234 



Bulletin 247. 



While the number of determinations here given and the time they 

 were taken are ^ot such as to base any important conclusions on, they 

 show as far as they go a great decrease in the water-soluble nitrogen 

 where the weeds grew and the land was not stirred as compared with 

 plats which were stirred and no weeds allowed to grow. 



I still have some other results to present, but taking the case thus 

 far presented was the less yield of maize due to decrease in supply of 

 water, to decrease in supply of water-soluble nitrogen, to decrease in 

 supply of other water-soluble salts, or to other causes? 



Influence of stirring the soil. 



The influence of stirring the soil is shown by the results from the 

 following three plats : Plat I was cultivated eight times between June 14 

 and August 22. On plat 2 the weeds were removed or kept from grow- 

 ing by scraping the surface with a hoe with as little disturbance of the 

 crust of soil as possible. On plat 3 the weeds were allowed to grow after 

 the first cultivation which took place on June 14. 



Table VII. Influences of Stirring the Soil. 



Aug. 



Green maize, lb . 



Stover, lb 



Ears, lb 



Water per cent.* 



22 



NO3 p.p. million j ijjg- 29 :::::::::: : 



[Oct. 6 



fjuly 14 



I Aug 28 

 Total soluble salts p. p. million \ gg^^' 



'[Oct. 6 



•Plat I 



Cultivated. 



! Plat II. 



Surface scraped , 



98. 



iZ- 

 35- 

 26 



115 



30 

 46 



63 



455 

 459 

 327 

 256 



5-1 13 



0-33 



0-28 



2 



88-1 1 1 



29-30 



32-28 



22 . 4 

 26 



16 



16 



54 

 644 

 217 

 366 

 259 



Plat III. 

 Weeds. 



53-2-77 

 2 6 . 0—2 1 

 I I . 0-9 

 22.5 



31 

 14 

 14 

 32 



775 

 196 

 310 

 252 



* Average of eight determinations. 



It will be seen that in this trial the plats which were scraped so as 

 to prevent the growth of weeds, but the soil not stirred, yielded nearly 

 as well as those that were stirred thoroughly in removing the weeds. 

 On the other hand the yield of grain was greatly reduced upon those plats 

 on which weeds were allowed to grow after the first cultivation. It 

 would seem, therefore, that it was the weeds and not the stirring of the 

 soil that caused the principal injury to the growth of maize, although 

 stirring the soil seems to have been slightly beneficial. This has been 

 repeatedly demonstrated, especially at the Illinois Station. When we 

 come to examine the water and soluble nitrogen content, it is found that 



