of^our materials if bouglit in seperate form, while we may not 

 be so certain about the mixed g;oods. But the secret of the in- 

 creased etBciency of chemicals is to be looked for in the ratio 

 in which they are mixed. It is assumed by most fertilizer man- 

 ufacturers that a complete fertilizer should contain twelve per 

 cent, of phosphoric acid, four per cent, of potash and two per 

 cent of nitrogen, but if we look at the composition of the ash of 

 plants we find a different ratio. 



In the table given on pages 7-8 is to be found the data for 

 determining the relative amount of potash and phosphoric acid 

 which various crops remove from the soil. These results are 

 represented in the following cut ; the lower part of the vertical 

 lines, or the solid black parts show the potash, the upper part, 

 or that simply outlined represents phosphoric acid ; each quar- 

 ter inch in height represents 12 pounds. The table of "ratios" 

 shows in each case the number of pounds of potash taken up 

 by the crop for every pound of phophoric acid. For example, 

 take the ensilage crop already described, it took from the soil 

 forty-four pounds of phosphoric acid and one hundred and 

 twenty pounds of potash, the ratio is i of PgOg to 2^ of potash 

 K^O with the hay crop the ratio is i :4j^. 



Ratio of phosphoric acid to potash in the ash of plants. 



