nitrate of soda was used at the rate of 500 pounds per acre in connec- 

 tion with an application of 10 tons of manure. In the first crop it 

 produced an increase in growth amounting to 49 per cent over the 

 manure alone, but had practically no residual effect, for the baskets 

 treated with barnyard manure alone in the two following periods gave 

 equally as large returns as did those which had been treated also with 

 nitrate of soda. 



Sulphate of potash is also beneficial on this soil, especially where 

 used in combination with manure, and in the above-mentioned ex- 

 periment, where used at the rate of 500 pounds per acre in connection 

 with manure and nitrate of soda, the increase attributable to the 

 potash amounts to 31 per cent. It is quite noticeable, also, that this 

 effect has been felt in the subsequent crop, and, in fact, the aggregate 

 increase attributable to the potash salts, when used in combination 

 with manure, for the four crops is equal to 28 per cent. Tricalcium 

 phosphate, on the other hand, has rarely given any increase in 

 growth. There is some question, however, as to whether this con- 

 stituent could be expected to show its effect in the early growth of 

 the wheat plant. It is quite possible that its effect might become 

 beneficial to the final growth of the plants. 



The following figures show the comparatively small increase from 

 applications of nitrate of soda, potassium sulphate, tricalcium phos- 

 phate, or a combination of two or all of these substances when used 

 without manure or lime. The plant-food constituents added to the 

 >oil by this treatment supply certainly an adequate amount for the 

 needs of the crops, and the small relative increase due to their use 

 indicates very clearly that the cause of the infertility of the Leonard- 

 town loam, poor, is not due to a lack of plant food, but is due to some 

 other unfavorable condition in the soil. 



Effect of different mineral fertilisers on Leonardtown loam, poor. 



EFFECT OF GREEX MANURE. 



The green manure applied in this case was cowpeas cut in the 

 early stages of growth. The peas were run through a mill and inti- 

 mately mixed with the soil at the rate of 9.000 pounds of the water- 

 free substance per million of soil, or an equivalent of 9 tons per acre. 



