the best results. Part may be put in at the same time as the 

 artificial or farmyard manure and the remainder in one or two dress- 

 ings. This saves it from being lost by being washed out by rain or 

 the moisture in the soil. The usual amount applied is from i to 

 2 cwt. per acre, and the part used as top-dressing should be mixed 

 with some soil to ensure uniform distribution of it over the land. 



The relative manndal values of nitrate of soda and sulphate of 

 ammonia are dependent on several circumstances. In some cases 

 the nitrate of soda is superior to the sulphate of ammonia and in 

 others the reverse is the case. Sulphate of ammonia cannot be 

 used in calcareous or chalky soils and is injurious to beet-root, rye, 

 and lupines, more especially when the plants are young. In the 

 case of barley, Prof. Tanner says, "that sulphate of ammonia im- 

 proves, and nitrate of soda invariably injures the malting character 

 of barley." But nitrate of soda gives the highest yield of 

 albuminoids, therefore, barley grown with nitrate of soda has a 

 higher leedii g value than that grown with sulphate of ammonia. 

 Tobacco appears to be most benefited by sulphate of ammonia, and 

 Lawes and Gilbert prefer it for their wheat experiments at 

 Rothamstead. 



Most soils can easily convert the ammonia into nitrates and 

 also fix it in the soil. When nitrates are applied to wet soils, or 

 after rain, they are liable to be washed from the soil or out of the 

 reach of the crops. Owing to their extreme solubility no result 

 can be expected from nitrates after the first crop, for the reason, if 

 the crop does not use up all the nitrates put into the soil, they are 

 beyond the reach of the next year's crop. Kven granting that 

 nitrates are more rapid in their actions on plant growth than the 

 ammonium sulphate, there are other things to take into considera- 

 tion that may counterbalance any superiority nitrates may have. 

 In this colony nitrate of soda is much dearer th:m sulphate of 

 ammonia, and, further, 100 Ibs. of the sulphate contains as much 

 nitrogen as 125 Ibs. of nitrate of soda. The price of nitrate of soda 

 is from /."in to {."17 per ton, while sulphate of ammonia is frm 

 \2 to /;u ios. per ton. The sulphate of ammonia is by tar the 

 cheapest, as it is only about 75 per cent of the price of the nitrate 

 and it contains 25 per cent, more nitrogen. Where it can be 

 applied in place of the nitrate of soda, it will be the cheapest and 

 verv nearly as effective. The following experiments by (iriltiths 

 will show to some extent the agricultural value of various nitro- 

 genous manures and the importance of top dressing : 



GYPSUM, 



Tin- tken for the experiments were wheat, potatoes, and 



clover. Twenty-one plots of land of one acre each were taken. 

 The lii-st *evcn consisted of good quality clay land, and grew 

 wheat, the second seven consisted of sandy loam, and grew 

 potatoes ; the third seven plots were laid down with clover. 



