The transport of substances by water

Different substances are transported by water in the soil in both horizontal and vertical directions. The mobility of pesticides, fertilizers or other pollutants was discussed in the previous section dealing with the adsorption of substances on the soil. An important point is that the transport by water 

The chelates formed are characterized by a considerable solubility over a wide interval of pH values and thus, they are very mobile in the soil. 

Substances which are either soluble or suspended in water are transported from their original sites by rinsing with flowing water or they are washed out and transported by water soaking into deeper layers. The intensity of this transport is affected mainly by the extent of precipitation, soil quality, slope and, to a lesser extent, by the type and density of the plant cover. 

Surface transport by water occurs when the amount of water is larger than that which can be soaked into the soil in a given time interval. Soil has good filtration characteristics and it is able to retain many substances which 

The soaking capacity is strongly deteriorated when the soil is both moist and compacted, e.g. by cattle or agricultural machines and when the soil is frozen. This soil is rapidly saturated with water in its top layer, and the excess water runs off, carrying with it particles separated by erosion, and nutrients. Losses of nutrients are high in rich soils and rather lower in poor soils. In acid soils, it is possible to observe a remarkably increased removal of phosphates. 

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