Commercial Fertilizers. 171 



to be grown, the time and manner of application and many other 

 factors. Five hundred pounds per acre may be considered a 

 heavy application for ordinary farm crops ; applications of more 

 than that amount will only give economical returns in the case 

 of special crops grown under an intensive system of farming. 

 Heavy applications at long intervals are not as productive of 

 good results as light applications more frequently. It is better 

 not to make applications of over 200 pounds per acre of any one 

 basal material and to vary the amount from year to year until 

 experience has shown that economical returns can be expected by 

 heavier applications. Lime may be applied at the rate of 1000 

 pounds per acre on light soils and double that amount on heavy 

 soils. This application once in 5 or 6 years is usually sufficient. 

 Fertilizer laws and guarantees. To protect the farmer against 

 the sale of fraudulent and spurious goods, the manufacturers are 

 compelled by law in most states, to give the actual amounts of the 

 different constituents contained in their products. Usually 

 they are compelled by law to state on each bag or parcel 

 offered for sale the percentage of nitrogen (or ammonia), 

 available phosphoric acid and potash. The enforcement of the 

 law and the chemical examination of the fertilizers to determine 

 if they agree with the guarantee, rests with the State Experiment 

 Station, or in some states with the State Department of Agricul- 

 ture. The results secured are published in bulletins available 

 to the farmers of the state, and should be consulted freely by 

 those buying such materials. These laws have resulted in almost 

 complete disappearance of materials compounded with the in- 

 tention of defrauding, as well as a great lessening in the number 

 of brands offered for sale. Nevertheless, statements often ap- 

 pear on the bags, which, to say the least, are confusing and may 

 mislead the buyer. Phosphoric acid, 10 per cent, for example, 

 is often stated as equivalent to bone phosphate, 22 per cent. To 

 the buyer the higher figure is attractive and he is led to believe 

 1hat he will obtain something more than the 10 per cent of phos^ 



