352 JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY. 



cases. Each of the other three methods proved workable in practice, 

 and each has its advocates, its advantages, and its disadvantages. It 

 is too early yet to judge between them, but the great determining 

 factor must necessarily be cost. This matter is therefore dealt with. 



In some of the trials with tomatos the soil was treated in situ, since 

 the plants were grown in borders. In these cases fear was entertained 

 that the plants might develop too vigorous a habit of growth to " set " 

 their fruit well. It was true that the " setting " was always good in the 

 Rothamsted experiments, but there the plants were grown in pots, 

 where the root system was necessarily restricted. It was found, how- 

 ever, that the vigorous growth induced did not necessarily interfere 

 with the " setting " of the fruit ; by adopting precautions as to the 

 varieties selected, size of the plant at the time of setting out,withholding 

 water and manure, and keeping on the heat, some of the growers suc- 

 ceeded in getting as good a " set," or better, on heated than on unheated 

 soil. The results from the various nurseries were alike in showing a 

 higher return for steamed than for unsteamed soils. Moreover, the 

 early pickings were higher on the steamed soils, and of course it is the 

 early results that pay. 



It is the usual practice with cucumber-growers to reject on account 

 of " sickness " soil which has already borne a crop, and to make new 

 borders with virgin loam and straw manure. Experiments at Rotham- 

 sted have shown that the " sickness " can be removed by steaming, and 

 that soil so treated will allow of normal healthy plant development. 

 The grower, however, is not particularly concerned with any comparison 

 between steamed and unsteamed " sick " soils, but wants to know 

 whether the steamed soil is as good as virgin loam. Trials were there- 

 fore made in several houses, and it was concluded that although 

 steamed old soil is probably not quite so good as virgin loam, it might, 

 on account of its cheapness, be with advantage used to replace virgin 

 loam partially in making new beds. 



In some earlier experiments with " chrysanthemum-sick " soil it 

 was shown that not only could chrysanthemums be grown with safety 

 on such soil after it had been steamed, but that in addition the flowers 

 produced were larger and of greater substance than those from un- 

 treated soil. During 1913 experiments were carried out with a view 

 to testing more completely the question of flower size. Four steri- 

 lizing agents were used, viz. heat, toluol, formaldehyde, and calcium 

 sulphide. The plants were all of the same variety. The flowers on 

 the heated soil were slightly earlier than those on the untreated. The 

 leaves and flowers were larger and heavier. The chemicals did not 

 cause any increased growth. These results are reflected in some 

 chemical and bacteriological analyses which are given. The nutritive 

 compounds available in the heated soil are not quite the same as those 

 in the untreated soil, and the percentages of nitrogen, phosphoric acid, 

 and potash in the leaves, stems, roots, and especially in the flowers of 

 plants grown in heated soil, are higher than in those raised on the un- 

 treated. This is clearly shown by the analyses quoted. — A . S. 



