HORTICULTUBE. 337 



The data show that "of nine conclusive experiments made on various soils 

 the huT:est increase in yield was afforded by phosphoric acid in five experiments, 

 and by nitrogen in two experiments. In none was kainit more effective than 

 acid phosphate. In five exr>eriments cotton-seod meal was more effective than 

 an equal weight of kainit, and In only one was kainit notably more effective 

 than meal. 



"Taken as a whole these experiments seem to indicate tliat the popular idea 

 that i)otash is the most important constituent in a fertilizer for sweet potatoes is 

 incorrect, at least as to ])ractically all of the soils here represented. On the other 

 hand, these tests show that phosphate and nitrogen were much more important 

 than potash. These experiments also seem to discredit the notion that the use 

 of a fertilizer containing nitrogen causes the sweet-potato plant to run to 

 vines to an injurious extent. In our experience this danger does not occur where 

 reasonable amounts of nitrogen are used in combination with acid phosphate. 



"The following general fertilizer formulas are suggested where the condi- 

 tions justify rather high fertilization: For sweet potatoes growing on fresh 

 land, or on sandy land in x-ather high state of fertility, a fertilizer consisting of 

 200 lbs. cotton-seed meal per acre, 400 lbs. acid phosphate, and 200 lbs. of kainit. 

 . . . For sandy land long in cultivation and not in a high state of fertility it 

 would seem advisable to increase the proportion of nitrogen, using, for example, 

 a formula somewhat like the following: Three hundred lbs. cotton-seed meal 

 per acre, 400 lbs. acid phosphate, and 2W) lbs. kainit." 



Irrigation practice in rice growing, C. G. Haskell (U. S. Dcpt. Agr., 

 Farmers' Bui. 673 {1915), pp. 12, fig. 1). — This discusses methods and means of 

 irrigation as developed in the rice fields of the United States, under the topics 

 of making a water supply available, preparing for irrigation, and applying the 

 water. 



Growing hard spring wheat, C. R. Ball and J. A. Clark ( U. S. Dcpt. Agr., 

 Fanners' Bui. 678 (1915), pp. 16, figs. ^). — This discusses the size, surface, soil, 

 and climate of the Great Plains area, describes rotations for spring wheat, and 

 gives directions for preparing the seed bed, sowing the seed, and cultivating 

 and harvesting the crop. 



Wheat silage, J. R. Shinn {Washington Sta. Popular Bui. 88 {1915), pp. 4, 

 fig. 1). — This gives results of harvesting wheat or wheat and vetch as a silage 

 crop for dairy purposes, obtained in cooperation with the Bureau of Plant 

 Industry of this Department. The yields of silage material ranged from 6,316 

 to 42,688 lbs. per acre. Better milk yields are claimed by its use than by the 

 use of corn silage. 



Control of tumbling mustard, R. G. Adams and B. Hunter {Washington 

 Hta. Popular Bui. 89 {1915), pp. 7, figs. 3). — As methods of control of this weed, 

 disking stubble in early fall, seeding winter wheat after and before rains, 

 harrowing winter wheat in spring, growing spring wheat, pulling scattering 

 mustard plants, and clipping the mustard plants are discussed, the work being 

 in cooperation with the Bureau of Plant Industry of this Department. Attach- 

 ments which may be put on the header of a combined harvester to enable the 

 machine to cut badly infested grain are described. 



HORTICULTURE. 



Progress in plant breeding, N. E. Hansen {South Dakota Sta. Bui. 159 

 {1915), pp. 179-192, figs. 7). — Descriptive notes are given on a number of 

 varieties of fruit and on a new rose, all of which were introduced in 1912 and 

 have been noted (E, S. R., 30, p. 640). 



