A THIRTY-YEAR FERTILIZER TEST. 143 



1. The effect of lime is very marked, but crop increase from its use 

 is less when it is added to phosphoric acid alone, or to ])hosplioric acid and 

 nitrogen, than when added to any other treatment. In general, the phos- 

 phoric acid and nitrogen treatment on the unlimed portion of the field 

 leads all except the complete fertilizer. On the limed portion, however, 

 complete fertilizer, phosphoric acid and potash, nitrogen and potash, and, 

 occasionally, potash alone are superior. 



2. The gain from appljdng lime in addition to a ration of potash alone 

 is very much greater than from applj'ing it in addition to phosphoric acid. 



3. Potash has not given as marked results as on the South Soil Test. 



4. The use of potash, phosphoric acid and lime has maintained yields 

 at a comparatively high level, despite the infrequency with which clovers 

 have been grown. 



5. Nitrogen, used in addition to phosphoric acid and potash, has given 

 fairly large increases in crop. 



Effect of Lime on the Availability of Soil Potash. 



On the limed half of this field there are three comparisons — namely, 

 nitrogen wdth and without potash, phosphoric acid ■with and without 

 potash, nitrogen and phosphoric acid with and without potash — ■ where 

 the effect of lime in increasing the availability of soil potash should be 

 apparent. Table 9 shows the crop yields secured and presents the esti- 

 mated gain from the use of potash in each case. 



