750 



Summary of Agricultural Experiments, [dec. 



With the potato crop similar results were obtained in 1909, the 

 crop being reduced when magnesia, carbonate of magnesia, magnesian 

 lime, and magnesian limestone were applied in quantities of from 3 to 

 10 cwt. per acre. These results did not bear out the conclusions 

 arrived at from experiments in 1908, which seemed to show that 

 magnesia would be a useful dressing for potatoes. 



Inoculation Experiment (Jour. Roy. Agric. Soc, Vol. 70, 1909). — 

 Field experiments in inoculating lucerne and white clover with Nitro- 

 bacterine were begun in 1908. The lucerne, however, was attacked 

 by a fungus disease, and the plots had to be given up. Two varieties 

 of white clover were sown in 1908 — Dutch white and "Mammoth 

 white." The seed was inoculated, and in 1909 the treatment was re- 

 peated by spreading on the plots soil which had been treated with 

 Nitro-bacterine preparation. No striking results have followed the 

 inoculation in either case. 



Pot-Culture Experiments (Jour. Roy. Agric. Soc, Vol. 70, 1909). — 

 Experiments are in progress as to the influence of lithium and 

 potassium salts on wheat. The presence of minute quantities of 

 lithium in the soil has been shown to be harmful. 



Green manuring. — The object of this experiment is to explain the 

 results of field experiments in green manuring, in which the ploughing 

 in of a non-leguminous crop like mustard has produced a better 

 manurial effect than the use of a leguminous crop like tares. This 

 has apparently been due to the soil being left after the mustard crop 

 in a better condition for retaining water than after tares. Soil was 

 taken from the plots on which tares and mustard had been ploughed 

 in green in 1907, and three colloidal substances— silicate of alumina, 

 silicate of soda, and kaolin — were added to it in order to see whether 

 they would alter its physical condition and enable it to retain moisture 

 better. The addition of silicate of alumina resulted in a very large gain, 

 and this was more marked with the tare soil than with the mustard. 

 Silicate of soda also gave an increase, though not so large a one, 

 while kaolin had no effect. Lime and magnesia were also added to 

 pots of the soils in order to test their effect in rendering the nitrogen 

 available. 



Influence of Magnesia on Soils. — Previous experiments had shown 

 that magnesia applied to Stackyard Field had very marked effects on 

 the wheat crop in accordance with the proportion of magnesia to lime 

 in the soil. When the proportion of magnesia exceeded that of lime 

 the crop was decreased, while the grain was changed from " soft " 

 or starchy to "hard" or glutinous. 



Further experiments in 1908 showed that the insoluble forms of 

 magnesia may be used with advantage so long as the proportion in 

 the soil does not exceed that of lime. The effects on the grain were 

 distinctly marked, it being more glutinous and less starchy. 



Artificial Fertilisers on Fen Soil. — The black fen soil of the Isle of 

 Ely is very rich in nitrogenous organic matter, and it is unusual in 

 practice to use any nitrogenous artificial manure on it, lest the crop 

 should "go down." This experiment was devised to ascertain whether 

 small dressings of nitrogenous manures with minerals would be advan- 

 tageous and would bring about a better consolidation of the soil. 

 The results suggested that this would be the case, substantial increases 



