942 EXPERIMENT STATION RECORD. 



Only ou soils very poor in phosphoric acid did water-soluble phosphoric 

 acid produce better effects than Thomas slag containing a high per- 

 centage of citrate-soluble phosphoric acid. The after effect of the 

 latter was also as a rule greater. Examinations of the soils used in 

 these experiments indicated that the total phosphoric acid was not 

 always a safe index of their phosphoric acid requirements, but this was 

 dependent largely upon the form in which the phosphoric acid was 

 present in the soil. Soils which contained phosphoric acid in form of 

 vivianite, or in the transition stages between vivianite and ferric phos- 

 phate, stood less in need of phosphoric acid fertilizing than those which 

 contained ferric phosphate. 



In experiments on the optimum water content of lowland moor soils 

 it was found that with leafy plants, like oil radish, the largest yield 

 was obtained with the highest amount of water (75 per cent of the water 

 capacity of the soil j. With oats the maximum yield was obtained with 

 a water content of 65 per cent. In similar experiments on upland moor 

 soils the highest yields of both crops were obtained with saturated soil 

 (84.7 per cent of water ). 



Eed earth containing 2.08 per cent and vivianite containing 14.51 per 

 cent of phosphoric acid, 2 substances which naturally occur in moors, 

 were tested in comparison with Thomas slag. The results show that 

 these substances have considerable value as fertilizers. 



Fertilizers, E. B. Voorhees {New York : The Macmillan Co., 1898, pp. XIV+335).— 

 When we consider the relation of the experiment stations in this country to the fer- 

 tilizer question it seems peculiarly fitting that the preparation of this volume of the 

 Rural Science Series should have been intrusted to the director of an agricultural 

 experiment station, and especially of a station like that of New Jersey, which has- 

 has done so much to promote the intelligent use of fertilizers. 



As the subtitle states, the book treats of the source, character, and composition of 

 natural, home-made, and manufactured fertilizers, with suggestions as to their use 

 for different crops and conditions. The following is a summary of the topics treated : 

 The natural fertility of the soil and sources of loss of the elements of fertility; the 

 functions of manures and fertilizers and the needs of artificial fertilizers ; the sources 

 and nature of the various commercial forms of nitrogen, phosphoric acid, and potash, 

 as well as of miscellaneous fertilizing materials, including, among others, green 

 manures and soil amendments; the analysis and purchase of fertilizers; methods of 

 using fertilizers ; and fertilizers for special crops — cereals and grasses, potatoes, sweet 

 potatoes, tomatoes, sugar beets, green forage plants, market garden crops, orchard 

 fruits and berries, cotton, tobacco, sugar cane, etc. 



The work is intended for ''the general reader as well as the student," and aims 

 "to point out the underlying principles and to discuss in the light of our present 

 knowledge of the subject some of the important problems connected with the use of 

 fertilizers." 



In order that each farmer may intelligently apply the results of scientific investi- 

 gation to his own conditions the author outlines a plan of farm experiments. Great 

 emphasis is laid on the importance of the systematic use of manures and fertilizers, 

 a chapter being devoted to a discussion of systems of fertilization adapted to various 

 systems of rotation and farm management, conditions of soil, etc, 



