SOILS FERTILIZERS. 817 



Pot tests with fertilizers compared with field trials, G. N. Coffey and H. F. 

 TuTTLE (Jour. Amer. Soc. Agron., 7 {1915), No. 3, pp. 129-139, fig. i).— Pot 

 fertilizer experiments with wheat on different soil types are reported, the 

 purpose of which -was to determine the value of pot tests for indicating the 

 fertilizer requirements of a given soil. 



The pot tests were made with soils as similar as possible to those upon 

 which field trials are being conducted and the results compared with those 

 secured in the field, the idea being to duplicate field conditions and fertilizer 

 treatments as nearly as possible. Five-gallon glazed clay pots about lOi in. in 

 diameter and 12 in. deep were used. The surface soil and the first 6 in. of 

 subsoil from dilferent fields were used, and equal weights (about 10 kg.) of 

 both soil and subsoil were used in each pot. It was found that the results of 

 pot tests and field trials made as indicated agreed on the whole very closely. 



Data on the experience with fertilizer pot tests at other experiment stations 

 were also obtained, the consensus of opinion of those reporting success being 

 that if one element is needed the pot test is quite reliable in indicating it, while 

 if two or more elements are lacking the pots may differ from field indications. 



It is concluded from the results of these experiments and the experience of 

 other stations that pot tests may be made of very great value in determining 

 the relative need of the soil for different plant food elements. To secure the 

 best results the soil should be placed in the pots in as nearly the same position 

 and condition as in the field and receive the same fertilizer treatment as in 

 field practice. "Both soil and subsoil should be used, the surface soil being 

 taken to the depth at which the most marked change takes place, usually about 

 the depth to which it is plowed. Air drying and excessive handling should 

 be avoided. . . . 



"A somewhat larger quantity of seed per acre should be sown and the plants 

 thinned to about the same number per acre as in the field and to an equal num- 

 ber per pot. While most stations have grown the plants to maturity, the 

 results secured here seem to show that with wheat a period of one month to six 

 weeks is sufficient to indicate the relative fertilizer need of the soils studied. 

 The dry weight is considered most reliable. The tests should be made in not 

 less than triplicates and statistical methods should be applied." 



General notes on manures, their value and use, J. S. J. McCall (Nyasaland 

 Dept. Agr, [Pt<&.], 2 {1915), pp. 8). — General information on the subject, includ- 

 ing brief instructions as to the purchase of fertilizers, is given with particular 

 reference to the tobacco-raising localities of Nyasaland. 



Illustration of important properties of peat litter, G. Keppeler {Mitt. Ver. 

 Ford. Moorkultur Deut Reiehe, S3 {1915), No. 3, pp. U-H, P^s. 2). — Comparative 

 experiments on the properties of peat litter and straw with reference to their 

 values when used in stable manure are reported. 



It was found that 300 gm. of peat litter absorbed 4,500 gm. of water as against 

 800 gm, of water absorbed by 300 gm. of straw. Two gm. of peat litter absorbed 

 approximately 1 liter of ammonia in the same time that 2 gm. of straw absorbed 

 only 0.2 liter of ammonia. It was also found that pulverized straw molded 

 much more quickly than pulverized peat with the same content of water and 

 nutritive solution. 



These results are taken to indicate that peat litter is much more valuable 

 than straw for use in stable manure, inasmuch as its superior absorptive power 

 for water and ammonia and its inhibitive action toward bacterial decomposition 

 will prevent the loss of ammonia from animal excrement. 



Investigations on the absorptive power of peat dust for water, H. Minssen 

 {Mitt. Ver. Ford. Moorkultur Dent. Reiehe. 33 {1915), No. 3, pp. 4//-52).— Ex- 

 periments with eight samples of four different kinds of peat are reported, the 



