نوع مقاله : مقاله پژوهشی
1 دانشجوی کارشناسی ارشد آبیاری و زهکشی گروه مهندسی آب دانشکدة علوم کشاورزی دانشگاه گیلان
2 استادیار گروه مهندسی آب دانشکدة علوم کشاورزی دانشگاه گیلان
عنوان مقاله [English]
Envelopment of drains improves hydraulic conductivity, by preventing the excessive small soil Particles from entering the pipes. Throughut the present study the performances of organic (rice husk), envelope, mineral envelope, as well as mixed envelope, comprised of rice husk and minerals, on the trend of hydraulic traits and chemical changes of the drain water was investigated. Towards this end, the physical model of the drainage system including pipe drains with diameters of 10 cm were buried under 37 cm of soil and then covered with a 7 cm transect of enveloping material as according to the envelope treatments. The experimental boxes were filled with soil of similar texture to those of the paddy fields in Guilan province (silt loam). Irrigation was so applied that a depth of 5 cm of irrigation water stood on the soil. Long term flow test was conducted under 1.9 dS/m of Electro conductivity for 500 hours of drainage flow. Salinity, Sodium Absorption Ratio, pH and TSS were recorded. The experimental treatments of envelopment were noted as the rice husk (H), Sand (G), a mixture of 80 percent sand and 20 percent rice husk (H20G80), A mix of 60 percent rice bran and 40 percent sand (H60G40), the mixture of 80 percent sand and 20 percent rice husk (H60G40), the mixture of 60 percent sand and 40 percent of rice husk (H40G60) as well as one with no envelope (B) taken as the blank. The results revealed that the discharge of the sample treated with H was more than that of G, treated and was reduced by decrease in rice husk depth in the mixed envelopes. H60G40 exhibited H80G20 exhibited lower EC means in their drain water, presenting more appropriate performances in their salinity control Treatments H and H80G20 performed well in decreasing TSS in their drain pipes.