THE POTATO. 625 



of the soil, and that it is too early for wet, heavy land, although it is the 

 best season for light soils. In reality, land cannot be advantageously 

 cropped with potatoes until all the superfluous moisture has been 

 drained or evaporated. 



" In all cases the plantation should be made in open places, fully 

 exposed to light. The quality of the potato depends upon the quantity 

 of starchy matter (mealiness) it contains. Now this starchy matter can 

 only be formed abundantly by the action of light upon the leaves, 

 which are the natural laboratory in which such secretions take place, 

 and from which they are conducted by sure, though hidden, channels 

 to the tubers, where they are stored up. To plant potatoes, then, in 

 plantations or orchards, or under the shade of trees, is to prevent the 

 formation of the mealiness which renders this plant so nutritious, and 

 to cause the tubers to be watery and worthless. This is probably one 

 reason why field potatoes are usually better than those raised in 

 gardens. 



" But the potato may suffer by its own shade as much as by the 

 shade of other plants. When its sets are planted too close, the branches 

 shoot up and choke each other, the leaves of the one smothering the 

 leaves of the other ; so that the more sets are planted, the smaller will 

 be the crop of this plant. Mr. Knight was the first to point out this com- 

 mon error, and to show that there is a certain distance at which the sets 

 of each variety of potato should be planted so as to ensure the greatest 

 produce. By planting too close, the plants smother, and so injure 

 each other ; by planting at too great a distance, land is uselessly wasted. 

 Practice and well-conducted experiments demonstrate what theory 

 suggested, that the true distance at which potatoes should be set is to be 

 determined by the average length of the haulm. One kind of potato is 

 dwarf, and only grows six inches high ; its rows should, therefore, be 

 only six inches apart. Another kind grows three feet high, and its 

 rows should be three feet asunder. The space from set to set in the 

 rows appears to be immaterial; six or eight inches are sufficient for 

 those which grow two feet high. An experiment formerly conducted 

 by the writer of these observations showed that, when the Early 

 Champion, a sort whose stems are on an average two feet long, was 

 planted in rows two feet six inches apart, the produce was 15 tons 

 1 9 cwt. 821bs. nett per acre; while, by reducing the distance between the 

 rows to two feet, the produce was increased to 24 tons ; but by diminish- 

 ing it still further to one foot six inches, the produce was reduced to 22 

 tons 16 cwt. 1021bs. ; and where the rows were only six inches apart, 

 the produce fell to 16 tons 17 cwt. llOlbs. Such an experiment seems 

 conclusive. 



" The depth at which the potato should be planted is not ascertained 

 with the same exactness, nor perhaps can it be ; for much will depend 

 upon the nature of the soil. In warm, dry land, we regard nine inches 

 as not too deep," provided the sets are large and strong ; " in cold, 

 stiff soil, four inches would be better. Six inches is a good depth for 

 average land," and, indeed, may be considered the best depth in most 

 soils. Weak sets do not come up well at nine inches deep ; but, on the 



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