PENAMBAHAN KLORIDA DAN BAHAN ORGANIK PADA BEBERAPA JENIS TANAH UNTUK PERTUMBUHAN BIBIT KELAPA SAWIT

ABSTRAK Kelapa sawit (Elaeis guineensis) berkembang pesat di Indonesia dan  penggunaan  pupuk  meningkat.  Pada  awalnya  pupuk  KCl memperhitungkan hara K, namun diketahui hara Cl juga merupakan hara mikro esensial. Penelitian bertujuan mempelajari penambahan Cl dan bahan organik terhadap pertumbuhan dan kadar Cl dalam tanaman dan akar kelapa sawit. Penelitian dilakukan di rumah kaca Balai Penelitian Tanah, Bogor, tahun 2011. Contoh tanah diambil dari Cinangneng, Bogor (Inceptisols), Cigudeg, Bogor (Oxisols), Kentrong, Lebak (Ultisols), dan Sumatera Selatan (Gambut). Bibit kelapa sawit varietas Avros umur tiga bulan ditanam dalam polibag dan dipanen setelah berumur 8 bulan. Percobaan menggunakan rancangan petak terpisah, dengan petak utama empat jenis tanah, dan empat anak petak, yaitu (1) Kontrol (-Cl), (2) KCl, (3) NPK, dan (4) KCl + bahan organik. Setiap perlakuan diulang 4 kali. Parameter yang diamati tinggi tanaman, diameter batang, bobot kering tanaman dan akar, analisis Cl dalam tanah, daun, dan akar. Hasil penelitian menunjukkan bahwa pemberian Cl menurunkan pertumbuhan bibit kelapa sawit pada Oxisols, namun meningkatkan pada Inceptisols, Ultisols, dan Gambut. Pemberian bahan jenis organik nyata meningkatkan pertumbuhan kelapa sawit pada ke empat tanah. Pemberian hara Cl tidak meningkatkan bobot kering tanaman kelapa sawit pada Inceptisols, Oxisols, dan Gambut, namun meningkatkan bobot kering tanaman pada Ultisols. Pemberian hara Cl meningkatkan bobot kering akar tanaman kelapa sawit pada ke empat jenis tanah, namun meningkatkan kadar Cl dalam akar kelapa sawit, sedangkan pemberian hara Cl tidak meningkatkan kadar Cl dalam daun, kecuali pada Oxisols. Pemberian bahan organik menurunkan kadar Cl dalam daun pada Ultisols dan tanah Gambut. Kata kunci: bahan organik, Elaeis guineensis, jenis tanah, klorida, pertumbuhan ABSTRACT Oil palm (Elaeis guineensis) was growing rapidly in Indonesia and fertilizers use increased. Initially KCl were calculated as K nutrient, but it is known that Cl is also an essential micronutrients. The research aimed at studying the Cl and organic matter application on growth and Cl content in plants and roots of oil palm. The study was conducted in the greenhouse of Soil Research Institute, Bogor, in 2011. Soil samples were taken from Cinangneng, Bogor (Inceptisols), Cigudeg, Bogor (Oxisols), Kentrong, Lebak (Ultisols) and South Sumatra (Peat). AVROS varieties of oil palm seedlings used 3 months being planted in polybags and harvested after 8 months. The experiment design used was split plot design, with four soil types as main plot, and four sub plots e.i. (1) Control (-Cl), (2) KCl, (3) NPK, and (4) KCl + organic matter. Every treatment repeated four times. Parameters observed are plant height, stem diameter, plant and root dry weight and Cl analysis in soil, leaves, and roots. The result showed that Cl application decreasing oil palm growth in Oxisols. Organic matter application siqnificant increase of oil palm growth on the fourth soil. The application of Cl nutrient did not increase the dry weight of plant in Inceptisols, Oxisols, and Peat soil, but increased the dry weight of plants on Ultisols. The application of Cl did not increase root dry weight in the four soils, but increased Cl content in the roots in the four soil. While the application of Cl did not increase of Cl content in leaves, except in Oxisols. Organic matter application can reduce the content of Cl in the leaves on the Ultisols and Peat soil. Key words: organic matter, Elaeis guineensis, soil type, chloride, growth