Electronic Theses and Dissertation

Air irigasi berperan penting dalam mendukung produktivitas lahan sawah, namun kualitasnya dapat berubah akibat pengaruh lingkungan sekitar, terutama pada daerah irigasi semi teknis yang berdekatan dengan permukiman. saluran irigasi di gampong siem, d.i. krueng aceh, yang menerima aliran dari saluran sekunder ujong blang dan mengalirkannya ke saluran pembuanganan lam sabang, berpotensi mengalami perubahan kandungan ion natrium (na⁺), kalsium (ca²⁺), magnesium (mg²⁺), karbonat (co₃²⁻), dan bikarbonat (hco₃⁻) yang memengaruhi kualitas air dan kondisi tanah sawah. penelitian ini bertujuan menganalisis kualitas air irigasi berdasarkan parameter sodium adsorption ratio (sar) dan residual sodium carbonate (rsc), serta membandingkannya dengan standar fao (1985). parameter ph dan daya hantar listrik (dhl) diukur sebagai data pendukung. sampel diambil di saluran sekunder ujong blang dan saluran pembuanganan lam sabang pada fase vegetatif (25 februari 2026) dan fase panen (6 april 2026) dengan teknik pengambilan sampel yang mengacu pada sni 8995:2021. analisis ion na⁺, ca²⁺, dan mg²⁺ dilakukan menggunakan inductively coupled plasma optical emission spectrometry (icp-oes), sedangkan ion karbonat dan bikarbonat dianalisis melalui titrasi asam-basa. data kemudian dikonversi ke meq/l untuk perhitungan sar dan rsc serta diklasifikasikan berdasarkan standar fao (1985). hasil penelitian menunjukkan nilai sar berkisar 0,279–0,665 dan seluruhnya termasuk kelas sangat baik, sehingga tidak berpotensi merusak struktur tanah sawah. nilai rsc pada saluran sekunder ujong blang fase vegetatif (0,5459 meq/l), saluran pembuanganan lam sabang fase vegetatif (0,3626 meq/l), dan saluran sekunder ujong blang fase panen (1,201 meq/l) juga tergolong sangat baik. namun, saluran pembuanganan lam sabang fase panen memiliki nilai rsc 2,713 meq/l yang termasuk kelas tidak baik akibat tingginya konsentrasi bikarbonat (252,0 mg/l). nilai ph berkisar 7,53–8,26 dan seluruhnya tergolong sangat baik, sedangkan dhl berkisar 0,276–0,702 μs/cm dengan saluran pembuanganan lam sabang fase panen tergolong baik. secara umum, air irigasi dari kedua saluran masih layak digunakan untuk budidaya padi berdasarkan standar fao (1985), kecuali nilai rsc pada saluran pembuanganan lam sabang fase panen. oleh karena itu, pemantauan kualitas air secara berkala perlu dilakukan untuk menjaga kualitas air irigasi pada musim tanam berikutnya.

Irrigation water plays an important role in supporting the productivity of paddy fields; however, its quality may change due to the influence of the surrounding environment, particularly in semi-technical irrigation areas located near residential settlements. The irrigation channel in Siem Village, Krueng Aceh Irrigation Area, which receives water from the Ujong Blang Secondary Canal and discharges it into the Lam Sabang Drainage Canal, has the potential to experience changes in the concentrations of sodium (Na⁺), calcium (Ca²⁺), magnesium (Mg²⁺), carbonate (CO₃²⁻), and bicarbonate (HCO₃⁻) ions that may affect irrigation water quality and paddy soil conditions. This study aimed to analyze irrigation water quality based on the Sodium Adsorption Ratio (SAR) and Residual Sodium Carbonate (RSC) and to compare the results with the FAO (1985) standards. pH and Electrical Conductivity (EC) were measured as supporting parameters. Water samples were collected from the Ujong Blang Secondary Canal and the Lam Sabang Drainage Canal during the vegetative stage (25 February 2026) and the harvesting stage (6 April 2026) using sampling procedures based on SNI 8995:2021. The concentrations of Na⁺, Ca²⁺, and Mg²⁺ ions were determined using Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES), while carbonate and bicarbonate ions were analyzed by acid-base titration. The analytical results were converted to meq/L for the calculation of SAR and RSC and subsequently classified according to the FAO (1985) standards. The results showed that the SAR values ranged from 0.279 to 0.665, all of which were classified as Excellent, indicating no potential risk of damaging paddy soil structure. The RSC values for the Ujong Blang Secondary Canal during the vegetative stage (0.5459 meq/L), the Lam Sabang Drainage Canal during the vegetative stage (0.3626 meq/L), and the Ujong Blang Secondary Canal during the harvesting stage (1.201 meq/L) were also classified as Excellent. However, the Lam Sabang Drainage Canal during the harvesting stage had an RSC value of 2.713 meq/L, which was classified as Unsuitable due to the high bicarbonate concentration (252.0 mg/L). The pH values ranged from 7.53 to 8.26 and were all classified as Excellent, while EC values ranged from 0.276 to 0.702 mS/cm, with the Lam Sabang Drainage Canal during the harvesting stage classified as Good. Overall, irrigation water from both canals was suitable for rice cultivation based on the FAO (1985) standards, except for the RSC value of the Lam Sabang Drainage Canal during the harvesting stage. Therefore, regular water quality monitoring is recommended to maintain irrigation water quality for future cropping seasons.