<p>ABSTRAK</p><p>Perluasan lahan perkebunan kelapa sawit lebih diarahkan padalahan-lahan di luar Pulau Jawa. Lahan yang tersedia bersifat marginalseperti pada tanah Ultisols dan Oxisols. Pada lahan tanah tersebut telahmengalami pencucian yang hebat karena curah hujan yang tinggi sehinggakadar hara Mg rendah. Sumber hara Mg yang banyak digunakan adalahpupuk kiserit (Mg dan S), dolomit (Ca dan Mg) dan pupuk majemuk.Penelitian bertujuan untuk mempelajari peranan pupuk kiserit terhadappertumbuhan dan produktivitas tanah. Penelitian dilakukan di kebunpembibitan Cimulang, Kabupaten Bogor (PTP. Nusantara VIII), padaFebruari – Desember 2005. Tanah yang digunakan untuk penelitian adalahUltisols dan Oxisols. Rancangan menggunakan acak kelompok, 5perlakuan, ulangan 9 kali. Satu perlakuan terdiri dari satu tanaman bibitkelapa sawit. Pupuk Mg yang digunakan adalah kiserit powder 2 Pandadan kiserit yang telah beredar di pasaran sebagai standar. Dosis pupukkiserit yang dicoba: 0; 0,5; 1,0; dan 1,5 g/tanaman. Pupuk kiserit danpupuk dasar diberikan setiap 2 minggu sekali atau 12 kali pemberian.Pemupukan pertama diberikan pada umur 1 minggu, mulai pemupukan ke-2 dosis pupuk dikalikan 2, mulai minggu ke 10 dosis pupuk dikalikan 3,dan mulai minggu ke-18 dosis pupuk dikalikan 4. Contoh tanah bulk darilapang dikeringanginkan, diayak dengan saringan 2 mm, ditimbang 20 kgdan dimasukkan ke dalam polybag. Hasil penelitian menunjukkan bahwapemupukan kiserit pada Ultisols dapat meningkatkan tinggi, jumlah daun,diameter batang, bobot kering tanaman bibit kelapa sawit, serta mening-katkan hara Mg dalam tanah dari 1,25 menjadi 3,04 me/100 g dan kadarMg dalam tanaman menjadi 0,31 g/100 g. Pemupukan kiserit pada Oxisolsmeningkatkan tinggi, jumlah daun, diameter batang, bobot kering tanamanbibit kelapa sawit, serta meningkatkan hara Mg dalam tanah dari 0,28menjadi 2,36 me/100 g dan kadar Mg dalam tanaman menjadi 0,34 g/100g.Dosis optimum pupuk kiserit pada Ultisols dan Oxisols sama yaitu 0,80 g/tanaman. Pengaruh pupuk kiserit terhadap pertumbuhan bibit kelapa sawitdan produktivitas tanah sama dengan kiserit yang telah beredar di pasaransebagai standar.</p><p>Kata kunci: Elaeis guineensis, pupuk kiserit, status hara Mg, pertumbuhantanaman, produktivitas tanah</p><p>ABSTRACT</p><p>The Effect of Kieserite Fertilizer to Oil Palm Growth andSoil Productivity</p><p>The expansion of oil palm plantation is driven to outside JavaIsland. The available lands are marginal such as Ultisols and Oxisols,where intensive bleaching occurs for the high rate of rainfall, and causesthe low content of magnesium in such land. There are three sources used toprovide the Mg nutrient, such as kieserite (Mg and S), dolomite (Ca andMg) and compound fertilizer. The objective of this experiment was tostudy the effect of kieserite fertilizer on plant growth and soil productivity.This research was conducted in the seedling plot of Cimulang Site, BogorDistrict (PTP. Nusantara VIII) in February- December 2005 on Ultisolsand Oxisols using a randomized complete block design with 5 treatmentsand 9 replicates. One oil palm seedling was planted in each treatment. Thisexperiment used kieserite powder 2 Panda to provide Mg and ordinaryKieserite as the standard. The kieserite dosages were 0, 0.5, 1.0, and 1.5g/plant. Fertilizing the plot was done every 2 weeks, using kieserite andbasic fertilizer or fertilizing 12 times, but the first fertilization was donewhen the plants reached 1 week of age. Starting on the second fertilization,the dosage was multiplied 2 times, and starting on the 10 th week, thedosage was multiplied 3 times, and starting on 18 th week the dosage offertilizing is multiplied 4 times. Bulk soil samples were air-dried, sievedpassing 2 mm siever, and put 20 kg into polybags. The research resultshowed that kieserite fertilization on Ultisols increased plant height,number of leaves, stems (leaf midrib) diameter, dry weight of biomass, Mgnutrient content in the soil (from 1.25 to 3.04 me/100 g), and alsoincreased the plant Mg content to become 0.31 g/100 g. In addition,kieserite fertilization on Oxisols increased plant height, number of leaves,stems (leaf midrib) diameter, plant dry weight of oil palm seedling, Mgnutrient content in the soil, (from 0.28 into 2.38 me/100 g), and increasedplant Mg content into 0.34 g/100 g. The optimum kieserite fertilizingdosage on Ultisols and Oxisols was just the same, i.e. 0.80 g/plant. Theeffect of these two kinds of kieserite to the plant growth and soilproductivity was just almost the same.</p><p>Key words: Elaeis guineensis, kieserite fertilizer, Mg nutrient status, plantgrowth, soil productivity</p>
Root Morphologycal Responses of Oil Palm (Elaeis guineensis Jacq.) Hybrids to Copper Toxicity