484 NATUEB AND PROPERTIES OF SOILS 



It is always true that the lower the grade of a fertilizer the 

 higher is the proportional cost of placing the goods on the 

 market. In other words, it costs just as much a ton to market 

 a low-grade material as a high-grade one. This accounts for 

 the fact that the nutrients are cheaper a pound in a high- 

 grade mixture, and that the value received for every dollar 

 expended is greater. 



273. The purchase of unmixed fertilizers. — There has 

 always been a tendency among fertilizer manufacturers to 

 discourage the purchase by the farmer of the separate car- 

 riers of fertilizer nutrients. When this was possible the fer- 

 tilizer manufacturer was able absolutely to control the mar- 

 ket. By selling only mixed goods the manufacturer could 

 not only realize a profit on the ingredients themselves but a 

 profit on the mixing in addition. In order to escape these 

 costs many farmers have begun the practice of buying the 

 separate carriers, thus avoiding the extra charges. In many^ 

 cases, the mixing on the farm costs nothing, as it can be done 

 in winter when the farm work is not pressing. Home-mixing 

 has been greatly encouraged by post-war conditions. In 1920 

 from ten to twenty dollars a ton was often saved on a high- 

 grade mixture by purchasing the carriers separately. 



In many instances the fertilizing materials purchased sepa- 

 rately need not be mixed at all, thus effecting a considerable 

 saving in time and labor. Acid phosphate is generally added 

 separately, especially to fall wheat. Bone-meal, basic slag, 

 and raw rock give excellent results when applied with farm 

 manure. Sodium nitrate and ammonium sulfate give good 

 returns as a top dressing on meadows, pastures, and small 

 cereals, especially if phosphates have been added at some 

 other point in the rotation. When farm manure is available, 

 the use of acid phosphate with lime and manure in a legume 

 rotation is generally desirable. Even where little manure 

 is available, the application of sodium nitrate or ammonium 

 sulfate as a top dressing for meadows, with acid phosphate in 



