Refill Point
- The water content of the soil below which the plant exhibits some form of stress, and a drop in yield.
- Expressed as mm of water over a certain depth (e.g. 0-70cm).
- Will not be constant down the soil profile.
- The advent of stress might be identified by a drop in the daily use water
- The consequence might be that the roots start extracting water at a greater depth.
- Dependant on both soil and crop.
Finding the Refill Point
- Identify the maximum rooting depth. This may not be possible because of roots deeper that measurements, or high water table.
- Look for the driest profile before which movement occurs below the rooting depth.
- The driest profile before a decrease in daily crop water use
- Extraction patterns wetter than this profile will be wedge shaped.
- Drier extraction patterns are parallel, with water extraction at all depths.
As the soil moisture content reaches the refill...
- Changes occur below the normal root zone on the depth graph
- The slope of the line on the time graph decreases
Case Studies:
Russet Burbank Potatoes |
Turf