191.'0] SOILS — FERTILIZERS. 215 



found In the winter. Crop residues were efTeclive In preventing the loss of 

 nitrates from leaching, as was also a growinj; cr<)[) occupying tlie soii. 



" Tlie period of greatest utilization of nitrates by corn, as judged l)y the 

 decreases found in the nitrogen supply in tlie soil, coincides with the period of 

 greatest visible increase in growth, which occurs usually between June 25 and 

 July 15. The period of greatest utilization of nitrates for wheat and oats is 

 earlier in the season than for corn, coming usually about the middle of May or 

 early in June. It occurred in these studies earlier with wheat than with oats. 

 The period of greatest utilization of nitrates, as well as the rate and amount of 

 production, is directly related to soil treatment. In these studies tlie properly 

 treated plats were taking in more nitrates and at an earlier period than those 

 receiving poorer treatment. The recovery of efficiency in nitrate production 

 occurred at an earlier date and in a greater degree on the plats receiving the 

 proper soil treatment." 



The formation of nitrates in a soil following the groAvth of red clover 

 and of timothy, T. L. Lyon, J. A. Bizzell, and B. D. Wilson (Soil Sci., 9 

 (11)20), No. 1, pp. 53-64). — Experiments conducted at Cornell University, in 

 which a sand soil of moderate fertility and good drainage and growing different 

 crops was leached are reixjrted. The leaching was accomplished while the 

 crops were on the soil. The soil was abundantly linied and fertilized with acid 

 phosphate, potassium chlorid, and dried blood. Six cylinders were planted to 

 timothy and 6 to red clover. The soil in aU cases was inoculated with Bacillus 

 radicicola. 



During the time the timothy and clover were growing, the soil was leached 

 with distilled water from time to time. Nitrogen was determined in the 

 drainage water and in the crops of timothy and clover. After these crops were 

 removed, the soil was allowed to remain in fallow for a month, leached, and 

 nitrogen determined in the drainage. Of the cylinders on which timothy had 

 been grown, two were planted to oats, two to maize, and two kept free of 

 vegetation. The clover cylinders were treated in the same way. All were 

 leached from time to time and nitrogen determined in the drainage water and 

 also in the crops. 



There was little difference in the quantities of nitrogen leached from the 

 timothy soil and clover soil during the time those two crops were growing on 

 them. There was about six times as much nitrogen leached from the clover 

 soil during the month that both soils stood fallow after the timothy and clover 

 crops had been removed. There was only about twice as much nitrogen leached 

 from the fallow clover soil as from the timothy soil during the next five months. 

 At the end of this period the rate of nitrate production in the clover soil was 

 little greater than in the timothy soil. The crops of oats and maize following 

 clover were larger and contained more nitrogen than did those following 

 timothy. 



The experiment taken as a whole shows that under the same conditions of 

 soil and treatment clover caused a greater production of available nitrogen 

 than did timothy. This effect is shown in the nitrate content of the drainage 

 water and the total nitrogen content of the oats and maize. 



Nitrification in semiarid soils, W. P. Kelley (Brasil Agr., 4 (1919), Nos. 6, 

 pp. 160-162; 7, pp. 202-205; 8, pp. 229-232; 9, pp. 25i-254).— Experiments con- 

 ducted at the University of California are reported. 



It was found that the nitrification of dried blood, bone meal, and ammonium 

 sulphate when used in different concentrations varied widely during four 

 weeks' Incubation. In certain soils in which nitrification with bone meal and 

 ammonium sulphate was acU\e, treatment with dried blood resulted in little 



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