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.
THE CLOVER HULLER.
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.
[YIELDS OF SWEET-CLOVER SEED.]
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 the excess 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.