MANURES FOE POTATOES. 



259 



feet apart each way. The following table shows the manures used 

 and the yield of potatoes per acre. 



EXPERIMENTS ON POTATOES AT MOKETON FAEM. 



The superphosphate of lime was made expressly for experimen- 

 tal purposes, from calcined bones, ground fine, and mixed with 

 sulphuric acid in the proper proportions to convert all the phos- 

 pnate of lime of the bones into the soluble superphosphate. It was 

 a purely mineral article, free from ammonia and other organic 

 matter. It cost about two and a half cents per pound. 



The manures were deposited in the hill, covered with an inch or 

 two of soil, and the seed then planted on the top. Where super- 

 phosphate of lime or sulphate of ammonia was used in conjunction 

 with ashes, the ashes were first deposited in the hill and covered 

 with a little soil, and then the superphosphate or sulphate of am- 

 monia placed on the top and covered with soil before the seed was 

 planted. Notwithstanding this precaution, the ram washed the 

 sulphate of ammonia into the ashes, and decomposition, with loss 

 of ammonia, was the result. This will account for the less yield 

 on plot 8 than on plot 2. It would have been better to have sown 

 the ashes broadcast, but some previous experiments with Peruvian 

 guano on potatoes indicated that it was best to apply guano in the 

 hill, carefully covering it with soil to prevent it injuring the seed, 

 than to sow it broadcast. It was for this reason, and for the greater 

 convenience in sowing, that the manures were applied in the hill. 



The ash of potatoes consists of about 50 per cent of potash, and 

 this fact has induced many writers to recommend ashes as a manure 

 for this crop. It will be seen, however, that in this instance, at 



