P. Field capacity - 3. Maximum quantity of water that a given soil can retain against force of
gravity Field capacity represents the moisture content remaining in the soil after excess
gravitational after has fully drained away (usually 2 to 3 days after a heavy rain or irrigation). It
is the upper limit of available water for plants.
Q. Permanent wilting point - 4. Moisture content of a soil at which the water is no longer available in sufficient quantity to sustain plants
This is the lower limit of available water. At this stage, the soil grains hold onto water film so tightly due to surface tension that plant roots cannot exert enough suction to extract it, causing the plants to permanently wilt.
R. Specific yield - 1. Volume of water that can be extracted by force of gravity from a unit volume of saturated earth material In groundwater hydrology, specific yield (Sy) is the ratio of the volume of water that a saturated soil or rock will yield by gravity to the total volume of that material. (The remaining un-drainable portion is called specific retention).
S. Infiltration capacity - 2. Maximum rate at which a soil can absorb water through its surface
Infiltration capacity (fp) dictates the maximum rate at which water can enter a specific soil under a given set of conditions. If the rainfall rate exceeds this capacity, surface runoff begins to accumulate.
