88 Effective Farming 



moting maturity of the plant, strengthens the straw, thereby 

 decreasing the tendency to lodge, improves the quality of the 

 seeds and fruit, and increases the resistance to disease. An 

 excess does not seem to have any bad effect on the crop. Phos- 

 phorus should be plentifully supplied and should balance the 

 nitrogen supply. As the lack of it is not readily observed, as 

 in the case with nitrogen, its absence from soils is not often 

 known to the farmer. The experiment stations, especially 

 those that have made chemical analyses of the soil types in 

 their states, usually give reliable information about the need 

 of phosphorus in soils of any community. 



Effects of potassium. It has been found that a sufficient 

 supply of potassium gives plump, heavy kernels and imparts 

 vigor to the plants ; also, it delays maturity and increases the 

 resistance of the plants to disease. In general it seems to have 

 a balancing effect on nitrogen and phosphorus. Excessive 

 quantities in soil have no bad effects. Experiment stations 

 can give information as to whether it is likely to be lacking in 

 any particular soil type of the state. 



39. Purchasing of fertilizers. Commercial fertilizers can 

 be purchased either mixed or unmixed. The mixed goods are 

 put together at factories and are given a name, or brand. These 

 brands usually contain two of the fertilizer elements and often 

 three. The fertilizers are made up of the ingredients previously 

 described, the quantity of each ingredient used being deter- 

 mined by the percentage of nitrogen, phosphorus, and potas- 

 sium desired in the fertilizer. The trade in mixed fertilizers 

 amounts to millions of dollars annually. Although farmers 

 can procure the ingredients and mix their own fertilizer, usually 

 for less money, the ease with which mixed goods are secured 

 and the attitude of fertilizer dealers against this home-mixing 

 will cause the mixed product to be most widely used. 



40. Fertilizer laws. Laws for controlling the sale of fer- 

 tilizers are in force in most states. The need of these laws is 

 obvious, when one considers the many opportunities for fraud 



