8 June.. 1908.] 



The Heath Land at Portland. 



335 



D, which was destroyed by kangaroos and rabbits, are not availab'e as 

 there is every reason to believe that the additional potash manure would 

 have materially increased the potato yields as was found to be the case 

 with the fodder crops. 



Effects of ^Ianures on the Quantity and Quality of Potatoes. 



It is satisfactory to find that, without exception, e\ery \ariety of potato 

 has responded uniformly to the manure dressings. The average returns 

 from section A show that i| cwt. of superphosphate has produced 2 tons 

 II cwt. of potatoes. Section 13 with the same amount of superphosphate, 

 plus J cwt. of sulphate of ammonia, has increased the yield to 3 tons 6 cwt. 

 Section C, without manure, has only produced 19 cwts. per acre. In other 

 words a dressing of \\ cwt. superphosphate and f cwt. sulphate of 

 ammonia — costing 15s. per acre — has been shown to be able to produce 

 2 tons 7 cwt. of potatoes over and above the yield of unmanured land. 



potato crop, examining tubers. 



Even at the worst of times potatoes are rarelv worth less than 30s. per 

 ton, so that what might appear to be a relatively costly application of 

 manures can be justified with potatoes at bed-rock prices. 



As regards the action of the manures on the size of individual tubers, 

 the classification into "marketable" and "unmarketable" clearly shows 

 the advmtage of intelligent manuring. For example the proportion of 

 the former to the latter in each section is as follows : — 



It will be noted that in Section A there are 2 cwt. of marketable 

 potatoes for every i cwt. of unmarketable. In section B there are nearly 



