HORTICULTURAL REPOSITORY. 



251> 



Another agency which has been ascribed to plaster 

 in the process of vegetation, is that of accellerati»g 

 putrefaction in the soil— of rendering ineit vegetable 

 matter soluble, and thus increasing the supply of ve- 

 getable food. The experiments of Sir H. Davy dis- 

 prove this theory, and show that gypsum rather re- 

 gards than increases animal and vegetable putrefac- 

 tion. 



Some, supposing that plants are gifted with sensa 

 tion, contend, that gypsum acts as a condiment to the 

 vegetable, as spices do to the animal system, and 

 benefit by stimulating their absorbent and assimila 

 ling organs. I am not physiologist enough to discuss 

 this point, and will therefore barely observe, that if 

 this is so, all plants are not equally sensitive ; for 

 many are certainly not affected by this stimulus. 



Others again have maintained, that plaster owes its 

 utility to the sulphuric acid (oil of vitriol) which it 

 contains ; and of course that a decomposition or se- 

 paration of parts, takes place in the soil. Sulphuric 

 acid has been applied, blended with different parts of 

 water, without seeming to confirm this theory. But 

 a sufficient objection is found in the fact, that gyp- 

 sum is detected in the clovers and other plants, show- 

 ing that no decomposition has taken place, and that 

 the sulphuric acid, remaining chemically combined 

 with its base, could not have acted separately. 



Sir H. Davy, I think, has suggested the true cause 

 of the fertility in gypsum: That it forms as necessa- 

 ry constituent of some plants,' as a few drops of pep- 

 permint do to a mint sling ; and that when the soil 

 does not contain it, m the small proportion needed, 

 its application is necessary for their complete devel- 

 opement and perfection — and that His only useful to 

 such crops as yield it on analysis, and on soils where ii 

 is deficient. Of the plants which contain gypsum, 

 SirH. Davy has enumerated the clovers, luzern, san- 



for by their generally abounding in bog soil, and not 

 usually producing plants which contain gypsum. 



As to the time and manner of applying plaster, dif- 

 ferent opinions prevail. It cannot enter the mouths 

 of plants until it is dissolved, or become soluble. To 

 effect this, 500 times its weight of water is found to 

 be requisite. This would seem to indicate that i ( 

 should be sown early on grass lands. My practice 

 has been to sow in March, or ea v ly in April, and if 

 practicable, upon a light snow. When sown late, 

 and a dry summer ensues, its benefits are frequently 

 not perceptible, probably from the circumstance of 

 its not having been dissolved. I have followed the 

 example of two great pioneers in the improvement of 

 American husbandry, the late Judge Peters and John 

 Taylor, in sowing it for Indian corn and potatoes be- 

 fore the last ploughing. I consider the benefit in this 

 method more certain and the labor less, than in that 

 of strewing it on the hills of the growing crop. 



The experience of practical men seems to have 

 fixed the proper quantity at from one to two bushels 

 the acre. 



Plaster appears partially to have lost its efficacy in 

 some parts of Pennsylvania, where it has been long- 

 est and most successfully used. It is said, to adopt 

 the common language, that the soil has become tired 

 of it. I suspect too much reliance has been placed 

 upon it ; and that it has been used as a substitute ra- 

 ther than as an auxiliary, for old fashioned barn yard 

 dt-ng. There is another way of accounting for its 

 apparent failure. Has not the soil become tired of 

 the plants which it aids, and which may have exhaus- 

 ted it of some other constituent 1 In the Norfolk 

 system of alternate husbandry, it was long ago as- 

 certained that clover could not be sown to advantage 

 oftener than every second course, or once in eight or 

 ten years, and other grasses were consequently al- 



foin and some other grasses ; in which he believes it ternated with it. The practice in Pennsylvania has 

 may exist to the amount of three or four bushels on been, I believe, to continue sowing clover every four 

 an acre of these plants. The turnip crop yields it in { or five years. 



small quantities ; and if this the try is correct, Indian 

 corn and potatoes will afford it, as it evidently bene- 

 fits these crops. He adds, that gtjpsum is not taken 

 up in corn crops, such as wheat, rye, barley, &c. A 

 course of experiments during ten years, has satisfied 

 me that these crops are not benefitted, directly, by its 

 application, but often indirectly, by increasing the 

 growth of other vegetables, which ultimately enrich 

 the soil. 



The soils which plaster most benefits, are the poor 



The preceding view of the subject and my person- 

 al experience, induce me to offer the following rules 

 for the consideration of the farmer : 



1. That plaster may be applied to pasture and! 

 meadow lands, not absolutely wet, with strong pro- 

 bability of profit — as it undoubtedly forms a consti- 

 tuent of many of the grasses, increases thsir vigor 

 and thickens the sole. 



2. That it may be applied, with equal prospect of 

 success, to the maize and potato crops, and I think, 



fean sands and sand loams ; and its effects diminish | to legumes, such as peas, beans, &c. These being 



in proportion as these become more rich, adhesive or 

 wet. The dung of cattle contains gypsum : so does 

 ocat or bog earth. To lands often dunged, its effects 

 are consequently less perceptible. That it does not 

 •jprove efficacious upon wet lands may be accounted 



sown, as good husbandry implies, upon lands natu- 

 rally free from surface water, or rendered so bf 

 draining. 



3. That its benefits are greatest upon sands, gra- 

 vels and light loartia ; and that these benefits, dliniu- 



