FIELD CROPS. 771 



case has tlie author IoiukI ''a system of small roots starting out below 

 and near the crown, extending- laterally for several feet and then turn- 

 ing' downward, forming a symmetrical conical system, whose broadest 

 part was near the surface." The depth to which the roots penetrate 

 diflers with the soil and with the height of tlie permanent water table. 

 The greatest observed depth was 12.25 ft. in a homogeneons clay. No 

 ai)parent relation was discovered between the age and the size or the 

 death rate of the roots. 



Tubercles ajipear on the roots in 3 forms, as warty excrescences 

 near the neck, and as single and colonized nodules on the roots. The 

 excrescences only api»ear at shallow depths, the colonies at from 3 to 5 

 ft., and the single nodules at all depths. These nodules were found 

 to differ greatl}^ in abundance on roots of plants in different localities, 

 though the plants appeared of eijual vigor and the proteids in the hay 

 varied little. Compare;! with vetches and red clover, alfalfa is poorly 

 supplied with nodules, but the groups are much larger, frequently 

 being 1.5 in. in diameter. Some of these groups were analyzed and 

 found to contain 5.725 per cent of nitrogen, while the cortex of the 

 roots contained only 2.25 per cent. 



The author believes that the total weight of roots equals or exceeds 

 that of the tops. The amount of the roots within reach of the plow, 

 added to the amount of stubble left by the first mowing, is two-thirds 

 the weight of green alfalfa removed. 



A full discussion is given of the manurial value of the stubble and 

 roots, with calculated amounts of constituents and of ash ingredients 

 in 1,000 lbs., and analyses of soils on which 2 samples were grown and 

 of ground water and seepage water in one instance. 



The author believes it safe to assume that 1 ton of leaves, broken 

 stems, etc., is lost in the making of every 5 tons of hay, and that there 

 is thus returned to the soil annually the equivalents of 25.79 lbs. of 

 calcium phosphate, 77.73 lbs. potassium chlorid, and 449 lbs. of sodium 

 nitrate. In addition to this, the principal fertilizing ingredients in the 

 stubble and roots have an estimated value of $35 per acre, and the 

 author thinks the easily decaying alfalfa roots possess a high value as 

 increasers of the humus in prairie soils. 



In an appendix tlie methods used in making the analyses are dis- 

 cussed, and the analyses of alfalfa are compiled. 



Canaigre, II. H. Fokbeh {Arizona ^Sta. Bui. 21^ pp. ^J^,Ji(/s. 6').— Pre- 

 vious work in this line was published in Uulletin 7 of the station 

 (E. S. 11., 4, p. 804). In studying the formation of tanning materials 

 3() lots of 25 one year-old roots, weighing nearly 2 lbs. ])er h)t, and as 

 uniform as possible, were planted November 2<; and closely observed 

 for 10 months. All were irrigated 4 times and 3 lots 3 times in addi- 

 tion. Samples were dug for analysis each week during the growing 

 season, and at intervals throughout the sunnner. The results are tab- 

 ulated. The author states that the tanning materials remain (piite 

 constant throughout the whole growing season. 



