This crop fits in well, over wide areas, with various rotations. As the purpose of all rotation is to keep the soil productive, oats should alternate every few years with one of the nitrogen-gathering crops. In the South, cowpeas, soy beans, clovers, and vetches may be used in this rotation. In the North and West the clovers mixed with timothy hay make a useful combination for this purpose. Spring-sowed oats, since they have a short growing season, need their nitrogenous plant food in a form which can be quickly used. To supply this nitrogen a top-dressing of nitrate of soda or sulphate of lime is helpful. The plant can gather its food quickly from either of these two. As fall-sowed oats have of course a longer growing season, the nitrogen can be supplied by well-rotted manure, blood, tankage, or fish-scrap. Use barnyard manure carefully. Do not apply too much just before seeding, and use only thoroughly rotted manure. It is always desirable to have a bountiful supply of humus in land on which oats are to be planted. The time of harvesting will vary with the use which is to be made of the oats. If the crop is to be threshed, the harvesting should be done when the kernels have passed out of the milk into the hard dough state. The lower leaves of the stalks will at this time have turned yellow, and the kernels will be plump and full. Do not, however, wait too long, for if you do the grain will shatter and the straw lose in feeding value. On the other hand, if the oats are to be cut for hay it is best to cut them while the grains are still in the milk stage. At this stage the leaves are still green and the plants are rich in protein. Oats should be cured quickly. It is very important that threshed oats should be dry before they are stored. Should they on being stored still contain moisture, they will be likely to heat and to discolor. Any discoloring will reduce their value. Nor should oats ever be allowed to remain long in the fields, no matter how well they may seem to be shocked. The dew and the rain will injure their value by discoloring them more or less. Oats are muscle-builders rather than fat-formers. Hence they are a valuable ration for work animals, dairy cows, and breeding-stock. SECTION XLIII. RYE Rye has the power of gathering its food from a wider area than most other plants. Of course, then, it is a fine crop for poor land, and farmers often plant it only on worn land. However, it is too good a cereal to be treated in so ungenerous a fashion. As a cover-crop for poor land it adds much humus to the soil and makes capital grazing. [Illustration: FIG. 208. RYE READY FOR CUTTING] There are two types of rye--the winter and the spring. The winter type is chiefly grown in this country. Rye seeds should be bought as near home as possible, for this plant thrives best when the new crop grows under the same conditions as the seed crop.