Importance of Nitrogen to Growth of Plants. 229 



an investigation which indicated clearly that cultivation of the soil did 

 not necessarily conserve soil moisture; that in a humid climate it might 

 in fact decrease the soil moisture, since stirring wet soil tends to increase 

 evaporation ; and, further, that under some circumstances it was con- 

 ceivable that this was beneficial. However, he has held strongly that 

 weeds are harmful because they exhaust the moisture from the soil and 

 that stirring the soil may increase the moisture in the soil even though 

 it does not decrease the evaporation or even increase it, because the 

 stirred, and hence looser soil, will absorb and hold more of the rainfall, 

 both by preventing it from running off the surface and by preventing 

 the water absorbed from draining away below the reach of the plants. 

 I do not now say that these things are not as I formerly believed. What 

 I do say is that these conclusions are too largely inferences based 

 on pot experiments and the whole question needs to be gone into 

 de novo under normal field conditions. 



The iniiuence of early and late spring plozving on corn production. 



In the year 1903, Modesto Quiroga conducted a thesis on " The 

 influence of early and late spring plowing upon com production."* 



The land, which was a silt loam, had been in maize the previous year. 

 Six plats, each 40 x 2 rods, were laid out and each alternate plat plowed 

 April 7, while the remaining three plats were plowed June 3, which 

 was the day before all the plats were planted to maize. Samples were 

 taken on each half of each plat at one, two and three feet in depth, thus 

 making 36 samples at each determination. The per cent, of water was 

 determined weekly from April 6th to September 29th. The water-soluble 

 nitrogen was determined April 6th and weekly beginning June 3d until 

 September 29th. Weekly temperatures were recorded from June 6th 

 to September 22d. The rainfall was exceedingly low, being 13.36 inches 

 for the six months April to September inclusive, while the normal is 

 probably not far from 20 inches. During the growing period, June to 

 September, the total rainfall was but 8.09 inches. In a favorable season, 

 the land on which this experiment was conducted would easily raise 60 

 bushels of maize per acre. 



In this summary only the surface foot is dealt with, both on account 

 of simplicity in presentation of results and because the other figures 

 would add little to the point under discussion. 



The first point of interest is to observe the per cent, of moisture and 

 the amount of water-soluble nitrogen in parts per million of dry soil on 



* Published in June, 1904, as Ohio State University Bulletin, Series 8, No. 28, 

 Agricultural Series No. i. 



