Fraksionasi Fosfor Pada Tanah-tanah Sawah di Pulau Jawa

Abstract

Statistical Resource Center data in 2008 showed that Java Island with 5.74 million hectare of harvested area contributed 55% from the total production of milled rice in Indonesia (BPS, 2009). Sixty precent of paddy field in Indonesia at located in Java Island (Kawaguchi dan Kyuma, 1976; Rayes, 2000). The increase of rice production is very important to fullfill the need of milled rice in Indonesia. One way to increase rice production is the use of fertilizers. One of them is Phosphorus (P). In general applied P fertilizers were transformed to be available P and not available P fractions in the forms of inorganic P and organic P as well. Reports about of P fraction distribution on paddy field in Java Island were still relatively few. The information of P fraction distribution in paddy field is needed to have good manajement of P fertilization on paddy field. The objective in this research was to evaluated the distribution P fraction on paddy field in the Java Island. The method that was used in P fractionation was the P Fractionation according to Tiessen and Moir method (1993). P fractions in the soils were determined sequentially using: (1) resin strip in bicarbonate form in 30 mL destilled water followed by 0.5 mol L-1 HCl extraction. This fraction is called Resin-Pinorganic (Resin-Pi). The fraction is interpreted as readily available to plant, (2) 0.5 mol L-1NaHCO3 pH 8.5. This fraction is called NaHCO3-Pi, -Porganic (NaHCO3-Pi, -Po). The fraction is interpreted as P which is strongly related to uptake by plants and microbes and bound to mineral surface or precipitated Ca-P and Mg forms, (3) 0.1 mol L-1 NaOH. This fraction is called NaOH-Pi and Po. The fractions is interpreted as P which is more strongly held by chemisorptions to Fe and Al components of soil surface, and (4) 1 mol L-1 HCl. This fraction is called HCl-Pi. The fraction is interpreted as Ca-P of low solubility. Residual-P is interpreted as occluded P and recalcitrant organic forms. Residual P is determined by subtracting from total P the sum of Resin-Pi, NaHCO3-Pi, -Po, NaOH-Pi, -Po and HCl-Pi. The result showed that in Java Island, HCl-Pi was dominant fraction followed by Residual-P, NaOH-Pi, NaOH-Po, NaHCO3-Pi, NaHCO3-Po and Resin-Pi respectively. In west Jawa, NaOH-Pi was dominant followed by NaOH-Po, Residual-P, HCl-Pi, NaHCO3-Pi, NaHCO3-Po and Resin-Pi respectively. In Central Java HCl-Pi was dominant fraction followed by Residual-P, NaOH-Pi, NaOH-Po, NaHCO3-Pi, NaHCO3-Po and Resin-Pi respectively. In East Java HCl-Pi was dominant farction followed by Residual-P, NaOH-Po, NaOH-Pi, NaHCO3-Pi, Resin-Pi, and NaHCO3-Po respectively. The results suggested that different management P fertilization in West Java, Central Java and East Java should be implemented.