158 THE POTATO. 



When tlie plants are from 10 to 12 inches high, and the weather i« 

 dry, the furrows are lightly earthed up. In dry soils the earthing 

 plough must not be carried very deeply ; and I may say that in the 

 elevated table lands of America, where the natural drought of the 

 climate is often to be apprehended, I have seen very fine crops of 

 potatoes which had never been earthed up at all. The potato, like 

 all plants that are hoed, requires considerable care ; but this care, 

 as it is immediately profitable, is still more so remotely upon the 

 white crops which are to follow. M. Crud reckons at 58.3 the 

 number of days work that are required upon an acre of land which 

 has received between 19 and 20 tons of manure. This is very 

 nearly what we have found to be the truth at Bechelbronn, where for 

 the same extent of surface, manured in the same way, we reckon 

 fifty days labor of a man, and rather better than eleven davs of a 

 horse. 



In Europe the potato harvest takes place at the end of autumn. 

 In the intertropical Cordillera, where the cultivation depends prin- 

 cipally upon the heat of a very steady climate, the potato remains 

 in the ground from four to seven months, as it is cultivated at a 

 greater or less height above the level of the sea ; it succeeds be=« 

 where the mean temperature ranges between 13° and 18° centigrade, 

 (56° and 65° Fahr.) In Venezuela, indeed, it is still cultivated in 

 places where the temperature is not far from 24° centigrade, (76.5° 

 Fahr.;) but I am doubtful that the culture is then advantageous. In 

 warm and moist regions the potato yields a large quantity of top, 

 and few tubers. I have gathered some very bad ones at Riosflcio 

 de Engurama, a village situate at the distance of about 5900 feet 

 above the level of the sea, where the mean and constant tempera- 

 ture is about 22° centigrade, (72° Fahr.) 



The produce per acre, noted by different observers, is as follows : 



There is an obvious relation between the quantity of seed-potato 

 planted and the amount of the crop. In Alsace from 25 to 30 

 buehels per acre are usually planted. In some places too much seed 



• This is the produce of two harvests, which they gather In the same year. 



