230 



Bulletin 247. 



April 6th just before the early plowed plats and on June 3d just before 

 the late plowed plats were plowed : 



Table I. Effect of Early and Late Plowing. 



Water, per cent. April 6 



Water, per cent. June 3 



NO3 p.p. million of dry soil, April 6 

 NO3 p.p. million of dry soil, June 3 



From this table it will be seen that up to the time of planting, viz., 

 during April and May, the moisture had been conserved by the early 

 plowing and a marked increase in soluble nitrogen had occurred due to 

 plowing. The increase in moisture was 13 per cent, while the increase 

 in soluble nitrogen was 70 per cent. 



Next we will examine the conditions during the growing and ripening 

 period. The data is divided into two parts, the first part consisting of 

 the data for June and July when intercultural tillage was given and the 

 largest visible growth made, and the second part consisting of data for 

 August and September, when the crop made its largest increase in 

 weight of dry substance and ripened. There is evidence to show that 

 it is during the first part that the plant takes up the largest proportion 

 of its nitrogen and during the latter part that the greatest demand is 

 made upon the soil for water. 



Omitting the samples of June 3 taken before the late plowed plats 

 were plowed and, of course, before the maize was planted, the average 

 percentage of water and the amount of nitrogen in parts per million for 

 each period were as follows : 



Table II. Water and Nitrogen During Growing Season. 



Water , 

 NO3 . . 



Part L June and July. 



Early'plowed plats, 

 per cent. 



22.5 

 32.8 



Late plowed plats, 

 per cent. 



23.2 

 21.7 



Part II. August and September. 



Early plowed plats, 

 per cent. 



159 

 ^3-3 



Late plowed plats, 

 per cent. 



71 



