Drip fertigation : effects on water movement, soil characteristics and root distribution

The aim of efficient drip irrigation scheduling is to replenish the water deficit within the active root zone while minimizing leaching below this depth. The objective of this study was to determine the water distribution pattern beneath a dripper in sandy soil. EnviroSCAN (Sentek) capacitance probes were installed directly below the dripper and at distances of 20, 40 and 60 cm from the dripper. The continuous monitoring of the soil water content (SWC) beneath the dripper provided a good indication of how the water applied through the dripper is distributed in the soil. In this study a semi-impermeable layer in the soil was detected through observing water accumulation patterns in the SWC. Water accumulated above the layer and SWC values increased to far above the upper level of easily available soil water (BAWupper),while the lower soil layers remained dry. The measurements also show that the horizontal water movement is restricted to 20 cm from the dripper. Specific parameters such as, the lower level of easily available soil water (BAWlower),can be used to determine optimal irrigation management. Together with the water distribution study, the root distribution beneath a dripper was also investigated. A high concentration of roots in the area beneath the dripper was found, which corresponds with the area wetted by irrigation. Stellenbosch University http://scholar.sun.ac.za

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