Injection of liquids into the soil with a high-pressure jet

Abstract

With regard to injection fertilizing, the more general topic of liquid injection into the soil with the aid of a high-pressure jet is of great importance.  Injection fertilizing means that liquid fertilizer is injected into the soil near the plant roots.  This provides many agronomical advantages.  However, currently available mechanical injection fertilizing techniques in the field use have some disadvantages, such as very heavy wear on individual components.  Therefore, research on the direct, contactless injection of liquids into the soil with the aid of a high-pressure jet is being carried out at the Institute of Agricultural Machinery and Fluid Power of the Technische Universitaet of Braunschweig.  The potential and the possibilities of injection by a high-pressure jet are being examined in trials on a stationary test rig.  In these trials, different soils were used under different conditions (soil moisture, and soil density), and the possibilities of injecting pure water in the form of a high-pressure water jet were studied.  It was shown that the variation of different parameters of the high-pressure jet, such as water pressure, volume flow, etc., allow different injection depths in the soil to be realized.  Especially soil moisture has a very great influence on injection.  In dry soils, for example, the binding forces of the soil bodies (solid body bridges, van-der-Waals forces, etc.) are very strong so that only small injection depths can be reached.  The higher the degree of soil moisture is, the larger the injection depth becomes.  Depending on the soil type, average soil moisture, water pressure of 40 MPa, and speed of the nozzle over the ground of 2 m/s provide injection depths of 70 – 90 mm.  In addition to application in the area of injection fertilizing, the considered injection of liquids into the soil also shows great potential in plant protection, irrigation, as well as the injection of decontamination agents into contaminated soils.

Keywords: injection of liquids, soil, fertilisation, high pressure, contactless, frictionless