526 EXPEKIMENTS WITH PHOSPHATES AND SlAGS. [SePT., 



plots, with the exception of the two receiving Florida Pebble, 

 were much superior to the open hearth fluorspar basic slag. 



Plots C and E unmistakably show that lime without phosphate 

 has little or no effect in improving this type of pasture. 



It is difficult to interpret the results from Plots B, D, F, G, 

 H and L. They were not sown until 1919, and the exceedingly 

 dry season prevented a rapid response. 



It has been quite obvious during the past two years that the 

 light dressing of superphosphate on Plot 14 has not been effec- 

 tive. The improvement was much less than the weight of hay 

 would appear to indicate, and during the seasons 1919 and 1920 

 Plot 14 looked very like an untreated plot. The heavy dressing 

 of superphosphate on Plot 13 was much more effective. It 

 was not, however, nearly so good as the high soluble slag plots 

 or the " superphosphate and lime " plot. Even on a soil of this 

 character, very deficient in phosphoric acid and with a small 

 reserve of calcium carbonate, an acid manure like superphos- 

 phate is not suitable. On Plot 15 the same dressing of super- 

 phosphate as on Plot 13, namely 200 lb. PoO^ per acre, and 

 one ton of lime per acre, were sown together. Under such 

 circumstances the reversion of the water-soluble phosphate in 

 the superphosphate would be practically instantaneous and the 

 dressing Vvould become a basic one comparable to the applica- 

 tion of a dressing of basic superphosphate. It is of interest to 

 note that Plot 15 gives results practically identical with those 

 secured on the plots receiving the most soluble type of basic 

 slag. A close observation was kept on Plots 15 and 17 through- 

 out the 1920 season, and the only noticeable difference was the 

 somewhat earlier start made by Plot 15. The difference in this 

 respect was not great, probably not more than 7 to 10 days, 

 and had visits to the plots been less frequent, might have been 

 entirely overlooked. 



Butcher's Farm, Lamhourne End: London Clay. — Tow^ards 

 the end of 1918 the writer was offered, through the courtesy 

 of Dr. J. E. Stead, a small quantity of two open hearth basic 

 slags from the same steel works but of widely different solu- 

 bilities. 



As a fair comparison could not be obtained by adding plots 

 to any of the seven experimental centres then in progress it was 

 decided to start a new experimental centre. 



The phosphates applied to Plots A, 1, 2, 4, 5, 6 and 9 

 were drawn from the same bulk as those used in the previous 

 experiments. 



