Water Problem Practice

1
Water Problem Practice

• Wt. of cylinder oven dry soil 440g
• wt. cylinder at field capacity 650g
• wt cylinder at wilt point 550
• Wt cylinder on June 1 590
• volume cylinder 330 cc
• BD 440/330 1.33
• water by wt. at FC (650-440)/440x100 47.7
• water by vol at FC (650-440)/330 x100 63.6
• and water by wt. X BD water by Vol or 47.7
  X 1.33 63.6
• water by vol at WP 550-440/330 33.3

2
1.

• What is the amount of AWC in inches per foot of
  soil.
• AWC (FC WP) x 12/ft.
• 63.3-33.6 30.3
• Or .303 x 12/ft 3.6 of AWC /ft of soil

3
2.

• What is the depth of wetting for a 2 inch
  rainfall on June 1?
• Depth wetting Inch rainchange in AWC
• Change in AWC FC June 1
• and June 1 water 590-44033015033045.4
  and
• 63.6-45.4 18.2 or
• 2 rain0.182 depth of wetting
• or 10.99 inches

4
3.

• If a soil sample is collected on June 1 in a 5
  gallon pail. What is the weight of the soil in
  the pail. Water 8 lbs/gallon.
• Soil bd x 8 lbs/gal x 5 gal or
• 1.33 x 8 x 5 53.2lbs
• water vol on june 1 45.4
• Or .454 x 5 gal 2.27gal water x 8lbs/gal
• 18.16 lbs
• And 18.16 53.2 71.36 lbs for a 5 gal pail of
  soil

5

4.

• If the plants growing in your soil on June 1 have
  roots in the upper 24 inches of soil and they use
  .15 inch of water per day, How many days before
  they wilt.
• Soil water goes from June 1 to WP
• WP 550-440/330.333 or 33.3
• Or June 1 WP 45.4-33.312.1
• And inches of water AWC x Inches of soil or
  .121 x 24 inches 2.9 inches of AWC at the use
  rate of .75 per day or days 2.9 /.75/day
• 3.9 days

6
5.

• --Suppose the pail of soil you collected is to be
  planted with flowers. You want to bring the pail
  to field capacity, but not more, since you dont
  want to saturate the soil and you dont have any
  holes in the bottom to let the water drain out.
  How much water should you add in gallons.?
• Soil Vol gal. x AWC change gal water or
  Change in water from PC to FC
• or FC-PC 63.6-45.417.9 water by volume
  change.
• Soil Volume 5 gal or 5 gal x.179 0.895 gal
  water is needed to add to 5 gal pail of soil to
  bring soil to field capacity.