Action Of Mineral Manures

John J. Willis, superintendent o( awes and Gilbert's experimental arm, Rothanisted, England, in suniniarizing the resul ts of the renowned xperimenU of Luwcs :uul Gilbert, writes in tbe American Aqrwuiturist: "The .experinients at Koiliamsted learly show thal mineral manares alone, tliough :ipplietl ia the most solu)le form, scarcely increaso the produce of wheat at all; that is, tbey do not enable the wheat plant in any material legree to assimilate more nitrogeq and carbon from atmospheric sourees than ' vhen it was grown on the 'practieally i exhausted. During tho first eight years of the experimenta '(1841-51)' the plot which nfterwards received mixed minerals alone received salts of unmunia as well as mineral Znanurè, and the average ! roduco of wheat 'during tliose eight easons was twenty-nino bushels per acre, or nearly twelve biishcls, amiually n excess of tho produce on the uuinanured plot; whilo Uin-iu ; the iirst eight eais of the mixed minerals without he ammonium saJts (1852-59) the average produce was nineteen bushels er acre only, or nbout three busliels more than the pcrmanently iinmanured prodñce. In tho secoud period of eight years, for whjch the resulls are ;iven in the table, tho produce of the nineral plot amountwl to lifteen and one-fourth bushds per acre, as against hirteen and a half bushels grown on ho unmanured plot, dLfforence of ono jushel and three-fourths in favor of he mixed minerals. In the third period of eight years the producé fröm the minerals was fourteen bnshels per acre, and in the last period enumerntied, t was twelve and iive-eighths, or an ; crease of one bushei and an eighth over the plot without ruanure. The whole period Óf thirty-two yeara as thus given an average of lifteen and i quarter bushels of wheat with minerals alone, as agaraït thirteen and an eighth bushels without any manure at all; and if we take tho average produce ot the unmanured plot for forty years, j theyield of wheat has been fourteen xishels per aero. The application, therefore, of a very liberal supply of mineral ingredients has qnly been cometent to increase the yield of wheat jy one bushei and a quarter per acre per annum." . ;