136 BOARD OF AGRICULTURE. 



Clilorino, 3.39 per cent. 



Snipluiric acid, 4.72 '' 



Pliospliorif acid, 16 84 *' 

 Silica, 1.36 ** 



In tliis analysis the potash is higher and the phosphoric acid lower 

 than usual. 



An average of thirty-one analyses cited by Johnson gave 19.1 per 

 cent phosphoric acid and 59.8 per cent potash. 



On account of the high percentage of potash in the ash of the 

 potato, heavy potash manuring has been advocated. 



P^xperimental data as well as the practical experience of many 

 farmers teach us, however, that the potato will in the majority of 

 cases respond quite as well to nitrogenous or phosphaic manuring 

 as to potash. 



It may be well to examine a little more closely the signification of 

 this 59 or 60 per cent potash found in the ash of potatoes. It must be 

 remembered that the total ash represents on the average only about 

 0.7 of one per cent of the fresh potatoes ; and 7 per cent of 60 

 per cent is potash, which would equal 0.42 per cent reckoned on the 

 fres.h substance. 



At this rate a crop of 200 bushels would take from the soil 50.4 

 pounds of potash. 



A soil that is capable of producing 200 bushels of potatoes is in 

 condition to produce two tons of English hay, which takes off on 

 the average some 53 pounds potash. Two tons of clover hay would 

 carry away some 73 pounds of potash ; so that a crop of 200 bushels 

 of potatoes will carr}- away no more potash from the soil than two 

 tons of hay. The quantity of nitrogen and phosphoric acid taken 

 from the soil by a crop of potatoes is as large if not larger in pro- 

 portion to the potash taken awa\' as in hay. 



In 1875 and 1876 Fittbogen, Grouland, and Fraude undertook 

 some investigation on the disappearance of the starch in the seed 

 potato during the growth of the plant. From the same lot of seed po- 

 tatoes seventy tubers were selected weighing from 63 to 73 grammes 

 each. Sixty of these were planted in six rows, ten potatoes to a row, 

 on April 13th. The ten remaining potatoes were analyzed. From 

 time to time the six rows were dug up and the seed tubers analyzed. 

 The first row was dug up on May 1st, seventeen days after planting, 

 and the last on Sept. 22d, one hundred and sixty-two days after 

 planting. 



The following table shows the result of the analysis : 



