Also, because if they leave our system, they enter someone else's, for example, the community downstream, and that system may already be overloaded with the surplus nutrients, minerals, soil, flood water, etc. One reason we lose minerals and nutrients from systems so easily is because the same material can change form within the environment. Chemical weathering is a process whereby an element or nutrient undergoes a chemical reaction and changes form or chemically attaches to another element. When an element or nutrient undergoes a chemical reaction and is dissolved in water, then leaching of the element or nutrient can occur. These elements or nutrients can then be lost to the system through the process of runoff, or moved to another part of the system by the process of sedimentation .
Disturbance occurs occasionally in most natural systems.
But in human agricultural systems it occurs frequently. To mimic nature we need to reduce or lessen the impact of disturbances. Without any chemical changes, minerals and nutrients can still be lost from systems by natural transport of materials by water or wind or evaporation of water from a site. In many cases human or natural disturbance can facilitate these losses. For example, fire can leave carbon in a form which is lost from the system much easier than if that carbon was still stored in plant material.