812 Sterilisation of Soil for Glasshouse Work. [jan.,. 



untreated soil. In spite of their improved growth they had 

 no appearance of coarseness or rankness. The advantage of 

 the treatment is obvious; it is well known that attempts to 

 force chrysanthemum cuttings by stimulating manures may 

 lead to disaster, but we saw no sign of any ill effects on our 

 plants. 



Spinach. — This crop was grown under glass by one of us 

 in a good loam rich in chalk. The plants in the heated soil 

 (200-2 1 o° F.) made good growth, producing large leaves of 

 a rich green colour, and showing little tendency to run to 

 seed. Those in the untreated soil were much smaller and 

 ran to seed more rapidly. The relative weights of the plants 

 obtained were : — 



Early 



Time of Sowing. Spring. Summer. Autumn. 



Untreated Soil 100 100 100 



Heated Soil (200-210 0 F. ) ... 447 150 184 



In our experience it very commonly happens, as here, that 

 the most marked effects are produced on the early spring 

 crops. 



Radishes. — This crop was grown along with the spinach 

 in some of the same soil. Seven successive sowings were 

 made, but no manure was supplied ; the first three crops were 

 much larger and earlier on the heated soil, but the last three 

 were practically alike on both soils. The relative weights 

 were : — 



1st Crop. 2nd Crop. 3rd Crop. 4th Crop. 5th Crop. 6th Crop. 7th Crop. 

 Untreated Soil ... 100 100 ico 100 100 100 100 



H T^F s f {20 °:} 2,6 355 172 128 103 1,4 103 



After the seventh crop the heated soil was reheated and sown 

 with an eighth crop; it was now found to be markedly 

 superior to the untreated soil, giving a yield of 186 against 

 100 on the untreated. 



These results show how advantageous partial sterilisation 

 is for soil thrown out from a greenhouse or a spent hot bed 

 into a cold frame, and sown with crops that have to go 

 through without much feeding or attention. 



Tomatoes in a Cool House. — A large grower of tomatoes 

 at Waltham Cross kindly furnished us with a quantity of 

 the soil used in that district for commercial growing. 

 The seed was sown in the usual way on February 22nd, 



