574 



Journal of Agriculture. 



[lo Sept., 190J 



The following comparisons are interesting : — 



Section A. — 15 tons farmyard manure per acre 



2 tons Superphosphate ,, ... 3.1 tons 



E. — 15 tons farmyard manure ,, ••• 3-6 ,, 



F. — No farmyard manure and 



2 cwt. Superphosphate... ,, .■• 2.5 ,, 



On Mr. Robb's land, the additional superphosphate in section A pro- 

 duced 2 cwt. per acre more potatoes than in section E, but on Mx. INlay's 

 land just the reverse was the case. 



The above results point unmistakably to the value of farm manure in 

 potato growing, not only for improving the yield, but for increasing the 

 proportion of marketable tubers as well : — 



Manure Dressing 



15 tons Farm Manure. 2 cwt. Superphos- 

 phate 



15 tons Farm Manure, 2 cwt. Super., i cwt. 

 Sulphate of Ammonia 



No Manure 



Same as B and i cwt. Sulphate of Potash... 

 15 tons Farm Manure ... 

 2 cwt. Superphosphate ... 



Here again the heaviest fertilisation in section D has given the highest 

 proportion of marketable tubers, thus confirming what was observed in 

 the preceding group of fields. 



Experiments Summarised. 

 Some facts stand out prominentlv as the result of the experiments 

 mider review. Where heavy yields of tubers are looked for, the applica- 

 tion of light dressings of artificial fertilisers is inadequate. The addition 

 of manures containing nitrogen and pota.sh to the light dressings of super- 

 phosphate has increased the vield in the majority of cases j but it has at 

 the same time so enormously increased the cost, that these complete 

 dressings from an economical point of view cannot compare with the cost 

 of the heavy dressings of superphosphate alone. Farm manure alone has 

 shown better results than a light dressing of superphosphate, but it is 

 probable thatt a heavier application of the latter would more than com- 

 pensate for the difference. While the u.se of farm, manure is recommended, 

 the fact is not lost sight of that it is not always procurable and moreover 

 entails costly and tedious handling. For this reason potato growers may 

 wish to at least partly replace it by artificial fertilisers. There is sufficient 

 evidence to show that intelligent fertilisation not only increases the quantity 

 of potatoes but diminishes the unmarketable proportion as well. In this 

 connexion I might observe that even as slight an improvement in the 

 proportion of marketable to unmarketable tubers, as i per cent., would 

 mean in a crop of 5 tons per acre an additional i cwt. for sale. 

 With potatoes at present prices, the extra 5s. or 6s. per acre would con- 

 tribute nearly one quarter of the cost of the fertilisers found most .service- 

 able. The higher the proportion the less the actual co.st of manures. 



