8 



limed portions of the plots receiving sulphate of ammonia, where the 

 soil is now markedly acid, the vegetation suffered considerably during 

 the drought, and the bare patches which have been developing of late 

 years are now very prominent. 



The Little I loos F'ield, on which the residual values of 

 manures are being tested, was sown with mangolds, and though an 

 even plant was obtained it grew very indifferently through the 

 drought and yielded but a small crop of about twelve tons to the 

 acre. The effect of the manure applied in the current year was 

 very evident, but the manurial residues had but a small influence 

 upon the yield. 



All experiments with root crops were unsatisfactory this year, 

 so that the yields were small and somewhat irregular on the plots 

 that are used to test the value of the new nitrogenous fertilisers — 

 cyanamide and nitrate of lime. As in previous years, nitrate of soda 

 has proved the most effective source of nitrogen for mangolds on the 

 Rothamsted soil, and the newer fertilisers did not give the results 

 which might have been expected. 



At the Laboratory the pot experiments on the continuous 

 growth of plants in the same soil have been continued for another 

 season without as yet any conclusive results, and the same statement 

 might be applied to the experiments upon clover sickness. The 

 vegetation house was very largely given up to a new series of 

 experiments on the treatment of "sick" greenhouse soils, which have 

 become unfit for the continued growth of crops after two years' use 

 in the greenhouse, though they are still exceptionally rich in plant 

 food. Methods of treating the soil by heating to various tempera- 

 tures and by the use of antiseptics were tested with satisfactory 

 results, and a method for dealing with soil on a commercial scale has 

 been worked out, which is being extensively tested. It seems 

 likely that at a very small cost the growers of tomatoes and 

 cucumbers under glass may be saved from what has hitherto been 

 the expensive necessity of frequently renewing their soil. Drs. 

 Russell and Hutchinson, with Mr. Petherbridge, have been studying 

 in detail the chemical, physical and biological changes brought about 

 in the soil by the treatment, and the results are almost ready for 

 publication. Dr. Russell has also been extending his work upon the 

 part played by the protozoa in the production of sewage-sick soils 

 and the effect of partial sterilisation in restoring their activity. This 

 work has been undertaken in connection with Mr. J. Golding on 

 sewage farms at Kegworth and Kingston, and a very considerable 

 measure of success has been attained by the treatment. 



The experiments on the toxic and stimulating effects of small 



