Fumigation method employing an aqueous solution comprising a hexametaphosphate, a thiocarbonate, and a sulfide
AssigneeUnion Oil Company of California
InventorsDonald C. Young, James A. Green, II
Life of this patent
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Abstract
Aqueous thiocarbonate solutions are stabilized by the addition of base, sulfide and/or polysulfide, and the stability and safety of the more concentrated solutions containing 1 weight percent or more equivalent CS.sub.2 as a thiocarbonate are achieved as reflected by significant reduction of CS.sub.2 partial pressure in such solutions. Also, deposit formation in irrigation systems delivering such thiocarbonates, such as drip emitters and sprinkler heads, is reduced or eliminated with minor amounts of sodium hexametaphosphate.
Claims35
A method for fumigating soil, which comprises applying to the soil through irrigation means an aqueous solution comprising:
- (a) an amount of sodium hexametaphosphate sufficient to inhibit the deposition of hard water deposits on the irrigation means;
- (b) a fumigation effective amount of a thiocarbonate selected from the group consisting of alkali and alkaline earth metal tri- and tetrathiocarbonates, and combinations thereof;
- and
- (c) an amount of a sulfide sufficient to increase the chemical stability of the thiocarbonate in the solution, the sulfide being selected from the group consisting of alkali and alkaline earth metal sulfides of the formula M.sub.n S.sub.x, wherein M is selected from alkali and alkaline earth metals and combinations thereof, x is at least 1, n is 2 when M is alkali metal, and n is 1 when M is an alkaline earth metal, and combinations thereof.
A method for fumigating soil, which comprises applying to the soil through irrigation means an aqueous solution comprising:
- (a) at least about 0.1 ppm sodium hexametaphosphate;
- (b) a thiocarbonate selected from the group consisting of alkali and alkaline earth metal tri- and tetrathiocarbonates, and combinations thereof, the thiocarbonate being present in the solution in a concentration less than 55 weight percent;
- and
- (c) a sulfide selected from the group consisting of alkali and alkaline earth metal sulfides of the formula M.sub.n S.sub.x, M is selected from alkali and alkaline earth metals and combinations thereof, x is at least 1, n is 2 when M is alkali metal, and n is 1 when M is an alkaline earth metal, and combinations, the sulfide concentration in the solution being sufficient to reduce the carbon disulfide concentration in the equilibrium vapor phase to below about 1 volume percent at 24.degree. C.
A method for fumigating soil, the method comprising the step of applying to the soil through irrigation means an aqueous solution comprising:
- (a) an amount of a hexametaphosphate sufficient to inhibit the deposition of hard water deposits on the irrigation means;
- (b) a fumigation effective amount of a thiocarbonate selected from the group consisting of alkali and alkaline earth metal tri- and tetrathiocarbonates, and combinations thereof;
- and
- (c) an amount of a sulfide selected from the group consisting of alkali and alkaline earth metal sulfides of the formula M.sub.n S.sub.x, wherein M is selected from alkali and alkaline earth metals and combinations thereof, x is at least 1, n is 2 when M is alkali metal, and n is 1 when M is an alkaline earth metal, and combinations thereof sufficient to increase the chemical stability of said thiocarbonate in said solution.
Dependencies are inferred from the claim text.