80 Progressive Agriculture 



must have been due to the greatly increased 

 amount of available plant food in the summer 

 tilled field. 



While we are giving you many practical illustra- 

 tions, dozens more could be given along the same 

 line. 



Cut No. 37, previously referred to, is further 

 evidence of increased fertility under specific soil, 

 moisture and climatic conditions. In this illus- 

 tration the evidence is along the line of diminish- 

 ing the amount of available plant food or fertility 

 by carrying a too low per cent of moisture in the 

 soil. Briefly explaining No. 37, some 30 acres of 

 land were being summer tilled by C. L. Morgan 

 at Sligo, Colorado in 1910, a season of very light 

 rainfall. About half of the field became somewhat 

 weedy because of a combination of rains and other 

 work to be done, while he had kept the weeds out 

 of the balance of the field ; however, the same depth 

 of mulch had been kept over the entire 30 acres. 

 The weedy part was plowed first, plowing of the 

 balance of the field followed immediately, same 

 depth of plowing and other work was all identical, 

 the seeding done at the same time and stools 

 pulled 43 days after seeding. The average stool 

 in the part kept clean was about 21 stalks, while 

 in the part where the weeds had grown the average 

 stool indicated about 6, which is unquestionably 

 due to the low per cent of moisture reduced by 

 weed growth in June and early July, checking 

 bacterial development. These facts are also 

 borne out to a degree in the contrast of Cuts Nos. 

 24 and 25, and Nos. 26 and 27, as well as in Cuts 



