20 MASS. EXPERIMENT STATION BULLETIN 290 



in 1910, these plots bore a crop of mixed clover and timothy hay at the rate of 

 6730 pounds per acre, followed in 1911 by a crop of corn at the rate of 83 bushels 

 of shelled corn and 5130 pounds stover per acre, which was slightly more than 

 was produced on the plots which had been receiving 45 pounds of nitrogen in 

 fertilizers every year. 



The practical aspect of these experiments may be more clearly perceived by 

 expressing the amounts of the fertilizers in pounds per acre. On this basis the 

 rate per acre for each plot was 45 pounds nitrogen, 80 pounds available phos- 

 phoric acid, and 125 pounds pota.sh, which is equivalent to 1200 pounds mixed 

 fertilizer containing 3.75 per cent nitrogen, 6.5 per cent available phosphoric 

 acid and 10 per cent potash. This is a heavy application to be made yearly to 

 some of the crops grown on these plots. 



Farm manure was used at the rate of 8000 pounds per acre, or about four 

 loads, and was supplemented l)y 500 poimds per acre of chemicals containing 

 6 per cent phosphoric acid and 16 per cent potash. The records of this plot 

 show that manure may be advantageously spread thin when reinforced by super- 

 phosphate and potash. 



The records indicate that for corn, oats, and hay in a suitable rotation, it 

 would be economical to make a reduction in the amounts of fertilizer to be used, 

 and this would necessitate re-arrangement of the ex-periment. 



EFFECT OF LIME WITH NITROGEN FERTILIZERS 



Rearrangement of the application of lime in 1919, by dividing each plot length- 

 wise, permitted a fair comparison of lime with no lime in relation to the different 

 forms of nitrogen. 



Two years, 1919 and 1920, supplied the data, with crops of corn and hay. 

 The different nitrogen fertilizers are compared by averaging the crops from the 

 separate plots. The crop from the manure plot is averaged with those from the 

 organic nitrogen plots. 



Liming the nitrate plots was ineffective with corn and barely helpful with 

 hay. It notably increased the yield of ears with the corn crops on the organic 

 plots and on those without nitrogen. The hay crop was also improved. 



Liming the ammonium sulfate plots increased the yields of both ears and stover 

 with corn, while the hay crop actually exceeded that on the nitrate plots. Red 

 top was the prevailing grass on the unlimed areas, but timothy and clover grew 

 freely on the limed areas and displaced it. 



Table 8 — Comparison of Limed and Unlimed Areas 



(Yields in pounds per half-plot.) 



