Fig. 13.—Thrashing sweet clover with a grain separator. Note the large sleds used for handling the plants from the field to the thrashing machine.
Fig. 13.—Thrashing sweet clover with a grain separator. Note the large sleds used for handling the plants from the field to the thrashing machine.
Fig. 13.—Thrashing sweet clover with a grain separator. Note the large sleds used for handling the plants from the field to the thrashing machine.
A grain separator (fig. 13) is used more than any other machine for thrashing sweet clover. This is because more grain separators than clover hullers are found in localities where sweet clover is grown and because the ordinary clover huller will not handle a large growth of sweet clover satisfactorily. When the grain separator is operated carefully no trouble should be experienced in removing the seed from the plants, but it is necessary to make certain adjustments if the seed is to be hulled. The adjustments required will vary somewhat with the make of machine and the dryness of the crop. The riddles should be adjusted or changed so they will handle sweet-clover seed properly. Alfalfa or red-clover riddles will answer this purpose. The speed of the fan should be decreased, so the seed will not be blown over, and this usually will be accomplished when the speed is reduced to about one-half that used in thrashing grain. The number of rows of concave teeth which should be used will vary with the dryness of the plants and somewhat with their size. When it is not desired to hull the seed, one or two rows of concave teeth will be sufficient. Some operators believe that one or two rows are sufficient to hull 40 to 50 per cent of the seed when the plants are very dry. Those are exceptional cases, and hulled seed should not be expected unless more rows of concave teeth are used. If hulled seed is desired it is recommended that a full set be used and that these be set to run closer to the cylinder teeth than is customary when thrashing grain. Some operators replace two rows of the smooth, concave teeth with corrugated teeth. This practice is recommended wherever possible, as the corrugated teeth will facilitate greatly the hulling of the seed. Even where these changes are made, only a small percentage of the seed will be hulled if the pods are damp. If the plants have been permitted to make a very largegrowth the machine may clog unless the number of rows of concave teeth is reduced. Clogging may be overcome for the most part by feeding the bundles to the machine slowly. This precaution is necessary regardless of the size of the plants if the seed is to be removed properly and hulled. It is possible to hull from 90 to 95 per cent of the seed when the proper adjustments are made and the plants are dry.
A clover-hulling attachment, which consists for the most part of special sieves and a number of rows of corrugated concave teeth which replace the ordinary concave teeth, has been used with success in different sections of the country.
As a rule, ordinary clover hullers do not handle sweet clover very satisfactorily. Machines with cylinders larger than those commonly used are giving fair satisfaction provided the plants do not make a large growth, but even these machines have not been so successful as properly adjusted and equipped grain separators. A clover huller will handle a 2 to 3 foot growth of sweet clover if the rows of thrashing concaves are reduced and the plants are fed slowly to the machine. It will not hull sweet clover as well as red clover, and it is very doubtful whether it will hull more seed than a grain separator equipped with a hulling attachment.
The manufacturer of at least one clover huller has designed special rasps for the hulling cylinder and concaves of his machine, and these rasps do better work than the ones ordinarily used for hulling red clover.
It is the custom in some localities to run the sweet clover through a thrashing machine without adjusting the concaves and then to run the unhulled seed as delivered by the grain separator through a clover huller. A fair quality of seed may be obtained by this process, but it calls for much extra labor and time, and for this reason should be avoided Whenever possible.
Many factors besides shattering influence the yield of sweet-clover seed. As only those portions of the plants exposed directly to the sunlight set seed abundantly, thin stands usually produce more seed to the acre than heavy stands. When very heavy stands make a large growth, seed is produced only on the upper 24 to 30 inches of the plants, whereas with thinner stands it is produced on the lower branches as well.
The quantity of moisture in the soil at the time the seed is maturing is an important factor also. During hot, dry weather the plants may not be able to absorb from the soil sufficient water to supply theexcess required by them for seed production. In this event many of the seed pods will abort and fall when partly mature. Pods abort and fall in a very short time, so that partly shriveled ones seldom are found on the plants, although the extent of the aborting is shown by the number of barren racemos. When such weather conditions prevail, the second crop usually will produce a heavier yield than the first crop. This is due for the most part to the inability of the large plants to obtain sufficient water for seed production. The much smaller plants of the second crop do not require as much moisture as the larger plants of the first crop, as the vegetative growth is seldom more than half as much.
The type of root growth has much to do with the quantity of water the plants are able to obtain during droughty weather. When sweet clover is planted on soil that has a tendency to be wet, the plants will produce a much-branched shallow root system instead of the normal deep roots which are found on well-drained soils. During dry weather the upper layers of soil become so depleted that plants having a very large percentage of their roots in these layers can not obtain a sufficient quantity of moisture to supply their requirements for seed production.
It is often stated that the first crop of sweet clover will produce more seed to the acre than the second crop. This depends very largely upon the thickness of the stand and on weather conditions. In regions where two crops may be grown in a season, the first usually will produce more seed to the acre than the second if the field has a thin stand. When the stand is thick the second crop ordinarily yields more seed. In regions where a crop of hay or pasturage may be obtained in addition to the seed crop, it is seldom an economical procedure to permit the first crop to mature. Not only will sweet clover produce an abundance of nutritious pasturage or a cutting of 1 to 3 tons of hay in addition to the seed, but the difficulty of handling the large, stemmy growth of the first crop for seed is avoided.
Yields of sweet-clover seed have been reduced during the last two seasons by several fungous diseases. Experimental work has not been completed to show the percentage of damage done by these organisms, but in some sections of the country seed yields were reduced considerably. The clover stem borer,[2]which is prevalent in red clover in certain sections of the country, also infests sweet clover. It is probable that this insect did some damage to the seed crop in certain sections of the country in 1916.
[2]Languria mozardi.
[2]Languria mozardi.
The yield of sweet-clover seed varies from 2 to 10 bushels of re-cleaned seed per acre.
Sweet-clover straw may be utilized for soil improvement or as a roughage for stock. When it is not needed for feeding it should be turned under, as it will add much humus and nitrogen to the soil. When the seed is flailed from the plants the straw may be easily and quickly spread over the land at the time of flailing, but when the crop is thrashed with a grain separator or a clover huller it will be necessary to haul the straw and scatter it over the field. When the crop is thrashed in this manner the straw will be broken and crushed so that stock will eat it freely. The straw may be run directly from the thrashing machine into the silo, where, by adding sufficient water, it can be made into good silage.Table Igives the analyses of nine samples of sweet-clover straw which were collected in Illinois in the fall of 1916.
Table I.—Analyses of sweet-clover straw.[3]
[3]These analyses were made by the Bureau of Chemistry.
[3]These analyses were made by the Bureau of Chemistry.
Transcriber NoteMinor typos may have been corrected. Illustrations were moved to prevent splitting of paragraphs. Content produced from files generously provided by the USDA through The Internet Archive and all resultant files are placed in the Public Domain.
Transcriber Note
Minor typos may have been corrected. Illustrations were moved to prevent splitting of paragraphs. Content produced from files generously provided by the USDA through The Internet Archive and all resultant files are placed in the Public Domain.