| 摘要 |
A knife for applying substances such as fertilizer in solid, liquid or gaseous form cuts a slice in the subsoil with its leading, rearwardly inclined cutting edge and simultaneously firms up and maintains the lower portions of the sides of the slice in readiness for receiving the substance in a pocket formed by a recess at the lowermost rear of the knife in conjunction with the firmed up portions. The slice taken by the slender knife is of such narrowness and the movement of the knife through the subsoil is of such a streamlined nature that the cohesive integrity and inherent resiliency of the subsoil is not destroyed, promoting self-closure of the slice behind the knife, thus greatly reducing the escape of the substance where it is a gas. A forwardly tapering wedge having downwardly converging faces on the bottom of the knife leads rearwardly from a lowermost, forwardly projecting, sharp point to prepare the lower portions of the slice sides in the proper manner, and laterally projecting, forwardly converging wings overlying the recess of the knife behind the wedge help seal the pocket to trap the substance when it is a gas, such wings also serving to return and press subsoil into the slide after the deposit of the substance.
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