jAHuarj, 1914 



340 



Soil-Sickness and Partial 

 Sterilisation. 



The recent endeavoiirs to deal 

 with cases of soil-sickness by 

 means of partial sterili/ation have 

 arisen from the disco\x>ry, some 

 few years ajjo, that this t'reatmeiit 

 increases bacterial activity in the 

 soil mainly throuii-h the reduction 

 of the number of lar<;cr compet- 

 in<T org'anisms. The change thus 

 broug-ht about increases the pro- 

 duction of plant nutrientsl and 

 hence inlluences favourably the 

 fjrowth of cultivated crops. 



During- the last year or two, at- 

 tention has been given toi the mat- 

 ter of partial soil sterilization 

 mainly from the pathological as- 

 pect. The healthy or unhealthy 

 nature of the soil, and not merely 

 its supply of plant nutrients, has 

 been the central object of investi- 

 gation. 



It has been established in the 

 United States, the Transvaal, as 

 well as in Bngland, that the so- 

 called sick soils .an, in many in- 

 stances, be rendered healthy by 

 subjecting them to a temperature 

 of loo degrees F. to 200 degrees 

 F. or by means of the application 

 of anti.septics. Valuable inform- 

 ation on tlie subject, contained in 

 a paper by Russel and Petber- 

 bridge, of Roth am. stead, deals 

 mainly with the application of an- 

 tiseptics in practical horticulture. 

 Sick soils to tomatos, cucumbers, 

 vines, ferns, peas and tobacco re- 

 cei\-ed special investigation. 



lit might be pointed out at once 

 that by a tomato-sick soil is 

 meant a soil that induces in to- 

 mato plants grown in it, a patho- 

 loeical or diseased condition of so 

 serious a nature that their cultiva- 

 tion ceases to be profitable. It is 

 of the greatest importance to bear 

 in mind that it is not the crop 

 that causes sickness of the soil, 

 but the soil that causes sickness 

 of crop. There are some virgin 

 soils, for instance, in wh ch vines 

 cannot be grown without artificial 

 treatment. That treatment is par- 

 tial sterilization. In <i^arden or 

 nurserv work, heatine of the soil 

 is not likely to be so ronveiisnt as 

 the anplication of antiseptics ; for 

 rfass house or pot work, however, 

 the heatin<r method can ^, be em'- 

 ployed wtth com^mercial success. 

 Of the common antiseptics, car- 

 bolic acid, calcium sulphide and 

 formaldeh\^e have o-i^en good 

 results — even better than those re- 



sults obtaiiuxl previously by using 

 toluol. The Selection of an anti- 

 .septic is cont'roUed bx- sovvral fac- 

 tors for example, efficiency, ori- 

 '.■■inal cost and expense of trans- 

 port, and has to be settled by con- 

 sidering the conditions of each 

 particular case. Hut the fact re- 

 mains that their use cures the 

 sickness, kills the disease organ- 

 isms in the soil, and incidentally 

 increases the supply of i)lant food. 

 What the diflercnt sicknesses really 

 are is not at present delinitoly 

 known : it may be that toxic or 

 poisonous sub.stances (to the par- 

 ticular crop affected) occur in the 

 soil as the excretions of certain 

 fungi and bacteria. Sometimes 

 the sickness can be, in part, .\tt'r - 

 buted to the presence of ' damping 

 off " fungi like the widely spread 

 P\"thium and Rhizoctonia. F'lture 

 investig-ations will in all probabili- 

 ty reveal the exact causes in everv 

 case. 



In concluding these, considera- 

 tions, it may be remarked that 

 the possibility of the local applica- 

 tion of partial sterilization to cer- 

 tain West India soils seems to be 

 sug-eestive, and the subject will 

 also bear consideration in ironnec- 

 tion w th specific root diseases. A 

 remedy for thesie may lie in the 



partial sterilization of the < soil. 



— Agricultural News. 



♦ 



The Potato. 



The potato is not a hardy plant. 

 The native of tropical or sub- 

 tropical countries, like Chili or 

 Mexico, cannot be expected to 're- 

 sist the rigours of frost unless its 

 constitution is changed to enable 

 it to accommodate itself to its 

 new environm-ent. This must be 

 the work of applied science. Fur- 

 ther, it is very liable to disease — 

 the " potato-murrain " was a 

 scourge, and still, under new 

 names, devastates fields before 

 growth is matured. Australian 

 growers, like the rest of the 

 Potato-raisers of the world, suffer 

 from both these troubles. One 

 well-known man has triied to come 

 to their rescue. This is Luther 

 Rurbank, whose name is associated 

 with some decided successes in hy- 

 bridizing flowers and fruits. He 

 turned his attent on to the tuber, 

 and a few years ago produced a 

 specimen which promised to meet 

 requirements, and was tested in 

 Ireland. Bnrbank's work has been 

 much misunderstood. He is neither 

 a wizard nor a charlatan. Ho is a 

 private gentleman, who loves 



plants, and tries to iinii)rove them 

 i)y scientific methods of selection. 

 For wars he worked on the pota- 

 to. Wild and tame si)ecies were 

 collected from different countries, 

 and from these he obtained many 

 crosses and combinations in his 

 .search for a better stock. He has 

 been trying to breed varieties suit- 

 able for every climate and all soils, 

 as well as to produce a vegetable 

 even more palatable than that 

 which is now put on the table. 

 The matter of the moment alike 

 to grower and consumer is whe- 

 ther crossing and selection will pro- 

 duce a variety which will be free 

 from so many of the v icissitudes of 

 the tuber's life. Therefore any ex- 

 periments made in this direction 

 deserve the clo.sest observation in 

 this country, which should never 

 have to import its vegetables. — 

 Sydney Morning Herald. 



— Mulching. — 

 It is during the drought and heat 

 that mulchings are beneficial and 

 are the means of saving consider- 

 able watering. Half decayed man- 

 ure is no doubt the best material 

 for mulching purposes, but grass 

 cuttine's, refuse, road scrapings, 

 all bieing of a non-absorbent char- 

 acter, are suitable, but in addition 

 to conserving the moisture in the 

 ground, manure also provides a 

 considerable amount of noiirish- 

 memt for the plants and trees 

 round which it is placed as water- 

 ings wash out its beneficial quali- 

 ties and carry them down to the 

 roots, and in cases where extra 

 nourishment is likely to he of as- 

 sistance in producing better crops 

 it is the wisest plan to emplov 

 manure for the purpose in ques- 

 tion. The surface of the ground 

 about the plants and trees to be 

 treated should first be well stirred, 

 and if the ground is drv it should 

 be well soaked with water. 

 ♦ 



Potato Tubers Not 

 Decaying. 



Non-decay in seed potatoes is 

 said to be due to the fact that 

 they are over-ripe, or, in other 

 words, to the absence of sap in 

 sufficient quantity to produce that 

 wet deca-v which characterises all 

 planted tubers that do decay. A 

 correspondent to the ''^ Dard'pn," 

 writes : — We seem to have in the 

 flesh of these saplessl of Qvcr- 

 matured Potatoes very much that 

 description of flesh which is found 

 in Columbian or Canadian Apples. 

 These, if bruised, never present the 

 form of wet -rot seen in British 



