EFFECT OF DRYING SOILS ON WATER-SOLUBLE CONSTITUENTS 187 



should be stated that there was considerable variation in the period between 

 sampling and the determination (the last one being made August 15, 1919) 

 so that biological action may account in part for the wide variations and the 

 frequent high probable error of the difference. Occasionally the ice was 

 allowed to get low in the refrigerator so the temperature became high enough 

 for good bacterial growth. There is, however, no case in which, if the nitrates 

 are calculated as Ca(N03)2 and deducted from the total solids, that the 

 conclusion or its significance is altered. 



Experiment 2 



The purpose of this experiment was to study the effect of storage for nine 

 weeks at 8 to 12°C. on the quantity of soluble material when the soils were 

 kept under somewhat carefully controlled conditions of moisture content, but 

 under different conditions of aeration. Determinations of total soluble solids 

 were made on both moist and dry soils. 



On October 23, 1919, three soils, Dunkirk silt loam (sod), Dunkirk silt 

 loam (stony), and Dunkirk sandy loam, were collected and treated as noted 

 above. The first and third are the same soils as were used in experiment 1 

 and are similar to them in every way, these samples being taken within a few 

 feet of the others. The third soil, Dunkirk silt loam (stony), was taken from 

 a field growing rye and vetch. It had been well manured before seeding and 

 has received considerable fertilizer during the past few years. 



Procedure 



The tube samples were sealed with paraffin at once and kept in the refrigerator for a period 

 of 68 days to determine the effect of this method of storage. The jars containing 

 the auger samples were kept in the refrigerator also. Total soluble solids and nitrates were 

 determined on all of the auger samples within the next 5 days, beginning on October 24. 



The remainder of each of these samples was kept in the ice-box in an open jar to allow free 

 aeration, weighed at intervals of 1 week, and distilled water added to make up for any loss 

 by evaporation in order to detemine the effect of this method of storage for 65 days. The 

 principal difference in the two methods of storage is in the opportunity for aeration in the 

 auger sample in open jars, particularly since the water evaporating was compensated at inter- 

 vals of one week. 



The results of the determinations are stated in table 2. 



These figures show that the oven-dried soil compared with the original moist 

 soil had in the two silt loams three to five times as much soluble solids and in 

 the sandy loam twice as much. 



The Dunkirk silt loam (sod) contained very little soluble matter, either 

 mineral or organic, and but little more than a trace of nitrates, 1.7 parts per 

 million in the fresh moist sample. This is in close accord with determinations 

 made on this soil collected the previous season, though both nitrates and total 

 solids were somewhat higher then. 



