492 



SCIENCE 



[N. S. Vol. XXVIII. No. 719 



188Y. Cropped with corn and oats (poorly) 

 every second or third year and idle between. 

 Fertilized 190Y with a cheap com fertilizer. 

 Yield 10 to 12 bushels of corn per acre." 



(j) " Cherry tree lot, west of campus. 

 Probably cropped since 1894. Was once part 

 of the campus. Cropped with corn and po- 

 tatoes, alternately, clover and oats also planted 

 twice, potatoes in 1906, millet in 1907, but 

 failed because of drought. Some sweet po- 

 tatoes planted there in 1907 but were also 

 poor because of the dry season. Corn yielded 

 there about 40 bushels to the acre. None of 

 this land has been fertilized more than twice 

 in thirty years and then with wood ashes or 

 a cheap commercial fertilizer." 



These soil samples were subjected to the 

 following treatment: The air-dry soil was 

 rolle(J with a small wooden roller to crush 

 the lumps and sifted through a sieve having 

 meshes of 2 mm. Three-pound portions of 

 the pulverized soil were each placed in a sep- 

 arate tray moistened with distilled water and 

 treated with various fertilizers. 



In the case of sample (a) to portion I. was 

 added nitrogen, as nitrate of soda, at the rate 

 of 200 lbs. to the acre; and phosphorus, as 

 acid phosphate (containing 14 per cent, of 

 soluble phosphoric acid) at the rate of 

 600 lbs. to the acre. Portion number II. re- 

 ceived nitrogen, as sodium nitrate, at the rate 

 of 200 lbs. per acre, and potassium, as sul- 

 phate of potash at the rate of 200 lbs. to the 

 acre. Number III. received phosphorus, as 

 acid phosphate (14 per cent, soluble phos- 

 phoric acid), at the rate of 600 lbs. to the 

 acre; and potassium, as sulphate of potash, 

 at the rate of 200 lbs. to the acre. Number 

 IV. received nitrogen, as nitrate of soda, 

 200 lbs. to the acre ; phosphorus, as acid phos- 

 phate (14 per cent.), 600 lbs. per acre; and 

 potassium, as sulphate of potash, 200 lbs. per 

 acre. Number V. received the same treat- 

 ment as number IV., and in addition cal- 

 cium, in the form of slaked lime, at the rate 

 of 2,000 lbs. per acre. Number VII. received 

 nothing and served as a cheek. 



Soil sample (j) was divided into five three- 

 pound, portions. Numbers I., II., III. and 



IV. received precisely the same treatment as 

 did numbers I., II., IH. and IV. of sample 

 (a). Nvunber V. served as a check and was 

 left untreated. 



All of these various portions were allowed 

 to remain in their respective dishes for several 

 days, with occasional stirring and moistening 

 in order to thoroughly distribute the fertil- 

 izers. Then, as nearly as could be judged, 

 enough distilled water was added to each por- 

 tion to supply the optimum or most favorable 

 moisture content for plant growth, which ac- 

 cording to Hilgard, is equivalent to from 40 

 per cent, to 60 per cent, of the water capacity 

 of a soil. Each portion was divided into 

 three approximately equal parts, and each 

 part was placed in a wire basket ; these baskets 

 were of standard dimensions, 3 inches in diam- 

 eter, 3 inches deep, mesh 3 mm., and contained 

 about 1 pound of the prepared soil, which was 

 well pressed into the bottom and sides of the 

 baskets. The baskets containing the soil were 

 then repeatedly dipped into a bath of melted 

 paraffin-wax until a good coating was ob- 

 tained. Six germinated kernels of wheat 

 were planted in a row in the soil of each 

 basket and a thin layer of clean white sand 

 was placed on the top of the soil. The filled 

 baskets were then weighed and placed in a 

 greenhouse where favorable conditions for 

 growth were maintained. 



When the wheat plants had reached a 

 height of about two inches enough distilled 

 water was added to each basket to bring the 

 weight up to the first weighing, and a paraf- 

 fined paper disk was fitted about the stems of 

 the plants and sealed to the sides of the basket 

 by means of a small amount of melted paraf- 

 fin-wax. By this device all escape of mois- 

 ture from the soil was practically cut off 

 except by way of transpiration through the 

 plants. The baskets were again weighed, and 

 thus the optimimi weight was ascertained. 

 The baskets were then returned to the green- 

 houses and maintained under favorable condi- 

 tions for growth. 



The amount of water transpired by the 

 plants was ascertained by weighing each 

 at intervals of three or four days. 



