aVPSUM, OR PLASTER PARI3. 239 



applyiilg gypsum as a manure for a crop of winter grain, in 

 which, it is observed, that this manure, when applied to suck 

 crops when sown, or in the spring following, has scarcely any 

 preceptible effect in increasing their growth. In order, there- 

 fore, to render the manure profitable,in applications of this kind, 

 the ground must be enriched with gypsum, previous to its be- 

 ing broken up, preparatory for what we call a summer fallowing 

 for the crops in question. If, for instance, a field is intended to 

 be broken up, say by the middle of June, for the purpose of be- 

 ing sown with winter grain in the fall, this manure is to be 

 strewn over the sward early in the spring, or perhaps in the 

 fall preceding ; at all events, a sufficient length of time pre- 

 vious, for tlie manure to exhibit its effect on the land. This 

 is to be known by a growth of white clover starting up, and 

 the sward exhibiting Eufine green appearance ; and as soon as 

 this change is effected in the appearance of the sward, it may 

 be turned over for a crop of winter grain. 



I have been more particular on the subject of gypsum, be- 

 cause it is become a very important item in the expence of ag- 

 ricultural operations, which is often lost to the farmer for 

 want of complete knowledge of its proper use and application, 

 and also fox the purpose of convincing the farmer of the ne- 

 cessity of attending to the information derived from the expe- 

 riments of others, as well as from philosophical investigations. 

 It is not impossible that its inefficiency, often attributed to a 

 defect in gypsum, may be owing to the peculiar state of the 

 6oil to which it is applied, or to the mode of its application. 

 Many of the most prevalent opinions respecting its efficient a- 

 gency, as amanure, have proved fallacious, both by experiment 

 and chemical facts. 



