16 MASS. EXPERIMENT STATION BULLETIN 333 



NONLEGUME CROPS CONTINUOUSLY 



A prime objective of this investigation was the effect on crops and on soils 

 of the continued production of nonlegume crops without nitrogen fertilizers. 

 Plots 7 and 9 have not had nitrogen fertilizers since 1882, a period of 53 years. 

 During the first 9 years, nonlegume crops were grown continuously. After 

 1891, legume crops were frequently used until 1921, when a crop of mixed 

 clover and grass was the last to occupy the entire plots. 



The early series of nonlegume crops are tabulated for comparison with the 

 series just completed. Weights of the early crops have been taken from 

 Bulletin 290 and were made on field-dry material. Weights of nitrogen have 

 been calculated by using analytical data obtained from these crops and similar 

 ones in the experiment station laboratory. The late series in the table includes 

 the data from the nonlegume subplots of Plots 7 and 9. Dry matter and total 

 nitrogen were determined for each subplot. The first crop of corn in the early 

 series had been grown on a "run-out" grass sod that probably bore little if 

 any clover. The late series was preceded by two crops of corn that must have 

 removed all effects of the last crop of mixed grass and clover. 



The amounts of nitrogen contained in stubble and roots of crops, which 

 may be used by succeeding crops, are difficult to measure and few have at- 

 tempted to do so. Woods is reported in the Connecticut ^Storrs) Experiment 

 Station Report for 1889 to have found 90 pounds per acre of nitrogen in the 

 roots and sod of timothy and 60 pounds per acre in roots and stubble of clover. 

 The two corn crops of 1922 and 1923 were calculated to have contained 87 

 pounds of nitrogen in 1922 and 71 pounds in 1923, which should have taken 

 up the residual nitrogen of the preceding crops. 



table 11. nonleguminous crops. pounds per acre of crop 



and Nitrogen, 1883-1891 



Yield — Pounds 



Year Crop Nitrogen 



Plot 7 Plot 9 Average Pounds per Acre 



per Acre 



1883 Corn, ears 197 191 1,940 25.2 



stover 356 355 3,555 24.9 50.1 



1884 Corn fodder 458 458 4,580 31.0 



1885 Corn fodder P 280 K 948 6,125 42.8 



1886 Corn fodder P 255 K 840 5,475 38.3 



1887 Corn fodder PK 730 K 655 6,925 48.4 



1888 Corn fodder K 676 K 553 6,145 43.0 



1889 Corn, ears PK 41 PK 58 495 6.4 



stover 484 417 4,505 31.5 37.9 



1890 Oats, grain PK 110 PK 101 1,055 19.0 



straw 210 189 1,995 11.9 30.9 



1891 Rye. grain PK 109 PK 109 1,090 17.4 



straw 341 316 3,285 16.4 33.8 



Total 47,170 356.2 



P — Phosphoric acid K — Potash 



