Required Lateral Inlet Pressure Head for Automated Subsurface Drip Irrigation Management

Abstract

Subsurface drip irrigation (SDI) is one of the most promising irrigation systems. It is based on small and frequent water supplies. Because SDI emitters are buried, their discharges are dependent on the water status at the vicinity of the outlets. This paper was targeted to design the SDI laterals accounting for the soil water-retention characteristics and the roots water extraction. The proposed approach provides systematic triggering and cut-off of irrigation events based on fixed water suctions in the vadose zone. In doing so, the soil water content is maintained at an optimal threshold ascertaining the best plant growth. Knowing the soil water-retention curve, the appropriate water suction for the plant growth, and the emitter discharge-pressure head relationship, the developed method allows the computation of the required hydraulics of the lateral (e.g., inlet pressure head, inside diameter, etc.). The proposed approach is a helpful tool for best SDI systems design and appropriate water management. An illustrative example is presented for SDI laterals’ design on tomato crop.

Assessment of a New Approach for Systematic Subsurface Drip Irrigation Management

“…According to Hammami et al [6], the soil capillary capacity ( ) is the highest if the second derivative of the soil moisture content with respect to the suction head is zero. Thus, using van Genuchten [15] model,…”

“…In fact, SDI system allows the direct application of water to the rhizosphere maintaining dry the nonrooted top soil. This pattern generates numerous advantages such as minimizing soil evaporation and then evapoconcentration phenomenon [6]. Comparing evaporation from surface and subsurface drip irrigation systems, Evett et al [7] reported that 51 and 81 mm were saved with drip laterals buried at 15 cm and 30 cm, respectively.…”

“…Also, with SDI systems more uniform moisture distribution, in the vadose zone (than with drip irrigation systems), was observed, and thus drainage and surface evaporation were less with SDI [10,11]. Automation of irrigation systems has the potential to provide maximum water use efficiency by maintaining soil moisture within an optimal interval ascertaining the best plant growth [6].…”

Devising a mathematical model for displacement estimation of the wetting pattern center from the emitter location resulting from the soil surface slope

“…However, with ongoing water adding, the wetting front commenced to be affected by the surface slope and water loss possibility in the deep percolation. The wetting pattern shape change displaced the wetting pattern center from the emitter position [13,14]. The best direction for laterals was in the direction of the short slope, and the trickle irrigation system was affected by the earth's surface slope, especially the slopes with a large inclination, Khalifa [15].…”