Soil Nutrient Management
SOIL 4234

Soil Nutrient Management

Salinity Lab

Laboratory 4

Saline and Sodic Soil Reclamation

Objectives     

To observe methods reclamation, of saline and sodic soils, in a laboratory environment.

To observe reclamation methods of saline and sodic soils in a laboratory environment.

Methods 

1.     Measure press cylinder to calculate Pore volume.

2.     Add prepared saturated paste to cylinder to 4/5 full.  Tap down until top of paste is glistening.  Measure distance from top of paste to top of cylinder to complete volume calculation. (assume 50% pore volume)

3.     At this point add treatments of 5 tons/ac (5.3 g) and 2.5 tons/ac (2.6 g) of gypsum to top 1/4 inch of paste.

4.     Put cylinder on press at regular intervals take up off press and replace the amount of solution with an equal amount of DI water.

5.     Measure EC and pH of solution.  Continue until approximately 6 pores volumes have been removed.

6.     Fill in table and create a graph of EC vs pore volumes of leached water and EC vs pH.

7.     As a group consider the case study presented and develop a solution that can be presented in lab in two weeks. 

SOIL 4234      CASE STUDY: SOIL SALINITY 

Situation:

A law suit has been filed in the District Court of Barber County, Kansas.  The Plaintiff is a land owner operating a 3,000 acre cattle ranch a few miles northwest of Medicine Lodge, KS (southwest Kansas).  Plaintiff alleges a saltwater storage tank overflowed spilling about 200 barrels of saltwater, and a few barrels of oil, onto her land.  The spill area is west of the salt water storage tanks and gently slopes toward a creek bank about 600 feet west of the storage tank.  The creek is about 20 feet below the grade (elevation) of the bank.  There is a saltwater injection well 300 feet to the northeast (upslope) of the saltwater storage tank, and into which salt water is normally pumped from the storage tank.  The spill occurred two years ago.  The soil is a sandy loam soil, containing naturally occurring small, crystalline, gypsum.  Normal land use is for range (cattle grazing).

EVIDENCE

Plaintiff.

Environmental/soils expert has taken several soil samples; each representing a six-inch layer of surface soil from the 1/20 acre area upon which the salt water spilled and from the almost vertical bank (took samples probing 6 inches into the face of the bank) where saltwater flowed during the spill.   Additional samples were taken from within the saltwater storage area (containment area of about 4/10 acre surrounded by an earthen berm and fenced).  All soil samples report salinity levels in the range of 40 mmhos/cm to 70 mmhos/cm.

 Suit seeks damages in the amount of $459,375 and removal of a volume of soil for an area 150 feet by 150 feet and 18 feet deep.

 Defendant. 

Defendant is an oil company operating an oil well about 50 feet upslope from the saltwater storage tanks.

 Soils expert has taken one 0-6 inch composite (mixture of 15 individual cores) sample of the area upon which saltwater spilled and one similar sample of an unaffected area upslope.  Salinity in the affected (bare soil, no vegetation) area (1/20 acre) is reported at about 70,000 micromhos/cm for the saturated paste extract.  For the unaffected area salinity is 1,800 micromhos/cm.  An additional soil sample taken in the center of the affected area to a depth of four feet and separated into one-foot segments reports salinity ranging from 40,000 to 60,000 micromhos/cm.

 Soils expert takes water samples upstream and downstream from the spill site and finds EC of the creek water to be about 650 micromhos/cm. 

Defendants offer $10,000 for damages.

 STUDENT PROBLEM (group)

 Evaluate the information provided and devise a plan for soil remediation that would return the soil to normal productivity within a year.  Estimate costs (very rough) assuming a water pump would cost $600.  Removal of damaged soil and replacement with normal soil would cost $20/cubic yard. 

The judge has made a ruling in this case and your grade will be determined by how close your remediation plan costs are to the monetary award from the judge.  Your report (no more than one page) is due at the beginning of lab Septmeber 29.