Biotiska faktorers inverkan på markstrukturen

Abstract: Soil structure is a key factor in the functioning of soil, including its ability to support root growth. Soil structure influences the circulation of nutrients and affects the gas exchange, and acts as habitat for the soil organisms. Soil structure influences which organisms that live in the soil, at the same time as the soil organisms affects the soil structure. The relationship between the soil structure and the soil organisms is a complex system where different interactions lead to feedback loops. Different soil organisms affect the soil structure in different ways. Earthworms, fungi and bacteria affect soil structure directly while collembola, mites, nematodes and protozoa have an indirect impact on the soil structure. Some of the soil organisms exudate extracellular polymeric substances that bind together soil particles and form aggregates. Roots create pores in the soil through their growth and contribute to the formation of aggregates by their exudates of extracellular substances. Roots and litter constitute an energy input into the soil that influence and shape the soil food web, which in turn influences the soil structure and feeds back on how the energy flows throw the soil. The quality and amount of organic matter from the roots and litter affect which organisms that live in the soil, and influence the durability of aggregation of soil particles. Soil management, in particular soil tillage and crop selection, have a large impact on soil structure and the organisms that live in the soil. The aim of this essay was to review how different biotic factors influence soil structure through aggregation of soil particles. This was performed through a literature study of the research that was available on the subject. The essay also and illuminates where more research is needed.