214 CALCAREOUS MANURES— APPENDIX. 



extensive applications of tiie Coggins Point gypseous earth as manure. 

 The results of my general practice, and also of many particular experi- 

 ments noted at the times wlien made, were reported in a communication 

 to the Farmers' Register, commencing at page 118, vol. ix. The effects 

 stated were very different and apparently contradictory — sometimes bene- 

 ficial and profitable in a remarl^able degree, but more generally of little 

 value, or of no benefit whatever. The inferences which I drew from all 

 my experience, (and there existed scarcely any other facts or experiments,) 

 were that this earth as manure acted in the same manner as gypsum, 

 though more powerfully — and in no other manner than as gypsum would 

 under like circumstances; that like gypsum, on my land certainly, and as 

 I inferred in our tide-water region generally, this earth had no effect what- 

 ever (unless used in excessive quantity) on any acid soils — and rarely on 

 any other crop than clover, even when properly applied on neutral or 

 calcareous soils ; and that when naturally acid soils were made calcareous 

 by being marled, this green earth then became generally operative thereon 

 as a manure for clover, (and for other plants of the clover or pea tribe,) 

 in the same manner as is usual in regard to gypsum.* And though the 

 effects, when any were produced, were greater than those of any usual or 

 known dressings of gypsum, and sometimes in a very remarkable degree, 

 still the failures and disappointments were so many that I did not deem the 

 practice worth being continued. In 1841, my son, the present occupant of 

 the Coggins Point farm, at my request, recommenced the applications of 

 gypseous earth, for experiment; and on the clover of this year, 1842, he 

 has extended the dressings over more than 60 acres.f The results were, 

 as in former years, very unequal, and for the greater space of ground 

 covered, unprofitable, and barely if at all perceptible. But on 25 to 30 

 acres the benefit was remarkably great, and in some cases (of summer dress- 

 ings) improvement was obvious within ten days after the application. But 

 what was most interesting in the results was, that a clue seemed to be there- 

 by furnished to explain the frequent previous failures of this manure, even 

 when applied to clover growing on neutral or calcareous soil, which are 

 the only circumstances in which it has ever been found profitable in practice. 

 My former applications had been generally made from the upper and 

 greener stratum of the gypseous earth, (designated in a succeeding page 

 as C,) or if from the lower and blacker part, (Z>,) the digging did not pene- 

 trate more than a foot, or, at most and rarely, two feet below the before 

 exposed outer surface. But in the recent larger operation, the digging 

 (made on the river beach) was so much more extensive as to furnish earth 

 from depths of three or four feet, as well as of portions nearer to and at 

 the surface. I ascribed the remarkable differences of effect to the kind 

 and place of the earth ; inferring that the exposed parts, and all perhaps 

 near the surface, had, by exposure to air or water, lost a large proportion 

 of the soluble or decomposable fertilizing ingredients. As the applications 

 had not been made with any view to this question, the experiments are 

 not to be deemed as conclusive, and the correctness of this inference is yet to 

 be fairly tested by future experiments. But the benefits from some of the 

 dressings, and all of those supposed to be from the deeper digging, were 

 so great, and so speedily produced, that renewed and strong interest was 



• See these views more fully set forth in the article above referred to, and also in an- 

 other on the green-sand maris of Pamunkey, at pp. 679 and 690, vol. viii. Farmers' 

 Register. 



t See the fads and results stated in two communications to Farmers' Register pp. 86, 

 135 and 252, vol. x. 



