Document Type : Research Paper
Authors
1
Professor, Department of Soil Science, College of Agriculture, Vali-e-Asr University of Rafsanjan University, Iran.
2
Assistant prof. of Irrigation and Drainage, Pistachio Research Center, Horticultural Sciences Research Institute, Agriculture Research Education and Extension Organization (AREEO), Rafsanjan, Iran.
3
Associate prof. of Soil Science, Pistachio Research Center, Horticultural Sciences Research Institute, Agriculture Research Education and Extension Organization (AREEO), Rafsanjan, Iran.
4
Assistant prof. of Soil Science, Pistachio Research Center, Horticultural Sciences Research Institute, Agriculture Research Education and Extension Organization (AREEO), Rafsanjan, Iran.
5
MSc Graduate, Department of Soil Science, College of Agriculture. Vali-e-Asr University of Rafsanjan. Iran.
Abstract
In the present study, the effect of design parameters of a subsurface irrigation system with perforated PVC pipes on the irrigation frequency of pistachio trees was studied for two years in Kerman Province. A split-split plot experiment was conducted with four factors: canal depth (40 and 60 cm), pipe diameter (110 and 160 mm), pipe hole diameter (9 and 12 mm), and pipe hole spacing (15 and 25 cm) in a randomized complete block design with three replications. All treatments were irrigated with an amount of 75% of water requirement and an irrigation frequency of 24 days. To measure the volumetric soil moisture content, a TDR device was used. Statistical analysis of the data was performed using MSTAT-C software, and means were compared with an LSD test at a 0.05 probability level. The results indicated that the volumetric soil moisture of pistachio trees increased by 12% and 6.2%, respectively, between two consecutive irrigations (2 and 23 days after irrigation). The optimal irrigation frequency for pistachio trees in this system was determined to be 20 and 24 days, respectively. Therefore, by optimizing the design parameters of the subsurface irrigation system using perforated PVC pipes, water savings of approximately 50% can be achieved without exposing the plants to severe or harmful moisture stress. According to the results obtained, among the design factors, channel depth of 40 cm, pipe diameter of 110 mm, hole diameter of 12 mm and hole spacing of 15 cm had a better situation in terms of crop yield and water consumption efficiency. This optimal treatment produced a yield of 11.1 (kg/tree) and water use efficiency of 1325 gr/m3 after leaching and 828 gr/m3 before leaching, and was recommended as the best treatment.
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