Where Are We and Where Are We Going? Pedogenesis Through Chemical Weathering, Hydrologic Fluxes, and Bioturbation

Abstract

: A review of the status of fundamental research into soil genesis and development is given, together with a discussion of the outstanding problems from various perspectives, such as the geological, hydrological, and soil ecological points of view. The urgency of understanding what soil is, how it forms and evolves, relates fundamentally to its connection with the cycling of water and those elements of deep significance to biology, e.g. carbon, nitrogen, and phosphorus, as well as to the uptake and fate of the (mostly) solar energy input. The coupling is inherent in the close relationships between soil genesis and the formative process of chemical weathering, together with its abiotic drawdown of atmospheric carbon, as well as the relationship between soil evolution and the biological processes that change the soil. Each of these phases links soils to the atmospheric carbon composition and the Earth’s climate system. More recently, the link between soil formation and Earth’s water cycle has become clearer with the recognition that field weathering rates are more likely flux‐limited (water, organic acids, and reaction products) than kinetics‐limited. While a link between water and CO2 drawdown appears explicit in the photosynthetic reaction, the relationship between plant productivity and transpiration fundamentally links water and cycling of elements such as carbon, nitrogen, and phosphorus. The summary is intended to place the works of the present book into the context of present research efforts and future goals. ABSTRACT A review of the status of fundamental research into soil genesis and development is given, together with a discussion of the outstanding problems from various perspectives, such as the geological, hydrological, and soil ecological points of view. The urgency of understanding what soil is, how it forms and evolves, relates fundamentally to its connection with the cycling of water and those elements of deep significance to biology, e.g. carbon, nitrogen, and phosphorus, as well as to the uptake and fate of the (mostly) solar energy input. The coupling is inherent in the close relationships between soil genesis and the formative process of chemical weathering, together with its abiotic drawdown of atmospheric carbon, as well as the relationship between soil evolution and the biological processes that change the soil. Each of these phases links soils to the atmospheric carbon composition and the Earth’s climate system. More recently, the link between soil formation and Earth’s water cycle has become clearer with the recognition that field weathering rates are more likely flux ‐ limited (water, organic acids, and reaction products) than kinetics ‐ limited. While a link between water and CO 2 drawdown appears explicit in the photosynthetic reaction, the relationship between plant productivity and transpiration fundamentally links water and cycling of elements such as carbon, nitrogen, and phosphorus. The summary is intended to place the works of the present book into the context of present research efforts and future goals.