1917] FIELD CROPS. 231 



or with loft sweepings. Tlie untended are those which have been plowed and 

 probably manured from 50 to 100 years ago and then, after yielding crops for 

 some seasons, allowed to revert to grass without any sowing (with the possible 

 exception of loft sweepings) and have so remained ever since without any fur- 

 ther manuring in most cases. 



Plants which colonize natural gi*asslands are called primary indigenous 

 species, and those which come in without beiig sown and contribute largely to 

 the herbage on seminatural grasslands are designated as secondary indigenous 

 species. Plants that come in alone but which disappear as the field approaches 

 the seminatural are called tertiary indigenous species, and are to be dealt with 

 in a subsequent paper. Plants which are indigenous in a district but do not 

 contribute to the flora of a well-marked type of grassland are called locally 

 exotic, and those not indigenous in a district exotic. These classifications and 

 distinctions are deemed applicable to all districts and tj'pe of grasslands. 



Considerable space is devoted to a discussion of the composition of the herb- 

 age on the various pasture lands observed and on the stabilization of grasslands. 

 The behavior of the chief plants found on all the types of grassland studied is 

 also discussed under a separate heading for each individual species. The gen- 

 eral conclusions may be summarized as follows: 



The number of primary species on most types is not considerable and they are 

 usually late in making their appearance in fields put down to grass after a 

 long period of rotation. Primary species which come in early are frequently 

 weeds of arable land, such as Poa trivialis, Festuca rubra, and Agrostis inilgaris. 



As regards the relation of primary and secondary species to their commercial 

 and sown counterparts, commercial seed may not appreciably hasten the appear- 

 ance or add to the quantity of the desired plant. This is especially true of the 

 fine-leaved fescues and even of Trifolium repens. Phosphatic manures often 

 prove to be sufficient to hasten the appearance of the indigenous plants. 



Commercial seed may produce a great bulk of the required plant and only 

 after several years will the plant attain its noi-mal development, indicating that 

 the final plant is the indigenous counterpart of the sown species. Commercial 

 seeding is ecnomically justified in such cases. Commercial seed may also 

 hasten the appearance of the desired species, but there is a risk of the sown 

 plant interfering with the development of the definitely lasting indigenous 

 species ; this is more a matter of local importance. The spontaneous appear- 

 ance of primary and secondary species on land long under rotation when put 

 down to grass may be due to the following: (a) Many species remain as arable 

 weeds; (b) the seeds of many species may be wind borne; (c) seeds may be 

 introduced as impurities in sown seed; and (d) the seeds of a great many 

 species are evidently capable of lying dormant in the soil for long periods. 



In addition to the conclusions given above, certain generalizations are pre- 

 sented regarding experimental work on grassland and the whole problem and 

 economics of putting land down to grass. A bibliography of 20 references is 

 given at the end of the paper. 



Observations on alfalfa, E. H. Jenkins {Connecticut State Sta. Bui. 192 

 (1917), pp. 12). — Limited observations of four years of alfalfa growing with 

 the Grimm, Sand Lucerne, Kansas-grown, Provence, Utah-grown, and Turkestan 

 strains are briefly noted. Grimm gave the highest average yield for the 4-year 

 period, 4.39 tons per acre, on limed soil. The lowest average yield, 3.4 tons, 

 was secured from the Turkestan variety. These two varieties suffered least 

 from winterkilling, while the Sand Lucerne and Provence suffered slightly, and 

 the Utah- and Kansas-grown strains the most. 



The determined cost of plowing, seed bed preparation, liming, and fertilizing 

 (basic slag, acid phosphate, and muriate of potash) amounted to $.53.91 per 



