Intensified rice fields in Java : minerals composition, chemical properties, and their classifications

anglais. Minerals composition, chemical properties and soil classifications of ricefields from Indramayu and Madiun had been studied both in the field and in laboratory. Results indicated that sand mineral in all pedons dominated by andesin followed by ferromagnesian minerals such as hornblende, augite, and hyperstene. Smectite was dominant clay mineral and in lesser extent kaolinite also present. Generally soil reaction in all pedons range from slightly acid to neutral, low in organic carbon content, and concentration of P (in 25 percent HCl) range from low to very high. The amount of exchangeable bases are high. Soil CEC range from 43.38 to 101.80 meq/100g while clay CEC range from 53.55 to 176.48 meq/100g. Relationship between P sorption capacity with pH, amorphouse Al and Fe are found only on pedons from Madiun. A positive correlation between P sorption and amorphous Al and Fe and a negative correlation between P sorption and soil pH were occured for rice fields from Madiun. Pedons from Indramayu are classified in one soil family as Vertic Tropaquepts, very fine, mixed, non acid, isohyperthermic (HP 1, HP 2, HP 3, HP 4, and HP 5). Pedons from Madiun are classified in three soil families as Chromic Hapluderts, very fine, montmorillonite, isohyperthermic (HP 6, HP 7, and HP 9), Typic Hapluderts, very fine, montmorillonite, isohyperthermic (HP 8) and Leptic Hapluderts, very fine, montmorillonite, isohyperthermic (HP 10)

indonésien. Komposisi mineral, sifat-sifat kimia, dan klasifikasi tanah dari tanah sawah intensifikasi di Daerah Indramayu dan Madiun telah diteliti di lapangan dan di laboratorium. Hasil penelitian menunjukkan bahwa pedon-pedon yang diteliti didominasi oleh mineral pasir andesin diikuti oleh mineral ferromagnesian seperti hornblende, augit, dan hiperstin. Mineral liat smektit dijumpai dalam jumlah banyak hingga dominan, dan mineral kaolinit sedikit. Secara umum pedon-pedon di daerah penelitian mempunyai reaksi tanah agak masam hingga netral, kandungan C-organik rendah, kadar P potensial (HCl 25 persen) rendah hingga sangat tinggi. Kandungan basa-basa dapat tukar umumnya tinggi dan kemasaman dapat ditukar rendah. KTK-tanah 43,38-101,80 meq/100g, sedang KTK-liat 53,55-176,48 meq/100g. Hanya pada pedon-pedon di Daerah Madiun dijumpai adanya hubungan antara kapasitas erapan P dengan pH, serta Al dan Fe amorf. Erapan P berkorelasi negatif dengan pH tanah dan berkorelasi positif dengan Al dan fe amorf. Pedon-pedon di Daerah Indramayu diklasifikasikan dalam ordo Inceptisols yaitu Vertic Tropaquepts, sangat halus, campuran, tidak masam, isohipertermik (HP 1, HP 2, HP 3, HP 4, dan HP 5). Sedangkan pedon-pedon di Daerah Madiun diklasifikasikan dalam ordo Vertisols yaitu Chromic Hapluderts, sangat halus, monmorilonitik, isohipertemik (HP 6, HP 7 dan HP 9), Typic Hapluderts, sangat halus, monmorilonitik, isohipertermik (HP 8) dan Leptic Hapluderts, sangat halus, monmorilonitik, isohipertermik (HP10)