1. Saturation:
The point at which all of the pores of the soil are full of water.
2. Holding capacity:
The ability of the soil to hold water against the pull of gravity.
3. Field capacity
The amount of water left in the soil after the excess has drained away.
4. Wilting point:
The soil moisture content at which the plants lose turgor pressure and wilt.
5. Permanent wilting point:
The point at which the soil moisture content is so low that plants can no longer pull any water from it and they lose so much turgor pressure that they will not revive even if watered immediately.
6. Available water
The water in the soil which is available to plants.
7. Hygroscopic water:
Water which is held so tightly to the soil, by static electricity, that it can not be taken up by the plant.
Model Agricultural Core Curriculum: Supplement
University of California, Davis
352.1

1. Question: What is the name of the water that is held so tightly by the soil that the plant can
_ d. Hygroscopic water to _ e. Wilting point
_ f. Holding capacity g. Available water excess
Answer: a. 5 b. 4 not take it up?
Answer: Hygroscopic water.
2. Question: You are a soil analyst, and have been hired by a farmer to determine the available water of his soil. Your tests show that the field capacity is -1\3 bars and the wilting point is -15 bars. What is the available water for his soil?
Answer: FC - WP = AW.
-1\3 - (-15) Bars = 14 2\3 Bars
3. Question: Match the following words with their corresponding definitions.
_ a. Field capacity 1. The pores of the soil are full of water.
_ b. Permanent wilting point 2. The soil's ability to hold water against the _ c. Saturated pull of gravity.
3. The water in the soil which is available plants.
4. The loss of turgor pressure from which plants cannot recover.
5. The water held in the soil after the water has drained away.
6. The point at which plants wilt due to a lack of water.
7. Water which is held by the soil particles and not available to plants. c. 1 d. 7 e. 6 f. 2 g. 3
Model Agricultural Core Curriculum: Supplement
University of California, Davis
352.2