profiles, developing over time. The historical nature of soils extends to including “libraries” of DNA. We conclude with an introduction to soils in their provision of ecosystem services, a major theme for the entire book.