200 



THE AGRICULTURAL NEWS, 



June 17. 1916. 



EDITORIAL 



He^d Office 





NOTICES. 



— Barbados. 



Letters and matter for publication, as well as all 

 -specimens for naming, should be addressed to the 

 •Commissioner, Imperial Department of Agriculture, 

 Barbados. 



All applications for copies of the 'Agricultural 

 News ' and other Departmental publications, should be 

 •addressed to the Agents, and not to the Department. 



The complete list of Agents, and the subscription 

 «nd advertisement rates, will be found on page 3 of 

 the cover. 



Imperial Commissioner of Francis Watts, CM. G., D.Sc, 



^griodture for the West Indies F.I.C., F.C.S. 



SCIENTIFIC STAFF. 



&ieutific Assisfa'>d and 



Assistant Editor 

 Jlntvmologist 

 Mycologist 



W. R. Dunlop. 



H. A. Ballon, M.Sc. 



W. Nowell, D.I C. 



CLERICAL STAFF. 



ijhief Clerk 

 A^ssistaitt (Jleri: 



•Clerical Assistants 



'Typist 

 Assistant for Publications 



A. G. Howell. 

 M. B. Connell. 



(h. A. Corbin. 



1 1 



P. Taylor. 



Miss B. Robinson. 



A. B. Price, Fell. Journ. Inst. 



^griciilliirat ^xm 



"Vol. XV. SATURDAY, .IINE 17, 1916. No. 369. 



NOTES AND COMMENTS. 



•Contents of Present Issue. 



The editorial in this number deal.s with the 

 importaiice of science for both the protection and 

 progress of industry. 



Interesting notes on the value of birds in the 

 West Indies for the control of pests appear on page 

 197. 



Part of the fourth day's proceedings at the West 

 Indian Cotton Conference is summarized on page 198. 



Information relating to pests and di.seases in this 

 issue concerns the native food plants of the cotton 

 stiiiiier and thrips, and die-biick of cacao in St. Vincent 



Moisture and Pressure in Soils. 



The latest .-mnuiil report of the Chief of the Bureau 

 of Soils, of the United StatesDepartnient of Agriculture, 

 refers to some important fresh ideas which have arisen 

 as a result of American research on the physical pro- 

 perties of soils. It i§_ stated that it has come to be 

 recognized that every physical property of the soil 

 affecting the growth of crops is itself determined by 

 the moisture content of the soil, and that thei'e is 

 a critical moisture content characteristic of each partic- 

 ular soil at which the aggregate of physical properties 

 produces an optimum condition for plant growth. 

 Consequently, the determination of this critical or 

 optimum water content has a practical importance, 

 and a comparatively -quick and rapid method for its 

 determination has been developed. 



The report then goes on to show how soil pressure, 

 is related to moisture It is pointed out that if 

 a soil containing less than the critical moisture content 

 be farther wetted, there are pressures developed which 

 are of enormous dimensions on the surface of 

 the individual grains as determined by theoretical 

 calculation, and which are often of considerable magni- 

 tude on the surfaces of the soil mass. Pressures of 

 600 ft), or more to the square inch of soil mass have 

 been observed in the work of the past year. These 

 observations have a considerable interest in theoretical 

 and pratcial studies on tilth. But they have a much 

 more direct importance to engineers and practical 

 constructors l.aving to deal with dams, earth- works, 

 foundations or other like problems, where the earth is 

 liable to continual or intermittent contact with water 



The Source of Nitrogen in Legumes. 



Valuable information is contained in Bulletin No. 

 179, issued by the University of Illinois Agricultural 

 E.xperiment Station, and dealing with the subject of a 

 biochemical study of nitrogen in certain legumes. For 

 experiment station workers the methods described will 

 be found very useful and valuable, while the general 

 reader concerned with leguminous crops will find the 

 conclusions drawn from these experiments especially 

 interesting. It is shown conclu.'^ively that the cowpea 

 and the soy bean utilize atmospheric nitrogen through 

 their roots and not through their leaves. No combined 

 nitrogen could have been assimilated in the gas experi- 

 ments conducted. The total nitrogen determination 

 shows that about 74 per cent, of the nitrogen of cowpea 

 and soy beans at the time of harvest is in the tops, 

 while the remainder is distributed between the roots 

 and the nodules. In the earlier peiiods, the njots 

 contain a larger proportion, while later they contain a 

 much smaller proportion. It appears that there is a 

 lai-ger percentage of soluble nitrogen in the tops than 

 in the roots or in the nodules. It is stated further that 

 fixation takes place at a very early period in the growth 

 of the seedling — sometimes within fourteen day.s. It 

 is rapid in some cases, especially with cowpeas. 

 Plants grown under the conditions of the experiments 

 described in the Bulletin contain no ammonia, nitrites 

 or nitrates as measured by the most accurate chemical 

 methods. 



