Abstract of DTXIV ICAL
Salinity management under a capillary driven automatic irrigation system based on electrical conductivity
2022 年 32 巻 3 号 p. 86
詳細
2022 年 32 巻 3 号 p. 86
Capillary driven automatic irrigation system (new sand ponics, NSP) has been known to have an advantage for famers to control saline stress and gving fruit with high brix, but it requires laborious application of water using a showering can for leaching salts. To save the labor cost for leaching, we present a new leaching method based on electrical conductivity (EC) in the reservoir of NSP. To evaluate the effectiveness of the new method, we carried out an experiment.
Tomato (Solanum Lycopersicum) was grown in a greenhouse in Arid Land Research Center, Tottori University. Water was applied through a drip irrigation tube with a spacing of 20 cm. We set following five treatments. 1) saline water was used for irrigation, and criterion of leaching (drainage) was carried out when EC reached at, 7dS/m which is based on 50% reduction in yield (NSP1). 2): same as NSP1, the threshold EC was 10dS/m which is based on 75% reduction in yield (NSP2) 3) saline water was used for irrigation, grown on sand beds with 60 cm wide and 7 cm thick and trigger volumetric water content was set at 0.06 (SP). 4): same as SP, but fresh water was used for irrigation (SPFW). 5) Gsaline water was used for irrigation and water was applied automatically when volumetric water content (theta) monitored with WD3 sensor decreased blow 0.06 (G). Three replicates were set with 12 plants for each. Leaching depths were determined according to the FAO’s guideline. Salinity of water for saline irrigation was 1 g/L NaCl solution with liquid fertilizer.
We compered net income using a price of 30 $/kg of the product of brix and fresh weight, a water price of 1 $/m3.
Results showed that G attained the highest net income, followed by NFSW and NSP1. NSP1 gave the highest yield of 0.267 kg/plant and sugar content of 9.9 brix%. New leaching method removed 76% and 60% of salts for NSP1 and NSP2, respectively indicating that difference in threshold EC affected saline percentage in soil.
