USE OF METAM SODIUM FOR PRESERVING HIGH-MOISTURE CROPS

Abstract: Metam sodium (sodium methyl dithiocarbamate) for preserving high-moisture baled crops like hay and seed cotton at application rates below about 4lbs/T.

Description: USE OF METAM SODIUM FOR PRESERVING HIGH-MOISTURE CROPS Field of the Invention This invention relates to the field of agricultural chemistry and particularly to compositions and m ethods for preserving high-moisture crops such as hay, grain, silage, and seed cotton. Background of the Invention 10 Some 150 million tons of hay are baled in the United States each year, yet hay losses are probably larger than those of any other crop. Dry matter losses in haymaking can reportedly range from 10-71% due to the various physiological and m echanical processes that the crop undergoes from the time the plant is cut until the hay is safely stored. Microbial degradation leading to 1.5 mold formation and heat generation is among the principal causes of field losses in haymaking. Hay will spoil if baled at moistures much over 12% unless preservatives are applied to prevent fungal spoilage. Microbial activity and chemical oxidation cause heating in hay containing more than 15% moisture. Heat generation in baled hay increases dry matter losses, reduces nutrient 20 digestibility, particularly protein, and causes discoloration. Spoilage also causes loss of palatability and production of toxins. If the disadvantages of microbial degradation, particularly mold formation and heat generation, could be alleviated, baling hay at higher moisture levels could provide direct benefits to the grower. The field-curing process 5 could be shortened, thereby reducing the exposure of plant nutrients to the destructive actions of sun, rain, and microbes. Entire cuttings are frequently lost due to untimely rainfall, for example, and these losses could be curtailed by baling the hay sooner, at higher moisture levels. Without a hay preservative, hay dry enough to bale without spoiling is crisp, and the fragile plant parts that are 0 the most nutritious crop components shatter easily and so are lost as chaff as the hay is tedded, raked, and baled. Higher moisture content also increases palatability and thus decreases waste after the hay is harvested. Indirect losses associated with field drying could also be reduced by baling high-moisture hay. Tractor wheel damage to rejuvenating plant crowns can be reduced by minimizing the tedding and crimping manipulations that are typically used to foster field drying. In addition, the grower can irrigate and fertilize sooner, and thereby enhance the production of the next cutting. It is consequently desirable to devise treatm ents that permit the grower to bale hay at higher moisture levels, on the order of 12% to 30% moisture, without heating or molding. It would also be useful to devise treatm ents that perm it storage of moist seed cotton without heating or molding. Generally, seed cotton can be stored with almost no risk if its moisture content is 12% or less. However, the risk of seed and lint (cotton fiber) damage due to heating and molding increases rapidly as the seed cotton moisture increases and as the storage period increases. Cotton harvested during periods of high atmospheric humidity or during a rai n shower, or cotton that becomes wet after harvesting, ordinarily must be ginned as soon as possible after harvesting. The present trend toward fewer cotton gins, the recent development of the cotton module storage system , and the high cost of ginning machinery suggest that gins of the near future may operate nine months of the year, ginning from a crop that is stored in modules or gin yards. The practice of storing seed cotton in modules has increased threefold in the last ten years. The success of this system depends on growers being able to harvest the crop when weather conditions permit picking and moduling dry seed cotton. However, during the harvest season there are frequent periods when weather conditions and harvest deadlines force moduling of seed cotton while the crop is still moist. It would also be desirable to devise treatm ents that permit storage without heating or molding of poultry rations having moisture levels on the order of 13% to 28% moisture. For example, microbial degradation of milled grains that serve as poultry rations severely impacts the poultry industry. Poultry are particularly sensitive to mycotoxins. The poultry rations leave the mill at about 12% moisture content but are typically stored for several weeks in farm grain bins before being fed out to broilers, layers, and turkeys. Due to condensation during transport and storage, and also metabolic water production, the milled grains tend to spoil in the grain bins, and so the rations are routinely treated with mold inhibitors. Such preservation treatments currently cost the poultry farmer on the order of one dollar or more per ton of rations. Considering that some four billion broilers are raised annually in the U.S., each consuming an average eight pounds of rations, there is and has been a tremendous incentive to find more cost-effective preservative treatments for milled grains. Many efforts have been made to provide compositions and m ethods for preserving high-moisture content crops such as hay and grain against the deleterious eff ects of microbial degradation. Propionic acid has been used with som e success as a hay preservative. See, for example, Agron. J. 68:120-123, 1976; Ann. Appl. Biol. 88:65-73, 1978. Propionic acid has also been combined with a variety of adjuvants for reported synergistic effect. Indeed, many if not all of the current comm ercial hay preservative preparations rely upon propionic acid as the sole or principal preservatively effective ingredient. Unfortunately, propionic acid is a volatile, pungent chemical that is highly corrosive to farm machinery and furtherm ore discolors cotton lint. Also of interest are references to the use of carbamate com pounds, particularly sodium methyl dithiocarbamate, as antimicrobial agents. U .S. Patent No. 2,792, 327 discloses the application of sodium monom ethyl dithio¬ carbamate to control fungus infestation of living vegetation. U .S. Patent No. 3,699,231 reports a synergistic mixture of sodium m ethyl dithiocarbamate and formaldehyde to inhibit the growth of sulfate reducing bacteria. U.S. Patent No. 3,836,655 reports a synergistic mixture of sodium methyl dithiocarbamate and propionic acid for preserving moist grain during storage, at dosages of about 32 ounces of the sodium m ethyl dithiocarbamate component per ton of grain. See also: U.S. Patent No. 2,614,957 (sodium dimethyl dithiocarbamate admixed with the sodium salt of 2-mercaptobenzothiazole); U.S. Patent No. 2,614,959 (zinc dimethyl dithiocarbamate admixed with the ferric salt of mercapto- benzothiazole); U.S. Patent No. 2,776,922 (zinc salt of 2-mercaptobenzothiazole admixed with zinc salt of dimethyl dithio carbarn ic acid); and U.S. Patent No. 4,203,999 (antifungal bis(dithiocarbam ate) salts). Sum mary of the Invention Sodium methyl dithiocarbamate is applied at dosages of not more than about 4 pounds per ton of forage or seed cotton crop having up to 35 percent moisture content, in order to effectively retard microbial degradation and thereby stabilize the lii h- oisture crop. Suitable forage crops for stabilization by the subject m ethod include liay crops, grains, and silage crops. Baled crops such as hay and moduled seed cotton can be effectively stabilized by the subject m ethod, using conventional spraying equipm ent at the baler pickup. In an illustrative embodiment, hay or seed cotton having less than about 35 percent by weight mositure is sprayed imm ediately prior to baling with an aqueous solution of sodium methyl dithiocarbamate at an application rate of not more than about 4 pounds dry weight of sodium m ethyl dithiocarbamate per wet ton of crop subs trate. Also provided are containers of sodium methyl dithiocarbamate with printed instructions for applying the contents to forage and seed cotton crops at the disclosed application rate. Detailed D escription of the Pref erred Em bodim ent Pursuant to the invention, sodium methyl dithiocarbamate is applied at dosages of not more than about 4 pounds per ton of forage or seed cotton crop having less than 35 percent moisture content, in order to retard microbial degradation an.d thereby stabilize the high-moisture crop. Suitable high-moisture forage crops for preservation by the subject m ethod include hay crops, grains, and poultry rations. In a preferred embodiment, baled hay and seed cotton crops are stabilized, meaning that heating and molding associated with microbial degradation of the crop are inhibited, by the application of a stabilizingly effective amount of sodium m ethyl dithiocarbamate imm ediately prior to baling. Hay crop as used herein refers to grasses and legum es such as alfalfa, timothy, and clover, which are cut and dried for animal f eed. Representative grains include whole and m illed corn, wheat, oats, barley, rye, sorghum , millet, buckwheat, and rice, as well as mixtures of the same, particularly as formulated as poultry rations. By silage crops are m eant agricultural substrates preserved by acid ferm entation, which substrates may include the foregoing hay crops and grain, and also corn, sugar cane, beet tops and pulp. Seed cotton as used herein refers to cotton crop as harvested with the lint still attached to the seed. By "high-moisture crop" is meant an agricultural substrate such as those discuss ed above containing from about 13 to about 30 and not more than 35 percent by weight moisture. By baled crops are meant agricultural substrates, like hay and seed cotton, that are put up for storage as packages of compressed vegetable matter, or bales, by machines generally term ed balers herein. Such bales, in the case of hay, may include conventional 100-lb bales, bound with twine, or large round bales, or 1-2 ton rectangular bales, or loaf-stack bales. The term bales is also m eant to encompass, in the case of seed coton, modules having dimensions, e.g., according to present practice, on the order of 8 x 10 x 35 feet. Applicant has discovered that sodium methyl dithiocarbamate effectively stabilizes high-moisture crops at surprisingly low dosages, at not more than about 2 pounds sodium methyl dithiocarba ate per ton wet weight of crop substrates containing less than about 30 percent by weight moisture. At 25 percent moisture content, only about 1 pound of sodium methyl dithiocarbamate per ton wet weight of hay is required to substantially inhibit heating and molding in hay bales. Due to the heterogeneity of actual field conditions it is considered preferred practice to field dry a cut hay crop to average m oisture levels in the range of from about 25 to about 18 percent, at which moisture contents stabilizing dosages of sodium methyl di thiocarbamate range from about 1 to about 0.5 pound per ton. Sodi um m ethyl dithiocarbamate is also known as m etam sodium , as well as by other chem ical and trade names as listed, for exam ple, i n Monograph No. 5808, The Merck Index, 10th Ed., 1983, hereby incorporated by reference. It is contem plated that fungicidal derivatives of sodium methyl dithiocarbamate, including sodium dimethyl dithiocarbamate, may also be effective for stabilizing high-moisture forage and seed cotton crops at relatively low dosages. It is further contem plated that other cations, i.e., either from the group of alkali metals or alkaline earth m etals or an am monium radical, may be substituted for the sodium on the methyl dithiocarbamate, and the resulting compound used in the practice of this invention. The stabilizingly effective dosage of not more than about 4 pounds sodium methyl dithiocarbamate per wet ton of high-moisture crop is unexpectedly low, considering the heterogeneous substrates that baled crops and poultry rations provide, and the compact and substantially isolated micro- environments in which they are put up and stored. Such substrates and environm ents are normally conducive to mold growth. Known preservative treatments involving sodium methyl dithiocarbam ate have prescribed much higher application rates of active ingredients. Thus, the invention surprisingly provides a cost-effective substitute for propionic acid, while avoiding the recognized disadvantageous side effects of the latter preservative. Sodium methyl dithiocarbam ate (at 2 lbs/T, 30%m) is significantly more cost effective as a crop stabilizer than either propionic acid or commercial preparations containing propionic acid applied at known and recom mended dosage rates. Sodium methyl dithiocarbamate typically wholesales at roughly four tim es the bulk price of propionic acid. Comparative test data indicate that the available bulk price of propionic acid would have to be reduced by two-thirds for propionic acid to be cost effective at equivalent degrees of stabilizing protection wi th sodium methyl dithiocarbamate, the latter applied at about 2 pounds per wet weight ton of 30% moisture crop. Even then, sodium methyl dithiocarbam ate is less destructive to farm machinery and more convenient to use. Relatively low volumes of spray need be applied, for exam ple, with consequent economies in storage, handling, and fuel consum ption. The sodium methyl dithiocarbam ate can be applied to high- moisture forage and seed cotton crops by conventional techniques. For exam ple, for hay preservative applications an aqueous solution of sodium methyl dithiocarbamate can be sprayed onto high-moisture hay at the baler, prior to baling. Alternatively, the sodium m ethyl dithiocarbam ate may be applied in the form of a dust prepared, for example, by m ixing anhydrous sodium methyl dithiocarbam ate with a conventional inert, solid diluent such as lime, beπtonite, talc, pyrophyllite, gypsum , chalk, or silica. The application should of course be as uniform as possible, that is, the sodium m ethyl dithiocarbamate should be evenly distributed throughout the crop mass in order to prevent the occurrence of spoiled slugs and hot spots. Considering the uncertainties associated with haymaking, including subjective assessments of field moisture contents, heterogeneous fi eld conditions, and nonuniform applications from single-point sprayers, a stabilizingly effective dosage of about 4 pounds sodium methyl dithiocarbamate per wet ton of hay is considered a practical and still cost- effective prescription. The invention - further provides articles of com merce useful for stabilizing high-moisture forage and seed cotton crops. Bottles, drums, sacks, and like shipping receptacles containing measured amounts of sodium methyl dithiocarbamate are labeled with printed instructions for applying the contents to high-moisture crops at application rates effective to apply about 4 pounds or less sodium methyl dithiocarbamate per ton wet weight of the high-moisture crop. As an example, a drum of 33% sodium methyl dithiocarbamate in aqueous solution is provided with attached or accompanying written instructions for diluting and applying the solution to high-moisture hay or seed cotton at dosages effective to apply no more than about 4 pounds sodium m ethyl dithiocarbamate per wet ton of the substrate. Coloring and flavoring agents may be added to the solution for conveni ence of application and enhancem ent of palatability, as can various masking agents that are routinely used in the industry. While the present invention has been described in terms of a pref erred embodiment, one of ordinary skill af ter reading the foregoing specification will be able to effect various changes, substitutions of equivalents, and other alterations to the methods and articles set forth herein. It is therefore intended that the protection granted by Letters Patent hereon be limited only by the defini tion contained in the appended claims and equivalents thereof .

Claims: The embodiments of the invention in which an exclusive property or privilege is claim ed are defined as follows: 1. A method of stabilizing a baled hay or seed cotton crop comprising less than about 35 percent by weight moisture against microbial degradation, comprising the step of spraying said hay or seed cotton immediately prior to baling with an amount of a composition effective to retard microbial degradation and thereby stabilize said crop, said composition consisting essentially of sodium methyl dithiocarbam ate and said stabilizingly effective amount comprising not more than about 4 pounds of sodium methyl dithiocarbamate per wet ton of said crop. 2. The m ethod of Claim 1 wherein said crop comprises hay. 3. The method of Claim 1 wherein said crop comprises seed cotton. 4. The method of Claim 1 wherein said crop comprises less than about 30 percent by weight moisture and said stabilizingly effective amount comprises about 2 pounds of sodium methyl dithiocarbam ate per wet ton of the said crop. 5. The method of Clai m 1 wherein said crop com prises less than about 25 percent by weight moisture and said stabilizingly effective amount comprises about 1 pound of sodium methyl dithiocarbamate per wet ton of the said crop. 6. The m ethod of Clai m 1 wherein said crop com prises from about 25 to about 18 percent by weight moisture and said stabilizingly effective amount comprises from about 1 to about 0.5 pound of sodium methyl dithiocarbamate per wet ton of the said crop. 7. An article useful for preserving a baled hay or seed cotton crop comprising less than about 35 percent moisture, com prising a preservative com position consisting essentially of sodium methyl dithiocarbam ate in combination with printed instructions for spraying a m easured amount of said preservative composition on said hay or seed cotton crop immediately prior to baling, said printed instructions cooperating with said m easured amount to effectively prescribe an application rate of not more than about 4 pounds of sodium methyl dithiocarbamate per ton wet weight of said crop. 8. The article of Claim 7 com prising a drum of aqueous solution consisting essentially of about 33 percent sodium methyl dithiocarbamate in combination with printed instructions for applying said aqueous solution to said crop at dosages effective to apply not more than about 4 pounds dry weight sodium methyl dithiocarbamate per wet ton of said crop.

Inventors: HUBER NEIL M, HUBER, NEIL, M.
Applicants: BIO TECH LAB INC, BIO TECHNIQUES LABORATORIES, INC.
Application year: 1987
Main classification: A23K3
IPC codes: A23K3