Air is then breathed into the windpipe and lungs, while the mucus is swallowed (figure 3). Other. Other interesting structures associated with the nasal and sinus tract: Tear duct (called the nasolacrimal duct): drains tears from the inside corner of the eye into the nasal cavity (figure 1).
Human activity is the main cause of soil degradation. Agriculture plays a large part in soil degradation, especially clearing, irrigation, the spreading of chemical fertilizer â¦ s and pesticides, overgrazing and even the passage of heavy farming equipment. Tillage and the clearing and deforestation of large plots of land also lead to soil degradation.
Soil erosion removes valuable top soil which is the most productive part of the soil profile for agricultural purposes. The loss of this top soil results in lower yields and higher production costs. When top soil is gone, erosion can cause rills and gullies that make the cultivation of paddocks impossible. The impacts of erosion on cropping lands include: reduced ability of the soil to store water and nutrients. exposure of subsoil, which often has poor physical and chemical properties.