|Handbook for Agrohydrology (NRI)|
|Chapter 5: Soils and soil moisture data|
Soil physical, chemical and moisture properties constitute a study in their own right and it is possible that any agrohydrological or water harvesting project may have available the services of a soil specialist, but this is not always the case. The effects of soil physical properties on hydrological behaviour are very important.
Four main aspects of soils and their influence on runoff and agriculture are considered. These are:
1. The physical and textural nature of soils which are influential in determining runoff.
2. The soil moisture status which can also influence runoff and control water availability for crops.
3. How to measure soil moisture.
4. The influence of these soil factors on the process of infiltration, the ability of soils to absorb water.
In many respects soil textures and soil moisture status are closely linked; the physical characteristics of soils may change with the addition or removal of water, while the physical characteristics of soils will determine their ability to absorb and retain rainfall. In terms of the study of soils for agrohydrological purposes and the quantification of soil characteristics, it is most convenient to study these aspects separately. Methods of determining infiltration, which is strongly influenced by texture and moisture status, are also discussed.