Effect of subsurface drip irrigation manners and percentages of moisture depletion on some hydraulic parameters and potato yield

Abstract

A field experiment was conducted in Silty Loam soil during the fall season 2020 in one of the fields of College of Agriculture (Jazeerat Al-Ramadi - Al Hamidiyah, Research Center) north of Ramadi city, latitude 33° 27" 10.8" N, and longitude 43° 23". 2.4" E. The soil was morphologically described and classified as (Torrifluvent) according to the American classification system (USDA, 2010). Three methods of subsurface drip irrigation were chosen Partial Drying of the Root zone PRD, Sub-surface Boarder irrigation SBI and conventional sub-surface irrigation SDI, with two moisture depletion of available water rates (25% and 50%). The results of the study showed that the PRD irrigation method had the highest mean of the total yield when depleting 25% of the prepared water which was 28.628 Meg h-1 and the lowest average was 27.088 Meg ha1 when depleting 50%. Whereas, the PRD treatment gave the highest yield value of 29.75 Meg h-1 when depleting 25% of the available water, Also the PRD method gave the highest average values of 29,217 kg ha-1 compared to 26,142 kg ha-1 for SDI method. This was reflected in the total infiltration, saturated hydraulic conductivity and addition efficiency, the total infiltration using PRD irrigation method recorded the highest average values of 31.2 cm compared to 24.7 and 22.5 cm for SBI and SDI drip irrigation treatments respectively. The 25% depletion treatment was significantly superior to the 50% depletion treatment, which gave an average of 28.1 cm and 24.1 cm respectively. As for the saturated hydraulic conductivity, the mean values of the saturated hydraulic conductivity increased significantly in the PRD irrigation method for the depth 0-15 m, reaching the highest average values of 2.92 cm h-1 compared to 2.32 and 1.97 cm h-1 for SBI and SDI irrigation methods respectively. The depletion rate of 25% gave the highest rate of conductivity of 2.63 cm per hour-1, while the depletion rate of 50% gave the lowest rate of water conductivity of 2.17 cm h-1. The PRD treatment gave the highest mean values of water conductivity at 3.38 cm h-1 compared to 2.17 and 2.49 cm h-1 for SBI and SDI irrigation methods at 15-30 cm depth respectively. Irrigation with partial drying of the root zone PRD gave the highest efficiency rate, adding depth 15-30 cm, which was 97.07%, compared to 96.52 and 95.35% for SBI and SDI irrigation methods respectively