84 BULLETIN 479, U. S. DEPARTMENT OF AGRICULTURE. 



contain only one of the desirable elements. However, if this is neces- 

 sary, it should be remembered that the growing of cover crops is the 

 most inexpensive way of introducing nitrogen; that phosphoric acid 

 can be introduced by the use of Thomas meal and bone meal, both 

 of which also add lime to the soil; and that potash is most cheaply 

 introduced by the use of kainites. 



Commercial fertilizers (with the exception of those containing 

 lime) do not improve the texture of the soil to any extent, and lime 

 does not improve loose soils; commercial fertilizer is rather rapid in 

 its action, making it preferable where quick effects are wanted, but 

 is likely to be quickly lost through leaching out; it is expensive and 

 sometimes difficult to obtain; and some of it contains only one or 

 two of the elements essential to plant growth. Manure is also often 

 difficult and expensive to obtain in sufficient quantities; if mixed 

 with much litter not well decomposed it is likely to cause drying out 

 of the beds; and it does not give such immediate results. On the 

 other hand, it does not leach out rapidly, it improves the texture of 

 both heavy and light soils, and it furnishes several of the elements 

 which are essential to plant growth. 



In choosing fertilizers the absorption capacity of the soil must 

 also be considered. This is much greater in fine and clayey than in 

 sandy soil; in the latter there is always danger of any soluble sub- 

 stance, such as saltpeter, being washed out. In such cases the nitro- 

 gen is best furnished by green fertilizing and stall manure, and 

 lime by carbonate of lime instead of unslaked lime. 



TIME AND METHOD OF INTRODUCING FERTILIZERS. 



Inferior soil, even before the first crop is grown, should be fer- 

 tilized. Fertilizer should be applied at a time when it will prove 

 most beneficial to the plants. Stable manure which has not been 

 well rotted should be applied the fall or winter previous to the 

 spring planting. Such manure can be used just before sowing or 

 planting if it is turned far enough under the soil so that it will not 

 come in contact with the roots. Compost, bone meal, and slaked 

 lime or carbonate of lime may be applied just previous to the sowing 

 or planting of the beds. Thomas meal, kainite, and carnallite should 

 be applied the previous autumn, or the last two in the spring just 

 before sowing or transplanting, if used only in small quantities. 

 Chili saltpeter should be scattered on the ground and worked in 

 between the rows after the seed has sprouted, because it dissolves 

 easily and is carried quickly into the soil by rain. The other 

 fertilizers mentioned should be well mixed with the soil which makes 

 up the root zone. It is better not to fertilize too deeply in order 

 to encourage lateral development of the roots rather than develop- 



