Efektivitas Beberapa Jenis Pupuk N Pada Pembibitan Kelapa Sawit / Effectiveness of Several Types of N Fertilizer on Palm Oil Nursery

Formula pupuk N lepas lambat diperlukan untuk meningkatkan efisiensi N. Tujuan penelitian adalah mempelajari pengaruh beberapa jenis pupuk N terhadap pembibitan kelapa sawit menggunakan tanah Inceptisols Bogor. Penelitian dilaksanakan di Rumah Kaca dan Laboratorium Balai Penelitian Tanah, Bogor. Rancangan percobaan yang digunakan Rancangan Acak Lengkap dengan 5 ulangan. Perlakuan yang dicobakan adalah (1) Kontrol lengkap, (2) Kontrol tanpa Urea, (3) Urea pril (standar), (4) N + Zeolit 50%, (5) N + Zeolit 75%, (6) N + Zeolit 100%, (7) N+ Zeolit + Kitosan 50%, (8) N + Zeolit + Kitosan 75%, (9) N + Zeolit + Kitosan 100%, (10) N + Zeolit + Humat 50%, (11) N + Zeolit + Humat 75%, (12) N + Zeolit + Humat 100%, (13) N-Humat 50%, dan (14) N-Humat 100%. Analisis tanah dilakukan sebelum tanam dan sesudah panen biomas dengan parameter: N-total (metode Kjeldahl), P-tersedia (Bray I), Kation dapat ditukar (Ca, Mg, K) dan kapasitas tukar kation (KTK) (ekstrak NH4Ac pH 7), kejenuhan basa (KB). Pengamatan agronomis tinggi tanaman umur 1, 2, 4, 6, 8 dan 9 bulan, bobot biomas basah dan kering, serapan hara N, P dan K. Hasil penelitian menunjukkan bahwa perlakuan N + Zeolit + Kitosan 75% nyata meningkatkan tinggi tanaman kelapa sawit umur 9 bulan sebesar 146,7 cm, bobot biomas kering sebesar 701,2 g pot-1 dengan nilai RAE 140% dan serapan hara N, P, dan K masing-masing sebesar 2,82; 0,25 dan 2,17 g pot-1. Peningkatan bobot biomas kering sebesar 22% dibanding Urea standar. Formulasi pupuk N dengan Zeolit dan penyalutan dengan Kitosan mampu mengefisienkan pupuk Urea hingga 25%

Solubility of Rock Phosphate and SP-36 in Peat Soils Amended with Mineral Soil

Rock phosphates application on peat soil has a good prospect because of its high solubility in acid condition. However, the study of the solubility of rock phosphate in peat soils is still limited. This study aimed to quantify the solubility of rock phosphate and the effects of some sources of rock phosphates and SP-36 in the peat soils, taken from South Sumatera amended with mineral soil. The study was conducted in the laboratory ofIndonesian Soil Research Institute, in Bogor. The study consisted of two activities: 1) study on the solubility of some rock phosphates (Marocco, Christmas, and Ciamis) in peat soils. For this study a 100 g of oven dried (105oC) peat soil for each treatment was used for this study. The treatments were eleven levels of P i.e. 0, 10, 20, 30, 40, 50, 60, 75, 100, 125, and 150 ppm P applied to dried peat soils. The treated peat soils werethen incubated for 2 weeks before analyses of soluble P was conducted. The molybdat blue method was used to analyze the samples at 2, 4, 8, and 12 weeks after the incubation. 2) The second study i.e. the application of some rock phosphates or SP-36 on the peat soils amended with mineral soils, four levels of P (25, 50, 74, and 100% of P sorption) plus partial and complete control treatments have been replicated twice. Two hundred grams of oven dried peat soils (105oC) amended with mineral soils at 7,5% maximum Fe sorption, incubated for four weeks, and then soluble P was analyzed using molybdat blue at 1, 2, 4, 6, 8, 10, and 12 weeks after incubation. The results showed that the order of rock phosphates solubility in peat soils was Marocco> Ciamis>Christmas. The solubility of P in peat soils amended with mineral soil and rock phosphates gave similarresults as rock phosphate was in the order of SP-36>Marocco>Ciamis> Christmas. Soluble P increased up to 8 weeks of incubation, and then decreased. The effect of soil mineral ameliorant and some rock phosphates application of soluble P at 12 weeks after the incubation around 15.7-34.2 ppm P. Rock phosphates that has high reactivity gave a high Psolubility on peat soils so it that can be used as P sources in the peat soil

Pengaruh Pupuk Majemuk NPKS Dan NPK Terhadap Pertumbuhan Dan Hasil Padi Sawah Pada Inceptisol

Rate of NPK fertilization on rice using NPK compound fertilizer needs to consider soil nutrient status and plant nutrient requirement. The research was aimed to determine the optimum rate of compound fertilizer and the effect of enriched S nutrient of NPKS compound (15-15-15-5S) and NPK compound fertilizer (15-15-15) on the growth and yield of rice. The experiments were conducted at two sites in Galuga, Ciampea Bogor, West Java from April to September 2013, using randomised complete block design with 3 replications. Experiment at site I consisted of 9 treatments: six levels of fertilizers NPKS i.e. 0; 150; 300; 450; 600; and 750 kg/ha, standard fertilizer, NPK compound fertilizer equivalent to standard, and standard fertilizer plus S. Rate of urea, SP-36, and KCl for standard fertilizer treatment was respectively 250, 75, and 50 kg/ha. At site II the treatments consisted of 6 levels of NPK compound fertilizer i.e. 0; 150; 300; 450; 600; and 750 kg/ha and the standard fertilizer with rate of 250 kg/ha of urea, 50 kg/ha SP-36, and 75 kg/ha KCl. Plot size was 4 m x 5 m planted with Ciherang variety. Data collection included chemical properties of soil before and after the experiment, plant height, number of tillers, straw weight, and dry grain weight and the nutrient uptake. The effectiveness of fertilizer was calculated by RAE (Relative Agronomic Effectiveness). Results showed that fertilizer NPKS (15-15-15-5S) at 600 kg/ha effectively increased dry grain weight from 3.63 t/ha to 4.67 t/ha, but was not significantly different from a standard fertilizer treatment. It increased dry grain weight by 29% compared to control. NPK fertilizer (15-15-15) effectively promoted growth and dry grain weight equivalent to standard fertilizer at rate of 300-750 kgha. The optimum rate of NPK compound fertilizer (15-15-15) was 440 kg/ha as was shown with the production performance of 4.12 t/ha with RAE by 58%. NPKS compound fertilizer with rate of 750 kg/ha showed the highest uptake of N, P, and K nutrients and significantly increased the available P in the soil. Whereas NPK compound fertilizer with a rate of 600 kg/ha indicated the highest P nutrient uptake. Fertilizer enrichment with sulfur on NPKS fertilizer (15-15-15-5S) did not significant affect on grain dry weight

Point of Zero Charge Determination and the Inluence of P, Basic Slag, Organic Matter and Lime Applications on Colloidal Charge and Quality of Oxisols

The colloidal charge manipulation of highly weathered soils using point of zero charge (PZC or pHo) approach is important in improving soil chemical properties. The objective of this study was to determine the PZC and manipulate colloidal charge surfaces of Oxisols in order to increase their quality. PZC was determined by adjusting pH values from 3 to 7 using potentiometric titration. The change of colloidal surface charges was measured using two extractants; NH4-acetat pH 7 and NH4Cl. A glass house experiment was carried out using 4.5 kg soil/pot. Soil was taken from Sonay, South East Sulawesi and from Sitiung, West Sumatra. Soil was taken from surface layer (0-20 cm) and subsurface layer (20-40 cm) for each location. Four factors consisted of P fertilizer, basic slag, organic matter and lime were used to manipulate colloidal surface charge. The treatment rates were 100, 200 and 400 ppm P for P fertilizer; 2, 4 and 8 t/ha for basic slag; 10, 20 and 40 t/ha for organic matter; 1.5, 3 and 6 t/ha for lime, and a complete control. All 13 treatments with three replications, were arranged using a randomized complete block design in which each layer of two Oxisols is used as a block. The results showed that values of PZC for a surface layer of Sonay Oxisol (OSY) and for surface and subsurface layers of Sitiung Oxisol (OSG) are similar, i.e, pHo was 3.5. In addition, the PZC value for the subsurface layer of OSY occurs at pH 5 which is the highest pHo value compared to three other layers. The PZC value of OSY, at a surface layer is higher than its soil pH value (5.0 vs 4.4) suggesting that colloidal surfaces bear a positive charge. In contrast, the PZC values for the surface layer of OSY and surface and subsurface layers of OSG were lower than their soil pH values, indicating the colloidal surfaces bear a negative charge. Application of P, basic slag, organic matter, and lime was able to manipulate colloidal charge surfaces having positive charges become negative and that the low negative charge of colloidal surfaces become more negative as evidenced from the increase cation exchange capacity (measured in NH4Cl) compared to a control treatment. Application of P, basic slag,organic matter, and lime could increased quality of Oxisols as shown by decreasing K leaching and by increased soybean yields, which drastically increased compared to a control treatment