470 



March, 1914 



streets. The most popular street 

 is one not seen in Sydney, yet well 

 worthy- of trial, though it jprows 

 wild from Tasmania to yucenslaud. 

 That is the JUacivwood (Acacia 

 melanoxylon |, one of the largest 

 of our wattles, and a vahiablc 

 timber tree. It is used in great 

 numbers, forming shapely, clean, 

 dark-green trees up to about 50 

 feet. It seems \ery free from the 

 troubles, insect and fungous, which 

 frequently bring about the prema- 

 ture death of acacias in Australia. 

 Last, and perhaps most striking of 

 all, are the Paliiis. The majority 

 belong either to genus Phoenix or 

 to Washingtonia. The Phoenix 

 palms are relatives of the date 

 palm, itself sometimes used. Being 

 relatively slow-growing it is not 

 so widely -used as the Washing- 

 tonias. Until a few years ago 

 the latter palms were known as 

 Washingtonia robusta. It has 

 been found that there are at least 

 three distinct species, the best and 

 hardiest being \V. lilifera. Another 

 species, W. gracilis, is sold by 

 seedsmen as W. robusta. Another 

 smaller palm, ^^"ashingtonia son- 

 oroe, is also used, and a glaucous 

 coloured species called Erythea ar- 

 mata. Magnolias are not uncom- 

 mon. 



In Arizona few evergreen trees 

 will survive the combined effects of 

 frost and great heat even under 

 irrigation, and the favourite tree is 

 the Umbrella Tree (Melia azedar. 

 ach), better known to us as the 

 \\%ite Cedar or Bead Tree. It is 

 usually topped to encourage the 

 umbrella habit. The ftimous Mag- 

 nolia Avenue at River.side, consists 

 of three> rows of trees— Peppers, 

 Blue-gums, and an alternating f ow 

 of Silky Oaks and Washingtonias. 

 These, with the Blackwood in the 

 streets, form the bulk of the tree- 

 plantings in Southern California, 

 and serve as a striking object les- 

 son of what can be accomplisluvd 

 among apparently unfavourable 

 surroundings. — .\gricultural Crazette 

 of X.S.W. ■ 



C. A. SMITH & CO. 



RNGINEERS, 



WAKEFIICLD STREET 

 ADELAIDE 

 (0pp. Gawler Place). 



Sole Makers of the 

 " DON " Centrifugal and Double 

 Action Pumjis, Horizontal and 

 V'crtical. 



The best on the market. Repairs 

 to all kinds of Machinery. 

 'Phone 766. 



Recent Investigations at 

 Rothamstead. 



Consideration attention has been 

 paid to the conditions under wliich 

 the production of plant food, and 

 especially of ammonia, and ni- 

 trates, goes on. It has been shown 

 that the process is mainly the 

 work of bacteria, but that in nor- 

 mal soils the bacteria are not 

 working at their maximum effici- 

 ency. A factor has been discover- 

 ed limiting the numbers of bacteria 

 and therefore the amoimt of de- 

 composition they effect. 



,Vll the available evidences goes 

 to show that this factor is biolo- 

 gical. It is capable of growth, is 

 put out of action by heat or anti- 

 septics and can onl}- be set up 

 again by infection from outside: it 

 does not, howe\er, appear to con- 

 sist of bacteria, and is provision- 

 ally identified with the protozoa, 

 of which numbers ha\e been found 

 in all the soils examined. Partial- 

 ly sterilised sods from which the 

 factocr has been extinguished are 

 found to contain larger numlsers of 

 l:)acteria than untreated soils and 

 to accumulate ammonia and ni- 

 trates at a greater rate : tliey are, 

 as might be expecected, more pro- 

 ductive. Methods are being work- 

 ed out for applying this kind of 

 soil treatment on the large scale, 

 but instead of setting up a large 

 number of field plots to discover 

 some cheap and con\"enient pro- 

 cess, the simpler alternative is 

 adopted of inducing horticulturists 

 who go in for intensive culture to 

 adopt some of the methods known 

 to work. This has proved very 

 satisfactory and has led to a con- 

 siderable cheapening of the method, 

 besides revealing some of the dif- 

 iiculties attendant on its apj)lica- 

 tion on the large scale. 



— Plant Work. — 



The amount of growth a 

 l)lant makes in a given soil is 

 known to depend on the connec- 

 tion between the plant nutrition 

 work and the soil work. But a 

 liypothesis is current, and is back- 

 ed by sufhcient circumstantial evi- 

 dence to make it worthy of con- 

 sideration, that inorganic plant 

 ])oisons -^ct as stimulants to 

 irrowth if supplied in sufficiently 

 small quantities. If this hypo- 

 thesis were well founded it would 

 introduce a wholly new set of fac- 

 tors into plant nutrition relation- 

 ships, and would, in addition, form 

 a basis for important practical de- 

 \ elopments. Very careful water 



cultures have therefore been made 

 by Dr. Winifred E. Brenchley to 

 test this hypothesis as completely 

 as possible. The compounds test- 

 ed ha\ e been copper sulphate, man- 

 ganese sulphate, zinc sulphate, so- 

 dium' arsenite arsenious acid and 

 boric acid, and a wide range of • 

 concentrations has been adopted. 

 Numerous plants have been tried, 

 but oil the whole bai^}' and peas 

 have proved most satisfactory. 

 Coppur sulphate was invariably 

 toxic even in such high dilutions 

 as I part of salt to ten milHons 

 of water. The effect varied, how- 

 ever, with the plant and was 

 somewhat masked in presence of 

 nutrient saltS. It is not entirely 

 simple. The fact that boric acid 

 decidedly increased the growth of 

 peas, but never that of barle\ , 

 raises the interesting -question whe- 

 ther boron is in some way advan- 

 tageous to the pea and therefore 

 to be regarded as a nutrient- 

 Some specific effecj: is clearly in- 

 dicated and the h>q3otheis is shown 

 not to hold in its general form. 



Starting from the other end, 

 i.e., from ^he soil, an attempt has 

 been made to ascertain whether 

 any toxins are thrown off from 

 the roots of plants that will ad- 

 versely aiiect succeeding crops. A 

 hypothesis to this efiect has long 

 been current, and has been de- 

 fended by the United States 

 Bureau of Soils. Plants have 

 therefore been grown in succession 

 in the same pots of soil, year after 

 year, and their yields have been 

 compared with those obtained 

 when a rotation was adopted. The 

 results were entirely negative and 

 no systematic difference could be 

 obser\ed : we are forced to con- 

 clude that if any toxic property is 

 develojied in soil by the cfrowth of 

 a crop its effect is transient and 

 does not persist long enough to 

 affect a subsequent crop. — Monthly 

 Bulletin. 



TBY 



JAMES WHITE & SON 



238, CARRINGTON ST., ADELAfDE, 

 — For — 



Baths and Bath Heaters, 

 Tanks, Skylights, Ventilators, etc.. 

 And all kinds of Plumbing Work. 



First Quality Work Only. 



'Phone— Central 2731. 



