186 A. F. GUSTAFSON 



For determining nitrates, two 50-cc. samples from each soil duplicate, four in all from each 

 soil, were evaporated to dryness, after adding a few drops of a saturated solution of sodiixm 

 carbonate, and nitrates determined colorimetrically according to Schreiner and Failyer (89). 



Experiment 1 



The object of this experiment is to study the effect of oven-drying on the 

 soluble solids and nitrate content of four types of soil found in this locality 

 and which cover a wide range of physical composition. 



Samples of four soils were collected October 24, 1918, from the Station 

 farm at Ithaca, 



1. Dunkirk silt loam 



A. Surface, yellow, heavy silt to clay loam 



B. Subsurface, yellow silt loam 



Both surface and subsurface soil contained a few small pebbles and were very low in organic 

 matter. This soil had been growing a heavy sod of Kentucky bluegrass for the past ten 

 3reais. 



2. Genesee gravelly loam 



A. Surface, brown gravelly loam, much coarse material 



B. Subsurface, yellowish brown gravelly loam to gravel 



This was a very coarse gravelly loam containing only a small percentage of sand, little more 

 than a trace of silt and clay, and was low in organic matter. It had been growing alfalfa and 

 some Kentucky bluegrass for several years. 

 3 Dunkirk fine sandy loam 



A. Surface, yellow line, sandy loam 



B. Subsurface, yellow sandy loam, sand below 18 inches 



The first 18 inches of this soil were very uniform in texture. The land was naturally not well 

 supplied with organic matter, but had been manured somewhat in recent years. It had 

 been fallowed during 1918 and was being planted to young orchard. 

 4. Volusia stony loam 



A. Surface, brown stony loam, loamy phase, not many stones in sample 



B. Subsurface, yellowish bro^\'n stony loam, more fragments of stone than in surface. 

 This sample was taken near the boundary between this type and Volusia silt loam as mapped 

 by Bonsteel, Fippin and others (4). This soil has been growing mixed grasses for some time. 



Table 1 gives the results of the determinations of total soluble solids and 

 nitrates in heated and unheated soils. The figures in the last column of tables 

 1, 2, 3 and 6 are in each case the product of the probable error of the difference 

 and 3.81. It is the quantity of total solids in milligrams that the dry soil 

 must exceed the moist (or air-dry) in order that the variation may be con- 

 sidered significant, that is, that the odds be 30:1 in favor of the difference 

 being due to variation in the conditions of the experiment and not to error 

 in manipulation. 



From table 1, it is readily seen that in every case the dry soil yielded more 

 total soluble solids than did the moist soil. The amount of nitrates varies 

 considcra1)ly. In five of the eight tube samples, denitrification had reduced 

 the nitrates to zero, of the remaining eleven comparisons, the moist soil was 

 slightly higher in nitrates in six, while the dry was ahead in five cases, so no 

 conclusion as to effect on nitrates can be drawn from this experiment. It 



