22 



MASS. EXPERIMENT STATION BULLETIN 290 



Kffect of Lime as an Accompaniment to Ammonium Sulfate 

 'I'he yearly ratios between yields of dry matter on sodium nitrate 

 (rated at 100) and on ammonium sulfate arc presented graphically. 



were using it with the aid of specific bacteria. Early in the present century it 

 was established that nitrogen compounds were formed from air by certain bac- 

 teria in the soil, without the presence of leguminous plants. 



The early corn crops indicated that "run out" hay land contained a stock 

 of nitrogen which had been accumulated without nitrogen fertilizers. 



In 1911, following four successive years of clover and grass, the plots without 

 nitrogen fertilizers led all others in their average yields of corn and stover. In 

 the last year of the experiment, clover hay was heaviest on these plots. 



Nitrogen fertilizers were most effe(;tive when a tilled crop followed a tilled 

 crop. 



Measured by crop yields, sodium nitrate was most frequently in the lead. 

 Ammonium sulfate required the iircscnce of calcium carbonate in the soil to be 

 most effective, ^^'hen recently limed, the ammonium sulfate plots were virtually 

 equal to the sodium nitrate plots. Farm manure, supplemented with phosphate 

 and potash, excelled several times with crops which made their growth in sum- 

 mer. Organic nitrogen was superior in three seasons. 



