It is a simple matter to determine the amount of usable water in soil for SCAF.  Dig down 18 inches, make a golf ball sized clod and put it in a Ziploc sealing plastic bag.  Remove the clod from the bag and weigh it in the lab, put it in a weighed metal pan, roast it in an oven at 220 degrees for one hour.  Cool and weigh it again.  The difference is the water mass.  This figure can be used to compute how much gas may be sequestered in a given area where each cubic yard of soil contains several hundred pounds of water.  Each pound of water can absorb about half a gallon of carbon dioxide gas at one atmosphere.

To determine how much gas to put through the nozzles we need only dig to the depth of the spike or permanent pipes, take samples of the soil, seal them in plastic bags to prevent evaporation. In the lab remove soil from the bags, weigh it, bake in an oven for one hour at 220 degrees F, cool and weigh the soil again to determine the percentage water in the soil.

Most soils have a density of about 2.5 g/ml or 4219 pounds per cubic yard 422 pounds of which will be water that will take 16 pounds of CO2 or 4027 liters at 20 Celsius degrees.  At a depth of 18 inches and spacing of 30 to 36 inches each spike will cover a bit more than one cubic yard per running yard.  At three miles per hour each spike should inject about 1/2 cubic yard per second and should be able to plant about eight pounds of CO2 per second or one long ton every 4.58 minutes.

Molecular Cohesion

The amount of water in the soil does not tell the whole story.  A cubic yard of soil with 10% water will take much more than 16 pounds of CO2.  All molecules have a tendency to stay with their own kind we think because of the similarity in surfaces and the attractive forces between them.  We see this in the virtually infinite friction between the iron wheel of a steam locomotive and the iron rail. Both surfaces must be brightly polished for the effect, but when pressed together with the weight of the locomotive the two are virtually inseperable, but the wheel can roll.  Without this odd effect trains would never have been developed.

The effect appears again in the formation of a suface skin on fluids like water where they meet the air.  Where we cannot see down to the size of one water molecule, but could for more an object more than ten molecules wide we believe this layer, or skin, is more than ten molecules deep as it is clearly visible.  The water molecules in it are clearly packed as if it were solid.  And, the density of this layer is greater than that of steel as a small steel objects like razor blades, pins and needles float on it.

Cohesion forms and holds bubbles that eventually dissolve in migrating water to get into plants in the soil.  The degree to which this improves the carrying capacity of soil has to be determined experimentally because soils are different in their characteristics.  A management program will include testing the soil for CO2 leakage after application with progressive increases until the capacity limit is found.

In a permanent underground distribution system you will estimate based on an effective diffusion radius of about one foot and compute how much gas that soil can take in each feeding. Gas injections should probably follow water injections by one day to give the fluid time to diffuse away from the injection tubing and better receive the gas which prefers still water.

Harrow wheels and perhaps a heavy roller following the spikes can restore ripped soil to cap and seal gas in the earth preventing escape from an open furrow.   Where this modification is only used for injection and not lifting it should have much less pulling resistance to tractors than subsoil plows with lifting and turning plows.