PRACTICAL AGRICULTURE. 216 



are not all that plants need. Plants could not grow 

 in plaster alone^ but that does not prove that they 

 should have none. The truth is, it acts partly as a ma- 

 nure — feeding the plants with its sulphuric acid and 

 lime, the very ingredients which clover, corn, pota- 

 toes, and some other crops largely require — and partly 

 as a stimulant — hastening, by its lime, the decay of 

 vegetable matter in the soil. In other words, it feeds 

 the plants a part of their food, and it hurries the vegetable 

 matter in the soil to feed them more. On dry soils it 

 performs another important office — that of attracting 

 moisture. Some say it has not this effect. I know 

 very well that in its unaltered state it has not. Set 

 an open barrel of plaster in the air, and it will remain 

 dry. But it does not long remain unaltered about the 

 roots of plants. The sulphuric acid and the lime part 

 company, and in their transformations they perform 

 the three offices I have described— /eec? the plants^ con- 

 vert half decomposed matter into vegetable nutriment^ and 

 attract moisture from the air and from the subsoil. This 

 last office is important on lands that are dry. On wet 

 .lands it should not be used till they have been tho- 

 roughly drained. 



411. Plaster will not do well permanently without 

 other manure. It requires that organic matter should 

 be present. In pastures this is supplied by the drop- 

 pings of the cattle and by the decay of grass roots. 

 On mowings it should be supplied by top-dressings , 

 and on plough-lands by harrowing in manure. It would 

 be as unreasonable to complain of plaster because it 

 will not act well always without other manure, as to 



