PHOSPHORUS FOR SOILS. 



179 



Practically speaking, all such pastures will yield a profitable 

 return to a suitable application of manures, and in some cases 

 the natural yield may be even trebled. 



Attention was first directed to the improvement of pasture 

 land by Dr. Somerville, while director of the Northumberland 

 County Farm at Cockle Park. His experiments were started in 

 1897, and the results to date are published in a report by his suc- 

 cessor, Prof. Gilchrist. The plots receiving different manurial 

 treatment are each 3 1-20 acres three acres being grazed each 

 summer, while the odd fraction is cut for hay. The live-increases 

 of the sheep and the yields of hay are carefully noted during 

 each year, and compared with the unmanured plot. Ten differ- 

 ent systems of manuring were contrasted in the experiments, but 

 the following four only need be referred to, as they were most 

 profitable of the various methods: 



Containing 100 Ibs. phosphoric acid. 



The profit is estimated from the extra mutton produced over 

 and above that on the unmanured plot. It is valued for the 

 purpose at 3%d. per pound, live weight. 



Basic slag here has proved at once the cheapest and most 

 profitable form of fertilizer on pasture. Its superiority to super- 

 phosphate (Plots 4 and 5) seem to be due to the fact that besides 

 containing easily available phosphate it also contains free lime. 

 Comparison of plots 5 and 8 bears this inference. The land at 

 Cockle Park is stiff clay, and has been under pasture for over 

 thirty years. 



Basic slag is purchased on its percentage of phosphate of 

 lime. The quality varies from about 20 to 45 per cent phosphate 

 (equal to 9 to 21 per cent phosphoric acid). The higher grades 

 are usually rather cheaper per unit. The unit prices of different 

 samples may be ascertained by dividing the prices per ton by the 

 percentages. Other things being equal, the quality which sup- 

 plies the unit of phosphate at the lowest cost on the farm should 

 be purchased. 



I devote this amount of space to basic slag be- 



