722 EXPERIMENT STATION EECOED. 



being best returned to the soil as farm manure and by the cultivation of legumes 

 and the use of catch crops, cover crops, and crop residues. Tlie general use of 

 complete fertilizers is not considered economical or conducive to a condition of 

 permanent soil fertility. It is recommended that systems of cropping be followed 

 v.'hereby plant food is returned to the soil through crop residues and manures, 

 that rotations containing leguminous and cover crops be used, and that de- 

 ficiencies in any plant-food element, as indicated by field experiments or chemical 

 analyses, be supplied in the cheapest available form and in quantities sufficient 

 to meet the requirements of a number of crops. 



Barnyard manure, P. H. Moore {Canada Expt. Farms Rpts. 1914, pp. 291, 

 292). — Comparative tests of a mixture of commercial fertilizer alone and the 

 same mixture together with 16 tons of barnyard manure per acre for mangels 

 showed that the plat receiving the second mixture yielded over 3 tons per 

 acre more than the plat receiving the first mixture. 



Experiments comparing spring application with winter application of fresh 

 manure, and spring application of manure staclied in the field during the winter 

 with winter application of fresh manure, favored the spring application in both 

 cases. 



The losses and preservation of barnyard ananure, O. B. Winter {Michigan 

 Sta. Circ. 26 {1915), pp. 2-8). — This circular calls attention to the losses of plant 

 food in barnyard manure under present systems of farm management and 

 describes methods for its preservation. 



The effect of fineness of peat litter on its absorptive power for water, 

 H. VON Feilitzen {Mitt. Yer. Ford. Moorkulttir Deut. Reiche, 33 {1915), No. 6, 

 pp. 85-91, fig. 1). — The work of others bearing on the subject is briefly reviewed 

 and experiments with peat litter and peat dust of various kinds, with reference 

 to their absorptive power for water, are reported. In addition to measuring 

 the size of grains the different samples were subjected to botanical analysis. 



It was found that the absorptive power for water increased with fineness 

 of grain until a fineness of from 1 to 2 mm. was reached, after which the 

 absorptive power gradually decreased until a fineness of 0.5 mm. was reached, 

 and then rapidly decreased. The botanical investigation showed that the 

 accessory plant constituents other than sphagnum, which has a much greater 

 absorptive pov,'er for water than the others, tend to collect in the finest grains. 

 It is concluded, therefore, that the different absorptive powers for water of 

 the different fine particles of peat dust depend not only on the degree of fine- 

 ness but perhaps more on the frequent occurrence of accessory plant con- 

 stituents and humus particles. 



The importance of micaceous minerals in agriculture, E. Blanck {FuJiUng's 

 Landio. Ztg., 64 {1915), No. 1, pp. 2JD-2S). — The author briefly reviews recent 

 work by himself (E. S. R., 27, p. 520; 29, p. 215) and others which shows that 

 the potassium of biotite is more available as plant food than that of feldspar 

 and much more available than that of muscovite. Experiments by Atterberg 

 (E. S. R., 30, p. 214) are referred to as indicating also that biotite plays a 

 special role in connection with the physical properties of certain stiff clays, 

 particularly in increasing their plasticity. 



The comparative value of different sources of phosphorus, B. L. Hartwell 

 and S. C. Damon {Rhode Island Sta. Bui. 163 {1915), pp. 515-560, pis. 2).— 

 This bulletin reports the unpublished results and a summary of published 

 results of twenty years' continuous field experiments on silt-loam soil composed 

 of glacial drift of granitic origin to compare different phosphatic materials. 



Three experiments were conducted. The first was a six-year comparison of 

 Chincha and Lobos guanos, ground bone, and dissolved phosphate rock so 

 applied as to furnish the same amount of phosphorus, the nitrogen and potas- 



