Water Storage Capacities in Soil Lecture
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1. At field capacity all the small pores are filled with water
At field capacity all the small pores are filled with water.
It is extremely important that you become familiar with identifying textural classes to perform water storage capacities in field situations.
- Important;
One liter of water spread evenly over a waterproof surface 1 m2 will give a depth of 1 mm.
- Calculating Water Storage Capacities of Soils
2. Calculating Water Storage Capacities of Soils
- Important;
One liter of water spread evenly over a waterproof surface 1 m2 will give a depth of 1 mm.
1 Liter of Water 1 mm H2O 1 m2
3. Table 1.0. Water Storage Capacities of Soils
- Textural Class
- Total Storage Capacity
- Macropore
Space (%) Plant Available Moisture (%) (mm H20/cm soil)
(%) (mm H20/cm soil) Coarse Sand 24.4 2.44 17.7 6.7
- 67 Coarse Sandy Loam 24.5 2.45 15.8 8.7 0.87 Sand
- 3 3.22 29.0 13.3 1.32 Loamy Sand 37 3.70 26.9
- 1 1.01 Loamy Fine Sand 32.6 3.26 27.2 5.4 0.54
- Sandy Loam
- 9 3.09 18.6 12.3 1.23 Fine Sandy Loam 36.6 3.66
- 5 13.1 1.31 Very Fine Sandy Loam 32.7 3.27 21.0
- 7 1.17 Loam 30.0 3.00 14.4 15.6 1.56 Silty Loam
- 3 3.12 11.4 19.9 1.99 Sandy Clay Loam 25.3 2.53
- 4 11.9 1.19 Clay Loam 25.7 2.57 13.0 12.7 1.27
- Silty Clay Loam
- 3 2.33 8.4 14.9 1.49 Sandy Clay 19.4 1.94 11.6
- 8 0.78 Silty Clay 21.4 2.14 9.1 12.3 1.23 Clay
- 8 1.87 7.3 11.5 1.15
4. Sample Calculation;
A 1250 m2 nursery has a topsoil layer of loam with a depth of
- 5 cm. How much available water will be held in this soil at field capacity?
Perform the following steps to solve the problem;
Step #1; Identify the depth of soil and textural class.
Step #2; Locate the appropriate soil texture in Table 1.0 and identify the available water held at field capacity for that textural class.
Step #3; AW = Soil Depth x Coefficient from Table #1
- Calculating Water Storage Capacities of Soils
5. Calculating Water Storage Capacities of Soils
- Sample Calculation;
A 1250 m2 nursery has a topsoil layer of loam with a depth of
- 56 cm. How much available water will be held in this soil at field capacity?
- Answer;
AW = depth of soil x coef. (from Table 1.0) Table 1.0 Loam - 1.56 mm H2O / cm of soil depth = 24.56 24.56 cm soil x 1.56 mm H2O
- AW = 38.22 mm H2O
6. Calculating Water Storage Capacities of Soils
Note
Soil depth always has to be in cm before plugging it into the equation.
7. Calculating Water Storage Capacities of Soils
- Sample Calculation;
A field production facility that is 650 m2 has a Silty loam root zone that is 7.5 inches in depth. How much available water will be held in this soil at field capacity?
8. Calculating Water Storage Capacities of Soils
- Sample Calculation;
A field production facility that is 650 m2 has a Silty loam root zone that is
- 5 inches in depth. How much available water will be held in this soil at field capacity?
- Answer;
Convert Inches of soil to cm of soil.by;
- 5 inches of soil x 2.54 cm = 19.05 cm of soil AW = depth of soil x coef. (from Table 1.0) Table 1.0 Silty Loam - 1.99 mm H2O / cm of soil AW = 19.05 cm of soil x 1.99 mm H2O
- AW = 37.91 mm H2O
9. Calculating Water Storage Capacities of Soils
- Sample Calculation;
How many liters of water will you have to apply to bring the following landscape from PWP to field capacity?
A field production facility landscape that is 650 m2 and has a Silty loam root zone that is 7.5 inches in depth.
10. Calculating Water Storage Capacities of Soils
- Sample Calculation;
How many liters of water will you have to apply to bring the following landscape from PWP to field capacity? A field production facility landscape that is 650 m2 and has a Silty loam root zone that is 7.5 inches in depth.
- Answer;
Convert Inches of soil to cm of soil.by;
- 5 inches of soil x 2.54 cm = 19.05 cm of soil AW = depth of soil x coef. (from Table 1.0) Table 1.0 Silty Loam - 1.99 mm H2O / cm of soil AW = 19.05 cm of soil x 1.99 mm H2O
- AW = 37.91 mm H2O
11. Calculating Water Storage Capacities of Soils
- Sample Calculation;
How many liters of water will you have to apply to bring the following landscape from PWP to field capacity. A residential landscape that is 650 m2 and has a
Silty loam root zone that is 7.5 inches in depth.
- Answer Continued;
1 litre of H2O spread over 1 m2 is 1 mm deep Therefore;
- 91 mm deep of H2O over 1 m2 = 37.91 L H2O 37.91 L H2O / m2 x 650 m2 of soil = 24641.5 liters of H2O