The application of soluble fertilizers with irrigation water has been practiced in some areas for several years. Special mixing equipment provides for introducing the desired amount of fertilizer steadily into the stream of irrigation water.

The application of fertilizer in liquid form with field machines is a recent practice that is not yet extensively used. Equipment for the purpose is essentially a container with some means of regulating the flow of liquid through tubes to furrows in the soil or directly to the soil surface. When the liquid is allowed to flow by gravity from the container to the soil, the flow is regulated either by an adjustable clamp on a rubber delivery tube or by the size of the fixed discharge openings. Gravitational or natural flow decreases as the level of liquid in the container is lowered. To overcome this objection the tank or container has been sealed in such a way that the liquid pressure remains constant as the tank is emptied. The principle is similar to that of common waterers for chickens and livestock. Positive regulation of flow according to the rate of travel of the machine is obtained by means of various types of pumps.

Anhydrous ammonia, and other materials like it, are applied as a liquid under pressure; they change to gas or vapor under ordinary air pressure. The material is stored in heavy steel cylinders. For field-tillage machines, special equipment has been devised so that the compressed gas or liquid 44, is released at a point near the bottom of the furrow. Provision for immediately closing the furrow is essential to prevent the escape of the gas.

THE AUTHOR Glenn A. Cumings is an agricultural engineer in the Bureau of Plant Industry, Soils, and Agricultural Engineering. After graduation from Iowa State College, he did engineering research in the Colorado Agricultural Experiment Station from 1919 to 1927, and since then has been a project leader on fertilizer placement and fertilizer distributing machinery research in the Department. Mr. Cumings is the author and coauthor of numerous bulletins, articles, and other reports on fertilizer-application methods; chairman of the Committee on Fertilizer Application in the American Society of Agricultural Engineers; Past General Chairman of the National Joint Committee on Fertilizer Application and present Chairman of two subcommittees.

Cotton Ginning

by CHARLES A. BENNETT THE PROCESSES that are broadly termed ginning in the cotton industry have undergone many changes and advances in the years since 1935, in keeping pace with farm production. The number of active gins has declined from approximately 13,000 in 1935 to 8,632 in 1945, but the ginning volume of each gin has increased and features have been added that sharply distinguish the modernized gins from the old.

Although mechanization in cotton production was in sight in 1935, it had become a reality by 1947. It has forced improvements and advances upon the ginning industry without which the cotton producer could not now continue. Among the improvements are all-metal buildings and machinery, standardized interchangeable parts, and machine production on dimensioned jigs under closer tolerances of finish and fit; these have replaced wooden construction and rough castings. Cotton driers, gin stands of greater capacity, better pneumatic apparatus, and greater accessibility are pronounced improvements.

Cotton drying processes, fostered and developed by the Department since 1929, have spread to more than a third of all of the active cotton gins-the third that handles at least 65 percent of all the cotton. Research in drying cotton has been extended to the application of a series of drying stages in succeeding machines, and the art of cleaning seed cotton has been furthered by many new designs.

Bulk extracting of heavier foreign materials from the harvested cottons gave way to the highly specialized development of unit extracting and feeding processes over each cotton gin stand; the result has been a resurgent improvement of the large master extractors to a position of primary importance in the mechanized production of cotton. Outstanding examples are the several types of cleaning and extracting machines that have angular bar grids, revolving knuckle-tooth disk grids, reciprocating cleaner cylinders in staggered vertical decension, and other ingenious devices for removing foreign matter gathered by machine harvesting. Two other research studies have been started : One seeks to find a way to restore necessary moisture to very dry fiber during ginning, and the other to clean even better the ginned fiber as it passes from gin-stands to the bale press.

The vigorous adoption of single-variety cotton planting by farsighted communities has effected a further advance in ginning processes for protecting purity of ginned cotton seed, cleaners and graders for the seed, and better methods for testing germination and prospective betterments in yield and fiber quality. The trend toward single-variety cotton communities has been sound and healthy, and should lead to visual bale identification in coverings and tags to assure consumers that they are receiving a specialized variety of cotton fiber from dependable producers.

The desirability of having definite supplies of quality cotton of preferred variety induces the spinner and processor of fibers to obtain such cottons direct from the producer. Here the greatest opportunity may exist for standard-density cotton gin presses, which are foreseen in the findings by the research engineers and technologists that cotton bales of standard density (22 to 25 pounds per cubic foot needed for domestic shipment at favorable rates) as compared to low density, bulky, gin bales (11 to 15 pounds per cubic foot) can be readily produced at the larger volume cotton gins in a mechanically practicable and economically feasible manner.

The size of the 500-pound square bale of standard density from a cotton gin press is approximately 22 inches wide, 30 inches high, and 56 inches long. It has eight ties, preferably held by heavy-duty steel rod buckles; and the cotton gin machinery ahead of the press needs no change from its present forms and dimensions.

The gin standard density presses now in use are of both down and up packing type, but new designs utilize either two or three rams, although three 9 1/2 inch rams have heretofore appeared to be somewhat preferable.

These presses do not kill the natural resilience of the cotton fibers, and the bales consequently open quickly at the spinning mills during the first blending processes that are otherwise delayed by the extreme crushing encountered when low-density bales undergo commercial compression between the gins and mills. The gin standard-density bales are pleasing in appearance, well protected, compact, and economical in floor space in the opening and picking processes at the mills.

Bale fires have not been experienced in any instance within standard-density gin bales, although fires during ginning processes have occurred at the gins where these presses have been installed.

A standard-density gin bale also effectively lends itself to high-density recompression, because it fits between the side doors of the high-density presses; the layering of the bale contents is therefore not disturbed by the high-density pressing.

It is estimated that the ginning volume of 5,000 or more bales a year at large cotton gins would enable the operators to produce standard-density gin bales for 7 cents each more than it costs to produce low-density or flat bales, and that in small volume gins of 1,000 bales capacity a season the increased cost would reach 27 cents a bale.

There are certain limitations, of course, in most industrial methods, and the immediate possibilities for beneficial use of standard-density gin presses appear to reside in the availability of single-variety cottons direct to the mills from large individual or cooperative producers. On 1,000-bale volume basis, the single stage compression of standard-density gin bales may save 43 cents per bale for the industry, while a 5,000-bale volume production at the gin could save up to 63 cents a bale.

It is realized that established methods of marketing must give way rather slowly to innovations and advances. The standard-density gin bale cannot quickly replace the need for commercial compression services in many regions where small volumes and irregular lots of cottons must be concentrated, sorted, and reassembled for trade disposal. But with mechanical sampling of bales during ginning now proved to be dependable, and with mechanized production of single-variety cottons revolutionizing the cotton industry in the United States, it is reasonable to conclude that standard-density gin bales will increasingly come into production by producer-to-consumer marketing.

THE AUTHOR Charles A. Bennett, as an agricultural engineer in the Bureau of Plant Industry, Soils, and Agricultural Engineering, has been in charge of the Bureau's Cotton Ginning Laboratory at Stoneville, Miss., since it was established in 1930. After graduation from the University of Nebraska, he worked successively as a draftsman in Omaha, a member of a firm of consulting engineers, a supervising draftsman with the machinery division of the United States Navy Yard at Puget Sound during the First World War, and a registered engineer at Portland, Oreg., and Alhambra, Calif. From 1926 to 1930 he engaged in cotton drying research with the Department at Tullulah, La.