6 



BULLETIN 219, U. S. DEPARTMENT OF AGRICULTURE. 



cow, AP. 



production of mature corn has been so uncertain at some stations as 

 to make the crop unprofitable if grown for grain alone. 



GENERAL PLAN OF THE INVESTIGATIONS. 



The method of work adopted in these investigations involved the 

 raising of different crops in various combinations or systems of rota- 

 tions and under differ- 

 ent methods of culti- 

 vation in systems of 

 continuous cropping. 

 Most of the work has 

 been done with 3-year 

 and 4-year rotations. 

 No rotations of greater 

 length than six years 

 have been used. Those 

 of this length have 

 been tried with sod 

 crops only. 



PLAT AND ROTATION OUT- 

 LINES. 



1 FAUOW 



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\ IVAEAT.AA 



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CO/tM 



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 £> 1 



\SU3S0/l£D 1 

 \£ \ 



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SAAl£Y,£). 



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 \B 29 \ 



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 \D Cm- 



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1 COAMSA 



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k 1 



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 1^ JO 1 



lc 



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 \C 1 



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 \o CM. 



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 [f 



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Figure 3 shows a di- 

 agram of the dry-land 

 rotation field at the 

 Akron Field Station. 

 This is one of the old- 

 est stations of the Of- 

 fice of Dry-Land Agri- 

 culture, and is a repre- 

 sentative one that will 

 serve to illustrate the 

 general scheme and 

 plan of work. The 

 plats involved in the 

 work at this station 

 and at all of the sta- 

 tions are one-tenth of 

 an acre in size. Their 

 dimensions are 2 by 8 

 rods. Along their larger dimension the plats are separated by 

 alleys 4 feet wide. Along the ends of the plats they are separated 

 by roads 20 feet wide. At all of the stations five crops are repre- 

 sented in a series of continuously cropped plats, lettered on the dia- 

 gram from A to G. In this group C and D are alternately cropped 



[Z=] 



Fig. 3.— Diagram of the dry-land rotation field at the Akron Field 

 Station. The lettering shows the cropping practiced in 1914. The 

 explanation of abbreviations used is as follows: D.= Disked, Fa?.= 

 summer tilled, FP.=fall plowed, Crikf.= green manured, Z.=listed, 

 M.= manured, S.= spring plowed, SS.= subsoiled. 



