Kemasaman Tanah dan Sifat-sifat Pertukaran Kation pada Mollisols dan Ultisols di Lahan Kering Kabupaten Aceh Besar

Abstract

Abstrak. Kemasaman tanah dan pertukaran kation merupakan indikator penting terhadap kesuburan tanah terutama pada lahan kering suboptimal. Kemasaman tanah dan pertukaran kation erat kaitannya dengan bahan induk tanahnya. Penelitian ini bertujuan untuk mengkaji tingkat kemasaman tanah dan pertukaran kation pada dua ordo tanah di lahan kering Kabupaten Aceh Besar yaitu pada Mollisols Krueng Raya dan Ultisols Jantho. Kedua ordo tanah tersebut terbentuk dari bahan induk yang berbeda. Mollisols Krueng Raya terbentuk dari bahan induk batuan sedimen gampingan, sedangkan Ultisols Jantho dari bahan induk batuan sedimen liat tua. Penelitian dilakukan dengan menggunakan metode survai deskriptif yaitu melalui pengamatan di lapangan dan analisis di laboratorium. Identifkasi profil dan ordo tanah dilakukan dengan menggunakan sistem klasifikasi tanah USDA (Soil Survey Staff, 2014). Pengambilan sampel tanah dilakukan pada setiap lapisan horizon dari setiap profil pewakil ordo tanah yang diamati di lapangan. Sampel-sampel tanah tersebut selanjutnya dibawa ke laboratorium untuk dianalisis pH (H2O), kapasitas tukar kation (KTK) dan kation dapat ditukar (Ca, Mg, K, dan Na) ditetapkan dengan metode 1N NH4COOCH3 pH7, sedangkan Al- dan H-dapat ditukar diekstrak dengan 1M KCl. Hasil penelitian menunjukkan bahwa kedua ordo tanah yang diteliti memiliki tingkat kemasaman dan pertukaran kation yang berbeda. Mollisols Krueng Raya mempunyai pH agak masam hingga agak alkalis (6,48-8,2) dan KTK tinggi, sedangkan Ultisols Jantho bereaksi masam (pH 6,50) dan mempunyai KTK dan kejenuhan basa yang rendah.Soil Acidity and Cation Exchange Properties in Mollisols and Ultisols in Dryland of Aceh Besar DistrictAbstract. Soil acidity and cation exchange is an important indicator of soil fertility especially on suboptimal drylands. Soil acidity and cation exchange closely related to the parent materials of soil. This study aims to assess soil acidity level and cation exchange in two soil orders of dryland in Aceh Besar District namely Mollisols Krueng Raya and Ultisols Jantho. The two soil orders are formed from different parent materials. The Mollisols of Krueng Raya are formed from limestone sedimentary rock, while Ultisols Jantho are formed from the parent material of the old clay sedimentary rock. The research is conducted using a descriptive survey method that is through field observations and analysis in the laboratory. Identification of soil profile and soil orders were conducted using USDA's soil classification system (Soil Survey Staff, 2014). Soil sampling is taken from each layer of the horizon of the soil orders that are observed in the field. These soil samples were subsequently brought to the laboratory for analysis of pH (H2O), cation exchange capacity (CEC) and exchangeable cations (Ca, Mg, K, and Na) are extracted by 1N NH4COOCH3 pH7, while exchangeable Al and H were extracted with 1M KCl. The results of analysis showed that both the soils orders being researched had a different level of acidity and exchange of cations. Mollisols of Krueng Raya has a moderately alkaline pH that is slighty alkalis (6.48-8.2) and high CEC, while the Ultisols Jantho has an acid pH (pH 6.50) and has low CEC and low base saturation.