HUBUNGAN ANTARA SIFAT FISIS DAN BAHAN ORGANIK TANAH TERHADAP KAPASITAS INFILTRASI TANAH PADA BERBAGAI PENGGUNAAN LAHAN DI SUB DAS BLONGKENG

MUH. LUTFI SETIAWAN, Dr. Ir. Ambar Kusumandari, M.E.S.

2017 | Skripsi | S1 KEHUTANAN

Sub DAS Blongkeng memiliki luas 7498,68 hektar atau 8,95 % dari total luas sistem DAS Progo. Sub DAS Blongkeng berada pada bagian hulu dan tengah dari DAS Progo yang berperan penting bagi kawasan hilir. Adanya perbedaan penggunaan lahan di sub DAS Blongkeng berdampak pada karakteristik tanahnya. Karakteristik tanah tersebut memengaruhi proses hidrologis yang terjadi, termasuk proses infiltrasinya. Penelitian ini bertujuan untuk mengetahui kapasitas infiltrasi di berbagai penggunaan lahan dan mengetahui hubungan sifat fisis dan bahan organik tanah dengan kapasitas infiltrasi di Sub DAS Blongkeng. Pengukuran kapasitas infiltrasi dilakukan dengan alat double ring infiltrometer. Lokasi pengambilan data infiltrasi dilaksanakan pada berbagai penggunaan lahan dengan tiga kali pengulangan di setiap titik pengukuran. Selain itu, dilakukan juga pengambilan sampel tanah untuk menganalisis karakteristik tanah pada setiap titik pengukuran infiltrasi. Karakteristik tanah yang diamati adalah sifat fisis dan bahan organik tanah. Sifat fisis tanah yang diamati adalah tekstur, struktur, permeabilitas, berat jenis, berat volume, dan porositas. Analisis data untuk mengetahui hubungan sifat fisis dan bahan organik tanah terhadap kapasitas infiltrasi dilakukan dengan uji regresi dengan menggunakan aplikasi statistik Sigma Plot. Hasil penelitian kapasitas infiltrasi tanah pada berbagai penggunaan lahan: sawah (8 mm/jam); sawah tadah hujan (12 mm/jam); belukar (12 mm/jam); rumput (184 mm/jam); pemukiman (104 mm/jam); tegalan (180 mm/jam); kebun campur (64 mm/jam); dan taman nasional (288 mm/jam). Pada penelitian ini, bahan organik tanah kurang memiliki hubungan yang signifikan terhadap kapasitas infiltrasi. Sifat fisis tanah yang memiliki hubungan paling tinggi terhadap kapasitas infiltrasi tanah yaitu berat jenis tanah.

Blongkeng subwatershed is a part of Progo watershed with 7,498.68 hectares in width or 8.95% from total Progo watershed. Blongkeng subwatershed is on the upstream and middle zone of Progo watershed, which has an impact for the region on downstream. Various land uses in Blongkeng subwatershed affected its soil characteristic. The soil characteristic determines hydrologic cycle, included soil infiltration. The aims of this research are to find out soil infiltration capacity in various land uses and to find out the relationship between soil physical properties and soil organic matter to soil infiltration capacity in Blongkeng subwatershed. Soil infiltration capacity was measured by double ring infiltrometer tool. Measurement of soil infiltration capacity was held in various land uses with three replications. Besides that, this research also observed soil characteristic data in every land uses. Soil characteristic that observed were soil physical properties and soil organic matter. Soil physical properties which observed were soil structure, texture, permeability, bulk density, and particle density. The relationship between soil physical properties and soil organic matter to soil capacity infiltration were analyzed with regression test using Sigma Plot application. The results showed soil infiltration capacity in various land uses are: field (8 mm/hour); paddy field (12 mm/hour); shrub (12 mm/hour); grassland (184 mm/hour); settlement (104 mm/hour); dry field (180 mm/hour); mixed garden (64 mm/hour); and national park (288 mm/hour). Soil organic matter had not significantly related to soil infiltration capacity. Soil physical properties that had the highest relationship to infiltration capacity were particle density.

Kata Kunci : infiltasi tanah, karakteristik tanah, penggunaan lahan;soil infiltration, soil properties, land use