Based on the existing literature, nutrient acquisition from arable subsoils may be conceptualised into three major process components: (I) mobilisation from the subsoil, (II) translocation to the shoot and long-term accumulation in the Ap horizon and (III) re-allocation to the subsoil.
The quantitative estimation of nutrient acquisition from the subsoil requires the linking of field experiments with mathematical modelling approaches on different spatial scales including Process Based Models for the field scale and Functional–Structural Plant Models for the plant scale.
The concept of action is of central interest to many disciplines: the social sciences including economics, the humanities including history and literature, psychology, linguistics, law, computer science, artificial intelligence, and probably others.
In philosophy it has been studied since the beginning because of its importance for epistemology and, particularly, ethics; and since a few decades it is even studied for its own sake.
Current knowledge of earthworm feeding ecology is reviewed, with particular reference to food selection, ingestion, digestion and assimilation, and the use of novel techniques to advance understanding of the functional significance of these processes.
Traditional research methods including direct observation of feeding behaviour, gut content analysis, choice tests, and litter bags have provided a wealth of information on earthworm feeding.
In arable farming systems, the term ‘subsoil’ refers to the soil beneath the tilled or formerly tilled soil horizon whereas the latter one is denoted as ‘topsoil’.
To date, most agronomic and plant nutrition studies have widely neglected subsoil processes involved in nutrient acquisition by crop roots.
Ueno,-Shun-Ichi-; Nishikawa,-Yoshiaki * 2001 * A new threatened species of the genus Trechiama (Coleoptera, Trechinae) from northeastern Honshu, Japan, with notes on an endangered species.
Ueno,-Shun-Ichi- * 2000 * New cave trechines (Coleoptera, Trechinae) from northeastern Guizhou, south China.
Based on our current knowledge it can be assumed that subsoil properties such as comparatively high bulk density, low air permeability, and poverty of organic matter, nutrients and microbial biomass are obviously adverse for nutrient acquisition, and sometimes subsoils provide as little as less than 10% of annual nutrient uptake in fertilised arable fields.
Nevertheless, there is also strong evidence indicating that subsoil can contribute to more than two-thirds of the plant nutrition of N, P and K, especially when the topsoil is dry or nutrient-depleted.
However, there is a lack of the mechanistic, quantitative information required to characterise adequately their functional role in soil ecosystem processes such as soil C sequestration and loss, decomposition of organic residues, the maintenance of soil structure and trophic interactions with plants and microorganisms.