circumstances after weighing out the quantities to be mixed they should be spread upon the floor in layers one upon the other. Then beginning at one side and working across, the whole should be shoveled over; this may be leveled somewhat and the operation re

An outfit for the home mixing of fertilizers. The grinding machine is necessary. If the materials are lumpy, but if they are fine the screen and shovel alone are needed.

peated until the mixing is satisfactory. In addition to the shovel and the barn floor a large screen such as is used in screening gravel or coal ashes, may be employed with decided advantage; the material at the first can be thrown upon the screen and by this means lumps may be separted and more easily broken up and the thoroughness of the mixing will be increased.

CHAPTER XX

USING COMMERCIAL FERTILIZERS

Fertilizers are used primarily in order to obtain an increased profit through the larger yield of the crop to which they are applied. From what has already been said, it must be evident that the fertilizer to be used depends on the soil and the particular crop to be raised. An economical and profitable use of commercial fertilizers calls for much more thought and study than the farmer has been accustomed to devote to the subject, for until he has a fair knowledge of the nature of his soil and the requirements of the crop he desires to produce he is not prepared to use good judgment in the selection of his fertilizing materials. Every farmer should conduct certain experiments on his own soil to ascertain what substances give the best results, but the majority of them are loath to undertake these experiments and prefer to follow some more general system (or lack of system) in the use of fertilizers. Commercial fertilizers have been on the market for a sufficient length of time to have been widely employed and as might have been surmised there have been developed a number of different plans or systems for their use which vary somewhat in the principles on which they are based, and which will be discussed. briefly.

Ville System.-"The one which has perhaps received the most attention, doubtless largely because

one of the first presented, and in a very attractive manner, is the system advocated by the celebrated French scientist, George Ville. This system, while not to be depended upon absolutely, suggests lines of practice which, under proper restrictions, may be of very great service. In brief, this method assumes that plants may be, so far as their fertilization is concerned, divided into three distinct groups. One group is specifically benefited by nitrogenous fertilization, the second by phosphatic and the third by potassic. That is in each class or group, one element more than any other rules or dominates the growth of that group, and hence each particular element should be applied in excess to the class of plants for which it is a dominant. In this system it is asserted that nitrogen is the dominant ingredient for wheat, rye, oats, barley, meadow grass and beet crops. Phosphoric acid is the dominant fertilizer ingredient for turnips, Swedes, Indian corn (maize), sorghum and sugar cane; and potash is the dominant or ruling element for peas, beans, clover, vetches, flax and potatoes. It must not be understood that this system advocates only single elements, for the others are quite as important up to a certain point, beyond which they do not exercise a controlling influence in the manures for the crops of the three classes. This special or dominating element is used in greater proportion than the others, and if soils are in a high state of cultivation, or have been manured with natural products, as stable manure, they may be used singly to force a maximum growth of the crop. Thus, a specific fertilization is arranged for the various rotations, the crop receiving that which is the

most useful. There is no doubt that there is a good scientific basis for this system, and that it will work well, particularly where there is a reasonable abundance of all the plant food constituents, and where the mechanical and physical qualities of soil are good, though its best use is in "intensive" systems of practice. It cannot be depended upon to give good results where the land is naturally poor, or run down, and where the physical character also needs improvement."

Wagner System.-"Another system which has been urged, notably by German scientists, is based upon the fact that the mineral constituents, phosphoric acid and potash, form fixed compounds in the soil, and are, therefore, not likely to be leached out, provided the land is continuously cropped. They remain in the soil until used by growing plants, while the nitrogen, on the other hand, since it forms no fixed compounds and is perfectly soluble when in a form useful to plants, is liable to loss from leaching. Furthermore, the mineral elements are relatively cheap, while the nitrogen is relatively expensive, and the economical use of this expensive element, nitrogen, is dependent to a large degree upon the abundance of the mineral elements. in the soil. It is, therefore, advocated that for all crops and for all soils that are in a good state of cultivation, a reasonable excess of phosphoric acid and potash shall be applied, sufficient to more than satisfy the maximum needs of any crop, and that the nitrogen be applied in active forms, as nitrate of soda, and in such quantities and at such times as will insure the minimum. loss of the element and the maximum development of the plant. The supply of the mineral elements may

be drawn from the cheaper materials, as ground bone, tankage, ground phosphates and iron phosphates, as their tendency is to improve in character; potash may come from the crude salts. Nitrogen should be applied as nitrate of soda, because in this form it is immediately useful, and thus may be applied in fractional amounts, and at such times as best meet the needs of the plant at its different stages of growth, with a reasonable certainty of a maximum use by the plants. Thus no unknown conditions of availability are involved, and when the nitrogen is so applied, the danger of loss by leaching, which would exist if it were all applied at one time is obviated."-Voorhees.

System Based on the Analysis of Plant.-Still another system is based on the food requirements of the plant, as shown by the analysis of the plant itself. The amount of plant food removed from each acre of ground is calculated from the analysis of the plant and a corresponding amount is returned to the soil. Different formulas are, therefore, recommended for each crop, and in these the nitrogen, phosphoric acid and potash are combined in the proportions in which they are found in the plant. Experience shows that it is necessary to add amounts of these fertilizers to the soil. that will supply more plant food than is removed by the crop if the maximum results are desired. This system may result in a large yield but cannot be considered an economical method of feeding the plant, as one or more of the elements is likely to be applied in excess of the requirements of the crop. It does not take into consideration, for instance, the fact that a plant which contains a large amount of one element