Potato Culture. 



the same variety at the same time, on 

 one half of which, that had no plaster, 

 the yield was but sixty bushels per 

 acre, and many rotten ; the other part, 

 to which plaster was applied in the 

 manner hereafter explained, yielded 

 three hundred and sixty bushels per 

 acre, and not an unsound one among 

 them. 



The action of plaster is often puz- 

 zling. From the fact that where land 

 has been strongly limed, a small quan- 

 tity of plaster applied shows such 

 decided benefit, there would seem 

 plausibility in Liebig's theory that 

 its effects must be traceable not to 

 the lime, but to' the sulphuric acid. 

 The ammonia in rain-water in the 

 form of carbonate (a volatile salt) is 

 decomposed by plaster, the sulphuric 

 acid having greater affinity for it, thus 

 forming two new compounds, sulphate 

 of ammonia and carbonate of lime. 

 But as arable soil has the same pro- 

 perty of absorbing ammonia from the 

 air and rain-water, and fixing it in the 

 same or even a higher degree than 

 lime, there is only the sulphuric acid 

 left to look to for an explanation of 

 the favorable action of plaster on the 

 growth of plants. 



It is found that plaster in contact 

 with soil undergoes decomposition, 

 part of the lime separating from the 

 sulphuric acid, and magnesia and pot- 

 ash taking its place, quite contrary to 

 the ordinary affinities. 



These facts show that the action 

 of plaster is very complex, and that 

 it promotes the distribution of both 

 magnesia and potash in the ground, 

 exercising a chemical action upon 

 the soil which extends to any depth 

 of it ; and that, in consequence of the 

 chemical and mechanical modifica- 

 tions of the earth, particles of certain 

 nutritive elements become accessible 

 and available to plants that were not 

 so before. 



It is said plaster is of most bene- 



fit in wet seasons; such is not always 

 the case. It is certainly beneficial to 

 clover, wet or dry ; so of potatoes. 



A few years since, when the drought 

 was so intense in this section as to 

 render the general potato crop almost 

 a total failure, the writer produced a 

 plentiful crop by the use of plaster 

 alone. On examination at the dryest 

 time, the bottoms of the hills were 

 found to be literally dust, yet in this 

 dust the tubers were swelling finely; 

 the leaves and vines were of a deep 

 rich green, and remained so until 

 frost, while other fields in sight, 

 planted with the same variety, but 

 not treated with plaster, were brown, 

 dead, and not worth digging. That 

 gypsum attracts moisture may be 

 proved by plastering a hill of corn 

 and leaving a hill by it unplastered ; 

 the dew will be found deposited in 

 greater abundance on the plastered 

 hill. But, according to Liebig, cer- 

 tain products of the chemical action 

 of plaster enter into and are incor- 

 porated with the structure of the 

 plant, closing its breathing pores to 

 such an extent that the plant is en- 

 abled to withstand a drought which 

 would prove fatal to it unassisted. 



Certain it is that plaster renders 

 plants less palatable to insects, and, 

 so far as the writer's experiments ex- 

 tend, it is fatal to many of the fungi 

 family. To obtain the best results, 

 the vines of potatoes should be dusted 

 with plaster as soon as they are fairly 

 through the soil, again immediately 

 after the last plowing and hoeing, and, 

 for reasons hereafter given, at inter- 

 vals throughout the whole growing 

 season. The first application may be 

 light, the second heavier, and there- 

 after it should be bountifully applied, 

 say two hundred pounds per acre at 

 one sowing. 



THE POTATO-ROT ITS CAUSE. 



The year 1845 will ever be memo- 



