256 STATE BOAKD OF AGRICULTUEE. 



LECTUEE OX PLASTER. 



BY R. C. KEDZIE. 



Tlie most characteristic feature of American agriculture is the use of "plas- 

 ter" or gypsum, just as lime is the leading characteristic of English agricul- 

 ture. In moist and cool climates and situations where the decomposition of 

 organic matter in the soil is slow and lingering, and where accumulation of 

 peaty matter is excessive, "we find lime is a favorite manural substance, and it 

 is used in large quantities. But in hot and dry climates where vegetable mat- 

 ter rapidly passes through its successive transformations into its final conversion 

 into carbonic acid, we find lime in less favor, or used in much smaller quanti- 

 ties. Thus in the United States, France, and German}^, 30 to 40 bushels of 

 lime to the acre is considered a liberal dose, Avliile 300 or 400 bushels are not 

 considered an excessive dose in England. 



In countries where lime is less beneficial we often find gypsum in high esteem. 

 Tlius gypsum is a favorite manural substance in the United States and Conti- 

 nental Europe, wliile it is considered of small worth or even useless in England. 

 The esteem in v/hich this substance is held seems to be largely determined by 

 conditions of climate. 



HISTORY. 



Tlie use of gypsum as a manure is of modern date. Attention was first 

 called to its value in agriculture by a German clergyman, Pastor Meyer, about 

 1750. Benj. Franklin introduced it into this country from Paris in 1772 — heuce 

 its common name " Plaster of Paris." In order to direct the attention of Amer- 

 icans to the manural value of this substance, Franklin adopted the ingenious 

 method of sowing plaster on a large clover field in AYashington so as to form 

 the words, "This has been plastered." The vigorous growth of the clover on 

 which the plaster had been applied enabled every passer-by to read the Avords 

 and thus grasp the fact and the explanation at tlie same time. 



The introduction of gypsum as a manure encountered vigorous opposition 

 from the salt-boilers. In boiling down brines in Europe to form salt, a deposit 

 forms in the pan called schlott, which was raked out and sold as manure. The 

 salt-boilers declared that "'gypsum Avas injurious to the land Avhile schlott was 

 the only improA'er — the stimulant of stimulants." A fierce paper war arose 

 which might have raged to this day had not some one analyzed schlott and 

 found it was sulphate of lime or gypsum. 



Like all ncAV substances of real value, gypsum was the victim of over praise. 

 Thus it Avas claimed that gypsum Avas a uniA'ersal manure, Avas capable of 

 replacing all other kinds of manure, Avas beneficial to all kinds of crops, and 

 that the most barren soil could be brought into fruitful condition by the use of 

 gypsum. But exjierience soon moderated these extravagant claims, and 

 assigned a much more contracted field to the useful application of this sub- 

 stance, showing that Avhile its application is very beneficial to certain plants, 

 the number of these Avas quite small, and the application of gypsum to other 

 I^lants had little or no influence. 



Gypsum Avas first imported into this country from the quarries of Montmar- 

 tre, near Paris. It Avas afterwards discovered nearer home at Nova Scotia, then 



